Download datasheet for Bonding Type by Nihon Dempa Kogyo Co., Ltd. (NDK)

Download datasheet for Bonding Type by Nihon Dempa Kogyo Co., Ltd. (NDK)
Optical Components
n λ/4 and λ/2 Wavelength Plates
l Terms and Definitions
Crystal Wavelength Plate: An element that uses the velocity
Extinction Ratio: This indicates a value for the phase accuracy of
difference between ordinary and extraordinary light beams to
a wavelength plate, and the conversion equation of the
create a phase difference between both beams; the difference is
extinction ratio V [%] and phase difference Г [deg] is as follows:
V [%] = 100×cosГ
obtained by using the birefringence of a crystal. When this
characteristic is used, a λ/4 wavelength plate converts
Io , 0 – Io , 90
Io , 0 + Io , 90
360 (ne−no)×t
linearly-polarized light into circularly-polarized light, and a λ/2
wavelength plate converts circularly-polarized light into
linearly-polarized light with its polarization plane rotated by 90
Io , 0 : Output in a parallel Nicol state
Wavefront aberration: This indicates the Peak-to-Valley
Io , 90 : Output in an orthogonal Nicol state
difference of a measured wavefront as a unit of design
ne : Refractive index of an extraordinary beam
wavelength: the Zygo Corporation’ s phase interference system
is used to provide the data.
no : Refractive index of an ordinary beam
P – V = (maximum phase angle – minimum phase angle)
t : Thickness of a phase plate
λ : Design wavelength
l Application
As shown in the figure below, wavelength plates are used mainly for picking up optical information files (DVD, etc) to prevent the back-talk
noise of laser beams.
Wavelength plate
Laser beam
Beam splitter
Laser diode
Example of how a wavelength plate is used
Optical Components
n λ/4 and λ/2 Wavelength Plates
l Features
1. A computer controlled and grown synthetic quartz crystal for optical
3. The bonding-type plate enables the influence on phase
components is used, and by accurately processing the thickness
accuracy caused by variations in optical rotation and the laser
of the plate, the extinction ratio is kept within a range of ±5%.
incident angle to be ignored. Therefore, it can be embedded in
2. A single board-type plate has good wavefront aberration and is
an optical system more easily.
thin. Therefore, it is convenient to use when bonded to a beam
splitter, etc.
Y factor
Y factor
X factor
Z factor
Z factor
X factor
Mechanism diagram of a λ/4 wavelength plate
Mechanism diagram of a λ/2 wavelength plate
l Standard specifications
Product name Single-board Type I
(x or y−cut)
Wavelength range
l Directional accuracy
of the optical axis
Single-board Type II
Bonding Type
Laser oscillation wavelength between 400 to 2,000 nm
Round plate of φ5 to 10 mm or square plate of
5 x 5 to 10 x 10 mm
Wavefront aberration
0.3 to 1.0 mm
Extinction ratio
0.5 to 1.0 mm
Max. λ/4 (λ = 633 nm transmission)
±5 %
Min. 99%
(AR coating on both surfaces)
Directional accuracy
of the light axis
Min. 98%
The reference and the optical axis
are parallel.
(AR coating on both surfaces)
±60’ (see the right)
* The size and thickness of wavelength plates can be changed
upon request.
The angle between the reference and the optical axis is 45°.
* The arrow shows the light axis.
l Environment Resistance
The following reliability tests guarantee the specified optical characteristics of NDK’ s optical components.
Subjected to high temperature
For 96 hours at +85 °C
Subjected to low temperature
For 96 hours at –40 °C
Subjected to high temperature and high humidity
For 96 hours at +60 °C and 95 %
Heat shock
10 cycles (one cycle is conducted for 30 minutes at –40 °C and 30 minutes at +85 °C)
Mechanical strength
No flaws after the surface is rubbed with absorbent cotton
Optical Components
n λ/4 and λ/2 Wavelength Plates
l How to Determine Wavelength Plate Specifications
When placing an order or asking for information, please inform us of the following items. (Check the boxes.)
1. Wavelength plate type
o Single-board type
: o Bonding type
2. Phase difference
o 1/4 wavelength plate
: o 1/2 wavelength plate
3. Used frequency
4. Coating
o Both surfaces
: o One surface
: o None
5. Dimensions
* Concerning wavelength plates other than square ones,
please give us your individual specifications.
6. Light axis direction
A : 0°
B : 45°
C : 22.5°
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