Linear diattenuation and retardance measurements in an IR spectropolarimeter
A technique to measure linear diattenuation and retardance spectra of IR samples in transmission is developed. A sample is rotated between two fixed linear polarizers in an IR spectrometer. The intensity modulation resulting from the rotation of the sample is Fourier analyzed and the diattenuation and retardation of the sample are calculated. For single-plate devices whose thickness is known, the birefringence spectrum can also be determined. This technique is utilized in the sample compartment of a Fourier transform IR spectropolarimeter to determine the linear diattenuation and retardance spectra from 2.5 to 16.5 microns of an IR multiple-order retarder, two achromatic retarders, and a liquid crystal sample.
This paper was published in SPIE Proceedings Vol. 1317