19 August 2005 Design of a machine for the universal non-contact measurement of large free-form optics with 30 nm uncertainty
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A new universal non-contact measurement machine design for measuring free-form optics with 30 nm expanded uncertainty is presented. In the cylindrical machine concept, an optical probe with 5 mm range is positioned over the surface by a motion system. Due to a 2nd order error effect when measuring smoothly curved surfaces, only 6 position measurement errors are critical (nanometer level). A separate metrology system directly measures these critical errors of the probe and the product relative to a metrology frame, circumventing most stage errors. An uncertainty estimation has been performed for the presented design, including a calibration uncertainty estimation and a dynamic analysis. Machine dynamics certainly cause relative motion between probe and product, but due to the non-contact nature of the measurement and the short metrology loop, these motions do not cause significant measurement errors. The resulting shape measurement error for aspheres up to medium free-forms is between 24 and 37 nm, and 30 - 85 nm for medium to heavily free-form surfaces. The suitability of the proposed design is herewith confirmed. A detailed design and a prototype of the machine are currently being developed.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rens Henselmans, Rens Henselmans, Nick Rosielle, Nick Rosielle, Maarten Steinbuch, Maarten Steinbuch, Ian Saunders, Ian Saunders, Rob Bergmans, Rob Bergmans, "Design of a machine for the universal non-contact measurement of large free-form optics with 30 nm uncertainty", Proc. SPIE 5869, Optical Manufacturing and Testing VI, 586919 (19 August 2005); doi: 10.1117/12.613919; https://doi.org/10.1117/12.613919


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