Dynamic Fabry-Perot Tunable Filter for MWIR

"We propose to develop a dynamic Fabry-Perot Tunable Filter (FPTF) capable of being tuned rapidly over the MWIR (medium wave infrared, 2-5 micron) spectral region for multi-spectral imaging and infrared detection. Micromachined out of a silicon wafer, usingthe so-called MEMS (micro electro-optical mechanical system) technology, the FPTF is a microchip containing an airgap cavity spacing between two partially-reflecting mirrors, one of which is made movable relative to the other, so that the spacing can bechanged when a voltage is applied across a series of capacitors disposed around the periphery of the cavity. This spacing will cause an interference between the incident and reflected IR beams within the cavity, resulting in an emerging narrow passbandcentered at a specific wavelength dependent on the spacing and a bandwidth dependent on the reflectivity of the mirrors. By changing this spacing, the tuning of the cavity can be made to pass any passband within the MWIR in microseconds. When this FPTF isplaced in front of an MWIR focal plane array and arranged with suitable IR optics, multi-spectral images will be obtained in the MWIR rapidly. Phase 1 will define the requirements of the FPTF device, design its structure, analyze its dynamic tunability inthe MWIR and delineate its fabrication process by micromachining using the MEMS technology. Phase 2 will fabricate and test a breadboard version the FPTF device. Multi-spectral imaging,