NIST logo

Publication Citation: Uncertainties in Aspheric Profile Measurements with the Geometry Measuring Machine at NIST

NIST Authors in Bold

Author(s): Ulf Griesmann; Nadia Machkour-Deshayes; Byoung C. Kim; Quandou Wang; Lahsen Assoufid;
Title: Uncertainties in Aspheric Profile Measurements with the Geometry Measuring Machine at NIST
Published: July 31, 2005
Abstract: 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 and subaperture-stitching interferometry.
Conference: SPIE
Proceedings: SPIE - Optics and Photonics
Volume: 5878
Pages: pp. 112 - 124
Location: San Diego, CA
Dates: July 31-August 4, 2005
Keywords: aspheric surface profile;profilometer;surface curvature
Research Areas: Dimensional Metrology