Angular Response Improvement of a Fabry-Perot Tunable Filter for Infrared Multispectral Imaging

A Fabry-Perot (FP) tunable filter for infrared multispectral imaging is designed, whose film system is optimized by genetic algorithm (GA) to stabilize its bandwidth during the tuning process. In addition, the blue shift of the transmission peak wavelength caused by the increase of incident angle can not be ignored in the imaging system. To lessen the angular influence, sub-wavelength metasurfaces are introduced on the inner sides of high reflection cavity mirrors, and some meaningful results are obtained.