Abstract: A system for testing an optical surface includes a rangefinder configured to emit a light beam and a null assembly located between the rangefinder and the optical surface. The null assembly is configured to receive and to reflect the emitted light beam toward the optical surface. The light beam reflected from the null assembly is further reflected back from the optical surface toward the null assembly as a return light beam. The rangefinder is configured to measure a distance to the optical surface using the return light beam.

Abstract: A system for measuring distance to an optical surface includes a range finder for transmitting a beam toward the optical surface, and a ring mirror disposed between the range finder and the optical surface. The ring mirror has (a) a circumferential reflecting surface for reflecting a portion of the transmitted beam back to the range finder, and (b) a central aperture for passing another portion of the transmitted beam toward the optical surface. The circumferential reflecting surface is effective in providing a zero reference point for the range finder. The central aperture is effective in passing the transmitted beam to the optical surface for sequentially addressing the optical surface at different locations on the optical surface. The transmitted beam may be steerable for (a) providing the zero reference point circumferentially about the reflecting surface, and (b) providing sequential addresses to locations on the optical surface.

Abstract: A method and apparatus for testing the configuration of an optical element includes an optical test-set having a holographic optical element designed to obtain a null wave front at the surface of an optical element under test; an interferometer for viewing the test-set, the optical test set and interferometer having optical distortions; and a distortion verification grid (DVG) located in the optical test-set, the DVG comprising a thin opaque sheet of material having a predistorted array of asymmetric holes arranged such that the image of the array of holes formed by the interferometer will be regular and the images of the holes will be symmetric when the optical distortions have been correctly understood and accounted for in the design of the DVG and the distortion correction function.