A Theoretical Investigation of Electrically Tunable Birefringent Optical Filters as the Special Discriminator in Hyperspectral Imaging Systems
AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
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This study investigated electrically tunable birefringent optical filters for use as the spectral discriminator in hyperspectral imaging systems. Spectral discrimination requirements for hyperspectral systems were defined using specification from two state-of-the-art hyperspectral imaging systems. The spectral discrimination requirements led to the definition of the ideal tunable optical filter for spectral discrimination purposes. Analytical and computer an analysis was performed for known birefringent filters which showed promise of electrical tunability excluding acousto-optic filters. No perfect match was found to the ideal tunable optical filter for hyperspectral imaging defined in this thesis. Both Lyot and Solc based filters exhibited two drawbacks for hyperspectral imaging application narrow tuning range with linear bandwidth dependence on center wavelength, or wide tuning range and quadratic bandwidth dependence on center wavelength. The An-tuned Solc filter provided the best compromise between tuning range and bandwidth control, however, it is not practical due to the excessive number of elements required This thesis provides the needed background for further research in this area and identifies a number of areas for further worthwhile research Acousto-optic filters offer another possible avenue for hyperspectral imaging and should be investigated Birefringent materials should also be studied to determine material limits on the electro-optic effect and spectral transmission characteristics to determine practical capabilities of filters discussed in this thesis. Birefringence, Filters, Multispectral, Imaging, Optical filters.