Interferometric alignment using parabolic and off-axis conical zone plates

Abstract

The use of zone plates in optical alignment and displacement measurement is discussed. A simple theory of positioning using two coherent wavefronts is proposed. A few examples, already described in the literature as well as new ones, are presented as an illustration of the theory. The application of the specific case of the offaxis cylindrical zone plate (so-called parabolic zone plate) and off-axis conical zone plate for sensing the motion along a straight line parallel and inclined to the hologram plane is established. There are also adduced results of simple experiments supporting the analysis.