IR CALCITE PLATE POLARIZER
Calcite crystal exhibits absorption of input radiation at 3.390 and 3.507 micrometers depending upon polarization of incident beam. This *dichroic property of calcite is used to make a 25.4 mm diameter, 1 mm thick plate polarizer for above given wavelengths. It is available without anti-reflection coating. It's part number is CPIR-25.4-Un.
* Reference : September 1965 / Vol. 4, No. 9 / Applied Optics / Page 1121
Specifications:
A grade calcite : quarter to one wave wavefront deformation @ 633 nm due to striae only
surface flatness : at least quarter wave @ 633 nm over the clear aperture
surface quality : 40-20 scratch dig
transmission ( uncoated ) : about 75% at 3.390 and 3.507 microns ( supplied uncoated )
Calcite is a natural mined crystal . Defects in bulk calcite are characterized by bubbles ( presence of randomly scattered bubbles vary from relatively large to small sizes and fine bubble lines), striae ( streaks of sudden variation of refractive index which can be detected interferometrically ), optical inhomogeneity ( gradual variation of refractive index in bulk material ) and stress birefringence ( variation of birefringence in bulk material due to defective growth of the crystal ). These defects cause degradation of polarization and transmission loss due to scattering and absorption.