Calcite

Calcite is a negative uniaxial crystal that has high birefringence, wide spectral transmission and availability in reasonably sized rhombs. It is used as visible and near IR polarizers.

Basic Properties:

Transparency Range:

350nm - 2300nm

Mohs Hardness:

Hygroscopic Susceptibility:

Low

Thermal Expansion Coefficient

aa =24.39 x 10^-6/K; ac = 5.68 x 10^-6/K

Refractive Indices, Birefringence
( Δn = ne - no ) and Walk-off
Angle at 45°( r ):

0.63mm no=1.6557, ne=1.4852, Δn=-0.1705, r=6.20°
1.30mm no=1.6629, ne=1.4885, Δn=-0.1744, r=6.32°

Sellmeier Equation (l in mm):

n_o² = 2.69705 + 0.0192064/(l² - 0.01820) - 0.0151624l²
n_e² = 2.18438 + 0.0087309/(l² - 0.01018) - 0.0024411l²

Main Specifications:

Surface Quality:

20/10 Scratch and Dig

Beam Deviation:

<2 arc min

o and e Beam Angle:

<90 arc secondes

Orientation:

±0.5°

Flatness:

λ/4 @ 632.8 nm

Transmission Wavefront Distortion:

<λ/2 @632.8 nm

AR-coating:

R<0.5%

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