CcoHERENT~ - NHMFL Ultrafast User Facility

CcoHERENT~ - NHMFL Ultrafast User Facility
Operator 's Manual
Evolution-} 5130
High-Energy, High-Average Powe1;
Diode-Pumped, Kilohertz., Q-Switched,
Intra-Cavity Doubled, Nd: YLF Laser
CcoHERENT~
5100 Patrick Henry Drive
Santa Clara, CA.95054
Evolution-15/30 Laser Operator's Manual
This document is copyrighted with all rights reserved. Under the copyright
laws, this document may not be copied in whole or in part or reproduced in
any other media without the express written permission of Coherent, Inc.
Permitted copies must carry the same proprietary and copyright notices as
were affixed to the original. This exception does not allow copies to be
made for others, whether or not sold, but all the material purchased may
be sold, given or loaned to another person. Under the law, copying
includes translation into another language.
Coherent, the Coherent Logo, Positive Light, Evolution, Legend, Libra,
Opera, Indigo, Verdi, Vltesse, and Mira are registered trademarks of
Coherent, Inc.
Every effort has been made to ensure that the data given in this document
is accurate. The information, figures, tables, specifications and schematics
contained herein are subject to change without notice. Coherent makes no
warranty or representation, either expressed or implied with respect to this
document. In no event will Coherent be liable for any direct, indirect,
special, incidental or consequential damages resulting from any defects in
its documentation.
Technical Support
In the US:
Should you experience any difficulties with your laser or need any
technical information, please visit our web site www.Coherent.com.
Additional support can be obtained by contacting our Technical Support
Hotline at 800-367-7890 (408-764-4557 outside the U.S.) or E-mail
(clg.tech.services@Coherent.com). Telephone coverage is available
Monday through Friday (except U.S. holidays and company shutdowns).
If you call outside our office hours, your call will be taken by our answering
system and will be returned when the office reopens.
If there are technical difficulties with your laser that cannot be resolved by
support mechanisms outlined above, please E-mail or telephone Coherent
Technical Support with a description of the problem and the corrective
steps attempted. When communicating with our Technical Support
Department, via the web or telephone, the model and Laser Head serial
number of your laser system will be required by the Support Engineer
responding to your request.
Outside the U.S.:
If you are located outside the U.S. visit our web site for technical
assistance or contact, by phone, our local Service Representative.
Representative phone numbers and addresses can be found on the
Coherent web site, www.Coherent.com.
Coherent provides telephone and web technical assistance as a service to
its customers and assumes no liability thereby for any injury or damage
that may occur contemporaneous with such services. These support
services do not affect, under any circumstances, the terms of any warranty
agreement between Coherent and the buyer. Operation of any Coherent
laser with any of its interlocks defeated is always at the operator's own risk.
11
Table of Contents
TABLE OF CONTENTS
Preface ................................................................................................................................ viii
U.S. Export Control Laws Compliance .............................................................................. viii
Symbols Used in this Document and on the System ............................................................ ix
Chapter One: Description and Specifications ................................................ 1-1
Introduction ......................................................................................................................... 1-1
Optical Laser Bench Assembly ........................................................................................... 1-2
Power Supply Assembly ..................................................................................................... 1-2
Control Computer ............................................................................................................... 1-2
Closed-Loop Chiller ........................................................................................................... 1-3
Specifications ...................................................................................................................... 1-3
Dimensions ......................................................................................................................... 1-4
Chapter Two: Laser Safety ........................................................................................ 2-1
Hazards ............................................................................................................................... 2-1
Optical Safety Precautions .................................................................................................. 2-2
Electrical Safety Precautions .............................................................................................. 2-3
Protective Eye Wear ............................................................................................................ 2-4
CDRH Compliance ............................................................................................................. 2-4
Key switch .................................................................................................................. 2-4
Warning Labels .......................................................................................................... 2-4
Remote Interlock Connector ...................................................................................... 2-8
Protective Housings ................................................................................................... 2-9
Cover Safety Interlocks ............................................................................................. 2-9
Emission Indicators .................................................................................................... 2-9
Beam Safety Shutter ................................................................................................ 2-10
Output Port Shutter .................................................................................................. 2-10
Location of Controls ................................................................................................ 2-10
Operating Instructions .............................................................................................. 2-11
CDRH Requirements for Operating the Evolution-15/30 via USB/RS-232 Software
Commands ............................................................................................................... 2-11
Maintenance Required to Keep Laser in CDRH Compliance .......................................... 2-11
Sources of Additional Information ................................................................................... 2-13
Laser Safety Standards ............................................................................................. 2-13
Equipment and Training........................................................................................... 2-13
Chapter Three: Installation and Utility Requirements ........................... 3-1
Receiving the Evolution-15/30 ........................................................................................... 3-1
Installation .......................................................................................................................... 3-2
Location ..................................................................................................................... 3-2
Pumping a Legend Amplifier .................................................................................... 3-2
Required Utilities ................................................................................................................ 3-2
Installing the Power Supply ....................................................................................... 3-3
iii
Evolution-15130 Laser Operator's Manual
Installing the Laser Bench ......................................................................................... 3-4
Installing the Control Computer ................................................................................ 3-4
Installing the Chiller .................................................................................................. 3-5
Chapter Four: Controls and Indicators ............................................................ 4-1
Product Overview ............................................................................................................... 4-1
Diode Pumping ................................... ................................................................................ 4-1
Nd:YLF Laser Material ...................................................................................................... 4-1
Acousto-Optic Q-Switching ............................................................................................... 4-2
Intra-Cavity Frequency Doubling ....................................................................................... 4-2
Lithium Triborate (LBO) ........................................................................................... 4-3
Optical Laser Bench Configuration .................................................................................... 4-3
Component Description ...................................................................................................... 4-5
Laser Pump Chamber................................................................................................. 4-5
Q-Switches ................................................................................................................. 4-5
LBO Crystal and Oven .............................................................................................. 4-5
Power Supply ...................................................................................................................... 4-6
Power Supply Front Panel ......................................................................................... 4-7
Power Supply Rear Panel .......................................................................................... 4-8
Electronic Control Module .................................................................. ...................... 4-9
Laser Diode Power Supply ............................................................ ............................ 4-9
Q-Switch Driver ......................................................................................................... 4-9
LBO Crystal Temperature Controller ........................................................................ 4-9
Chapter Five: Daily Operation ............................................................................... 5-1
Current Settings .................................................................................................................. 5-1
Start-up Procedure .............................................................................................................. 5-1
Diode Start-up and Lasing Initiation.......................................................................... 5-1
System Shutdown ............................................................................................................... 5-4
Long-Term Shutdown ......................................................................................................... 5-4
Chapter Six: External Control Computer ....................................................... 6-1
USB/RS-232 Connection .................................................................................................... 6-1
Control Software ................................................................................................................. 6-1
Main Controls ..................................................................................................................... 6-2
SYSTEM Panel ................................................................................................................... 6-4
FAULT Panel ......................................................................................... ............................. 6-6
ERROR LOG Panel ............................................................................................................ 6-8
FACTORY Panel. ................................................................................................................ 6-9
Chapter Seven: Maintenance and Troubleshooting ................................... 7-1
Maintenance/ Service .......................................................................................................... 7-1
Lasing Optimization ........................................................................................................... 7-1
Cavity Mirror Adjusttnents ........................................................................................ 7-1
LBO Crystal Temperature Optimization ............................................................................. 7-4
Cleaning Optics ................................................................................................................... 7-6
Accessing the Evolution-15/30 Optics ...................................................................... 7-7
iv
Table of Contents
Mirrors ....................................................................................................................... 7-7
For Hard-to- Reach Optics ......................................................................................... 7-7
Q-Switch .................................................................................................................... 7-8
Routine Maintenance - Cooling Water.. ............................................................................. 7-8
Directions for New Systems, First-Time Use ............................................................ 7-9
Directions, After First-Time Use ............................................................................... 7-9
Troubleshooting ................................................................................................................ 7-10
Troubleshooting Guide ..................................................................................................... 7-10
Appendix A: Double-Pulse Option ...................................................................... A-1
Overview ............................................................................................................................ A -1
Theory of Operation ........................................................................................................... A-1
System Description ............................................................................................................ A-2
Evolution DPO Connections and Controls ........................................................................ A-3
DPO Laser Operation ......................................................................................................... A-6
Characterize Single-Pulse Performance .................................................................... A-6
Connect DPO Signals ............................................................................................... A-6
Setting DPO Timing Parruneters ............................................................................... A-7
Pulse Energy Measurement....................................................................................... A-8
DPO Parameter Optimization: Energy Measurement Method ................................. A-9
DPO Parameter Optimization: Average Power Measurement Method .................. A-1 0
Appendix B: Material Safety Data Sheets ........................................................ B-1
Warranty ............................................................................................................................... C-1
Optical Products .................................................................................................................. C-1
Conditions of Warranty ....................................................................................................... C-1
Other Products .................................................................................................................... C-2
Responsibilities of the Buyer .............................................................................................. C-2
Limitations of Warranty ...................................................................................................... C-2
Parts List .............................................................................................................................. D-1
Glossary ..................................................................................................................... Glossary-1
Index ................................................................................................................................. Index-1
v
Evolution-15130 Laser Operator's Manual
LIST OF FIGURES
1-1.
1-2.
1-3.
Evolution-15/30 System .................................................................................................. 1-1
Laser Bench Dimensions ................................................................................................. 1-4
Power Supply Dimensions ............................................................................................... 1-5
2-1.
2-2.
2-3.
2-4.
CDRH/CE Radiation Control Drawing, Scientific Version ............................................. 2-5
Power Supply Cabinet CDRH/CE Radiation Control Drawing ...................................... 2-6
CDRH/CE Radiation Control Drawing Labels ................................................................ 2-7
External Interlock Connector (Evolution Power Supply) ................................................ 2-9
4-1.
4-2.
4-3.
Optical Laser Bench.... ..................................................................................................... 4-3
Power Supply Front Panel ............................................................................................... 4-7
Power Supply Rear Panel ................................................................................................ 4-8
6-1.
6-2.
6-3.
6-4.
6-5.
6-6.
Evolution Control Software ............................................................................................. 6-2
Control Software SYSTEM Panel ................................................................................... 6-4
Control Software FAULT Panel. ...................................................................................... 6-6
Control Software ERROR LOG Panel ............................................................................ 6-8
Control Software FACTORY Panel ................................................................................. 6-9
Control Software FACTORY Panel.. ............................................................................... 6-9
A-1.
A-2.
A-3.
DPO Electronics Enclosure ............................................................................................ A-3
Interconnection Diagram for Evolution-DPO ................................................................. A-4
Control Panel in Evolution-DPO Control Software Showing DPO Controls ................ A-5
vi
Table of Contents
LIST OF TABLES
1-1.
Specifications ............................................................................................... .................... 1-3
2-1.
Label Translations ............................................................................................................ 2-8
3-1.
Evolution Utility Requirements ....................................................................................... 3-3
4-1.
4-2.
Power Supply Front Panel ............................................................................................... 4-7
Power Supply Rear Panel ................................................................................................ 4-8
6-1.
6-2.
6-3.
Main Controls .................................................................................................................. 6-3
Control Software SYSTEM Panel ................................................................................... 6-5
Control Software FAULT Panel ....................................................................................... 6-6
7-1.
7-2.
7-3.
7-4.
7-5.
Symptom: Laser Will Not Start ..................................................................................... 7-10
Symptom: Variations In Output Power .......................................................................... 7-11
Symptom: Emission Light Comes On, But No Output ................................................. 7-11
Symptom: Power Is Below Specification ...................................................................... 7-12
Symptom: Laser Does Not Q-Switch or CW Laser Output. .......................................... 7-12
A-1.
A-2.
Range and Increment for DPO Timing Signals .............................................................. A-5
Example Laser Parameters and Output Power for Single-Pulse
Operation of an Evolution-30 at 1kHz Repetition Rate ................................................. A-6
Example DPO Parameters and Output Power for Operation
of an Evolution-30 at 1 kHz Repetition Rate .................................................................. A-8
A-3.
D-1.
Parts List ......................................................................................................................... D-1
vii
Evolution-15/30 Laser Operator's Manual
Preface
This document contains user information for the Evolution-15/30 a
High Energy, High Average Power, Diode-Pumped, kHz,
Q-Switched, Intra-Cavity Doubled, Nd:YLF Laser.
Read this Operator Manual carefully before operating the laser
for the first time. Special attention should be given to the material in Chapter Two: Laser Safety.
Use of controls or adjustments or performance of procedures
other than those specified in this operator's manual may result
in hazardous radiation exposure.
Use of the system in a manner other than that described herein
may impair the protection provided by the system.
U.S. Export
Control Laws
Compliance
It is the policy of Coherent Inc., to comply strictly with U.S. export
control laws.
Export and re-export of lasers manufactured by Coherent are subject
to U.S. Export Administration Regulations, which are administered
by the Commerce Department. In addition, shipments of certain
components are regulated by the State Department under the International Traffic in Arms Regulations.
The applicable restrictions vary depending on the specific product
involved and its destination. In some cases, U.S. law requires that
U.S. Government approval be obtained prior to resale, export or
re-export of certain articles. When there is uncertainty about the
obligations imposed by U.S. law, clarification should be obtained
from Coherent or an appropriate U.S. Government agency.
viii
Preface
Symbols Used in
this Document
and on the
System
This symbol is intended to alert the operator to the presence of
dangerous voltages associated with the laser that may be of sufficient magnitude to constitute a risk of electric shock.
This symbol is intended to alert the operator to the presence of
important operating and maintenance instructions.
This symbol is intended to alert the operator to the danger of
exposure to hazardous visible and invisible laser radiation.
This symbol is intended to alert the operator to the danger of
electro-static discharge (ESD) susceptibility.
ix
Evolution-15130 Laser Operator's Manual
X
Description and Specifications
CHAPTER ONE: DESCRIPTION AND
SPECIFICATIONS
Introduction
The Evolution-15/30 is a diode-pumped, intra-cavity doubled,
Q-switched Nd:YLF laser capable of producing average energy
> 12 mJ (Evolution-15) and > 20 mJ (Evolution-30) at 527 nm at
repetition rates above 1 kHz. The Evolution-15/30 represents a
significant advance in this class of laser, offering the high efficiency,
low maintenance, and excellent beam quality afforded by laser diode
pumping.
The Evolution-15/30 laser system comprises four main elements:
•
•
•
•
Optical laser bench assembly
Power supply assembly
Control computer
Closed loop chiller
Shown with "Optional baseplate"
Figure 1-1. Evolution-15/30 System
1-1
Evolution-15/30 Laser Operator's Manual
Optical Laser
Bench
Assembly
The Evolut:i.on-15/30 optical laser bench is a sealed monolithic
aluminum chassis, containing integrated opto-mechanical, electrical, and cooling assemblies, including:
•
A diode-pumped, water-cooled, Nd:YLF laser head (pump
chamber)
•
An optical resonator
•
Acousto-optical Q-switches
•
A LBO frequency-doubling crystal in a temperaturecontrolled oven
•
Safety shutter
The Evolution-15/30 is available in two variants-GEM and Scientific. In the Scientific version of the Evolution-15/30, the aluminum
chassis described above is mounted on an aluminum base with an
emission indicator, and four feet that allow adjustment of beam
height. To minimize footprint and allow simple integration into
other instruments, the OEM Evolution-15/30 is supplied without the
aluminum base.
Power Supply
Assembly
Control
Computer
The power supply assembly includes a master control board and all
the electronics to drive the laser diodes, stabilize the temperature of
the LBO crystal, Q-switch the laser, and monitor interlocks. The
power supply cabinet connects to the optical laser bench through a
removable 3-meter umbilical cable. The power supply contains:
•
Master control electronics
•
Diode power supply
•
LBO temperature controller
•
Q-Switch driver
•
Accessory electronics
The Evolution-15/30 comes with a commercial laptop computer and
software to control and monitor the functions of the laser via an
USB/RS-232 interface. Because of frequent changes in the availability of specific computer models, the particular computer delivered with each laser may vary in brand and features, but in general
it will have a Pentium class processor ~400 MHz, ~32 MB of
RAM, 2::,2 GB hard drive, a CD-ROM drive, and a floppy drive. The
control software for the Evolution-15/30 is pre-installed and tested
with each laser, and is also delivered on CD-ROM.
1-2
Description and Specifications
Closed-Loop
Chiller
A closed-loop chiller is included to dissipate the waste heat generated and maintain the wavelength of the laser diodes to ensure
maximum absorption of the pump light in the gain medium. The
chiller has two hoses with quick-release connectors, a water filter,
and an internal pressure regulator valve to reduce the water pressure
at the laser bench. A chemical additive is included to prevent algae
growth and corrosion in the water system.
Specifications
Table 1-1. Specifications
1KHz
5KHz
Average Power [W]
> 12/20 w
> 15/30W
Energy per Pulse [mJ]
> 12120 mJ
> 3/6 mJ
PERFORMANCE*
Wavelength
527nm
Beam Diameter (nominal at output)
5mm
Energy Stability (RMS)
< 1%
Beam Profile
Multi-mode, quasi flat-top
Polarization
Linear, horizontal
*
Specifications subject to change without notice. Specifications on purchase order supersede all other published
specifications.
1 -3
Evolution-15130 Laser Operators Manual
Dimensions
- ~13. 78c m[ 5.43"]
j'"
t
t
19 .08cm [ 7.51"]
2 1.59cm [ 8.50"]
i
!
'
(
1.59cm[ .t3"]
3. 09cm [ 1. 22"]
l---
. -l-16.87cm[ 6.6 4"]
SIDE OUTPUT
r--- - 6 4.29cm[25.2>1 "] - - +----1
4. 94c m[ 1. 95"]
5.08cm[ 2.00"]
'1-+-- ------..------ FRON T OUTPU T
. 53cm[.~·1
g:J mJ ;~
I
OUTPUT
9 0 4cm [3 56"j"
~~~~~~==========~
a~'
J
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f
~
r-4.11 cmLr 1.6 2"]
37.46cm[ 14. ~5"]
Figure 1-2. Laser Bench Dimensions
1-4
Description and Specifications
~4 8 . 26c m[1 9.0 0"] ~
•
•
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8 · 0~
13.25 cm[5.22 "]
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48. 26c m[ 19. 00"]
~4 3.68cm [ 17.20 " ] ~
•
•
•
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•
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Figure 1-3. Power Supply Dimensions
1- 5
Evolution-15130 Laser Operators Manual
1-6
Laser Safety
CHAPTER
TWo:
LASER SAFETY
This user information is in compliance with section 1040.10 of
the CDRH Performance Standards for Laser Products from the
Health and Safety Act of 1968. Use of controls or adjustments,
or performance of procedures other than those specified herein,
may result in hazardous radiation exposure.
The Evolution-15/30 is a Class IV-High Power Laser whose
beam is a safety and iire hazard. Take precautions to prevent
exposure to direct or reflected beams. Diffuse as well as specular
reflections can cause severe eye or skin damage.
This safety chapter should be thoroughly reviewed prior to operating
the Evolution-15/30 system described in this manual. Safety instructions presented throughout this manual must be followed carefully.
Hazards
Hazards associated with lasers generally fall into the following categones:
•
Exposure to laser radiation that may result in damage to the
eyes or skin.
•
Exposure to chemical hazards such as particulate matter or
gaseous substances released as a result of laser material
processing or a by-product of the lasing process itself.
•
Electrical hazards generated in the laser power supply or associated circuits.
•
Secondary hazards such as:
•
•
Pressurized lamps, hoses, cylinders, etc .
•
Pressurized liquids and gasses
X-radiation from faulty power supplies
2-1
Evolution-15130 Laser Operator :SO Manual
Optical Safety
Precautions
Because of its special properties, laser light poses safety hazards not
associated with light from conventional sources. The safe use of
lasers requires that all laser users-and everyone else near the laser
system-are aware of the dangers involved. The safe use of the laser
depends upon the user becoming familiar with the instrument and
the properties of intense and coherent beams of light.
Direct eye contact with the output beam from the laser will cause
serious damage and possible blindness.
Laser beams can ignite volatile substances such as alcohol, gasoline,
ether and other solvents, and can damage light-sensitive elements in
video cameras, photomultipliers and photod.iodes. Reflected beams
may also cause damage. For these reasons, the user is advised to
follow the precautions below.
1.
Observe all safety precautions in the operator's manual.
2.
Exercise extreme caution when using solvents in the area of
the laser.
3.
Limit access to the laser to qualified users who are familiar
with laser safety practices and who are aware of the dangers
involved.
4.
Never look directly into the laser light source or at scattered
laser light from any reflective surface. Never sight down the
beam into the source.
5.
Maintain experimental setups at low heights to prevent inadvertent beam-eye encounter at eye level.
Laser safety glasses can present a hazard as well as a benefit
while they protect the eye from potentially damaging exposure;
they block light at the laser wavelengths that prevents the operator from seeing the beam. Therefore, use extreme caution even
when using safety glasses.
6.
As a precaution against accidental exposure to the output beam
or its reflection, those using the system should wear laser
safety glasses as required by the wavelength being generated.
7.
Avoid direct exposure to the laser light. The intensity of the
beam can easily cause flesh burns or ignite clothing.
2-2
Laser Safety
8.
Use the laser in an enclosed room. Laser light will remain
collimated over long distances and therefore presents a potential hazard if not confined.
9.
Post warning signs in the area of the laser beam to alert those
present.
10.
Advise all those using the laser of these precautions. It is good
practice to operate the laser in a room with controlled and
restricted access.
Electrical Safety
Precautions
Normal operation of the Evolution-15/30 should not require
access to the power supply circuitry. Removing the power
supply cover will expose the user to potentially lethal electrical
hazards. Contact an authorized service representative before
attempting to correct any problem with the power supply.
The following precautions must be observed by anyone when
working with potentially hazardous electrical circuitry:
•
Disconnect main power lines before working on any electrical
equipment when it is not necessary for the equipment to be
operating.
•
Do not short or ground the power supply output. Protection
against possible hazards requires proper connection of the
ground terminal on the power cable, and an adequate external
ground. Check these connections at the time of installation,
and periodically thereafter.
•
Never work on electrical equipment unless there is another
person nearby who is familiar with the operation and hazards
of the equipment, and who is competent to administer first aid.
•
When possible, keep one hand away from the equipment to
reduce the danger of current flowing through the body if a live
circuit is touched accidentally.
•
Always use approved, insulated tools when working on equipment.
•
Special measurement techniques are required for this system.
A technician with a complete understanding of the system
2-3
Evolution-15130 Laser Operator's Manual
operation and associated electronics must select ground references.
Protective
Eye Wear
It is recommended that laser-safe eyewear protecting across at least
the following wavelength ranges be worn at all times when the
Evolution-15/30 is operating:
•
1047 to 1053 nm - covers the fundamental wavelength at
which the Evolution-15/30 operates
•
523 to 527 nm - covers the second harmonic wavelength
output of the Evolution-15/30
•
794 to 810 nm - covers the wavelength emitted by the laser
diodes
During normal operation of the laser, the operator must not be
exposed directly to hazardous diode laser emission. Removal of the
mechanical housing cover, however, will not only invalidate the
user's warranty, but will also expose the laser operator to hazardous
diode laser radiation.
CDRH
Compliance
The safety features listed below have been incorporated into the
Scientific version of the Evolution-15/30 to conform to Federal
performance standards, as required by 21 CFR 1040.10(h)(1)(iv).
Any modification or use of the Evolution-15/30 that changes,
disables, or overrides the function of the engineering controls and
safety features invalidates the Class IV certification of the laser
described in this manual.
Keyswitch
A separate keyswitch is provided to enable power to the laser. The
key cannot be removed from the switch except in the oFF position.
This assures that use of the laser by unauthorized or unqualified
personnel can be prevented.
Warning Labels
Certification and warning labels are affixed to the Evolution-15/30
to verify compliance with 21 CFR 1040, to provide information on
the wavelength and power emitted, and to warn the user against accidental exposure to laser radiation. The location and type of warning
logotype labels used on the Evolution-15/30 laser bench for both the
Scientific and OEM versions, as well as the laser power supply, are
shown in Figure 2-1, Figure 2-2 and Figure 2-3 respectively.
2-4
Laser Safety
4
1
4
4
4
0
0
•
00
7
2
2 PL
Figure 2-1. CDRHICE Radiation Control Drawing, Scientific Version
2-5
Evolution-15130 Laser Operator :s- Manual
•
•
•
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.
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'"5" '@" (I) ~
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Figure 2-2. Power Supply Cabinet CDRH/CE Radiation Control Drawing
2-6
Laser Safety
.----__--
.........
.CD DElL
--~
-.&lie/fa--
wooo.. NO. I
PART NO.
IP=====l
SER. NO.
I...___ _ _....J
•
IDENTIFICATION/CERTIFICATION
LABEL (1)
VISIBL£ AND /OR
INVISIBLE LASER
RAOIAllON IS EMITTED
FROt.l lHIS APERTURE.
WHEN 01'01 AND INTERLOCK DEF£ATEDI
AvrYD E'1'E OR st<JN EXPOSURE TO DIRECT
OR SICATlERED RADIA11<»1.
--
. . , _ . . . .'ICil.
G.-Pt...-,_.,..
MADE IN U.S.A.
AVOID EXPOSVREI
VISIIIl£ AND/OR INVISIBLE LASER -llON
,._,
Awamca-
ClASS tv L.ASD! PRODUCT
DANGER LASER
BEAM LABEL, HEAD (2)
--
INTERLOCKED COVER
LABEL, HEAD (3)
\'ISIBLE AND/OR ltMSIBlE LASER RAW.llON
AVOID E'1'E OR st<JN E:lCI'OSUAE TO DIRECT
OR SCATlERfD RAD1Al10N.
le
1.1
*
ClASS tv LASER PRODUCT
IIAX OU1P\1T < 50W
WA\aDIG!H 527nm
PUt..SUENa1K 21l0na
.....
DANGER LABEL,
HEAD-EVOLUTION (5)
APERTURE LABEL,
HEAD ( 4)
CAUTION LABEL (6)
CAUTION
VISIBLE, INVISIBLE AND
RF ELECTROMAGNETIC
RAOIA liON WHEN OPEN.
8011-7Cee
RF CAUTION LABEL (8)
CAUTION LABEL (7)
DANGER
VISIBLE AND/OR INVISIBLE l..AS£R RAOIAliON
WHEN OPEN AND INlERLOCK DEfEATED.
AVOID m OR SKIN EXPOSURE TO DIRECT
OR SCATlERED RAOIAliON.
CLASS 4 l..AS£R PRODUCT
DANGER
VISIBLE AND /OR INVISIBLE LASER RAOIAliON.
AVOID m OR SKIN EXPOSURE TO DIRECT
OR SCATlERED RADIAliON. CONSULT
INSTRUCliON MANUAL.
CLASS 4 LASER PRODUCT
VORSICHT
SICHTBARE UND/OOER UNSICHTBARE
LASERSTRAHLUNG, VoejN ABOECKUNG
GEOFFNET UNO SICHERHEilSVERRIEGLUNG
UBERBRUCKT.
BESTRAHLUNG VON AUGEN ClOER HAUT
DURCH DIREKTE ClOER SlREUSTRAHLUNG
\'ERMEIDEN.
LASER KLASSE 4
VORSICHT
SICHTBARE UND/OOER UNSICHTBARE
LASERSTRAHWNG.
BESTRAHWNG VON AUGEN ClOER HAUT
DURCH DIREJ<TE ClOER SlREUSTRAHWNG
VERI.IEIDEN.
NAHERE INFORI.IAliONEN: SIEHE
BEDIENUNGSANLEITUNG.
LASER KLASSE 4
DANGER
RAYONNEWENT l..AS£R VISIBLE ET/OU
INVISIBLE DANGEREUSE EN CAS D'OUVERTURE
ET LORSQUE LA SECURITE EST
NEUTRAUSEE.
EXPostliON DANGEREUSE DE L'OEIL OU DE
LA PEAU AU RAYONNEWENT DIRECT OU
DIFRJS.
l..AS£R CLASSE 4
DANGER
RAYONNEWENT LASER VISIBLE ET/OU
INVISIBLE. EXPOSiliON DANGEREUSE
DE L'OEIL OU DE LA PEAU AU
RAYONNEWENT DIRECT OU DIFFUS.
CONSULliER L£ MANUEL D'INSTAllAliON.
LASER CLASSE 4
808-7~
808-7097
CE WARNING LABEL,
POWER SUPPLY (10)
CE WARNING LABEL,
INTlERLOCK DEFEATIED (9)
Figure 2-3. CDRHICE Radiation Control Drawing Labels
2-7
Evolution-15/30 Laser Operators Manual
For safety, translations of the warning labels are provided in for
non-English speaking operators. The number in parentheses in the
first column corresponds to the label number listed on the previous
page.
Table 2-1. Label Translations
LABEL#
FRENCH
GERMAN
SPANISH
DUTCH
Danger
Label (5)
Interlocked
Cover
Label (3)
Danger! Rayonnement Laser Visible
et/ou Invisible en Cas
D' Ouverture et lorsque
Ia securite est neutralisee; exposition
dangereuse de I' oeil ou
de la peau au rayonnement direct ou diffus.
Laser de Classe 4.
Vorsicht! Sichtbare
und/oder unsichtbare
Laserstrablung wenn
geoffnet und Sieberheits-verriegelung
uberbruckt.
Bestrablung von
Augen oder Haut
durch direkt oder
Streustrahlung
vermeiden. Laser
Klasse 4.
Peligro! A1 abrir y
retirar el dispositivo de
seguridad exist radiacion laser visible y
invisible; evite que los
ojos o Ia piel queden
expuestos tanto a Ia
radiacion directa como
a Ia dispersa. Producto
laser clase 4.
Gevaar! Zichtbare en
onzichtbare laserstraling! Vermijd blootstelling van oog of
huid ann direkte
straling of terugkaatsingen daarvan!
Klas 4 laser produkt.
Aperture
Label (4)
Exposition
Dangereuse! Rayonnement visible et/ou
invisible est emis par
cette ouverture
Austritt von sichtbarer
und unsichtbarer
Laserstrahlung.
Bestrahlung
vermeiden!
Por esta abertura se
emite radiacion laser
visible e invisible;
evite la exposicion
Vanuit dit apertuur
wordt zichtbare en
onzichtbare laserstraling geemiteerd!
Vermijd blootstelling!
Remote Interlock
Connector
There are two interlock connectors, one interlock for the door and an
"Aux Interlock" for the power supply software to accept a command
from the Evolution computer software to set CW mode (RF off).
The remote interlock connector at the back of the power supply
cabinet (marked INTERLOCK) must be used to connect an external
CDRH interlock (such as a switch on the door to the laser room).
The interlock circuit will then terminate laser action automatically if
the door is opened to the laser operating area. To connect the interlock switch, remove the supplied external jumper plug, and either
re-wire according to the wiring diagram in Figure 2-4, or use a
similar connector. Wire the external interlock switch normally
closed, such that if the door or safety device and the switch opens,
the power supply will immediately turn the laser diodes off. This is
a safety precaution to prevent any unaware personnel from inadvertent exposure to laser radiation.
2-8
Laser Safety
Figure 2-4. External Interlock Connector (Evolution Power Supply)
The interlock function causes the diodes to switch off when the
interlock contacts are opened. Lasing can only be resumed by
closing the external interlock circuit contacts and cycling the
keyswitch to clear the interlock function. The laser must not be operated unless the remote interlock function is in use.
Protective
Housings
The laser beam path is contained within the mechanical housing of
the laser bench until it exits at the front (or side) output port. The
diode-pumped head is also contained within this housing to shield
the user from stray laser diode light and to protect the laser diodes
from exposure to dust and electrostatic discharge.
Cover Safety
Interlocks
Interlock micro-switches are used to ensure that the Evolution-15/30
cannot be operated if the machined metal cover protecting the
optical cavity is not in place.
Do not operate the Evolution-15/30 with any covers removed,
except when absolutely necessary while performing required
service. Operation without the covers may expose users to
hazardous voltages and laser radiation, and also increases the
rate of optical surface contamination. Unauthorized removal of
the cover protecting the optical cavity will void the warranty.
Emission
Indicators
After issuing a START command, an emission indicator lights at the
laser bench to warn that the laser is about to emit laser radiation.
2-9
Evolution-15/30 Laser Operator's Manual
Scientific Evolution-15/30
An indicator light on the front of the laser housing lights any time
current is supplied to the laser diodes. This warns the user that
hazardous laser radiation is present or can be accessed.
Note: When the emission indicator is illuminated, diode laser light
is present inside the housing, even though the laser cavity may not
be emitting green or infrared laser radiation. (This situation may
occur if the laser is in Hold-Off mode, for example.)
OEM Evolution-15/30
A detachable emission indicator is supplied with the laser that may
be mounted on the laser bench, or removed and post-mounted in a
remote location by the user. This indicator illuminates in the same
manner as described in paragraph titled "Remote Interlock
Connector" on page 2-8. The detachable indicator is useful if the
operator installs the OEM Evolution-15/30 in an instrument, and the
indicator would not be clearly visible if attached to the laser bench.
If the indicator is detached from the laser bench, it must be placed in
a clearly visible location no more than 10ft. (- 3m) from the Evolution-15/30 output port to maintain CDRH compliance.
All emission indicators remain on as long as the laser is capable of
lasing. The indicators illuminate a few seconds prior to actual emission to give nearby personnel time to prepare for laser radiation
emission.
Beam Safety
Shutter
A solenoid-actuated safety shutter is mounted in the optical cavity to
interrupt laser action when necessary. The shutter is actuated when
the laser is turned on (either by pressing the ON button or by issuing
a software command). The interlock fault and fail-safe mode is the
closed position.
Output Port Shutter
A manually operated shutter mounted on the front laser output port
is provided for blocking the beam, if required. If the optional side
port is used, a metal disc (supplied) may be inserted in this port by
the user to block emission.
Location of
Controls
Controls for operation of the Evolution-15/30 laser are accessed
through the control software via USB/RS-232 control so operators
are not exposed to laser radiation during operation of the laser. If the
2- 10
Laser Safety
software is tenninated, the computer malfunctions, or the
USB/RS-232 connection is broken, the Evolution-15/30 will stop
lasing within three seconds.
Operating
Instructions
This manual contains instructions for operating and maintaining the
Evolution-15/30 safely.
CDRH
Requirements for
Operating the
Evo/ution-15/30
via USB/RS-232
Software
Commands
The Evolution-15/30 and power supply comply with all applicable
CDRH safety standards when operated via commands sent to the
USB/RS-232 port on the front of the power supply cabinet. A software indicator indicates that laser energy is present or can be
accessed.
Maintenance
Required to Keep
Laser in CDRH
Compliance
This section presents the maintenance required to keep this laser
product in compliance with CDRH Regulations.
This laser product complies with Title 21 of the United States Code
of Federal Regulations, Chapter 1, Subchapter J, Parts 1040.10 and
1040.11 , as applicable. To maintain compliance, verify the operation
of all features listed below, either annually or whenever the product
has been subjected to adverse environmental conditions (e.g., fire,
flood, mechanical shock, spilled solvents). This maintenance is to be
performed by the user, as outlined below.
•
Verify that removing the laser cover closes the intracavity
shutter and illuminates the interlock LED on the remote box
and on the laser power supply.
•
Verify that, when the cover interlock is defeated, the defeat
mechanisms are clearly visible and prevent installation of the
cover until they are removed.
•
Verify that all the warning labels listed in Figure 2-1 to
Figure 2-2, Evolution-15/30 Radiation Control Drawings, are
present and fumly affixed in the correct locations.
•
Verify that removing the user interlock connector on the back
panel of the power supply prevents laser operation. Figure 2-4
shows the interlock with the jumper plug in place.
2 - 11
Evolution-15130 Laser Operator's Manual
•
Verify that the time delay between turn-on of the emission
indicator and start of laser emission gives enough warning to
allow action to avoid exposure to laser radiation.
•
Verify that the internal beam attenuator (shutter):
•
Operates properly when the laser is turned off from the
remote box (or remote computer controller, if being
used)
•
Closes when the keyswitch is turned off
•
Blocks access to laser radiation
2- 12
Laser Safety
Sources of
Additional
Information
The following are some sources for additional information on laser
safety standards and safety equipment and training.
Laser Safety
Standards
Safe Use of Lasers (Z136.1)
American National Standards
Institute (ANSI)
1430 Broadway
New York, NY 10018
Tel: (212) 354-3300
Occupational Safety and Health
Administration (OSHA)
U.S. Department of Labor
200 Constitution Avenue N.W.
Washington, DC 20210
A Guide for Control of Laser Hazards
American Conference of Governmental
and Industrial Hygienists (ACGIH)
6500 Glenway Avenue, Bldg. D-7
Cincinnati, OH 45211
Tel: (513) 661-7881
Laser Safety Guide
Laser Institute of America
12424 Research Parkway, Suite 130
Orlando, FL 32826
Tel: (407) 380-1553
Equipment and
Training
Laser Focus Buyer's Guide
Laser Focus World
One Technology Park Drive
P.O. Box 989
Westford, MA 01886-9938
Tel: (508) 692-0700
Photonics Spectra Buyer's Guide
Photonics Spectra
Berkshire Common
Pittsfield, MA 01202-4949
Tel: (413) 499-0514
Lasers and Optronics Buyer's Guide
Lasers and Optronics
301 Gibraltar Dr.
P.O. Box 650
Morris Plains, NJ 07950-0650
Tel: (210) 292-5100
2 - 13
Evolution-15/30 Laser Operator's Manual
2- 14
Installation and Utility Requirements
CHAPTER THREE: INSTALLATION AND
UTILITY REQUIREMENTS
Receiving the
Evolution-15/30
The Evolution-15/30 power supply is in a cardboard box strapped
inside a shipping crate.
To remove the power supply from the cardboard box:
1.
Remove the clamps from the bottom edge of the crate
2.
Lift off the top section of the crate
3.
Remove the straps
4.
Lift the cardboard boxes out of the crate. These boxes contain:
•
•
The power supply
•
Accessories
Laptop computer
The water chiller is strapped to the base of its shipping crate. To
remove the chiller:
1.
Remove the straps
2.
Carefully lift the chiller off the base of the crate.
If any damage is evident, such as dents or scratches on the covers,
broken knobs, etc., notify the carrier and an authorized sales representative immediately.
Keep the shipping crates. If damage is present and a damage claim
must be filed, you may need them to demonstrate that the damage
occurred as a result of shipping.
If the systems must be returned for service at a later date, the
specially designed container will assure adequate protection.
The Evolution-15/30 can now be moved to the location in which it
will be installed (see Chapter Four: Controls and Indicators).
Do not attempt to install the laser without a Coherent authorized personnel present, or remove the lid covering the optical
cavity of the laser bench. Either action will void the warranty,
and you will be charged for the repair of any damage incurred.
3- 1
Evolution-15130 Laser Operators Manual
Installation
location
Before installation, select a suitable location for the Evolution-15/30. The Evolution-15/30 is constructed using a temperature-stabilized monolithic body, but Coherent recommends that the
laser be located in a laboratory-type environment that is free from
dust and drafts, with low humidity (< 50%) and does not exhibit
temperature fluctuations greater than ± 5°C.
Pumping a
legend Amplifier
When pumping a Legend regenerative amplifier, the Evolution-15/30 should be placed as close as possible to the Legend. The
distance between the Evolution-15/30 and Legend is determined at
the factory during the fmal test procedure. Relatively large deviations (> 1 ft. or 30 em) from this distance can affect the overall
performance of the system. For safety, it is also inadvisable to have
an exposed laser beam travel long distances. Consult with an authorized service representative for further information.
Required Utilities
Do not apply AC power to the power supply chassis; this will
activate the LBO crystal heater. Programming the crystal heater
improperly will permanently damage the crystal. Such damage
will not be covered under warranty.
The Evolution-15/30 power supply is compatible with
100-240 VAC and 50-60Hz frequency; however, each Evolution-15/30 is optimized to operate at the customer-specified line
voltage and frequency. Do not attempt to operate the Evolution-15/30 at a different voltage or frequency without consulting
with an authorized service representative.
The closed-loop chiller supplied with the Evolution-15/30 is only
compatible with a specific line voltage and frequency range. Do
not attempt to operate the Evolution-15/30 chiller at a different
voltage or frequency under any circumstances.
3-2
Installation and Utility Requirements
The Evolution-15/30 system requires the utilities listed in Table 3-1.
Table 3-1. Evolution Utility Requirements
DESTINATION
ACCEPTABLE LINE VOLTAGE I
FREQUENCY (VAC/Hz)
USA
JAPAN
LASER
CIDLLER
(110 ± 10) VAC, 60Hz
15
15
(110 ± 10) VAC, 50/60Hz
15
15
(220 ± 20) VAC, 50 Hz
10
10
(220 ± 20) VAC, 50 Hz
10
15
OR
EUROPE
Installing the
Power Supply
CURRENT REQUIREMENTS (A)
Consider the following when placing the power supply:
•
Place the power supply within 10 ft. (3 m) of the laser bench to
avoid straining the umbilical.
•
If available, place the power supply in a ventilated 19-in.
(48-cm) equipment rack.
•
Allow 6 in. (15 em) clearance to the front and back panels of
the power supply cabinet and 3 in. (8 em) on each side for
proper airflow.
•
Prevent the heated air exhaust from the back panel fans from
returning to the intake on the back of the power supply or from
exhausting toward the laser bench. Ensure adequate distance
for good air flow, failure to do so will cause overheating in the
power supply and instability in the laser output.
•
Verify the interlock jumper plug is inserted at the back of the
power supply. If the laser is to be used in a limited access area,
remove the jumper and wire it to a safety switch. The switch
must be wired such that when the device is actuated (a door is
opened, for example), the switch opens and the laser turns off
(see "Remote Interlock Connector" on page 2-8 of
Chapter Two: Laser Safety).
•
Verify that the local line frequency and voltage are within the
acceptable input ranges.
•
Ensure that all electrical cables and umbilical are routed safely
and are not under any strain or compression.
•
Verify that the power cable is secured with the built-in bracket
on the AC socket on the power supply chassis.
3-3
Evolution-15/30 Laser Operators Manual
Installing the
Laser Bench
Note the following when placing the Evolution-15/30 laser bench:
•
The laser bench is attached to the power supply chassis by a
10-ft. (3-m) umbilical consisting of four cable assemblies:
•
•
•
A 4-pin current cable
•
One/Two BNC cable(s) that connect to the RF Out
connector(s) on the rear of the power supply chassis
A 26-pin signal cable
Ensure that the weight of the umbilical does not drag the laser
bench off the table or create a trip-hazard in the laboratory.
Identify the location of output port (front or side) at the time of
installation so the service engineer can expedite the installation
of the laser according to its intended purpose.
Secure the laser bench in a position on an optical table or other flat
mounting surface as follows:
OEM Evolution-15/30:
Two slots are located at the center of the front and back of the laser
housing for securing the laser bench. Use standard table screws (M6
or %-20) to fasten the laser to the table.
Ensure that the flexure arm at the front of the laser is bolted in
place last; securing this first will defeat its purpose of allowing
for thermal expansion/contraction of the housing.
Scientific Evolution-15/30:
Place the laser bench on the table and adjust the four mounting feet
for the correct height, ensuring that the instrument is level. The
height of the feet may then be locked in place using the locking ring
on each leg. Secure the laser to the optical bench using a mounting
clamp on each foot. If the laser is directed out the side port, remove
the metal disk from the side of the Evolution 15/30 housing.
Installing the
Control Computer
1.
Position the Evolution-15/30 control computer within 10ft. of
the power supply chassis.
3-4
Installation and Utility Requirements
2.
Set up the computer according to the manufacturer's instructions included in the computer box.
3.
Connect the USB/RS-232 cable from the front of the Evolution
power supply to the computer.
On control computers that ship with Windows 2000, the default user
name is "Administrator", and the default password is "evolution"
(passwords are case sensitive, and do not type the quotes). The
control software is pre-installed on the control computer.
Installing the
Chiller
When installing the chiller, observe the following instructions:
1.
Check that the local line voltage and frequency is within the
acceptable input range for the chiller supplied.
2.
Place the chiller on the floor close enough to the Evolution-15/30 bench such that the cooling hoses will reach the
system without causing undue strain.
Position the chiller so that its warm air exhaust is not drawn into
the laser power supply and does not adversely affect the stability
of the laser output.
3.
To avoid hot air exhausting from one unit being drawn into the
other, ensure that an air gap of at least 6 in. (15 em) exists
between the chiller and Evolution-15/30 power supply.
4.
Do not place the chiller above the laser or power supply.
(Should the unit be installed incorrectly and a leak develops,
dripping water will damage the laser system.)
5.
Attach the chiller hoses to the laser bench.
Note: The hose connectors are not polarized, so check that the
feed line (marked with an arrow pointing towards the laser
bench) is attached to the lower hose connector on the laser
bench. This ensures that any air is purged upwards and out of
the laser bench.
3-5
Evolution-15130 Laser Operator's Manual
Before handling OPTISHIELD water treatment, read the Material Safety Data Sheet included in Appendix C that describes the
potential hazards and handling precautions associated with this
chemical. This chemical may be harmful if swallowed, inhaled,
or absorbed through the skin or eyes.
Use only steam-distilled water in the Evolution-15/30 cooling
system. The use of de-ionized or common tap water will cause
damage to the entire system.
6.
Add the contents of the one pint bottle of OPTISHIELD to the
chiller reservoir.
7.
Fill the chiller with high-quality, steam-distilled water.
8.
Thrn the chiller on and verify that water is flowing.
9.
Inspect for leaks at the hose connections to the laser bench and
at the chiller.
10.
Thrn the chiller off.
Note that it takes the chiller approximately 15 minutes to stabilize the temperature of the laser bench cold plate and therefore
the output of the laser.
Leave the chiller on between periods of use if the laser is used
frequently. This will eliminate the stabilization period. If the
laser is used infrequently, turn the chiller off after use.
3-6
Controls and Indicators
CHAPTER FOUR: CONTROLS AND INDICATORS
Product
OveNiew
The Evolution-15/30 is designed around a Nd:YLF laser head
pumped by AlGaAs (Aluminum Gallium Arsenide) laser diode
arrays. The laser resonator is acousto-optically Q-switched at repetition rates from 1 to 10 kHz. In order to produce the maximum
possible output power in the second harmonic, the laser uses
intra-cavity frequency
doubling
with a non-critically
phased-matched LBO crystal. Overall doubling efficiency is excellent, and the damage threshold of LBO is five times higher than
other commonly used crystals, ensuring long-term trouble-free operation. Non-critical phase matching minimizes the angle sensitivity
of the crystal for adjustment-free operation.
The Evolution-15/30 is ideally suited to pumping Ti:sapphire
ultrafast amplifiers, and has been optimized as a pump source for the
Legend and Libra Ti:sapphire regenerative amplifier systems.
Diode Pumping
The Evolution-15/30 employs laser diode pumping to excite the
laser gain medium, as opposed to more conventional arc-lamp
pumping schemes. Unlike the broadband light emitted by arc-lamps,
the narrow spectral emission of laser diodes allows extremely efficient pumping of laser materials, with little or no diode light falling
outside of the absorption band of the gain medium. This results in
negligible waste heat generation.
The high efficiency results in low electrical- and cooling-utility
requirements. The low waste heat generation also results in negligible deleterious thermal effects in the laser rod (such as thermal
lensing and depolarization).
Another key advantage of laser diode pumping is that diodes offer
lifetimes of many thousands of hours, compared to only hundreds of
hours for arc-lamps.
Nd:YLF Laser
Material
The Evolution-15/30 uses Nd:LiYF4 (Nd:YLF) as its gain medium,
which provides numerous advantages over other common neodymium-based lasers such as Nd:YAG The long upper-state lifetime
(470 JlS) provides efficient energy storage for high-pulse energy
operation a low repetition rates. The low thermal lensing and natural
4-1
Evolution-15130 Laser Operator's Manual
birefringence of Nd:YLF enables scaling to higher power, avoiding
the loss of beam quality and efficiency or the requirement for
complex resonator designs.
With an intra-cavity polarizer one can select either the 1047 nm
(extraordinary) or 1053 nm (ordinary) transition. All lines originate
on the same Stark split 4F 3n upper level. The Evolution-15/30 lases
on the 1053 nm transition because of the lower thermal lensing
exhibited at this wavelength.
The relatively high thermal conductivity ofNd:YLF allows efficient
heat extraction, and its natural birefringence overwhelms thermally
induced birefringence, virtually eliminating the thermal depolarization problems found in optically isotropic hosts such as Nd:YAG
Acousto-Optic
Q-Switching
In acousto-optic Q-switching, an ultrasonic wave is launched into a
block of transparent optical material. The photoelastic effect couples
the modulating strain field of the ultrasonic wave to the optical index
of refraction of the material. The resulting optical phase grating has
a period equal to the acoustic wavelength and amplitude proportional to the sound amplitude.
When a light beam is incident upon this grating, a portion of the
intensity will be diffracted out of the beam into one or more discrete
directions. By choosing beam parameters properly, the diffracted
beam can be deflected out of the laser cavity, thereby providing an
energy loss that is sufficient to spoil the "Q" of the cavity.
The ultrasonic wave is launched into the Q-switch block by a piezoelectric transducer that converts incident electromagnetic energy
into ultrasonic energy. The laser is returned to the high Q-state by
switching the driving voltage to the transducer off. With no ultrasonic wave propagating through it, the fused silica block returns to
its usual state of high optical transmission, the deflected beam disappears, and a Q-switched laser pulse is emitted.
Intra-Cavity
Frequency
Doubling
High-frequency conversion efficiencies require power densities that
are not normally available from a CW-pumped laser. The solution to
the problem employed by this laser is to place the non-linear
doubling crystal inside the laser resonator, subjecting it to high
circulating power. The power is coupled out of the resonator at the
second-harmonic wavelength by replacing the output mirror with
one that is 100% reflective at the fundamental and transmitting at the
second harmonic wavelength. The second harmonic crystal acts as
an output coupler in a manner analogous to the output coupler of a
normal laser.
4-2
Controls and Indicators
Because of the advantage of the high power density inside the laser
cavity, it is only necessary to achieve a conversion efficiency equal
to the optimum mirror transmission to convert the available output
power at the fundamental completely.
Lithium Triborate
(LBO)
LBO is a nonlinear optical crystal characterized by good UV transparency, a relatively high optical damage threshold, and a moderate
non-linear optical coefficient. The birefringence in LBO is small,
which enables non-critical phase matching and provides a larger
acceptance angle for high efficiency frequency-conversion. These
properties, with its mechanical hardness, chemical stability, and
non-hygroscopic nature, make LBO an ideal material for nonlinear
optical frequency conversion.
Optical Laser
Bench
Configuration
.
u
u
,--,
0
L_j
JA<'<~,.,
I
/, / v
'..
).
r---------
,' ~
,' .,/
--~---------------,-------,- --,_,(,/
.---
.._
_
D
[0
[c-
'--
,,
/
/ ~.
..,
r--
~
r'-
1-
t-
t- 1-
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,,.. '
......
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(/ ,1/
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/·-:)
L-
i'<f
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C'
0
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I
t _________
a!
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,,
~~Q
_'!.'
EVOLUTION-15/30
Figure 4-1. Optical Laser Bench
The optical laser bench of the Evolution-15/30 is shown in
Figure 4-1. The laser resonator is in a folded configuration, which
enables efficient output coupling of the second harmonic light and
4-3
Evolution-15/30 Laser Operators Manual
reduces the overall size of the Evolution-15/30. All mirrors are high
reflectivity at 1053 run unless otherwise noted. From left to right, the
optical cavity consists of the following components:
•
•
•
•
•
•
•
0° , curved rear-cavity mirror
•
45° intracavity dichroic folding mirror (high reflector at
1053 nm, high transmission at 527 nm)
•
LBO frequency-doubling crystal in temperature-stabilized
oven
•
0° curved end mirror (high reflector at 1053 nm and 527 nm)
Diode-pumped laser head
Intracavity safety shutter
0° curved intracavity mirror
Acousto-optic Q-switch (Ev-30 only)
45° turning mirror
Acousto-optic Q-switch
The laser head contains the Nd:YLF laser rod and laser diodes. The
diodes provide optical excitation to the laser rod and lasing between
the cavity mirrors is established. The 1053 nm radiation is contained
entirely within the laser resonator because there is no output coupler
at this wavelength.
The laser is Q-switched (typically at 1 to 10kHz), producing
intra-cavity laser pulses of duration 100 to 350 ns, depending on the
pulse energy.
Because of the high intra-cavity radiation fluence, the 1053 nm radiation is converted to 527 nm in the LBO crystal.
This 527 nm light transmits through the dichroic mirror, and exits
the laser bench directly from the forward output port, or reflects
from a turning mirror and exits through the side output port. The
beam waist is located at the oo , a flat-end mirror, so the beam
diverges at either output port of the laser. A lens is located at the
output port to collimate the beam.
4-4
Controls and Indicators
Component
Description
Laser Pump
Chamber
The Nd:YLF laser rod and laser diodes are contained in the laser
pump chamber. The pump chamber is mounted to the laser bench in
a mechanically indexed bracket that allows for easy extraction and
insertion of the pump chamber. The laser rod is held with 0-rings in
a water flow-tube. A gold-coated reflector surrounds the flow tube;
slits in the reflector allow the passage of the pump light from the
laser diodes. Both the laser rod and laser diodes are water-cooled in
parallel by the internal cooling system that enters the pump chamber
through 0-ring sealed ports in the base of the pump chamber.
The diodes are arranged in three blocks of two/four (two for Ev-15,
four for Ev-30) high-power diode bars that share a single
water-cooled heat sink and electrical connections. Three blocks of
diodes are mounted 120° apart down the length of the laser rod. The
diodes are connected electrically in series to the Evolution-15/30
diode driver through a high-current connector on the pump chamber.
Q-Switches
The Q-switch is enclosed in a metal housing and mounted on a riser
block with a coarse azimuthal adjust. The Q-switch is made of
high-quality fused silica to which an RF transducer is bonded. The
fused silica is cut and polished optically to be optically oriented at
Brewster's angle for S-polarized intra-cavity laser radiation.
Approximately 20-30 W RF power is delivered to the Q-switch
through a 50QBNC cable. The Q-switch is water-cooled, and has a
built-in temperature interlock to shut the RF power off if an
over-temperature condition occurs. The power supply for the
Q-switch is located in the Evolution-15/30 power supply chassis.
LBO Crystal
and Oven
The LBO crystal is located in a crystal housing that maintains its set
temperature in the range 315° F (157° C) to 340° F (171 ° C) to
within 0.10° F (0.056° C). At this temperature, the crystal is non-critically phase-matched for the intra-cavity 1053 nm radiation,
ensuring high conversion efficiency to the second harmonic. The
crystal should be maintained constantly at this temperature, even
when the laser is not in use. If necessary, the crystal can be ramped
down to room temperature for long-term storage of the laser (see
"Long-Term Shutdown" on page 5-4). The LBO crystal is
anti-reflection-coated for both 1053 nm and 527 nm.
4-5
Evolution-15130 Laser Operator :SO Manual
The temperature controller is a microprocessor-based device and is
pre-programmed. It can maintain the crystal to within 0.10° F
(0.056° C), which ensures stable operation of the laser. If the LBO
temperature is not maintained at the factory set-point, an interlock
will prevent laser operation.
Power Supply
The power supply assembly consists of a rugged steel frame in a
19-in. (48-cm) rack-mount configuration. The power supply
contains the master control board, diode power supply, Q-switch RF
driver, LBO crystal temperature controller, and various control electronics. In general, it should not be necessary to access any components inside the power supply.
Removing the power supply cover will expose the user to electrical hazards. Potentially lethal voltages and currents are
contained in the power supply. Normal operation of the Evolution-15/30 does not require access to the power supply circuitry.
Contact an authorized service representative before attempting
to correct any problem with the power supply.
4-6
Controls and Indicators
Power Supply
Front Panel
EvoUtlon
@
0
POWER
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[63]: ~~
LIIO IEAnll
COimiOL
Q
0 0
@...-I'AIA.T
0
e
08W 8'tNC OIIT
@
08WTNG 11'111'
0
e
GCCIERBIL
e
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Ul8
0
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EVOLUTION-15/30
Figure 4-2. Power Supply Front Panel
Table 4-1. Power Supply Front Panel
CONTROL
Powerswitch
FuNCTION
Enables main AC power to the power supply. Green LED illuminates when AC power is activated.
~
Keyswitch
AC power to the LBO crystal heater circuit in the power supply
is always present when the power supply is plugged in, even
when the AC breaker is deactivated.
Functions as an interlock. In the OFF position it prevents operation of the laser.
The keyswitch is designed such that the key can be removed only in the OFF position. The
keyswitch is also used to reset latched interlocks by cycling from the OFF position to the ON
position.
Laser Active
illuminates when current is flowing through the laser diode arrays, regardless of the state of
the laser output (Q-switched, CW, hold-off, etc.)
Laser Fault
illuminates when the Evolution encounters an interlock fault.
LBO Heater
Control
Maintains the temperature of the LBO crystal oven.
USB/RS-232 I/0
Connects the USB/RS-232 port of a computer to control the laser.
Normally it is not necessary to change the settings of this controller.
4 -7
Evolution-15/30 Laser Operator :s- Manual
Table 4-1. Power Supply Front Panel (Continued)
CONTROL
FuNCTION
QSWSYNCOUT
Provides a fixed TIL synchronization signal (in BNC output) that is coincident with the triggering of the Q-switch.
QSWTRIG
INPUT
The Evolution Q-switch can be triggered externally by applying a TIL voltage levels (i.e.
4-5 V) and a trigger pulsewidth of around 5 flS for 1 kHz operation and 2.5 flS for 5 kHz
operation. Adjust the trigger pulsewidth for optimal power and pulsewidth.
The input is terminated with high impedance; if the external triggering source has a 50-0.line
drive output, a 50-Q terminator should be added at the QSW TRIG INPUT input to avoid
multiple pulses from ringing. External triggering of the laser is possible. Using this mode
requires the user to select EXT trigger mode in the control software.
Note: External triggering outside the tested I manufactured rep rate is not recommended and may cause damage to YLF rod or LBO optics.
Power Supply
Rear Panel
IP<NfCifl
_..,.
©
©
IP<NfQil
-
EVOLUTION-15/30
Figure 4-3. Power Supply Rear Panel
Table 4-2. Power Supply Rear Panel
CONTROL
ACIN
FuNCTION
Main input power required must be in the range lOOto 240 VAC ± 10%, 50/60Hz.
Fuses meeting the following specifications are used:
Line Voltage
F1/F2: 3AG SLO BLO®
RFOUT
(Ev-15/30)
200 to 240 VAC
100 to 120 VAC
10 N10A
15 N15 A
BNC output, 20-30 W, 100-150 V RMS sine wave at 27.11 MHz into a 500.load, used to do
drive the Evolution Q-switch. DO NOT connect these signals to anything other than the
supplied BNC connectors in the umbilical to the Evolution laser bench.
4-8
Controls and Indicators
Table 4-2. Power Supply Rear Panel (Continued)
CONTROL
FuNCTION
26-pin connector
(unlabeled on
Ev-15-30)
Supplies interlock and control signals to the laser bench. Connects to the 26-pin umbilical
cable.
4-pin connector
(unlabeled on
Ev-15-30)
Supplies current to the laser diode arrays in the laser bench. Connects to the four-pin umbilical cable.
Interlock
Three-pin connector used for interlocking the laser to a controlled access point, such as a
laboratory door. Shorting pins J1 and J2 (shown in Figure 2-4) enable laser operation.
ACIN
Main input power required must be in the range 100 to 240 VAC ± 10%, 50/60Hz.
A/D1NPUT
Reserved for future use.
AUXINPUT
Used to enable CW operation for testing. (Note: the software has to be enabled in CW mode
and the fac tory password setting enabled to test in CW mode).
Electronic Control
Module
The Evolution-30 Electronic Control Module (ECM) is a
USB/RS-232 control device for setting and monitoring the laser
diode power supply, the laser interlocks, and the Q-switch driver.
The ECM is controlled via USB/RS-232 by software on the supplied
laptop computer.
Laser Diode
Power Supply
The laser diode power supply is a completely self-contained unit,
enclosed in a metal housing to provide protection for the power
supply components and to service personnel. The Evolution-15/30
power supply operation is controlled and monitored by the ECM.
Q-Switch Driver
The Q-switch driver provides RF power to the one/two Q-switch( es)
on the optical laser bench. It is an all solid-state electronics driver,
consisting of a crystal-controlled oscillator, double-balanced modulator, pulse generator with gate, and broad-band power amplifier that
provides > 20 W drive power into each Q-switch. The Evolution-15/30 Q-switch driver is controlled and monitored by the ECM.
LBO Crystal
Temperature
Controller
The LBO doubling crystal is temperature tuned for non-critical
phase matching. The LBO is housed in a temperature-stabilized
oven. A resistive heating element, combined with a local temperature sensor, is used with the heater controller to stabilize the crystal
4- 9
Evolution-15/30 Laser Operators Manual
temperature to within ± 0.1oF (0.056° C). The heater controller is
programmed to limit the rate at which the crystal temperature is
changed (typically no faster than l0°F (5.6° C) per minute) to
prevent the crystal anti-reflection coatings from cracking.
The power for the temperature controller is wired directly to the AC
lines so the crystal stays heated, even when the front-panel breaker
is turned off. The LBO crystal temperature should be ramped down
before disconnecting power to the chassis. See "Long-Term Shutdown" on page 5-4, in Chapter Five: Daily Operation for instructions.
LBO crystal temperature controller [WATLOW] is pre-programmed
at the factory. It should be unnecessary for any customer adjustment
of the WATLOW controller during normal operations.
4- 10
Daily Operation
CHAPTER FIVE: DAILY OPERATION
Safety glasses for all lasing wavelengths must be worn at all
times when operating this or any laser system. Consult your
laser safety officer to select appropriate safety glasses. See
"Chapter Two: Laser Safety".
Current Settings
The Evolution-15/30 comes with a set of performance data that
gives the factory-measured output power as a function oflaser diode
current at the nominal Q-switch rep-rate specified when the laser
was ordered. When the laser is installed, the authorized service rep
will verify these measurements.
Coherent recommends establishing at least three nominal current
settings: a low, medium, and high setting produce, for example, 4 W,
8 W, and 12 W for a standard 1kHz Evolution-15 system. In this
chapter, these current settings will be referred to as low, medium,
and high.
If the Evolution-15/30 is not normally operated at its maximum
specified output power, scale these settings appropriately when
following the procedures in this chapter and in the troubleshooting
chapter at the end of the manual.
After several hundred hours of operation, the laser diode output
power will decrease slightly. The maximum possible current setting
is set at the factory to ensure that each laser will meet its specification power for thousands of hours of operation.
Start-up
Procedure
Diode Start-up and
Lasing Initiation
The following procedures should be used during normal start-up and
operation of the Evolution-15/30 laser system.
5-1
Evolution-15130 Laser Operator~ Manual
The following procedure will result in a laser beam emitting
from the Evolution-15/30 output port. Ensure all persons in the
room are wearing adequate laser eye protection. Ensure that the
anticipated beam is safely terminated into a high-power beam
block or power meter.
1.
Plug in the power supply chassis and connect the umbilical
cables according to specifications.
2.
Verify that the LBO heater control temperature is at the proper
factory-set temperature.
3.
Turn the external cooling water supply on.
4.
If the control computer was disconnected, reconnect the cable
between the control computer and the power supply chassis.
5.
Boot the computer and log in (if necessary).
6.
Set the power switch on the power supply chassis to the ON
position.
7.
Insert the key into the keys witch and turn to the ON position.
8.
Launch the Evolution-15/30 control software on the control
computer.
9.
After the control software communicates with the Evolution-15/30 and all interlocks are met, the STOP indicator will
light, indicating that laser can be started.
Note: If the FAULT indicator on the power supply chassis is
blinking, or if the FAULT state indicator on the control software is illuminated, see the trouble-shooting guide for assistance in clearing the interlocks.
10.
Set the Current Control in the control software to the nominal
low current setting.
11.
If the Evolution-15/30 is to be internally Q-switched, set the
QSW Frequency control to the proper rep-rate (e.g., 1.0 kHz),
and set the QSW MODE switch to INTERNAL.
12.
If the Evolution-15/30 is to be externally Q-switched, connect
a TIL-level signal (at least 1 JlS duration) at the proper
frequency to the EXT QS TRIG IN connector on the front
panel of the power supply chassis, and set the QSW MODE to
EXTERNAL. Q-switch operation is synchronized to the rising
edge of the input pulse.
5-2
Daily Operation
The Evolution-15/30 was optimized at a specific Q-switch repetition rate. Operating the laser at a significantly different rate
may result in decreased performance or optical damage.
13. Rotate the output shutter open on the front of the Evolution-15/30. Ensure that the laser output will be directed into an
appropriate termination (e.g. beam dump, power meter,
Ti:sapphire rod, etc.)
The following procedure will result in a laser beam emitting
from the Evolution-15/30 output port. Ensure all persons in the
room are using adequate laser eye protection. Ensure that the
anticipated beam is terminated properly.
14. Slide the Laser State slider to the RUN position. The LASER
ACTIVE LED on the power supply chassis will illuminate, as
will the LASER ACTIVE LED and the FIRE LED in the
control software. The Current Monitor will ramp up to the
set-point current in approximately five seconds.
15. Measure the output power with a power meter capable of
measuring at least 100 Watts. Within several minutes, the
527 nm power should be the same or close to the power that
was previously measured at the low current setting.
16. Manually increase the current setting at a rate of no more than
1 A per second to the medium current setting. Monitor the
power continuously while increasing the current to ensure a
monotonic increase in power with current.
If the power is low, wait ten minutes for the laser temperature
to stabilize.
When the power reaches the value corresponding to the
medium setting, increase the current to the high setting and
verify the power.
If the beam does not reach operating power it may be neces-
sary to optimize the lasing output as described in
"Chapter Seven: Maintenance and Troubleshooting".
5-3
Evolution-15130 Laser Operator 's Manual
System
Shutdown
Long-Term
Shutdown
1.
Slide the Laser State switch to STOP in the control software.
The shutter will close and the diodes will shut off immediately.
2.
Close the control software window.
3.
Thrn the key in the keyswitch to the OFF position.
4.
Remove the key from the keyswitch.
5.
Thrn the main power switch off.
6.
Turn the water chiller off.
If the Evolution-15/30 must be disconnected from line voltage for an
extended period of time, the LBO crystal temperature must be
ramped down slowly to room temperature to avoid thermal shock to
the crystal. Use the following procedure.
1.
Press and hold the down arrow (lower right) on the LBO
Heater Control until the temperature setting is 75°F or from the
control software change the LBO software, change the LBO
setting to 7 5°F.
2.
Allow the crystal temperature to ramp down until it reaches
75°F.
3.
Turn the Evolution-15/30 power supply off and disconnect the
power cord.
4.
To return the Evolution-15/30 to normal operation, plug in the
power supply and reset the temperature to the factory-set
temperature. When the LBO crystal reaches the set point, the
laser can be operated normally.
5-4
External Control Computer
CHAPTER SIX: EXTERNAL CONTROL COMPUTER
The Evolution-15/30 comes with a commercial laptop computer and
software to control and monitor the functions of the laser via
USB/RS-232 interface. Because of frequent changes in the availability of specific computer models, the particular computer delivered with each laser may vary in brand and features, but in general,
it will have a Pentium-class processor 2:....400 MHz, 2:.._32 MB of
RAM, 2:....2 GB hard drive, a CD-ROM drive. The control software
for the Evolution-15/30 is pre-installed and tested with each laser,
and is also delivered on CD-ROM.
The Evolution-15/30 was built and tested using the control
computer and control software that shipped with the laser.
Coherent does not endorse or support the use of other
computers or software to control the Evolution-15/30; doing so
may void the warranty and/or cause damage to the laser.
USB/RS-232
Connection
The control computer is connected to the Evolution-15/30 power
supply using the included USB/RS-232cable.
Control
Software
The included control software for the Evolution-15/30 is called
"Evolution-15/30 Control", and is accessed by a shortcut in the
"Programs" folder in the "Start" menu. The exact layout of the front
panel varies depending on the version of the software, but all
versions of the software share the same general controls. The latest
version of the software is available by contacting an authorized
service representative.
This chapter describes the controls for the Version 4.1.6 of the software.
6-1
Evolution-15/30 Laser Operators Manual
Main Controls
I..
.....
Figure 6-1. Evolution Control Software
6-2
External Control Computer
Table 6-1. Main Controls
CONTROL
RUN/STOP
FUNCTION
Button control (on the software, not the front panel of the power supply); changes the state
of the Evolution-15/30.
RUN. The laser diodes turn on and the Evolution-15/30 starts lasing.
COUNTDOWN. If the RUN state is entered from the STOP state, COUNIDOWN will
occur before lasing begins, during which time a tone will emit and the LED on the
power supply and laser bench will flash.
STOP. The Evolution-15/30 stops lasing.
FAULT. This state is initiated if the interlock circuit is tripped; in this state, the laser
cannot be put into the RUN state until the interlock is cleared and keys witch on the front
of the power supply is cycled off and on.
Run/Stop/Fault
/CountDown
/Ramping
LED indicators; describes the Evolution-15/30 state (see above).
Keyswitch
LASER FAULT LED indicator; describes the state of the access control key:
Illuminated = The key is in the OFF position
Flashing =The keyswitch must be recycled to reset the FAULT state
Laser Active
LED indicator on the front panel of the power supply; illuminates when current is supplied
to the laser diodes.
Current Setting
Numeric control accessed via software; sets the output current of the laser diodes (in A) up
to the factory limit set point.
The setting can be entered directly, or incremented by 0.1 A using the adjacent buttons.
When the current setting is increased, the current will ramp up to the setpoint at a factory-set
rate (max 0.3 Nsec), and the Countdown LED will illuminate.
When the current setting is decreased, the current will decrease immediately without
ramping.
Current Monitor
Software-driven numeric/meter indicator; monitors the current (A) detected by the power
supply.
Evolution Settings
Button control accessed via software; shows or hides additional controls and indicators.
Exit & Save
Button control accessed via software:
Stops the laser (if running)
Stops execution of the control program
Saves the settings
6-3
Evolution-15/30 Laser Operators Manual
SYSTEM Panel
Figure 6-2. Control Software SYSTEM Panel
6-4
External Control Computer
Table 6-2. Control Software SYSTEM Panel
CONTROL
QSWMODE
&
FuNCTION
Slider control to set the mode of the Q-switch driver and LED indicators to show the active
Q-switch mode.
Changing Q-switching modes is not possible while the laser is in RUN mode.
INTERNAL
RF power on, Q-switch trigger source is the internal clock on the interanl main circuit board,
rep-rate set by the software QSW Frequency control.
EXTERNAL
RF power on, Q-switch trigger source is the EXT QS TRIG lN BNC on the front panel of the
power supply. The external trigger frequency must be > 500 Hz, or the laser will interlock.
HOLD OFF
RF power on, no Q-switch trigger(s). Used to check alignment of the Q-switch(es) during
construction and servicing of the laser.
CWRFOFF
CW RF power off. Used for setting and checking laser cavity alignment during construction
and servicing of the laser.
QSW Frequency
[kHz]
Numeric control to set the frequency of the internal Q-switch trigger source.
QSW Pulse Width
[J.LS]
Numeric control to set the width of the internal trigger pulse to the Q-switch driver.
Elapsed Time
Numeric indicator of the elapsed cumulative hours and minutes of laser operation.
Low Frequency
Enable
Boolean indicator that the low frequency mode has been enabled (see control on Factory
panel), and the QSW LOW FREQ interlock has been disabled.
6-5
Evolution-15130 Laser Operator :s- Manual
FAULT Panel
Figure 6-3. Control Software FAULT Panel
Table 6-3. Control Software FAULT Panel
FuNCTION
CONTROL
COVER/USER
illuminated if any of the micro-switches on the Evolution- 15/30 laser bench are not engaged,
or if the user interlock is open. Check covers or interlock defeats on laser bench and door
interlock switch or interlock defeat, then cycle keyswitch to clear.
FLOW
illuminated if the water flow from the chiller is less than 4 GPM. Check chiller function,
water pressure, reservoir level, and water hoses to ensure adequate flow, then cycle
keyswitch to clear.
LBO TEMP
illuminated if the LBO temperature is outside a 2° window around the factory set point.
Allow temperature to return to specified temperature range.
QSWLOWFREQ
illuminated if the QSW MODE is EXTERNAL and the external source of triggers drops
below 500 Hz. Ensure that the source of external Q-switch triggers is producing TfL pulses
at 500 Hz or higher. Note that this interlock is disabled if the ENABLE LOW FREQUENCY
control (factory panel) is in the ON position.
QSWTEMP
illuminated if the thermal sensor in the Q-switch exceeds safe operating temperature. Check
chiller function, water pressure, reservoir level, water hoses, and water contamination, then
cycle keyswitch to clear.
QSWVSWR
illuminated if the Q-switch driver detects a significant amount of power reflected from the
Q-switch. Check cable connections between the power supply and the laser head. Also check
for adequate water flow, then cycle keyswitch to clear, and change to INTERNAL or
EXTERNAL Q-switch triggering to test for error. If the problem persists, contact an au thorized service representative.
COMMERROR
illuminated if communications are interrupted between the computer and the Evolution-15/30 power supply. Check USB/RS-232 cable connections and ensure that the power
supply is turned on. Exit the control software, cycle the AC on the power supply, and restart
the control software to clear.
6-6
External Control Computer
Table 6-3. Control Software FAULT Panel (Continued)
CONTROL
FuNCTION
DRIVER TEMP
illuminated if the temperature of the Diode Drive (PET) heat sink becomes overheated due
to inadequate aitflow to the driver, or a shorted or "over current" condition. Check aitflow
of the power supply and allow it to run without lasing for at least 10 minutes, then restart the
laser.
DIODE TEMP
illuminated if the temperature sensor located inside the laser head and mounted on the diode
array heat sink exceeds safe operating temperature. Turn off power supply, allow the chiller
to run for 10 minutes, then restart the laser, running at a lower current.
CLEAR FAULTS
Enables the user to clear any latched faults - an alternative to cycling the keyswitch.
6-7
Evolution-15/30 Laser Operator :SO Manual
ERROR LOG
Panel
The ERROR LOG panel records all fault conditions, fault corrections, and their timestamps. The path and file name of the error log
is shown in the top text box. The faults are shown in the lower text
box. A new error log file is created each calendar day with the date
included in the file name in YYYYMMDD format.
C.lProgran Frle.>\Evoluhon_3 O'Evolulion_Log\
'!, Evululiull_lu!:J_2 0 030211 l l<l
2/3/ 2003 7 58 PM "-e.v Sw1tch
21312003 7 58 PM "-ey Sw1tch Cleared
Figure 6-4. Control Software ERROR LOG Panel
6- 8
External Control Computer
FACTORY Panel
..
Figure 6-5. Control Software FACTORY Panel
Figure 6-6. Control Software FACTORY Panel
CONTROL
FuNCTION
PASS CODE
Factory use only.
COMPORT
Sets the computer USB/RS-232 communications port (user settable).
CURRENT RATE
[A/SEC]
Current ramp rate in A per second. The operational range is 0.05 to 0.3 A/sec. The default is
0.3 A/sec. Do not exceed 0.3 A/sec.
MAX CURRENT
Maximum current setting for the laser diodes; set at the factory.
ENABLE LOW
FREQUENCY
Enables the Evolution to operate at Q-switch trigger frequencies below 500Hz (only available on power supplies shipped in 2003 or later). This control is set to the OFF condition each
time the program is started.
The Evolution should only be operated at frequencies below
500 Hz if the LBO temperature has been optimized for operation at 1 kHz or below. If the Evolution bas been optimized for
operation at a higher rep rate (e.g., 5kHz), operating at lower
rep-rates could cause optical damage.
6-9
Evolution-15130 Laser Operators Manual
6- 10
Maintenance and Troubleshooting
CHAPTER SEVEN: MAINTENANCE AND
TROUBLESHOOTING
Maintenance/
Service
The Evolution-15/30 has been designed for minimal and easy maintenance. However, certain routine operations are recommended to
maintain the system in good operating order. For more information,
contact an authorized service representative.
The maintenance and/or service of the laser must be performed
either by Coherent personnel or by persons authorized by
Coherent. Maintenance and/or service by unauthorized persons
results in all warranties being voided. Coherent assumes no
liability for any damages and malfunctions caused by disregarding or ignoring this information.
Lasing
Optimization
Cavity Mirror
Adjustments
All of the optical mounts in the Evolution-15/30 are securely
fastened to the rigid base plate of the optical laser bench, which is
temperature-stabilized. Nevertheless, the mirrors may become
slightly misaligned due to severe changes in room temperature,
bumps or shocks, or other stresses on the optical bench. Under these
circumstances, the end-mirrors of the Evolution-15/30 laser cavity
may require adjustment.
Improper adjustment of the Evolution-15/30 laser can result in
damage to the laser rod, LBO crystal, or Q-switch. Do not
attempt to adjust the Evolution-15/30 mirrors without a full and
complete understanding of the procedures outlined in this
chapter. Contact an authorized service representative for more
details or to answer any questions.
7-1
Evolution-15/30 Laser Operator :SO Manual
Laser protective eyewear MUST be worn to protect the eyes
from all wavelengths emitted by the Evolution-15/30. (See
Chapter Two: Laser Safety.)
The following procedure may be used to optimize the cavity mirrors.
Materials required:
•
Laser safety goggles
•
Infrared viewer or card
•
Two 1/8" ball-tipped Allen wrenches
•
Calibrated power meter capable of measuring at least 100 W
Procedure:
1.
If the Evolution-15/30 is operating, stop the lasing output by
sliding the Laser State switch to STOP button. (Pushing it is
not necessary to turn off the power to the power supply
chassis.)
2.
Lift the sheet metal cover from the Evolution-15/30 optical
laser bench.
3.
Locate the two interlock defeat plates (with orange warning
labels), and use them to lock down the cover interlock
switches. These defeats allow the Evolution-15/30 to be operated with the sheet metal cover removed. They must be
removed and the cover replaced as soon as the optimization
procedure has been completed.
4.
Cycle the keyswitch on the power supply chassis to clear the
cover interlock circuit.
5.
Place the power meter at the Evolution-15/30 output.
6.
Set the QSW MODE to INTERNAL and the QSW frequency
to the last operational frequency, typically 1 or 5 kHz.
7.
Start the laser at the low current setting, allow the power to
stabilize, and make note the stable power level.
8.
Remove the set screws covering the mirror adjustment ports on
the side of the housing. Place the screws in a safe place.
9.
Using the Allen wrenches, carefully adjust the vertical adjustment screw of the end-mirror while monitoring the power.
Make very small adjustments (less than 1 turn total travel).
7-2
Maintenance and Troubleshooting
Use this process to maximize the output power, and make a
note of the maximum stable power.
10. Using the same procedure, carefully adjust the horizontal
adjustment screw while monitoring the power. Again, make
very small adjustments (less than 1 turn total travel). Use this
process to maximize the output power, and make a note of the
maximum stable power.
11.
Set the laser state switch to STOP and set the QSW MODE
switch to HOLD OFF.
12. Set the current to the low setting. Set the power meter to its
most sensitive reading. Slide the laser state switch to RUN to
start the Evolution-15/30, and ensure there is no visible or IR
laser output (using an IR viewer or IR card).
Note: If there is some laser output, STOP, turn the laser off, and
contact an authorized service representative for assistance.
13. Slowly turn the current up to the high setting while monitoring
the laser power. The laser power must remain zero all the way
up to 21 A or 22 A.
Check for visible or infrared output (with an IR viewer or
card).
If there is any laser output at the high setting, STOP, turn the
laser off, and contact an authorized service representative for
assistance.
14. Monitor the power meter and make small(< 114 turn) adjustments to the horizontal adjustment screw of the end mirror in
both directions around the set point, and return the screw as
close as possible to its starting point.
Make the same adjustment scan for the vertical adjustment
screw on the same mirror.
If any lasing is detected at any time during these adjustments,
STOP, turn the laser off, and contact an authorized service
representative for assistance.
7-3
Evolution-15130 Laser Operator's Manual
15.
If no lasing was measured in the preceding step, turn the
current back down to the low setting at which the mirrors were
optimized.
16.
Stop the laser with the laser state switch, and slide the QSW
MODE selector to INTERNAL.
17.
Restart the laser with the laser state switch. Note the output
power.
18.
Fine-tune the vertical and horizontal adjustment screws on the
mirror to return the output power to the maximum value previously recorded.
19.
Once the power is optimized, slowly turn the current control
up to the medium current setting and then to the high current
setting while monitoring the power meter. When the current
setting is high, allow the laser to stabilize, and note the stable
power level.
If at any time the laser power starts to fluctuate rapidly, STOP,
turn the laser off, and contact an authorized service representative for assistance.
If this procedure does not enable the Evolution-15/30 to meet its
specified power, it may be necessary to optimize the LBO crystal
temperature.
LBO Crystal
Temperature
Optimization
Depending on environmental conditions, the optimum temperature
of the LBO crystal for efficient intra-cavity doubling may vary from
the factory set point.
The LBO crystal temperature can be varied ±1 ° F from the
factory-set temperature.
7-4
Maintenance and Troubleshooting
If, at any time, the Evolution-15/30 output power drops by more
than 2 W while optimizing the LBO temperature at the medium
current setting, turn the laser off immediately. (If the LBO
temperature is severely detuned and insufficient second
harmonic light is coupled out of the optical resonator, optical
damage may occur.) Reduce the current to the low setting,
perform the optimization procedure described in the next
section, then slowly increase the current to the medium setting
to check for optimized performance. Contact an authorized
service representative for assistance, if necessary.
If the temperature of the LBO heater deviates from the factory
setting by more than 1oF, an LBO TEMP Fault will occur. In
this event, return the setting to the factory setting, and restart
the optimization procedure in the opposite temperature direction. If the optimum LBO temperature setting is more than 1o
away from the factory setting, contact an authorized service
representative.
To Optimize the LBO Temperature:
1.
Note the factory temperature setting in the laser test document
that shipped with the laser.
2.
Note the present temperature setting if different from the
factory setting.
3.
Set the current to the medium setting.
4.
Tum on the laser.
5.
Allow it to stabilize for 10 minutes.
6.
Make a note of the power reading with a power meter.
7.
While monitoring the power, use the up and down arrows on
the LBO HEATER CONTROLLER to change the temperature
set point by 0.5° F.
8.
After the temperature stabilizes at the new setting, note the
power.
If the power has increased, change the temperature by another
0.5° Fin the same direction (up or down).
If the power has decreased, set the temperature 0.5°F in the
opposite direction.
7-5
Evolution-15/30 Laser Operator~ Manual
9.
Repeat step 8 until power is maximized.
10. When the output power is maximized, make a note of the
temperature setting for future reference.
Cleaning Optics
The Evolution-15/30 is sealed against dust and debris, but,
depending on the cleanliness of the environment, it is possible that
some dust may get into the optical laser bench.
Cleaning the Evolution-15/30 optics may result in misalignment
of the laser cavity. After cleaning, the cavity must be realigned
using the procedure in this chapter.
Cleaning the optics will require the optical cavity to be opened.
This procedure must not be executed without prior approval of
an authorized service representative. Unauthorized opening of
the seal will void the warranty, and may damage the laser.
The Evolution-15/30 is assembled with chemically cleaned parts.
To prevent contamination, do not work inside the housing unless
wearing latex gloves, fmger cots, or the equivalent.
Materials Required:
•
Safety goggles
•
•
Plastic gloves or finger cots
Scientific-grade lens cleaning tissue (Kodak brand or equivalent quality)
•
Reagent-grade methanol or acetone
•
Eyedropper
•
•
•
Hemostat (surgical pliers)
English hex-wrench set
Bright lamp or flashlight
The LBO crystal is kept above 320° F (160° C). Prolonged
contact with the LBO crystal housing can burn skin, melt
plastic, and ignite flammable material.
7-6
Maintenance and Troubleshooting
Never attempt to clean the LBO crystal or the Nd: YLF laser rod
in this system. Optical damage will occur and the warranty will
be voided if these two optics have been manipulated in any way.
If optical damage has occurred or cleaning of these optics is
necessary, contact an authorized service representative.
Accessing the
Evolution-15/30
Optics
Mirrors
1.
Turn the Evolution-15/30 power supply off.
2.
Remove the screws holding the metal cover in place and
remove the cover.
3.
Put the screws in a safe place.
4.
Remove the lid and place it on a clean surface.
Mirrors must be cleaned carefully with soft optical tissue and
reagent-grade methanol or acetone as described below.
1.
Always wash hands first in order to remove all dirt and oil residues and wear fmger cots or gloves at all times optics are
handled.
2.
Attempt to remove any surface contamination from the optic
with either a blower brush or gentle stream of dry, filtered
nitrogen or air. This will remove any particulates that would
otherwise be dragged across the optic's surface if cleaning
with solvent is necessary. Ensure that the contamination is not
merely blown onto another optical surface.
3.
If solvent cleaning is necessary, hold one sheet of lens tissue
over the optic to be cleaned.
4.
Using an eyedropper, place a single drop of spectroscopic-grade methanol or acetone on top of the lens tissue.
5.
Drag the lens tissue across the optic once only.
6.
If a residue of solvent is left on the optic, repeat the procedure
using less solvent and a new lens tissue until no residue
remains.
For Hard-toReach Optics
1.
Wear finger cots or gloves.
2.
Fold a piece of lens tissue repeatedly to form a pad approximately 1 em wide.
7-7
Evolution-15/30 Laser Operator's Manual
3.
Hold the pad with a pair of hemostats so 3 mm of the folded
edge protrudes from the hemostat blades.
4.
Saturate the pad with spectroscopic-grade methanol or acetone
and shake to remove excess solvent.
5.
Reach slightly below the center of the optic and wipe the
surface of the optic toward the outside in one motion. Be
careful that the tip of the hemostats does not scratch the optic.
6.
Repeat the operation with a clean tissue on the other faces of
the optic.
Q-Switch
The Q-switch can be difficult to clean; attempt to clean only if dust
or debris is clearly visible. When cleaning the Q-switch crystal
faces, it is easier to remove the U-shaped cover around the Q-switch
in order to gain unobstructed access to the quartz faces.
Routine
Maintenance Cooling Water
To prevent metal corrosion and algae growth in the closed loop
cooling water system of the Evolution-15/30, Coherent recommends
using OPTISHIELD corrosion inhibitor. This chemical treatment
prevents galvanic corrosion from dissimilar metals and prevents
oxidation of ferrous metals in the system, and acts as an effective
algaecide. The first-time application of OPTISHIELD is normally
performed at the factory when the Evolution-15/30 is manufactured.
Coherent recommends changing the OPTISIDELD solution every
6 months for most systems.
Follow the procedure below to change OPTISHIELD in the cooling
water system.
Before handling OPI'ISHIELD water treatment, read the Material Safety Data Sheet included in Appendix C that describes the
potential hazards and handling precautions associated with this
chemical. This chemical may be harmful if swallowed, inhaled,
or absorbed through the skin or eyes.
Use only steam-distilled water in the Evolution-15/30 cooling
system. The use of de-ionized or common tap water may cause
corrosion damage.
7-8
Maintenance and Troubleshooting
Directions for
New Systems,
First-Time Use
Directions, After
First-Time Use
1.
Flush the cooling circuit with distilled water.
2.
Fill cooling system with distilled water-leaving 5% volume for
OPTISHIELD.
3.
Calculate system capacity/volume in gallons. (Example:
1 gallon (3.8 L) of OPTISHIELD to 20 gallons (75.7 L) of
water for first "coating cycle")
4.
Add OPTISHIELD to the distilled water.
5.
Circulate this solution for about 30 minutes.
6.
Drain fluid. DO NOT RINSE!
7.
Fill cooling system with distilled water, leaving 10% volume
for OPTISHIELD.
8.
Add OPfiSHIELD to the distilled water. (Example: 1 gallon
(3.8 L) of OPTISHIELD to 10 gallons (37.9 L) of water)
Every 6 months
1.
Drain used fluid from the chiller.
2.
Flush the chiller with clean distilled water.
3.
Change particle filter.
4.
Add 1 pint of OPfiSHIELD water treatment
(Coherent Part# 470-9345).
5.
Fill the chiller with steam-distilled water.
6.
Run the system.
7.
Refill the reservoir after the water lines and head have filled
with water.
Use only steam-distilled water. The use of de-ionized or common
tap water may cause corrosion damage.
8.
The system is ready for use.
7-9
Evolution-15130 Laser Operator's Manual
Troubleshooting
This section contains a general user-troubleshooting guide. It is
provided to assist in isolating some of the problems that might arise
while using the system.
A complete repair procedure is beyond the scope of this manual. For
information concerning repair by Coherent, see Appendix titled
"Warranty" or contact an authorized service representative.
Troubleshooting
Guide
Use this guide if Evolution-15/30 performance drops unexpectedly.
If you take corrective measure and are unable to bring the Evolution-15/30 performance up to specification, call an authorized
service representative for assistance.
Table 7-1. Symptom: Laser Will Not Start
POSSffiLE CAUSES
No ACpower
CORRECTIVE ACTION
Check that the green "AC Power" LED is illuminated.
If not, check that the breaker on front of the power supply is in the correct
position.
Check that the power cord at rear of power supply is tight.
Check fuse.
Interlocks not met
Check interlock display on power supply.
If there are lighted interlock LEDs, turn keyswitch off and back on to clear
latched interlocks.
Investigate any interlocks that are not cleared by this action (e.g., make sure the
chiller is turned on and the hoses are not constricted, make sure the cover is on,
make sure the user interlock is in place, etc.).
See Chapter Four: Controls and Indicators, for more information about each
interlock.
Keyswitch not in ON position
Turn the keyswitch to the ON position (vertical). The key cannot be removed
when it is in the ON position.
Communications error with
laptop
Check for good connection of USB/RS-232 cable.
Exit Evolution-15/30 control software application.
Switch AC power on the Power Supply to OFF.
Wait 5 seconds.
Switch AC power ON.
Re-launch Evolution-15/30 control software application.
7 - 10
Maintenance and Troubleshooting
Table 7-2. Symptom: Variations In Output Power
CORRECTIVE ACTION
POSSIBLE CAUSES
LBO crystal temperature has
drifted
Check the output power across the tuning range of the LBO crystal for the
highest output power, as described in Chapter Seven: Maintenance and Troubleshooting.
Water temperature variation
Make sure that the water chiller temperature is adjusted to the correct temperature that was set when it was installed (typically in the range 62"F (l7°C) to
81°F (27°C).
Cavity optics out of alignment.
The cavity mirrors can be adjusted slightly to optimize the output power.
Read the detailed instructions in Chapter Seven: Maintenance and Troubleshooting, before attempting to adjust the mirrors.
Optics are dirty
Inspect the optics for dirt or contamination. If dirty, clean the optics as
described in "Cleaning Optics" on page 7-6.
Q-switch breakthrough
With the current at the high setting, tum the QSW MODE selector to the HOLD
OFF position, and tum the laser on.
Using an infrared viewer or card, check that there is no infrared and/or visible
output beam from the laser.
If there is any laser power, the Q-switch is malfunctioning or misaligned.
Contact an authorized service representative for assistance.
Table 7-3. Symptom: Emission Light Comes On, But No Output
POSSffiLE CAUSES
Output shutter is closed
CORRECTIVE ACTION
If front port is being used, rotate shutter open.
If side port is being used, check that the metallic disc has been removed.
QSW MODE set to HOLD OFF
Check the setting of the QSW MODE selector in the SYSTEM panel of the
control software.
Cavity optics are out of alignment.
If the cavity optics are so severely misaligned that the laser will not start, call
an authorized service representative for assistance.
7- 11
Evolution-15130 Laser Operators Manual
Table 7-4. Symptom: Power Is Below Specification
CORRECTIVE ACTION
POSSmLE CAUSES
Diode current set too low
Verify the expected output power for the low-, medium-, and high-power
settings.
Q-switch frequency set too high
or too low
Power output depends on Q-switch frequency. If the Evolution-15/30 is operated at a different Q-switch frequency than specified at time of order, contact
an authorized service representative for the power specification at that partieular frequency.
Cavity optics misaligned
The cavity mirrors can be adjusted slightly to optimize the output power. Read
the detailed instructions in "Cavity Mirror Adjustments" on page 7-1 before
attempting to adjust the mirrors.
LBO crystal temperature has
drifted
Check the output power across the ±1 o tuning range of the LBO crystal for the
highest output power.
Algae growth in cooling water
Follow maintenance procedure given in the paragraph titled "Routine Maintenance- Cooling Water" on page 7-8.
Diode power is low
After several thousand hours of operation, the optical power of the laser diodes
decreases, and the current to the diodes must be increased to compensate.
Contact an authorized service representative for assistance.
Table 7-5. Symptom: Laser Does Not Q-Switch or CW Laser Output
PossmLE CAUSES
CORRECTIVE ACTION
External Q-switch input not valid
If an external Q-switch signal is used, ensure that the signal is at least 4 V with
- 4 J..LS duration adjusted for maximum power output. Ensure the frequency is
set to the manufacturer tested rep rate (e.g. 5 K or 10 K).
QSW MODE set to CW RF OFF
Change setting of QSW MODE control to INTERNAL.
QSW BNC cable removed
If the QSW cable is removed, the Evolution-15/30 will report a VSWR error
and change to the CW RF OFF QSW MODE.
Verify that the BNC cables is attached at the power supply and laser bench.
7 - 12
Double Pulse Option
APPENDIX A: DOUBLE-PULSE OPTION
OveNiew
The Double-Pulse Option (DPO) produces two closely spaced,
high-energy laser pulses at repetition rates up to 10 kHz for applications in high-speed imaging and Particle Image Velocimetry (PIV).
This Appendix explains the theory of operation, a set-up and operation procedure, and a troubleshooting guide.
The Evolution-DPO incorporates hardware and software that enable
the Evolution laser to produce dual laser pulses at repetition rates
from 1 kHz to 10 kHz. The relative timing of the laser pulses can be
adjusted from 1 to 150 flS using the integrated software. The energy
of each of the pulses in the pair can also be controlled by the software (nominally adjusted to be identical in the two pulses). The total
energy of the two pulses depends on the repetition rate and the model
of Evolution laser.
Theory of
Operation
The Evolution is normally operated as a single-pulse, Q-switched
laser, commonly at a repetition rate of 1 kHz. Q-switching refers to
the process of changing the laser intra-cavity losses from a high
value, in which the laser does not emit laser light, to a low value, in
which a pulse of laser light can be emitted. The Evolution is
Q-switched by an acousto-optic device (referred to as the
"Q-switch"), in which an acoustic wave is resonantly driven by a
transducer driven by an RF amplifier.
The output of the RF amplifier is modulated on and off by a trigger
input. When no voltage is applied to the trigger input, the RF output
is applied to the Q-switch, and the cavity loss is high. When a positive logical high voltage is applied to the trigger input, the RF output
shuts off. (A more detailed explanation of the operation of the
Q-switch can be found in the Chapter Five: Daily Operation.)
In normal operation, a trigger pulse is applied to the Q-switch driver
with a duration that is long enough to extract all of the stored energy
in the laser rod, (typically a few microseconds). The duration of the
laser pulse is determined by several factors including the laser gain,
the cavity length, and the output coupling. The typical pulse duration
of the Evolution is around 150 ns to 200 ns(for a 20 mJ pulse at
1kHz).
The energy normally extracted in a single pulse can be extracted in
two pulses by adjusting the duration of the Q-switch trigger pulse.
This is the principle upon which the Evolution-DPO is based. In the
A-1
Evolution-15130 Laser Operator's Manual
simplest terms, two trigger signals are applied: the first pulse
extracts half the available stored laser energy, and the second
extracts the remaining energy after a user-selected delay time.
In more detail, the first pulse allows the laser to begin to extract
energy from the laser rod, but then turns the Q-switch back on
(preventing lasing) before all of the energy is extracted. After some
delay (e.g., 1-150 f..lS), a second trigger pulse is applied, and the laser
then depletes the remaining energy.
Typically the difference in the laser gain between the two pulses
results in different pulse durations between the first and second
pulse.
There are several advantages to this method of generating a double
pulse compared to conventional dual-laser-head technology:
System
Description
•
Both pulses are produced by the same resonator, ensuring that
they are collinear and have the same polarization
•
A single resonator has fewer components, is simpler to align,
and is more compact
•
The ratio of energy in the two pulses can be adjusted easily by
adjusting the duration of the first trigger pulse
•
The timing between the two laser pulses can be adjusted easily
by adjusting the timing between the two trigger pulses
•
The laser can be operated at any repetition rate that the Evolution can operate, with simple adjustments of the trigger pulses
to ensure a consistent energy ratio between laser pulses
•
The technique of dividing the energy into two pulses can be
extended to more than two pulses by adding and adjusting
more trigger pulses (contact Coherent for more information
about this option).
The DPO electronics are contained in a 1U rack-mount enclosure
(Figure A-1) designed to be mounted in the same rack as the Evolution power supply. The front panel contains three connectors:
•
Trigger In (BNC). Input for TTL level external trigger signal
(not 50-Q terminated).
•
Trigger Out (BNC). Produces double-pulse TTL level signal
capable of driving 50-Qload. Normally connected to "External
Q-switch Trigger Input" on Evolution power supply.
•
USB/RS-232 (type-A female). Connects to laptop computer
using supplied USB/R.S-232 A-male to A-male cable.
A- 2
Double Pulse Option
t1
tt
lRJGGffiOUr
lRGGffi IN
0
0
LSB
aQo
l: :\ "
----------·--Figure A-1. DPO Electronics Enclosure
Evolution DPO
Connections
and Controls
The connection diagram for the DPO is shown in Figure A-2. The
user provides a single TIL trigger signal at the repetition rate of the
laser (e.g., 1 kHz). This trigger pulse is connected to the input of the
DPO electronics, which produces the trigger signal for the Evolution
laser required to generate double-pulse output at the same repetition
rate as the input trigger.
The user external trigger source should produce a clean, TTL-level
trigger signal at the desired repetition rate of the dual-pulse output.
If the trigger source has a 50 (!line driver output, a 50 Q terminator
should be added to the input of the DPO. The DPO electronics are
triggered off of the rising edge of the input trigger, and pulses with
duration as short as 20 ns have been tested to work properly.
The DPO is controlled by a modified version of the standard Evolution control software. The general description of the Evolution
control software is provided in Chapter Six: External Control
Computer; this chapter only describes the controls for the DPO,
shown in Figure A-3. The control parameters for the DPO electronics are:
A-3
Evolution-15/30 Laser Operator's Manual
External Trigger Source
(customer)
TIL
CD
DPO Electronics
II
USB-
DPO Tri gger Si gnal
- ,
i,
Ji
. I
-_- + - - - ---
E v o l u t i o n - - - - - - - -....
- ...
- : ..
•
~
-
"''
--
OIW":"'OUT - "'' :
.r ,;.
rI I
il
Cca-EREm:
'
o:
-. RS-232~~~~~\
""'~""', -r
~ ~ ! or USB
i!
........_.,..YI.F,_.,._ I
-----·-----------·------------
~
1
I
.J
~
Laptop computer
~
t====siiiiiJ
Evolution-30 Power Supply
Figure A-2. Interconnection Diagram for Evolution-DPO
•
Tl [uS]. Numerical control of pulse width of first DPO trigger
pulse in microseconds
•
T2 [uS]. Numerical control of pulse width of second DPO
trigger pulse in microseconds
•
Delay [pS]. Numerical control of timing delay between the
falling edge of Tl and the rising edge of T2 in microseconds
•
DPO Output. Toggle switch control to enable or disable the
DPO output triggers (enabled by default)
•
DPO Err. Indicator illuminated when the control software
detects an error or is unable to communicate with the DPO
electronics
Note that the Evolution Q-Switch Mode is set to EXTERNAL,
which is required for DPO operation.
A-4
Double Pulse Option
Figure A-3. Control Panel in Evolution-DPO Control Software Showing DPO Controls
The range of values for the DPO timing signals is shown in
Table A-1.
Table A-1. Range and Increment for DPO Timing Signals
SIGNAL
MINIMUM [flS]
MAxiMuM [flS]
INCREMENT [flS]
T1
0.2
2.55
0.01
T2
0.3
5.1
0.02
Delay
1.28
163.2
0.64
There is an internal delay of - 5 ns with a jitter of up to 10 ns
between the rising edge of the input trigger and the rising edge ofT1.
Note that there will be a delay between the rising edges ofT 1 and T2
and the respective laser pulses. This delay is caused by the time
required for the laser to Q-switch after the start of the trigger, and
varies depending on the energy per pulse and repetition rate of the
laser.
A- 5
Evolution-15130 Laser Operator:s- Manual
DPOLaser
Operation
Characterize
Single-Pulse
Performance
Before operating the Evolution laser in DPO mode, it is important to
have a good operating knowledge of the laser in its single-pulse
mode of operation. Ensure that the user is familiar with the operating
principles and procedures provided in this manual. Specifically, the
user should record the standard laser operating parameters (diode
current, LBO temperature, and output power) at several different
power levels for each repetition rate at which it is planned to run the
laser in DPO mode. This data can be taken by triggering the Evolution with INTERNAL Q-switch mode and using the standard chiller
temperature and LBO temperature provided with the Evolution at
the time of installation. An example of these parameters is listed in
Table A-2.
Table A-2. Example Laser Parameters and Output Power for Single-Pulse
Operation of an Evolution-30 at 1 kHz Repetition Rate
LBO TEMP
(1KHz) [W]
CHIT..LER TEMP
[° C]
17.0
7.8
20
323.0
20.0
13.5
20
323.0
24.0
21.5
20
323.0
DIODE CURRENT
[A]
AVERAGE POWER
ConnectDPO
Signals
[oF]
1.
Connect the supplied USB/RS-232 cable to the DPO electronics and to the Evolution control computer.
2.
Connect the external trigger signal to the TRIGGER IN BNC
on the DPO box using a 50 O.BNC cable.
3.
Connect the TRIGGER OUT BNC to the External Q-switch
Trigger Input on the Evolution power supply using a 50-0.
BNCcable.
Note: if a 50-0.in-line terminator was supplied with the DPO
electronics, attach it in-line with the BNC cable at the Evolution power supply.
4.
Start the Evolution-DPO control software and verify that the
"DPO Err" indicator is not illuminated.
A- 6
Double Pulse Option
5.
SeHing DPO Timing
Parameters
Start the Evolution at a low current setting (e.g., 10 A), and
verify that the laser does not indicate any interlock faults. If the
trigger signals are not connected correctly, the QSW LOW
FREQ interlock will trip.
In this chapter it is assumed that the performance will be optimized
to provide equal energy in each of the two laser pulses (P1 and P2).
The value of timing parameters for equal pulse energy in DPO operation depend fundamentally on the repetition rate of the laser, the
delay between the pulses, and the pump level of the laser. Some
general guidelines for setting the parameters are:
•
For a given repetition rate, pump level, and delay setting, the
balance of energy between Pl and P2 is controlled by the value
ofT1
•
At low repetition rates (e.g., below 5 kHz), the value of T2 can
ordinarily be set to its maximum value (5.1 J..lS)
•
At higher repetition rates (e.g., 5kHz and above), the value of
T2 can be optimized to give higher average output power, but
cuts off the long, low energy tail of the second pulse
•
At all repetition rates, as the delay between pulses is increased,
the energy in P2 increases, due to the additional pump energy
absorbed during the delay time between pulses
•
Because the laser gain is higher before P1, the full-widthhalf-max (FWHM) pulse width of Pl will always be shorter
than the FWHM of P2
•
The maximum average output power of the Evolution in DPO
mode may be somewhat lower or higher than the average
power in single-pulse mode, depending on the repetition rate
and the delay between pulses
•
The exact timing of the peaks of T1 and P1 and of T2 and P2
will vary at different pump powers and repetition rates; in
general, the delay between T2 and P2 will be greater than the
delay between T1 and P1
If the Evolution was originally provided with the DPO option, a set
of DPO timing parameters measured at the factory was provided
with the laser. If the DPO option was ordered separately, refer to the
sample parameters listed in Table A-3. (Note: In both cases, these
parameters are intended to provide a starting reference point; final
optimization of the DPO parameters must be performed by the
customer for each individual application of the laser.)
A -7
Evolution-15/30 Laser Operator's Manual
Table A-3. Example DPO Parameters and Output Power for Operation
of an Evolution-30 at 1 kHz Repetition Rate
CURRENT [A]
AVERAGE POWER
(1 Kllz) [W]
Tl [ps]
DELAY [pS]
T2 [pS]
17.0
8
1.02
100
5.1
20.0
12.5
0.80
100
5.1
24.0
20
0.70
100
5.1
17.0
7.5
0.95
50
5.1
20.0
12
0.80
50
5.1
24.0
19
0.70
50
5.1
17.0
7.2
0.95
10
5.1
20.0
11.6
0.80
10
5.1
24.0
18.4
0.70
10
5.1
17.0
7.2
0.95
1.28
5.1
20.0
11.5
0.80
1.28
5.1
24.0
18
0.70
1.28
5.1
Pulse Energy
Measurement
To measure the energy balance between Pl and P2 precisely, an
instrument capable of resolving the energy of each pulse individually is required. In the event that an instrument capable of direct,
high-rep-rate, precisely timed energy measurement is not available,
the next-best option is to use the integrated exposure of triggered
frame-captures from a high-speed charge-coupled device (CCD)
camera.
A somewhat simpler method is to use a fast (few nanosecond
rise-time) photodiode and a high-speed digital oscilloscope to
monitor an indirect reflection of the DPO output. In this arrangement, the energy of each DPO pulse is proportional to the integrated
photodiode signal; i.e., the area under the photodiode trace in units
of volt-seconds. Many digital oscilloscopes can measure the area of
a signal directly. Alternatively, the signal can be captured and the
area can be integrated numerically or manually. Because the photodiode traces of Pl and P2 are approximately triangular, half the
product of the peak voltage and the FWlTh1 gives a reasonable
first-order approximation of the area.
A- 8
Double Pulse Option
Note that the sum of the energies of Pl and P2 in DPO mode will be
slightly lower than the pulse energy in single-pulse mode at the same
repetition rate and diode current. This can be explained by the fact
that the gain for P2 is always lower than for Pl, resulting in lower
extraction efficiency for P2. Furthermore, if the delay between Pl
and P2 is relatively long (e.g., 100 !J.S), the gain for Pl will also be
reduced by the decreased pump duration between the end of P2 and
the start of Pl.
DPO Parameter
Optimization:
Energy
Measurement
Method
Assuming a photodiode is being used to monitor the signals, use the
following procedure to set the energy of Pl and P2 equal.
1.
Determine the average output power level needed for the
experiment, and set the laser parameters (LBO, diode current)
according to the single-pulse parameter table.
2.
Place a power meter and photodiode at the output of the laser.
3.
Set the delay to the desired value between the two pulses.
4.
Set T2 to the maximum at 5.1!J.S (assuming low repetition rate
operation).
5.
Set T1 close to the reference value in the table provided for the
Evolution, or to the value given in the example reference data
in this manual.
6.
Turn the Evolution on and set the current to the operating
value.
7.
Measure the area of the photodiode signal for P1 and P2.
8.
Adjust the value ofT1 in 10-ns increments, andre-measure the
area of each pulse after each adjustment.
9.
Adjust T1 until the two areas are almost the same, which
means the energy of the two pulses are about the same.
10. If the total power must be increased, increase the pump
current.
11.
Repeat the above adjustment of T1 to get the same energy for
each pulse.
12.
If the system is operating at higher repetition rates (>5kHz),
decrease the value of T2 while monitoring the average power.
13. When the average power is maximized, readjust T1 to get the
same energy for each pulse.
A-9
Evolution-15/30 Laser Operators Manual
DPO Parameter
Optimization:
Average Power
Measurement
Method
At lower repetition rates (e.g., 1 kHz), a simpler method can be used
to get approximately equal energy for each pulse by measuring the
average power.
1.
Place a power meter at the output of the laser.
2.
Set the delay to the desired value between the two pulses.
3.
Set Tl and T2 at the reference value in the table provided for
the Evolution, or to the value given in the example reference
data in this manual.
4.
Turn the laser on and ramp the current up to the operating
power level; measure the average power.
5.
Reduce T2 to its minimum setting (0.3 ~s) .
6.
Adjust Tl until the power is about half of the power measured
in step 4.
7.
Increase T2 to the maximum setting (5.1 ~s) . If the average
power doubles from step 6, the energy in Pl and P2 should be
about the same.
A - 10
Material Safety Data Sheets
APPENDIX
8: MATERIAL SAFETY DATA SHEETS
This Appendix contains the material safety data sheet (MSDS) that
is supplied by the vendor of the chemical algaecide that is used in the
Evolution-15/30 laser closed loop cooling system. Read the MSDS
carefully before handling or disposing of the chemical (or cooling
water containing the chemical) described therein. The information
contained in the MSDS description is applicable exclusively to the
chemical substance identified therein and for its intended use and to
the unit quantity intended for that purpose. The information does not
relate to, and may not be appropriate for, any applications or larger
quantity of the substance described. The product is intended for use
by individuals possessing sufficient technical skill and qualification
to use the material with suitable discretion and understanding of the
risk of handling any potentially hazardous chemical.
This information has been obtained from sources believed to be reliable and accurate but has not been verified independently. Accordingly, NO REPRESENTATION OR WARRANTY, EXPRESSED
OR IMPLIED, WITH RESPECT TO MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE is made with respect
to the information contained in the MSDS. For further information,
contact the manufacturer at the address listed on the MSDS sheet.
B -1
Evolution-15130 Laser Operator's Manual
MATERIAL SAFETY DATA SHEET: OPfiSIDELD
June,1999
DATE REVIEWED:
DISTRIBUTOR:
OPTI TEMP INC.
P.O. Box 5246
Traverse City, Michigan
49696
Telephone: 231-946-2931
Emergency Hot Line
Chern-Tel 800-255-3924
International 813-977-3668 (Collect)
USE OF PRODUCT: Treatment of select cooling water systems.
SECTION I. Product Identification
Special Components Chemical Names
This is a proprietary blend that contains the following components:
%In Product
Sodium Nitrate
< 1%
Sodium Molybdate
1-2%
Sodium Hydroxide
1-2%
Phosphoric Acid
< 1.5%
Triazole
<2.5%
The Hazardous Materials Index Rating is as follows: Health=l; Flammability=O; Reactivity=!
SECTION ll.
Physical Data
•
•
%Volatiles: Nil
•
Odor: Mild
•
•
Specific Gravity: 1.03
•
pH of 100% solution (concentrated) 11 to 12; typica111.5
Color: Light Golden-Yellow
Solubility: 100% in water
SECTION lll.
Fire and Explosion Hazard
•
Non-Flammable
•
Flash Point: Unknown
B -2
Material Safety Data Sheets
MATERIAL SAFETY DATA SHEET: OPfiSillELD
SECTION IV.
Reactivity Data
•
Stability: Stable
•
Polymerization: None
•
Exposure to Other Chemicals: Keep away from concentrated acids
•
Reactivity in Water: None
SECTION V.
Shipping Information
Regulation: This material is not a DOT regulated material.
This product is a freezable liquid when and where applicable.
SECTION VI.
Spill
Small spills: Small spills may be soaked up using common absorbent material, and using appropriate safety equipment. Dispose of and handle in accordance with local, state, and federal regulations.
Large spills: Large spills must be pumped into suitable containers located in diked areas.
Residual material must be cleaned up with water. Dispose of and handle in accordance with local,
state, and federal regulations.
SECTION VII.
First Aid
•
Ingestion: Give milk or water, induce vomiting, and get medical attention.
•
Skin: Flush with fresh water, wash with soap and water. Remove contaminated clothes and
shoes.
•
Eyes: Flush with fresh water for at least 15 minutes. Get medical attention.
•
Inhalation: Inhalation must not occur during normal operation. However, should it occur,
close container and move to well-ventilated area. If irritation persists, get medical attention.
SECTION VIII.
Special Instructions
•
Do NOT pressurize container.
•
Keep container closed at all times when not in use.
•
Store in cool area above 60° F. Do not allow fluid to freeze.
•
Use in well-ventilated area. Do not breathe mist or vapor.
•
Wash hands thoroughly after handling product.
•
Protect eyes with safety goggles or glasses with side shields.
B- 3
Evolution-15130 Laser Operator's Manual
B-4
Warranty
WARRANTY
Coherent, Inc. warrants to the original purchaser (the Buyer) only,
that the laser system, that is the subject of this sale, (a) conforms to
Coherent's published specifications and (b) is free from defects in
materials and workmanship.
Laser systems are warranted to conform to Coherent's published
specifications and to be free from defects in materials and workmanship for a period of twelve (12) months. This warranty covers travel
expenses for the first ninety (90) days. For systems that include
installation in the purchase price, this warranty begins at installation
or thirty (30) days from shipment, whichever occurs first. For
systems which do not include installation, this warranty begins at
date of shipment.
Optical
Products
Coherent optical products are unconditionally warranted to be free
of defects in materials and workmanship. Discrepancies must be
reported to Coherent within thirty (30) days of receipt, and returned
to Coherent within ninety (90) days. Adjustment is limited to
replacement, refund or repair at Coherent's option.
Conditions of
Warranty
On-site warranty services are provided only at the installation point.
If products eligible for on-site warranty and installation services are
moved from the original installation point, the warranty will remain
in effect only if the Buyer purchases additional inspection or installation services at the new site.
For warranty service requiring the return of any product to Coherent,
the product must be returned to a service facility designated by
Coherent. The Buyer is responsible for all shipping charges, taxes
and duties covered under warranty service.
Parts replaced under warranty shall become the property of Coherent
and must be returned to Coherent, Inc., Santa Clara, or to a facility
designated by Coherent. The Buyer will be obligated to issue a
purchase order for the value of the replaced parts and Coherent will
issue credit when the parts are received.
c-1
Evolution-15130 Laser Operators Manual
Other Products
Other products not specifically listed above are warranted to, (a)
conform to Coherent's published specifications and (b) be free from
defects in materials and workmanship. This warranty covers parts
and labor and is for a period of twelve (12) months from the date of
shipment.
Responsibilities
of the Buyer
The Buyer must provide the appropriate utilities and operating environment outlined in the product literature and/or the Preinstallation
Manual. Damage to the laser system caused by failure of Buyer's
utilities or the Buyer's failure to maintain an appropriate operating
environment, is solely the responsibility of the Buyer and is specifically excluded from any warranty, warranty extension, or service
agreement.
The Buyer is responsible for prompt notification to Coherent of any
claims made under warranty. In no event will Coherent be responsible for warranty claims later than seven (7) days after the expiration of the warranty.
Limitations of
Warranty
The foregoing warranty shall not apply to defects resulting from:
1.
Components or accessories with separate warranties manufactured by companies other than Coherent.
2.
Improper or inadequate maintenance by Buyer.
3.
Buyer-supplied interfacing.
4.
Operation outside the environmental specifications of the
product.
5.
Improper site preparation and maintenance.
6.
Unauthorized modification or misuse.
Coherent assumes no responsibility for customer-supplied material.
The obligations of Coherent are limited to repairing or replacing,
without charge, equipment which proves to be defective during the
warranty period. Repaired or replaced parts are warranted for the
duration of the original warranty period only. This warranty does not
cover damage due to misuse, negligence or accidents, or damage due
to installations, repairs or adjustments not specifically authorized by
Coherent.
C-2
Warranty
This warranty applies only to the original Buyer at the initial installation point in the country of purchase, unless otherwise specified in
the sales contract. Warranty is transferable to another location or to
another Buyer only by special agreement which will include additional inspection or installation at the new site.
THE WARRANTY SET FORTH ABOVE IS EXCLUSIVE IN
LIEU OF ALL OTHER WARRANTY, WHETHER WRITTEN,
ORAL OR IMPLIED, AND DOES NOT COVER INCIDENTAL
OR CONSEQUENTIAL LOSS. COHERENT SPECIFICALLY
DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
C-3
Evolution-15/30 Laser Operators Manual
C-4
Parts List
PARTS LIST
Table D-1. Parts List
PART NUMBER
DESCRIPTION
EVOLUTION 15
Chiller for 11 0 V
100-5377
Chiller for 220 V
100-9277
Diode Array Laser 40 W
714-5022
Mirror, HR. 1053 run, 0 Deg, fold mirror
703-5018
Mirror, HR1053/527 nm, 0 Deg, end mirror
704-5019
EVOLUTION 30
Chiller for 110 V
100-9734
Chiller for 220 V
100-2036
Diode Array Laser 80 W
714-9358
Mirror, HR. 1053 run, 0 Deg, fold mirror
703-9792
Mirror, HR1053/527 nm, 0 Deg, end mirror
705-2010
COMMON FOR EVOLUTION 15/30
Mirror, HR. 1053 nm, 0 Deg, end mirror
703-5011
Mirror, HR. 1053, 45 Deg, fold mirror
705-5229
Mirror, Dicroic, 45 Deg, fold mirror
705-2011
Mirror, HR. 527 nm, 45 Deg, turning mirror
705-0791
Output Lens, AR 527 nm
701-1098
LBO assembly with crystal
100-2255
D-1
Evolution-15130 Laser Operator~ Manual
D-2
Glossary
GLOSSARY
oc
1fe2
Degrees centigrade or Celsius
Degrees Fahrenheit
Microns
Microradian(s)
Microsecond(s)
Beam diameter parameter
A
AC
AGC
Amperes
Alternating current
Automatic gain control
BPF
Band pass fllter
CDRH
em
cw
Center for Devices and Radiological Health
Centimeter(s)
Continuous wave
DC
Direct current
EMC
Electromagnetic compliance
GHz
Gigahertz
Hz
Hertz
IR
Infrared
kg
kHz
Kilogram(s)
Kilohertz
LED
Light emitting diode
Low voltage directive
op
~
~rad
~sec
LVD
m
rnA
MHz
mm
mrad
msec
mV
mW
Meter(s)
Milliampere(s)
Megahertz
Millimeter(s)
Milliradian(s)
Millisecond(s)
Millivolt(s)
Milliwatt(s)
Nd:YLF
nm
Neodymium doped yttrium Lithium Fluoride
Nanometer(s)
OEM
Original equipment manufacturer
PZT
piezo-electric transducer
Glossary - 1
Evolution-15130 Laser Operator's Manual
RF
rms
Rx
Radio frequency
Root mean square
Receive
TEM
Tx
Transverse electromagnetic (cross-sectional laser beam mode)
Transmit
VAC
VDC
Volts, alternating current
Volts, direct current
W
Watt(s)
Glossary - 2
Index
INDEX
A
Accessing the Evolution optics 7-3
Acousto-Optic Q-Switching 4-2
After ftrst time use 7-4
Average power 1-3
B
Beam diameter 1-3
Beam proflle 1-3
Beam safety shutter 2-10
c
Cable connection 6-1
CDRH
Compliance 2-4
Requirements 2-11
Closed loop chiller 1-3
Component description 4-5
Conftguration
Optical laser bench 4-3
Control computer 1-2
Control software 6-1
Cooling water
Routine maintenance 7-3
Cover safety interlocks 2-9
Current setting 5-1
D
Dimensions 1-4
Laser bench 1-4
Power supply 1-5
Diode pumping 4-1
Diode start-up and lasing initiation 5-1
E
Electrical safety precautions 2-3
Electronic control module 4-9
Emission indicators 2-9
Energy per pulse 1-3
Energy stability 1-3
Eye wear, protective 2-4
I
Installation 3-2
Chiller 3-5
Control computer 3-4
Laser bench 3-4
Location 3-2
Power supply 3-3
Interlocks, safety 2-9
Intra-cavity frequency doubling 4-2
K
Keyswitch
2-4
L
Labels
Translations 2-8
Warning 2-4
Laser bench dimensions 1-4
Laser diode power supply 4-9
Laser material 4-1
Laser pump chamber 4-5
Laser safety 2-1
LBO crystal and oven 4-5
LBO crystal temperature controller 4-9
LBO crystal temperature optimization 7-1
Lithium Triborate (LBO) 4-3
Location of controls 2-10
Location, installation 3-2
Long term shutdown 5-4
M
Main controls 6-2
Maintenance 7-1
Required to keep laser in CDRH compliance
Requirements 2-11
Routine 7-3
MESSAGES panel 6-10
H
0
Operating instructions 2-10
Optic
Products, warranty B-1
Optical laser bench
Assembly 1-1
Conftguration 4-3
Optical safety precautions 2-2
Output port shutter 2-10
Hazards 2-1
p
F
FACTORYpanel 6-11
FAULT panel 6-8
First-time use 7-3
Parts list C-1
Polarization 1-3
Index- 1
2-11
Evolution-15/30 Laser Operator :S Manual
POWER panel 6-6
Power supply 4-6
~s sembly
1-2
Dimensions 1-5
Front panel 4-7
Rear panel 4-8
Electronic control module
Product overview 4-1
Protective eye wear 2-4
Protective housings 2-9
Q
Q-Switch 4-5
Driver 4-9
R
Remote interlock connector
Requirements
CDRH 2-11
Cooling 4-1
Current (~) 3-3
Installation 3-1
Maintenance 2-11
Utility 3-2, 3-3
Routine maintenance 7-3
s
Safety
Electrical 2-3
Eye wear 2-4
Interlocks 2-9
Keyswitch 2-4
Laser 2-1
Optical precautions 2-2
Warning labels 2-4
2-8
4-9
Setting current 5-1
Shutdown
Long-term 5-4
System 5-4
Software control 6-1
Software menus
F~CTORY panel 6-11
FAULT panel 6-8
Main controls 6-2
MESSAGES panel 6-10
POWER panel 6-6
SYSTEM panel 6-4
Specifications 1-3
Start-up procedure 5-1
System shutdown 5-4
T
Troubleshooting 7-1, 7-5
Emission light comes on, but no output 7-6
Laser does not Q-Switch or CW laser output 7-7
Laser will not start 7-5
Power is below specification 7-6
Variations in output power 7-6
u
Utility requirements
3-3
w
Warning labels 2-4
Warranty
Conditions of B-1
Limitations of B-2
Wavelength 1-3
Index- 2
r-
r--
r
Evolution-15130 Laser Operators Manual
© Coherent, 1nc. 0812006, Printed in the U.S.A.
Part No. 1063004, Rev AA
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