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Proceedings Paper

Integrated Ray Tracing (IRT) simulation of SCOTS measurement of GMT fast steering mirror surface
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Paper Abstract

The Software Configurable Optical Testing System (SCOTS) is one of the newest testing methods for large mirror surfaces. The Integrated Ray Tracing (IRT) technique can be applicable to the SCOTS simulation by performing non-sequential ray tracing from the screen to the camera detector in the real scale. Therefore, the radiometry of distorted pattern images are numerically estimated by the IRT simulation module. In this study, we construct an IRT SCOTS simulation model for the Fast Steering Mirror Prototype (FSMP) surface of the Giant Magellan Telescope (GMT). GMT FSMP is an off-axis ellipsoidal concave mirror that is 1064 mm in diameter and has PV 3.1 mm in aspheric departure. The surface error requirement is less than 20 nm rms. The screen is modeled as an array of 1366 by 768 screen pixels of 0.227 mm in pitch size. The screen is considered as a Lambertian scattering surface. The screen and the camera are positioned around 4390 mm away from the mirror and separated by around 132 mm from each other. The light source are scanning lines and sinusoidal patterns generated by 616,050 rays per one screen pixel. Of the initially generated rays, 0.22 % are received by the camera’s detector and contribute to form distorted pattern images. These images are converted to the slope and height maps of the mirror surface. The final result for the height difference between input surface and reconstructed surface was 14.14 nm rms. Additionally, the simulated mirror pattern image was compared with the real SCOTS test for the GMT FSMP. This study shows applicability of using the IRT model to SCOTS simulation with nanometer level numerical accuracy.

Paper Details

Date Published: 16 November 2015
PDF: 8 pages
Proc. SPIE 9575, Optical Manufacturing and Testing XI, 957513 (16 November 2015); doi: 10.1117/12.2188845
Show Author Affiliations
Ji Nyeong Choi, Yonsei Univ (Korea, Republic of)
Dongok Ryu, Yonsei Univ. (Korea, Republic of)
Sug-Whan Kim, Yonsei Univ. (Korea, Republic of)
Logan Graves, College of Optical Sciences, The Univ. of Arizona (United States)
Peng Su, The Univ. of Arizona (United States)
Run Huang, The Univ. of Arizona (United States)
Dae Wook Kim, The Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 9575:
Optical Manufacturing and Testing XI
Oliver W. Fähnle; Ray Williamson; Dae Wook Kim, Editor(s)

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