Microbolometer-infrared imaging Stokes polarimeter

Abstract

A long-wave infrared division of amplitude imaging Stokes polarimeter is presented. For the first time, to our knowledge, application of microbolometer focal plane array (FPA) technology to polarimetry is demonstrated. The sensor utilizes a wire-grid beamsplitter with imaging systems positioned at each output to analyze two orthogonal linear polarization states simultaneously. Combined with a form birefringent wave plate, the system is capable of snapshot imaging polarimetry in any one Stokes parameter (S1, S2, or S3). Radiometric and polarimetric calibration procedures for the instrument are provided, and the reduction matrices from the calibration are compared to rigorous coupled wave analysis and ray-tracing simulations. Image registration techniques for the sensor are discussed, and data from the instrument are presented, demonstrating the ability to measure intensity variations corresponding to polarized emission in natural environments. As such, emission polarimetry can be exploited at significantly reduced cost, sensor size, and power consumption over instruments based on more expensive mercury-cadmium telluride FPAs.