Abstract

The four-detector photopolarimeter (FDP) is an arrangement of four photodetectors for measuring the state of polarization of light. The output current vector I of the FDP is related to the input Stokes vector S by I = AS, where A is called the instrument matrix. The rows of A can be viewed as projection operators that determine the output currents of the detectors. This leads to the recognition of four special totally polarized input states, each of which maximizes the output of one detector. The associated four orthogonal states produce minimum signals. Because each detector is absorptive and its output is non-negative, eight inequalities must be satisfied by the elements of A. For optically isotropic detectors, one element is identically zero, and another can be made zero by an appropriate coordinate rotation.

© 1988 Optical Society of America