<title>3-D inspection of large objects by moire profilometry</title>

Abstract

A moire profilometry method has been developed that is capable of inspecting objects whose size is limited only by the available laser power.The moire contours are generated in real time by projecting variable spacing gratings upon the target and filtering the image either optically, in the video signal, or in the computer.The system is designed to compare the surface shape of a test object with a previously stored image of a perfect object, and to display the surface errors superimposed on a video image of the test object. A unique feature of the system is the continuously variable depth resolution which makes it usable either for human or robot adjustment of the test object or for automated pass/fail inspection.