TA17 Design of Wideband Optics I
INO Qubec Canada
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This design study was originally motivated by the recent apparition of new sensors with unconventional sensitivity spectral band covering the NIR up to nearly MWIR upper limit. More specifically, the design study was oriented in function to the Kinglet sensor developed by SCD of Israel. The study consisted in the draft optical design of two types of imaging configurations operating in the 1-4.2 micron wide spectral band, namely a version with a 4x5 degree narrow field-of-view FOV and its wide FOV counterpart with 8x10 degree total angular field-of-view. The design of a wide-band optics for the SWIR-MWIR bands encompasses various challenges. One of the questions arising from the specifications concerns the correction of the chromatism inherent to a wideband design. The question should be put into the perspective of a limited choice of materials with reasonable internal transmission over the entire 1-4.2 micron spectral band. Obviously, the control of the chromatism is evacuated if the choice of using only reflective elements is made. However in the context of the actual imaging systems, a refractive approach presents many advantages over a reflective counterpart in terms of the simplicity, compactness and mass. The reflective approach involves off-axis unobscured configurations OUC because of the difficulties associated with centered reflective systems for the control of parasitic light emitted by the mechanical parts surrounding the optical elements support or baffles. The difficulty of placing the stop outside an off-axis unobscured reflective system is also a drawback for the reflective approach. For all these reasons, the priority was put on the refractive approach and efforts on the identification of materials have been put on the generation of a catalog that includes commercially available materials with interesting transmission characteristics in the desired waveband.
- Infrared Detection and Detectors
- Ceramics, Refractories and Glass