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Proceedings Paper

High precision interferometric measurement of freeform surfaces from the well-defined sub-aperture surface profiles
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Paper Abstract

We report an interferometric method for smooth freeform optics from the amount of sub-aperture surface profiles. The overall experimental system is composed of a 5-axis precision stage and a sub-aperture measuring interferometer, which is carefully calibrated to achieve 2 nmRMS precision. The sub-aperture interferometer adopts a broadband source in order to maximize the reliability of profile measurement, and a preliminary assumption of the overall surface is derived from the measured local 2nd derivatives which is robust to tip/tilt alignment errors during the sub-aperture acquisition. The optical surface of a 200 mm diameter 2D polynomial freeform mirror is measured based on this system and traditional contact surface profiler for the cross-validation. The experiment shows the effectiveness of the system that the mismatch against a commercial interferometer is less than 20 nmRMS.

Paper Details

Date Published: 15 November 2019
PDF: 5 pages
Proc. SPIE 11175, Optifab 2019, 111752B (15 November 2019); doi: 10.1117/12.2536867
Show Author Affiliations
Sangwon Hyun, Korea Basic Science Institute (Korea, Republic of)
Soonkyu Je, Korea Basic Science Institute (Korea, Republic of)
Geon-Hee Kim, Korea Basic Science Institute (Korea, Republic of)

Published in SPIE Proceedings Vol. 11175:
Optifab 2019
Blair L. Unger; Jessica DeGroote Nelson, Editor(s)

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