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Optical Engineering

Calibration And Use Of Optical Straightedges In The Metrology Of Precision Machines
Author(s): W. Tyler Estler
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Paper Abstract

We describe techniques used to measure straightness errors of precision machines. These measurements employ a dimensionally stable mechanical reference surface that is sampled with a laser interferometer-hence the term optical straightedge. The figure error of the reference surface and the straightness error motion of a coordinate measuring machine carriage in a horizontal plane are each measured with an estimated accuracy of 0.5 un. (13 nm) over 40 in. (1 m) of travel. When measuring straightness error in a vertical plane, the results are complicated by deformation of the reference surface by gravitational forces. We use a computational algorithm, based upon simple beam theory, to correct straightness data for this distortion. While inadequate for accuracies better than about 2 un. (50 nm), we believe that the algorithm, which may be tested using an uncalibrated straightedge, may be improved using finite-element calculations of gravitational sag.

Paper Details

Date Published: 1 June 1985
PDF: 8 pages
Opt. Eng. 24(3) doi: 10.1117/12.7973492
Published in: Optical Engineering Volume 24, Issue 3
Show Author Affiliations
W. Tyler Estler, National Bureau of Standards (United States)

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