Wavefront Generator for Electronic Speckle-Pattern Interferometers

A common method to measure the shape of optically rough surfaces is the Electronic Speckle-Pattern Interferometry (ESPI). In ESPI, the shape is reconstructed by means of characteristic fringe patterns which are similar to a contour map. In the event that the combination of the surface shape and the measuring wavelengths results in either too high or too low local fringe densities, ESPI is at its limits. By using wavefront generators, the fringe density of the fringe pattern can be manipulated locally. In the present study, the physical limits and the feasibility of this method are analyzed theoretically and experimentally.