A system that estimates the global radius of curvature (GRoC) of a segmented telescope mirror has been developed by the Marshall Space Flight Center for use in a larger system that exerts precise control over the displacements of the mirror segments. This system makes it possible to control the GRoC of the mirror with sufficient precision to obtain the best possible image quality, and to impose a required wavefront correction on incoming or outgoing light.
A theoretical analysis of photon-arrival jitter in an optical pulse-position-modulation (PPM) communication channel has been performed at NASA's Jet Propulsion Laboratory. Photon-arrival jitter is an uncertainty in the estimated time of arrival of a photon relative to the boundaries of a PPM time slot. The analysis is now the basis of a methodology for designing receivers to compensate so that errors due to photon-arrival jitter would be minimized.