Wideband Acousto-optic Tunable Filter and Retarder for Spectropolarimetric Imagers

It is critical to extract maximum information from IR images for target detection, identification and classification purposes. Besides acquiring intensity variations, rapid collection of corresponding polarization signatures at desired wavelengths with animaging spectropolarimeter could enhance the information content of an IR scene. Present spectropolarimeters operate over a narrow spectral band. Furthermore, they are heavy, slow due to moving mechanical parts, and operationally complex. CoherentTechnologies Inc. (CTI) is proposing to design and develop two key components namely, an acousto-optic tunable filter (AOTF) and a matched active retarder required for a spectropolarimetric imager to operate over the 2-12 micron spectral band. Thesecomponents will enable the imager to simultaneously measure the spectral intensity and polarization content of an image in real time. These components are anticipated to guide the development of a versatile spectropolarimetric imager that will bebroadband, wavelength agile, electronically tunable, all-solid-state, compact, field-deployable, and rugged. In Phase I, detailed designs, including material trade-off study and performance evaluation, of an AOTF and active retarder for a broadbandspectra-polarimeter will be generated. An active retarder will be fabricated and tested. In Phase II, a portable, field-deployable, brassboard components operating over 2-12 micron spectral band will be developed and delivered. The proposed components havewide applications in sensitive target detection, identification, and discrimination systems, active and passive remote chemical sensing systems, imaging lidars, IR spectroscopy, terrestrial and space surveillance systems, machine vision systems, etc.