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15 January 1976 Metal Optics For A Visible Infrared Spin-Scan Radiometer (VISSR)
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A three-mirror electroless nickel- slated beryllium optical system is described which is used as the collecting telescope for the Visible Infrared Spin-Scan Radiometer (VISSR). The 16-inch diameter aper-ture, 114.7-inch focal length system is comprised of a flat, elliptically-shaped object-space scan mirror and a Ritchey-Chretien primary-secondary mirror pair. Hot pressed beryllium is used as the substrate material because of its light weight, structural rigidity, and thermal stability. Specific selection criteria include precision elastic limit (PEL), homogeneity, and isotropy. PEL is measured mechanically. Homo geneity and freedom from voids and inclusions are ensured by X-ray inspection. Anisotropy is evaluated from thermal expansion coefficients measured along three perpendicular axes. The scan mirror uses a structure of hollow triangular ribs to provide maximum strength and rigidity with minimum weight. The primary and secondary mirrors are three-point tangent bar mounted. All mirrors are plated with low-stres s electroless nickel. Phosphorus content analysis is used as a low stress indicator. Maximum plating stress levels are specified and are calculated from test strip measurements. Reflective surfaces are optically figured and coated with evaporated aluminum overcoated with silicon oxide. The finished system is designed for near diffraction limited performance in the visible.
© (1976) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John C. Campbell "Metal Optics For A Visible Infrared Spin-Scan Radiometer (VISSR)", Proc. SPIE 0065, Design, Manufacture and Application of Metal Optics, (15 January 1976);


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