Broadband Full-Stokes Polarimetry

Abstract

Broadband full-Stokes polarimetry can capture polarization images over a wide wavelength spectrum, for example visible spectrum (380nm to 740nm), near infrared spectrum (780nm to 2500nm) or both. In this dissertation, we discuss several topics on designing a broadband full-Stokes polarimeter and then demonstrate two polarimeters experimentally. We first study two theoretical problems, the first one is the optimized sensor design for color polarization imaging. This includes three parts, the tiling of N types of optical filters on a 2D rectangular grid that minimizes interpolation error, the choice of color filters and the choice of analyzers, to minimize the influence from noise on color polarization reconstruction. The second problem is how to design achromatic polarization elements. This is the key to enable broadband polarization measurement. We analyze a special case that uses two linear retarders of the same birefringent material and one linear polarizer to achieve an achromatic elliptical polarizer/analyzer. We also address several concerns on choosing the right achromatic analyzer design for polarimeters. Two types of RGB full-Stokes imaging polarimeter are constructed, calibrated and tested. The first one uses a beam splitter and two linear-Stokes cameras to form a division-of-amplitude polarimeter. The second type applies a patterned micro-retarder on a pixelated wire-grid micro-polarizer to form a division-of-focal plane polarimeter. Both can capture the intensity, color and polarization of an optical field in a single shot.