Extremely Narrowband Cascaded Holographic Adjustable Range Tunable (ENCHART) Filter

Physical Optics Corporation's R&D Division (POC R&D) proposes a new Extremely Narrowband Cascaded Holographic Adjustable Range Tunable (ENCHART) filter based on the combined use of two holographic Fabry-Perot filters (HFPFs): a coarse filter to select the desired portion of the optical range, and a fine filter operating within this selected range at any arbitrary wavelength with an extremely narrow (0.1 angstrom) bandwidth; the fine filter will use an electrically tuned liquid-crystal cell. This design is based on three of POC's existing technologies: coherently-coupled (phase synchronized) HFPFs, tunable liquid-crystal cell preparation, and fabrication of high-efficiency controlled-bandwidth holographic mirrors in the UV to the IR regions of the spectrum, using a high-order harmonic recording technique and a proprietary photopolymer processing technique. The ENCHART filter will exhibit extremely high (0.1 angstrom) resolution with fine tuning over a range of at least 3 angstroms in a selected range of the spectrum ( from UV to IR), high out-of-band rejection (OD > 2) with adequate suppression across an operating range 1000 times broader than that passband, and superior performance under harsh operating conditions. The ENCHART filter will be lightweight, small-size, and inexpensive.