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.
Scott DeFisher, Greg Matthews, and James Ross, "New advancements in freeform optical metrology," Proc. SPIE 10179, Window and Dome Technologies and Materials XV, 101790P (Presented at SPIE Defense + Security: April 12, 2017; Published: 3 May 2017); https://doi.org/10.1117/12.2269469.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 14,000 conference presentations, including many plenary and keynote presentations.