26 October 2004 Wide Field Collimator 2 (WFC2) for GOES Imager and Sounder
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Two of the GOES instruments, the Imager and the Sounder, perform scans of the Earth to provide a full disc picture of the Earth. To verify the entire scan process, an image of a target that covers an 18o circular field-of-view is collimated and projected into the field of regard of each instrument. The Wide Field Collimator 2 (WFC2) 1 has many advantages over its predecessor, WFC1, including lower thermal dissipation, higher far field MTF, smaller package, and a more intuitive (faster) focusing process. The illumination source is an LED array that emits in a narrow spectral band centered at 689 nm, within the visible spectral bands of the Imager and Sounder. The illumination level can be continuously adjusted electronically. Lower thermal dissipation eliminates the need for forced convection cooling and minimizes time to reach thermal stability. The lens system has been optimized for the illumination source spectral output and athermalized to remain in focus during bulk temperature changes within the laboratory environment. The MTF of the lens is higher than that of the WFC1 at the edge of FOV. The target is focused in three orthogonal motions, controlled by an ergonomic system that saves substantial time and produces a sharper focus.
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Shahriar Etemad, Shahriar Etemad, James C. Bremer, James C. Bremer, Barbara J. Zukowski, Barbara J. Zukowski, Bert A. Pasquale, Bert A. Pasquale, Tmitri J. Zukowski, Tmitri J. Zukowski, Robert E. Prince, Robert E. Prince, Patrick A. O'Neill, Patrick A. O'Neill, Robert W. Ross, Robert W. Ross, "Wide Field Collimator 2 (WFC2) for GOES Imager and Sounder", Proc. SPIE 5542, Earth Observing Systems IX, (26 October 2004); doi: 10.1117/12.559623; https://doi.org/10.1117/12.559623

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