Some applications of a HOE-based desensitized interferometer in materials research

A holographic method suited for the measurement of flatness deviation is presented. This method takes advantage of the basic Fizeau arrangement usually meant for contouring analysis of relatively flat bodies. A desensitized interferometer is described allowing the measurement of rough objects, as frequently encountered in engineering practice. The key component of this interferometer is a diffractive optical element produced by recording two-wave interference patterns. Desensitization factors ranging from 1 to 100 with respect to a Fizeau interferometer can be achieved. Flatness checks of computer disks demonstrate the possibilities of the interferometer; deformation measurements performed with the desensitized interferometer on classical experimental mechanics specimens are presented: static testing on notched C-rings and on welds, and fatigue testing on notched three-point bend tests.