Moiré Interferometry

Moiré interferometry combines the concepts and techniques of geometrical moiré and optical interferometry. In his definitive monograph, Guild1 shows that all moiré phenomena can be treated as cases of optical interference, although moiré generated by low-frequency bar-and-space gratings can also be explained by obstruction or mechanical interference. Moiré interferometry is capable of measuring in-plane displacements with very high sensitivity. A sensitivity of 2.4 fringes/µm displacement is demonstrated for all the patterns in this chapter except Figs. 4.7 and 4.45, where the sensitivity is 4.0 and 1.2 fringes/µm displacement, respectively. In Chapter 5, the sensitivity is even higher.