Detection comparisons between LWIR and MWIR polarimetric sensors

Abstract

Polarimetry sensor development has been in work for some time to determine the best use of polarimetry to differentiate between manmade objects and objects made by nature. Both MWIR and LWIR Focal Plane Arrays (FPAs) have been built at Raytheon Vision Systems each with exceedingly higher extinction ratios. This paper compares field imagery between MWIR and LWIR micro-grid polarimetric sensors independently and during simultaneous image collects. LWIR polarimetry has the largest polarimetric signal level and an emissive polarimetric signature which allows detection at thermal crossover and is less dependent on sun angles. Polished angled glass and metal objects are easily detected using LWIR polarimetry. While LWIR polarimetry has many advantages its resolution is not as good as MWIR. MWIR polarimetry has higher resolution than LWIR. With good sun angles plastic drums, and wet surfaces provide good polarization signatures. With poor sun angles detection can be challenging. To gain acceptance polarimetric sensors must provide intelligence signatures that are better than existing nonpolarimetric Infrared sensors. This paper shows several examples of images without polarimetric processing and identical images with MWIR and/or LWIR polarimetric fusion onto the non-polarized images to show the improvement of detection using polarimetric sensors. It is the author's belief that the fastest way to gain acceptance of polarimetric remote sensing is through field demonstration as shown in Figure 1.