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Proceedings Paper

New advancements in freeform optical metrology
Author(s): Scott DeFisher; Greg Matthews; James Ross
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Paper Abstract

Metrology of freeform shapes has traditionally been difficult, especially at the sub-micron level. Sub-aperture polishing techniques and diamond turning allow optical designers to incorporate freeform surfaces into their systems. Contact measuring systems typically lack the accuracy or resolution required for optical qualification and can potentially damage the surfaces. Interferometric systems are unable to handle high spherical departures and may require complicated lateral calibration to generate feedback for deterministic grinding and polishing. OptiPro has developed UltraSurf, a noncontact coordinate measuring machine to determine the form, figure, and thickness of freeform optics. We integrated several non-contact sensors that acquire surface information through different optical principles. Each probe has strength and weaknesses relative to an optic’s material properties, surface finish, and figure error. The measuring probe is scanned over the optical surface while maintaining perpendicularity and a constant focal offset. Incorporating datums from mechanical prints into the non-contact measuring method is especially important for freeform surfaces. UltraSurf has the ability to measure a wide range of surface roughness and has the degrees of freeform needed to scan datums and surfaces. The metrology method of UltraSurf and the non-contact probes will be presented. Form, figure, and thickness data will highlight the capabilities of UltraSurf to measure freeform surfaces.

Paper Details

Date Published: 3 May 2017
PDF: 7 pages
Proc. SPIE 10179, Window and Dome Technologies and Materials XV, 101790P (3 May 2017); doi: 10.1117/12.2269469
Show Author Affiliations
Scott DeFisher, OptiPro Systems (United States)
Greg Matthews, OptiPro Systems (United States)
James Ross, OptiPro Systems (United States)

Published in SPIE Proceedings Vol. 10179:
Window and Dome Technologies and Materials XV
Brian J. Zelinski, Editor(s)

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