High Spatial Resolution Phase Measurements Of Optical Surfaces

The requirements on figure quality of large optics, particularly in the mid to high spatial frequen-cies have pushed beyond the limits of resolution of some common wavefront analysis methods such as the reduction of interferograms. The smoothness requirement for some large mirrors on spatial scales of a few centimeters can be on the order of 0.01 χ rms, making fabrication and testing of these mirrors difficult. The advent of direct phase measuring interferometry with the use of high density CCD or photodiode arrays can provide the means to achieve the needed spatial resolution.