title: Distortion compensation in interferometric testing of mirrors.
abstract: We present a method to compensate for the imaging distortion encountered in interferometric testing of mirrors, which is introduced by interferometer optics as well as from geometric projection errors. Our method involves placing a mask, imprinted with a regular square grid, over the mirror and finding a transformation that relates the grid coordinates to coordinates in the base plane of the parent surface. This method can be used on finished mirrors since no fiducials have to be applied to the surfaces. A critical step in the process requires that the grid coordinates be projected onto the mirror base plane before the regression is performed. We apply the method successfully during a center-of-curvature null test of an F/2 off-axis paraboloid.
authors.affiliation: University of Alabama in Huntsville, Center for Applied Optics, 301 Sparkman Drive, Optics Building Room 400, Huntsville, Alabama 35899, USA. Brian.Robinson@uah.edu
authors.forename: Brian M
authors.initials: BM
authors.lastname: Robinson
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Reardon