Review of design and signal processing of polarimetric imaging cameras

Thermal-imaging systems respond to infrared radiation that is naturally emitted by objects. Various multispectral and hyperspectral devices are available for measuring radiation in discrete sub-bands and thus enable a detection of differences in a spectral emissivity or transmission. For example, such devices can be used to detect hazardous gases. However, their operation principle is based on the fact that radiation is considered a scalar property. Consequently, all the radiation vector properties, such as polarization, are neglected. Analysing radiation in terms of the polarization state and the spatial distribution of thereof across a scene can provide additional information regarding the imaged objects. Various methods can be used to extract polarimetric information from an observed scene. We briefly review architectures of polarimetric imagers used in different wavebands. First, the state-of-the-art polarimeters are presented, and, then, a classification of polarimetric-measurement devices is described in detail. Additionally, the data processing in Stokes polarimeters is given. Emphasis is laid on the methods for obtaining the Stokes parameters. Some predictions in terms of LWIR polarimeters are presented in the conclusion.