Autocollimation polarimeter for measuring two-dimensional distribution of birefringence

A device for studying samples with nonuniform distribution of birefringence and corresponding measurement techniques are proposed. The optical arrange ment of a polarimeter is of the autocollimation type with combined probing and reverse beams. The birefringence distribution is found by processing 8 or 16 images of an object for various azimuths of polarization elements of the polarimeter, the sample being fixed. Basic formulas describing the oper ation of the polarimeter and sources of measurement errors are presented. V arious factors that limit the sensitivity of the polarimeter are estimated and methods for weakening their influence are suggested. The experimental s etup has a threshold sensitivity equal to 0.4 degrees or 0.7 nm for a radia tion wavelength of 633 nm. The setup permits the study of samples up to 18 mm in diameter with a resolution of 1024 x 1024 pixels. Results of experime nts confirming the reliability of measurements and illustrating the operati on of the polarimeter are presented. (C) 2000 MAIK "Nauka/Interperiodica".