We define an approach for measuring wavefront quality of any system that focuses a collimated beam, including telescopes, parabolic mirrors, and many lenses. It is a self-referencing plane wavefront sensor utilizing a point source at the tested system's focal plane. We measure the local wavefront direction at many points, compare to a stable reference direction, and integrate to obtain a wavefront map. the approach can operate in any orientation, measures across the full aperture without relying on any reference optics of similar size, and can be configure to work with essentially any wavelength of point source. Preliminary analysis indicates wavefront measurement accuracy on the order of lambda over 100 P-V (633 nm), even for meter-class aperture diameters. Objectives are to define a baseline system, and to develop ac comprehensive performance prediction model. We anticipate a successful Phase I effort leading to a Phase II effort where we breadboard, characterize, and demonstrate the instrument. NASA applications include many telescope systems, particularly those with large apertures and/or IR wavelengths. Benefits include assurance of total wavefront quality before a system is launched.An instrument derived from this project would be capable of measuring wavefront quality of any system that focuses a collimated beam, including telescopes, parabolic mirrors, and many lenses. This would be of interest to many government users and commercial producers of such systems.
