Calcite
Calcite is a natural crystal that has high birefringence, wide spectral transmission and availability in reasonably sized rhombs. It's a negative uniaxial crystals and mostly used as visible and near IR polarizers
Specifications:
| Optical Axis Orientation: | +/-0.5° |
| Diameter Tolerance : | +/-0.1mm |
| Thickness Tolerance: | +/-0.1mm |
| Surface Quality: | better than 20/10 scratch/dig |
| Parallelism: | < 30 arcsec |
| Flatness: | < l/8 @632.8nm |
| Perpendicularity: | < 5 arcmin |
| Wavefront Distortion: | < l/2 @632.8nm |
| Coating: | Coating upon Request |
Properties:
| Transparency Range | 350~2300nm |
| Density | 2.7 g/cm3 |
| Partical Shape | Crystalline rhombihedral |
| Hygroscopic Susceptibility | Low susceptibility to moisture |
| Mohs Hardness | 3 |
| Thermal Expansion Coefficient | a a=24.39x10 -6 /k; a c=5.68x10 -6 /k |
| Crystal Class | Negative uniaxial with no=na=nb, ne=nc |
| Refractive index, | n o =1.6557, n e =1.4852 Δn=-0.1705, ρ= 6.20° @ 630nm |
| birefringence(Δ=ne-no) and walk-off angle at 45°C (ρ) | n o =1.6629, n e =1.4885 Δn =-0.1705, ρ= 6.20° @ 1300nm |
| Sellmeier Equation | n o 2 =2.69705+0.0192064/(λ 2 -0.01820)-0.0151624λ 2 n e 2 =2.18438+0.0087309/(λ 2 -0.01018)-0.0024411λ 2 |