In surface figure testing, most of them are relative tests, and the reference
surface usually limits the accuracy of test results. Absolute calibration is one
of the most important and efficient techniques to reach subnanometer accuracy in
surface figure testing. An absolute testing method, a shift-rotation method
using Zernike polynomials, is presented, which can be used to calibrate both
flat and spherical surfaces (concave or convex). Calibration contains at least
three position measurements: one basic position, one rotation, and one lateral
shift of the test surface.
Experiments show that the
repeatability of this method is 0.13 nm RMS, and pixel-to-pixel comparison
with the two-sphere method is 0.2 nm RMS.
© 2012 Optical Society of America
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