Abstract

Obtaining accurate measurements for regions of a workpiece to be tested, spaced closer than about D/25 (D = workpiece diameter) is typically not easy to do with current test methods. Yet, there are occasions when such data would be meaningful. The limitations arise from practical considerations, i.e., how many holes one can put across a Hartmann mask diameter, or how many fringes one can have in an interference pattern and still be able to distinguish unambiguously between them in the digitizing stage, or how many lenslets can be squeezed into a pupil plane array. Of the several approaches, however, improving the analysis of interferograms may be the best approach because all of the workpiece surface is tested at the same time.

© 1986 Optical Society of America