Holographic and moire aspherical compensators

Computer generated aspherical compensators are superimposed on an interfero meter wavefront or fringe pattern to generate a null fringe pattern. This p rocess has been understood and widely described in the literature. On the o ther hand, when we superimpose an ideal fringe pattern on top of the pictur e of an interferogram to be analyzed, we obtain a moire pattern between the two images. These two apparently different procedures have much in common, but also some important differences to be described here.