<title>Spectral and polarimetric analysis of hyperspectral data collected by an acousto-optic tunable filter system</title>

Analysis of data collected during a ground-based experiment of an acousto-optic tunable filter (AOTF) hyperspectral imaging system shows potential for utilizing this technology for feature identification. The unique capability of an AOTF system to simultaneously acquire two orthogonally poiarized images allows both spectral and polarimetric characterizafion of ground features. The AOTF sensor used in the experiment operated over a wavelength range from 0.5 1 to 0.77 microns, collecting two differently polarized images for each of 33 bands. The experiment data images selected for analysis contain camouflaged military equipment deployed in a desert background. The Spectral Image Processing System (SIPS) software package was used for data correction and spectral analysis. Processing the AOTF data required geometric correction in addition to removing the solar and atmospheric effects. Two methods of spectral analysis are addressed in this research. The first method assesses the spectral analysis accomplished using the Spectral Angle Mapper utility in SIPS. The other method illustrates the spectral information gained through band ratioing a combination of carefully selected bands which highlights a particular target within a scene. Comparison of images created by the difference between polarizations for each band provides the basis for polarimetric analysis of the data. Finally, an algorithm developed to combine the information provided by spectral and polarimetric analysis shows how features within a scene can be distinguished from the background. Results show that AOTF hyperspectral technology has potential to enhance current military intelligence collection capability.