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Abstract

A shearing interferometer produces a matrix of loops of wavefront phase difference vector signals derived from the interferogram indicative of wavefront slopes, where each loop corresponds to a sub-aperture portion of the wavefront under examination. Curl operators are applied to sum the vector signals in one direction about the loops to provide sums which are set equal adjacent loops are identified having such modified sums differing from each other by at least one integer, and in certain cases having modified sums of integers of opposite sign indicative of phase difference measurements greater than the dynamic range of the interferometer, and thus having error components therein. The phase difference values at the boundary of each of such particular identified adjacent loops are operated upon to set the modified sums to zero, to in turn eliminate the error components due to operation of the interferometer outside of the limited dynamic range. Particular edge loops are also identified at the outer edges of the matrix having a positive or negative modified sum, and also having all three loops bounding the particular loops having modified sums of zero. The edge position phase difference values are modified in one or more steps, until the positive or negative modified sums of the particular edge loop are reduced to zero. Eight algorithms for executing the above stated functions are setforth herein.

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