Interferometric polarization interrogating filter assembly and method

Abstract

A method and apparatus for instantaneous measurement of the complete state of polarization across an image. A polarimetric encoding scheme is employed to uniquely map the spatially-varying state of polarization across a partially-polarized image to irradiance variations in a polarization-encoded interference pattern. In one embodiment of the method, two spatially-varying retarders and a linear polarizer comprise an interferometric polarization interrogating filter assembly. When a conventional irradiance image is presented to the filter assembly, it is decomposed into polarized and unpolarized components. While the unpolarized component passes through the filter substantially unaffected, the polarized component gives rise to a polarization-encoded interference pattern that overlaps the scene so that local regions within the image having specific polarization content may be recognized. Discretization of the interference pattern by an array of electronic point detectors produces an electronic image from which the polarimetric parameters of interest may be calculated using a mathematical reconstruction algorithm.

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