title: Pixel-based absolute topography test for three flats.
abstract: 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.
authors.forename: R E
authors.initials: RE
authors.lastname: Parks
authors.forename: L
authors.initials: L
authors.lastname: Shao
authors.forename: C J
authors.initials: CJ
authors.lastname: Evans