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Rochon Polarizer
Rochon
polarizer is one of the earliest polarizer designs. They are made of two
birefringent crystal prisms cemented together. Both ordinary and extraordinary
beams propagate collinearly down the optic axis in the first prism under
the ordinary refractive index. Upon entering the second prism the ordinary
beam experiences the same refractive index and continues undeviated. The
extra-ordinary beam, however, now has a lower refractive index and is
refracted at the interface. The angle of refraction is further increased
at the birefringent material/air exit surface. Any separation angle can
be designed for specific wavelength upon the requirement. The separation
angle of standard products vs wavelength is listed in the following table.
Table - Rochon Polarizer Separation Angle vs Wavelength
|
Wavelength(nm)
|
MgF2
|
a-BBO
|
YVO4
|
Quartz
|
|
130
|
1.40
|
-
|
-
|
-
|
|
150
|
1.62
|
-
|
-
|
-
|
|
170
|
1.59
|
-
|
-
|
-
|
|
190
|
1.55
|
13.93
|
-
|
-
|
|
200
|
1.53
|
12.78
|
-
|
1.46
|
|
266
|
1.44
|
9.82
|
-
|
1.23
|
|
355
|
1.39
|
8.80
|
-
|
1.12
|
|
400
|
1.37
|
8.58
|
13.09
|
1.09
|
|
532
|
1.35
|
8.25
|
11.45
|
1.04
|
|
633
|
1.34
|
8.14
|
10.93
|
1.03
|
|
808
|
1.33
|
8.05
|
10.50
|
1.01
|
|
980
|
1.32
|
8.02
|
10.29
|
1.00
|
|
1064
|
1.32
|
8.00
|
10.22
|
1.00
|
|
1319
|
1.31
|
8.01
|
10.09
|
1.00
|
|
1550
|
1.30
|
8.03
|
10.03
|
1.00
|
|
2000
|
1.28
|
8.11
|
9.96
|
1.00
|
|
2500
|
1.25
|
8.23
|
9.91
|
-
|
|
3000
|
1.22
|
8.39
|
9.88
|
-
|
|
4000
|
1.13
|
8.83
|
9.83
|
-
|
|
5000
|
1.01
|
9.43
|
9.79
|
-
|
|
6000
|
0.85
|
-
|
-
|
-
|
Specifications
|
Material: Wavelength Range: Parallelism: Extinction Ratio: Surface Quality: Beam Deviation: Wavefront Distortion: Damage Threshold: Coating: Mount: |
a-BBO, Calcite, YVO4 or Quartz, etc. a-BBO: 190-3500nm, YVO4: 400-4000nm <1 arc minutes Quartz: >45dB; a-BBO/YVO4: >55dB 20-10 < 3 arc minutes < 1/4 @633nm > 500MW/cm^2 Single Layer MgF2 Black Anodized Aluminum |
