Calcite

Calcite


Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It's a negative uniaxial crystal and mostly used as visible and near IR polarizers.
It 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 NIR polarizers such as Glan Thompson, and Glan Taylor and so on.

 Basic Properties

Transparency Range 350~2300nm
Partical Shape Crystalline rhombohedra
Density 2.7g/cm3
Thermal Expansion Coefficient Low susceptibility to moisture
Mohs Hardness 3
Thermal Expansion Coefficient aa=24.39x10-6/k; ac=5.68x10-6/k
Crystal Class Negative uniaxial with no=na=nb, ne=nc
Refractive index, birefringence(Δ=ne-no) and walk-off angle at 45℃(ρ) no=1.6557,ne=1.4852
Δn=-0.1705,ρ=6.20@630nm
no=1.6629,ne=1.4885
Δn=-0.1705,ρ=6.20°@1300nm
Sellmeier Equation no2=2.69705+0.0192064/(λ2-0.01820)-0.0151624λ2
ne2=2.18438+0.0087309/(λ2-0.01018)-0.0024411λ2

Capability

Common Specification
Size: max. 45mm
Length: max. 35mm
Optical Axis Orientation: +/-0.5°
Surface Quality: S/D 40-20
Optical Deviation: <1 arc minute
Parallelism <15 arc seconds
Perpendicularity <10 arc minutes
Flatness < Lambda/8 @633nm
Wave Front: < Lambda/8 @633nm
Coating: According to customer’s request