Large deformable mirrors, such as those envisioned for advanced space telescopes and the space laser program, will require a method for actively sensing the mirror figure while it is in use. Figure sensing is usually done at the center of curvature of the mirror; placing an interferometer at this point requires extending the telescope structure by many meters, which is not desirable because it introduces additional structural and packaging problems. There have been a variety of schemes presented in the past for figure sensing near the focal plane of the mirror. Of these schemes, the full aperture holographic zone plate studied by Erickson1 is particularly attractive, since it provides full aperture phase information and does not require modifications of the mirror other than to the coating.
© 1982 Optical Society of AmericaPDF Article