Abstract

In the four-detector photopolarimeter (FDP) a light beam, whose state of polarization is to be measured, experiences three successive partial specular reflections at the surfaces of three photodetectors, with noncoincident planes of incidence, before the remaining flux is substantially totally absorbed by the last detector. A 4 × 1 current vector I is thus developed which is linearly related, I = A S, to the input Stokes vector S, where A is called the instrument matrix. The FDP is robust in that its operation is unaffected by (1) the insertion between detectors of beam-forming elements such as apertures and lenses, (2) spatially uniform optical anisotropy of the detector surfaces, (3) differences of the photoelectric responses associated with the nonreflected p- and s-polarized radiation, as may be caused by the excitation of surface plasmons, and (4) optical feedback as may occur if the last detector is placed exactly normal to the beam. Whereas all these factors influence the A matrix, this is inconsequential inasmuch as A is determined by calibration.

© 1989 Optical Society of America