OPERATING INSTRUCTION 3/5$-2 AUTOMATIC POLARIMETER .

OPERATING INSTRUCTION  3/5$-2  AUTOMATIC POLARIMETER .
3/5$-2 AUTOMATIC POLARIMETER
OPERATING INSTRUCTION
Please read through these operating instruction before using
MRC.VER.01-.
CONTENTS
I.
APPLICATIONS………………………………………………….1
II.
PERFORMANCE…………………………………………………1
III.
CONSTRUCTION AND PRINCIPLE……………………………2
IV.
HOW TO USE…………………………………………………….4
V.
MAINTENANCE……………………………………………….....6
VI.
COMMON BREAKDOWN AND HANDING…………………...6
I.
APPLICATION
The polarimeter is a kind of instrument for measuring the optical rotation of a
substance. Through measuring the optical rotation, the polarimeter can be used to
analyze the concentration, content, and purity of a substance. The 3/5$-2 automatic
polarimeter utilizes the photoelectric detection automatic balance principle and the
results are displayed by LCD. It not only preserves the advantages of 3/5$—1
polarimeter, but also overcomes the shortcoming of inconvenience in reading.
3/5$-2 automatic polarimeter is characterized by its small size, high sensitivity,
human error-free, easy reading, and so on. Furthermore, this instrument is also
suitable to the sample of low optical rotation which is difficult to be analyzed by
visual polarimeter. Therefore, it can widely be used in various fields of the organic
chemical industry.
Agriculture: use in contents analyses of agricultural antibiotic, hormone, microbial
agro-pharmaceuticals and agricultural products.
Medication: use in analyses of antibiotic, vitamin and glucose and in pharmacological
research of Chinese medicinal herbs.
Food: use in analyses of sugar, monosodium glutamate and soy sauce, in inspection of
their final products and determination of sugar content in food.
Petroleum: use in analyses of mineral oil and in control of oil ferment process.
Essence: use in analyses of essential oil.
Health: use in analyses of diabetics’ urine.
II.
PERFORMANCE
Measuring range: ±45°
Accuracy: ±0.02° (-15° ≤optical rotation ≤+15°)
±0.05° (optical rotation<-15° or optical rotation>+15°)
Minimum sample transmittance: 10%
Repeatability: ≤0.01°
Minimum indicating value: 0.002°
Monochromatic light source: LED (589.44nm)
Sample tube: 200mm, 100mm
Power supply: 220V±22V, 50Hz±1Hz
Outer size: 600mm × 320mm × 220mm
Weight (net): 30kg
RS232 interface
III.
CONSTRUCTION AND PRINCIPLE
The polarimeter utilizes LED, a small aperture stop and a lens to make up a
collimated point light source as shown in figure 1. The parallel light passes through
polarizer and becomes a polarized light whose vibration direction is denoted by line
OO in figure 2a. When the polarized light is passing through the Faraday modulation
coil, its vibration direction will generate a β angle swing (50Hz), as shown in figure
2b. Then the polarized light passes through the analyzer and is projected onto the
photomultiplier, an ac signal will be produced.
The optical zero point of the polarimeter is obtained when the polarization plane of
the polarizer is perpendicular to that of the analyzer (i.e. OO⊥PP), and at the time
α = 0 (see figure 3). A photo-signal of 100Hz will be obtained at the optical zero
point, due to the β angle swing which is generated by the Faraday coil, as shown in
curve C. But in the case where samples α 1 ° and α 2 ° exist, two 50Hz signals with
inverse phases are obtained, as shown in curve B’ and D’. Therefore, this will enable
the servomotor with an operating frequency of 50Hz to be driven. The polarizer will
be turned through α angle ( α = α 1 , or α = α 2 ) by means of a worm-worm wheel.
Now, the polarimeter has returned back to the optical zero point. At the frequency of
100Hz the servomotor keeps stationary and the optical rotation of the sample is
indicated.
1.LED
2.Condenser
3.Lens
4.Polarizer
5.Modulator
6.Collimator
7.Sample Tube
8.Analyzer
9.Lens
10.Filter
11.Aperture
12.Detector
13. Auto H.V
14.Pre-AMP
15.FREQ-Selection 16.Power-AMP
17.Non-Linear control
18.Speed-Feedback
19.Servo Motor
20.Drive Gear
21.Coder
22.Display
Fig.1 Block Diagram
A
D'
B'
t
t
a
-90°
B
a
C
ββ
a
0
a
t
+90° a
a
D
ββ
C'
t
ββ
Curve A: light intensity varied with the magnitude of optical
rotation α
Curve B,C,D: optical rotation αvaried with time t due to
Faraday effect (βswing)
Curve B',C',D': photo-current varied with time t—photo-signal
Figure 3
IV.
HOW TO USE
Operation
The instrument can be operated under normal illumination, temperature
and moisture. Extreme heat, excess moisture and corrosive gases may
cause damage to it. The instrument should be placed on a sturdy and
roughly level support.
Insert the power plug of the instrument into the 220V power source. [It is
required to use an AC electronic voltage regulator (1 kVA).] And
connect the grounding terminal to the earth reliably.
Put the test tube containing distilled water or other blank solvent into the
sample chamber, and close the cover. After the indicating value has
got stabilized, press the “clear” button. If there are air bubbles in the
test tube, the first thing should be done is to make the air bubbles
float on the protruded tube-neck. The atomized water-drops on the
both ends of the test tube should be wiped dry. The screw-nut of the
test tube should not be screwed down too tightly, so as to avoid stress,
otherwise, the readings may be affected. When placing the test tube,
care should be taken for the marked position and direction.
Take out the test tube, then, inject the sample to be measured into the test
tube. According to the same position and direction, put the test tube
into the sample chamber, then close the cover. Now the instrument
will indicate the optical rotation of the sample, “1” will shows on the
LCD. Remark: use the sample to wash the tube (inside) three or
five times before measurement.
Press the “Re-M” (repetition- measurement) button once, “2” will shows
on the LCD, the instrument display the result of 2nd measurement,
press the “Re-M” button again, “3” will shows on the LCD, display
the result of 3rd measurement, press the “1 2 3” button, shift display
the values of measurement each time, press the “Average” button,
display the value of average, the diode “AV” light.
If the polarized angle of the sample exceeds the measuring range, the
instrument will be oscillating at ±45°, at this time, the test tube
should be taken out, then the instrument will reset to zero
automatically. After diluting the sample, measure again.
Temperature correction
After taking the temperature of the sample, correct the measured result
by calculation.
V.
MAINTENANCE
The polarimeter should be placed in a dry place with good ventilation and kept from
corrosion. The instrument should be handled with care and vibration is not allowed.
The light source can be cleaned or changed if it is dirty or faulty.
If the instrument mechanism is operated in great friction, it is advisable to put some
oil into the bevel gears, the worm gear as well as the worm through the rear door.
If the instrument is damaged or some other parts are in failure, please ask professional
to check or contact with our repair department.
1. LED
2.Faraday Coil
3.Digital Display
4.Sample Chamber
5.Worm Gear
6.Correcting Slide
7. Holding Screw
8.Photo-Detector
9.Pre-A.M.P
10.Supply Transformer
11.Power Socket
12.Coder and Motor
13.Digital Board
14.Phase Potentiometer
15.Non-Linear Potentiometer
16.Freq-Selection Board 17.Power AMP. Board
18.Gain Potentiometer
19.Damp Potentiometer
20.H.V. Potentiometer
21.Current adjuster of sodium lamp
22.Light Source & H.V Board
23.Fan
24.Heat Sink
25.Servo motor
Fig.4 Inside View
The instrument was calibrated before leaving our factory. If test values deviate from
the correct ones, the instrument should be regulated with our standard quartz test tube
(available to customer’s order) or with the sample whose Optical Rotation is
accurately known.
Fig4 is the inside view of the instrument after taking off its top cover Undo the
holding screw shown in Fig.4, correct the test value by slightly moving the
correcting slide until the standard value is obtained. Then tighten the holding
screw. If the procedure above doesn’t succeed somehow, send the instrument
back to our factory for a thorough inspection.
VI.
COMMON BREAKDOWN AND HANDING
Breakdown Appearance
ANALYSES FOR REASON
Handling method
After turning on the power The LED or the fuse is Change
source (AC), the lamp doesn’t break.
light up.
After turning on the power The LED is break.
Change
source (DC), the lamp doesn’t The power board is break.
Send to our repair
light up.
department.
The instrument can’t balance The light can’t go through Clear sundries.
automatically.
the sample chamber.
The lamp is not lit up Waiting.
completely.
The
high
voltage
or Send to our repair
servosystem has problem.
department.
No display or display not Display circuit has problem.
Send to our repair
completely
department.
The sound is too loud.
Mechanical friction
Open the rear door,
moving parts oiling.
Repeatability is bad and value is The lamp is aging.
Change
deviating.
Send to our repair
The optical system has dust.
department.
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