Infrared(IR) systems have been widely used in the past. Current systems generally require bulk optical systems having multiple moving parts for polarization control. Image forming radiation is typically collected for a fixed polarization state. Optical filters must be used in the optical train before the receiving detector array. The selection of the polarization state requires mechanical motion of the optical filters. The typical weight of the necessary filter and switching assemblies is on the order of 1 kg or more. The required time to switch between polarization states can be on the order of 2 seconds or more. Polarization-resolved imagery is largely unexploited, because of inconvenient implementation.
Many U.S. Patents have been proposed for Infrared detectors but have many of the problems previously described. See for example U.S. Pat. Nos.: Re.30,131 to Javan; 4,652,885 to Saffold et al.; 5,239,179 to Baker; 5,248,884 to Brewitt-Taylor et al.; 5,404,146 to Rutledge; 5,432,374 to Norton; 5,436,453 to Chang et al.; 5,442,176 to Eckel, Jr. et al.; 5,446,284 to Butler et al.; 5,512,750 to Yanka et al.; 5,519,529 to Ahearn et al.; and 5,523,570 to Hairston.
USPTO Backgrounds
USPTO Backgrounds