Real-time Stokes polarimeter using three polarized beam splitter (Conference Presentation)

Abstract

This paper describes real-time, very small and cheap Stokes polarimeter using three polarized beam splitters (PBSs). Each s1, s2 and s3 of Stokes parameters is measured by the PBSs. However this technique has to separate three beams keeping unknown incidental polarization state. To overcome this problem, three same normal beam splitters (BSs) are possible to separated two beams keeping polarized state. An alignment of three BSs is set orthogonal in transmission part and reflection part. In transmission part, the polarization state after two BSs can be canceled change of polarization state of first BS by change of second orthogonal BS. In reflection part is same theory. If you set two pear of this keeping polarization beam splitter, you can separate three beams keeping incidental polarization state. After separated beams, three PBS can measure Stokes parameters easily. At first we checked effect of the keeping polarization beam splitter using spectoscopic Mueller matrix polarimeter. We got Mueller matrixes having max 3.3% value of transmission and reflection from unit matrix during from 450nm to 700nm. In second we checked Stokes parameters after a rotating polarizer and a quarter wave plate in this Stokes polarimeter. In two condition results, an error had 5.6%. Finally we checked measurement speed of this real-time Stokes polarimeter using rotating quarter wave plate. From this result this Stokes polarimeter is possible to measure Stokes parameter in 15Hz. This measurement speed depends on detection speed of six PIN photodiodes and transfer speed of AD convertor.