Measurement of large on-axis and off-axis mirrors using software configurable optical test system (SCOTS)

Andrew E. Lowman; Greg A. Smith; Lori Harrison; Steven C. West; Chang Jin Oh

doi:10.1117/12.2313855

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10 July 2018 Measurement of large on-axis and off-axis mirrors using software configurable optical test system (SCOTS)

Andrew E. Lowman, Greg A. Smith, Lori Harrison, Steven C. West, Chang Jin Oh

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Proceedings Volume 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III; 107061E (2018) https://doi.org/10.1117/12.2313855
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

One of the major challenges of optical fabrication is measurement of the surface when first polished out, before its figure is within the capture range of interferometry. A high dynamic range instrument with good accuracy is needed to efficiently guide the processing. Our approach is to use the Software Configurable Optical Test System (SCOTS), a deflectometry technique that uses a camera and liquid crystal display to measure the surface slope. We describe the use of SCOTS in the fabrication of a 6.5 m on-axis mirror and an 8.4 m off-axis mirror segment (Giant Magellan Telescope primary). SCOTS has the dynamic range to measure high slope errors early in the mirror figuring process, with sufficient accuracy to corroborate later interferometric measurements. Accurately measuring low order figure errors with SCOTS requires careful calibration of the system geometry. Details of the data collection and processing, and comparison to interferometry measurements are presented.

Conference Presentation

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Andrew E. Lowman, Greg A. Smith, Lori Harrison, Steven C. West, and Chang Jin Oh "Measurement of large on-axis and off-axis mirrors using software configurable optical test system (SCOTS)", Proc. SPIE 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 107061E (10 July 2018); https://doi.org/10.1117/12.2313855

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