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Proceedings Paper

Slanted-edge MTF testing for establishing focus alignment at infinite conjugate of space optical systems with gravity sag effects
Author(s): T. Newswander; David W. Riesland; Duane Miles; Lennon Reinhart
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Paper Abstract

For space optical systems that image extended scenes such as earth-viewing systems, modulation transfer function (MTF) test data is directly applicable to system optical resolution. For many missions, it is the most direct metric for establishing the best focus of the instrument. Additionally, MTF test products can be combined to predict overall imaging performance. For fixed focus instruments, finding the best focus during ground testing is critical to achieving good imaging performance. The ground testing should account for the full-imaging system, operational parameters, and operational environment. Testing the full-imaging system removes uncertainty caused by breaking configurations and the combination of multiple subassembly test results. For earth viewing, the imaging system needs to be tested at infinite conjugate. Operational environment test conditions should include temperature and vacuum. Optical MTF testing in the presence of operational vibration and gravity release is less straightforward and may not be possible on the ground. Gravity effects are mitigated by testing in multiple orientations. Many space telescope systems are designed and built to have optimum performance in a gravity-free environment. These systems can have imaging performance that is dominated by aberration including astigmatism. This paper discusses how the slanted edge MTF test is applied to determine the best focus of a space optical telescope in ground testing accounting for gravity sag effects. Actual optical system test results and conclusions are presented.

Paper Details

Date Published: 5 September 2017
PDF: 11 pages
Proc. SPIE 10401, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems, 104010U (5 September 2017); doi: 10.1117/12.2273071
Show Author Affiliations
T. Newswander, Space Dynamics Lab. (United States)
David W. Riesland, Space Dynamics Lab. (United States)
Duane Miles, Space Dynamics Lab. (United States)
Lennon Reinhart, Space Dynamics Lab. (United States)

Published in SPIE Proceedings Vol. 10401:
Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems
Tony B. Hull; Dae Wook Kim; Pascal Hallibert, Editor(s)

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