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 visible and near IR polarizers, such as Glan Thompson,   and Glan Taylor Glan laser.

Specifications

Dimension Tolerance	±0.1
Optical Axis Orientation	±0.5deg
Wavefront Distortion	<λ/2 at 633nm
Surface Flatness	<λ/4 at 633 nm
Surface Quality	20/10 Scratch and Dig
Parallelism	< 15 arc seconds
Perpendicularity	< 10 arc minutes
Clear Aperture	> Central 90%
AR-Coating	R<0.25%@ 1550 nm±40 nm

Physical and Optical Properties

Crystal Structure	Crystalline rhombihedral
Density	2.7 g/cm3
Mohs Hardness	3
Hygroscopic Susceptibility	Low
Transparency Range	350nm ~ 2300nm
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	no=1.6557, ne=1.4852, Δn = -0.1705, ρ=6.32 @633nm
Birefringence (Δn=ne-no)	no=1.6381, ne=1.4783, Δn = -0.1598, ρ=6.20 @1300nm
Walk-Off Angle at 45 deg (ρ)
Sellmeier Equations ( in um)	no2=2.69705+0.0192064/( λ2-0.01820)-0.0151624λ2
	ne2=2.18438+0.0087309/( λ2-0.01018)-0.0024411λ2

                                                                                               ORDER