Short-wave infrared (SWIR) polarization imaging using division-of-focal-plane imaging polarimeter

This study investigates the polarization properties of materials in the short-wave infrared (SWIR) spectrum using a compact division-of-focal-plane imaging polarimeter. The polarimeter is constructed by packaging a micro-polarizer array on top of an InGaAs sensor. Experiments conducted in both indoor and outdoor environments revealed unique transparency, absorption, and polarization behaviors across various materials. Transparent materials such as plastics, silicon, and black glass exhibited high SWIR transmission, allowing internal visualization, while opaque materials like aluminum, wood, and water demonstrated strong absorption. Polarization analysis identified strong linear polarization in birefringent materials and minimal polarization in isotropic ones, with elliptical or circular polarization arising from mechanisms like total internal reflection, complex refractive index, and birefringence. Outdoor observations showed the interaction of polarized skylights with reflective surfaces, enhancing contrast and revealing surface features. These findings underscore the potential of SWIR polarization imaging for applications in non-destructive testing, remote sensing, biomedical imaging, and optical communication.