Waveguide grating (moire) microinterferometer for inplane displacement/strain field investigation

Analysis of microelements requires a local approach to their mechanical behavior and material constants distribution. This requires modern full-field measurement tools, among which automated grating (moire) interferometry (GMI) is one of the best-suited measurement methods. A new type of grating microinterfetometer is presented. It is based on the concept of an achromatic grating interferometer combined with a glass block waveguide and designed to work with standard optical microscopes. The various types of waveguide plates are presented and discussed. The interferogram obtained may be modified and design for analysis by means of carrier frequency phase shifting methods. The methodology of measurement is described. The usefulness of the micro-interferometer is demonstrated by an example of in-plane displacement and strain distribution determination in the two-phase steel polycrystalline material. (C) 2002 Society of Photo-Optical Instrumentation Engineers.