Dual-photoelastic-modulator-based polarimetric imaging concept for aerosol remote sensing

David J. Diner, Ab Davis, Bruce Hancock, Gary Gutt, Russell A. Chipman, Brian Cairns
2007 Applied Optics  
A dual-photoelastic-modulator-(PEM-) based spectropolarimetric camera concept is presented as an approach for global aerosol monitoring from space. The most challenging performance objective is to measure degree of linear polarization (DOLP) with an uncertainty of less than 0.5% in multiple spectral bands, at moderately high spatial resolution, over a wide field of view, and for the duration of a multiyear mission. To achieve this, the tandem PEMs are operated as an electro-optic circular
more » ... ance modulator within a high-performance reflective imaging system. Operating the PEMs at slightly different resonant frequencies generates a beat signal that modulates the polarized component of the incident light at a much lower heterodyne frequency. The Stokes parameter ratio q ϭ Q͞I is obtained from measurements acquired from each pixel during a single frame, providing insensitivity to pixel responsivity drift and minimizing polarization artifacts that conventionally arise when this quantity is derived from differences in the signals from separate detectors. Similarly, u ϭ U͞I is obtained from a different pixel; q and u are then combined to form the DOLP. A detailed accuracy and tolerance analysis for this polarimeter is presented.
doi:10.1364/ao.46.008428 pmid:18071373 fatcat:2svpv2vkfvbtfg267poqfsfv74