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18 August 2005 Uncertainties in aspheric profile measurements with the geometry measuring machine at NIST
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The Geometry Measuring Machine (GEMM) of the National Institute of Standards and Technology (NIST) is a profilometer for free-form surfaces. A profile is reconstructed from local curvature of a test part surface, measured at several locations along a line. For profile measurements of free-form surfaces, methods based on local part curvature sensing have strong appeal. Unlike full-aperture interferometry they do not require customized null optics. The uncertainty of a reconstructed profile is critically dependent upon the uncertainty of the curvature measurement and on curvature sensor positioning. For an instrument of the GEMM type, we evaluate the measurement uncertainties for a curvature sensor based on a small aperture interferometer and then estimate the uncertainty in the reconstructed profile that can be achieved. In addition, profile measurements of a free-form mirror, made with GEMM, are compared with measurements using a long-trace profiler, a coordinate measuring machine, and subaperture-stitching interferometry.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ulf Griesmann, Nadia Machkour-Deshayes, Johannes Soons, Byoung Chang Kim, Quandou Wang, John R. Stoup, and Lahsen Assoufid "Uncertainties in aspheric profile measurements with the geometry measuring machine at NIST", Proc. SPIE 5878, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies II, 58780D (18 August 2005);

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