| Calcite is a negative uniaxial
crystal that has high birefringence, wide spectral
transmission and availability in reasonably sized
rhombs. Although is a fairly soft crystal and is
easily scratched, it is ideal material used as visible
and near IR polarizers, such as Glan Taylor, Glan
Thompson and Glan laser.
Carefully selct the raw calcite crystals by inspecting
them with a cw green laser beam. We have perfected
a number of proprietary processes for cutting, grinding
and polishing good quality optical surfaces for
calcite prism. These skills are evident in the high
quality of the finished components, and enable polarizers
to be used with very high peak power lasers. |
Basic Properties of Calcite crystals
| Transparency
Range: 350nm - 2300nm |
Transparency Curve of Calcite |
| Particle
Shape: Crystalline Rhombihedral |
| Density:
2.7 g/cm 3 |
| Hygroscopic
Susceptibility:
low susceptibility to moisture |
| Mohs
Hardness: 3 |
| Thermal
Expansion Coefficient
a a =24.39 x 10 -6 /K; a c = 5.68 x 10 -6 /K |
| Crystal
Class
negative uniaxial with n o
=n a =n b ,
n e =n c |
Refractive
Indices, Birefringence ( D n = n e - n o ) and Walk-off
Angle at 45 “ ( r ):
n o = 1.6557, n e = 1.4852, D n = -0.1705, r = 6.20°
at 0.63 m m
n o = 1.6629, n e = 1.4885, D n = -0.1744, r = 6.32°
at 1.30 m m |
Sellmeier
Equation ( l in m m):
n o 2 = 2.69705 + 0.0192064/( l
^2 - 0.01820) - 0.0151624 l
^2
n e 2 = 2.18438 + 0.0087309/( l^
2 - 0.01018) - 0.0024411 l ^2
|
Specifications of Calcite
| Surface
Quality |
20/10
Scratch and Dig |
| Beam
Deviation |
<3
arc min. |
| Optical
Axis Orientation |
+/-0.5°
|
| Flatness
|
<l
/4 @ 632.8 nm |
| Transmission
Wavefront Distortion |
<
l /2 @632.8 nm |
| AR-coating
|
R<0.5%
|
|
Birefringent Crystals