A null-type photoelectric universal polarimeter (or ellipsometer) utilizing Faraday cells and a quarter-wave plate is described and its precision evaluated. For elliptically polarized light of small circularity (i.e., almost linearly polarized), the azimuth could be determined with a precision of 10 sec and the circularity to within 20 sec of arc. For light of large circularity (on the order of 35 deg), the corresponding precisions were 7 min (0.12 deg) for azimuth and 14 min (0.24 deg) for circularity. Errors due to a nonexact quarter-wave plate and nonperfect alignment of the compensator with respect to the elliptically polarized light are discussed. The use of this instrument as a high-precision Sénarmont compensator for the measurement of birefringence is also described.
S. J. WILLIAMSON, J. M. WEINGART, and R. D. ANDREWS, "New High-Precision Photoelectric Universal Polarimeter and Birefringence Compensator," J. Opt. Soc. Am. 54, 337-341 (1964)