Calcite Crystal

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.

CASIX selects carefully 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.

1.Basic Properties of Calcite crystals

Transparency Range: 350nm - 2300nm


Transparency Curve of Calcite

Particle Shape: Crystalline Rhombihedral

Density: 2.7 g/cm3

Hygroscopic Susceptibility:
low susceptibility to moisture

Mohs Hardness: 3

Thermal Expansion Coefficient
aa =24.39 x 10-6/K; ac = 5.68 x 10-6/K

Crystal Class
negative uniaxial with no=na=nb, ne=nc

Refractive Indices, Birefringence (Dn = ne - no) and Walk-off Angle at 45“ (r):
no = 1.6557,  ne = 1.4852,  Dn = -0.1705,    r = 6.20° at 0.63 mm
no = 1.6629,  ne = 1.4885,     Dn = -0.1744,    r = 6.32° at 1.30 mm
Sellmeier Equation (l in mm):
no2 = 2.69705 + 0.0192064/(l2 - 0.01820) - 0.0151624l2
n e2 = 2.18438 + 0.0087309/(l2 - 0.01018) - 0.0024411l2


2.Specifications


Surface Quality

20/10 Scratch and Dig

Dimension tolerance

± 0.1mm

Beam Deviation

<3 arc min.

Optical axis orientation

+/-0.5°

Flatness l/4@632.8nm
Transmission wavefront distortion l/2@632.8nm
AR-coating R<0.5%