We demonstrate a method of performing the absolute three-flat test by using reflection symmetries of the surfaces and an algorithm for generating the rotation of arrays of pixel data. Most of the operations involve left/right and top/bottom flips of data arrays, operations that are very fast on most frame grabbers and are available on most commercial phase-measuring interferometers. We demonstrate the method with simulated data as well as with actual data from 150-mm-diameter surfaces that are flat to less than 25 nm peak to valley.
© 1998 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.4630) Instrumentation, measurement, and metrology : Optical inspection
Robert E. Parks, Lianzhen Shao, and Chris J. Evans, "Pixel-Based Absolute Topography Test for Three Flats," Appl. Opt. 37, 5951-5956 (1998)