Sensitivity-variable moire topography with a phase shift method

We propose a projection moire topography with a phase shift method for measuring the fine profile of an object, In this method, a set of interference fringes made using a Mach-Zehnder interferometer and a dove prism is projected on an object surface to generate moire fringes. The interval between the moire fringes can be easily changed in a range of 160 to 300 mu m and we can realize sensitivity-variable moire contouring. Also, the phases of the moire-fringe pattern are easily changed by shifting one of the interference fringe patterns and the depth at each point on the object are computed with a high accuracy from the several moire-fringe patterns with different phases. Although the interferometer is used in the system, the setup is robust against vibrations. (C) 1996 Society of Photo-Optical instrumentation Engineers.