Phase-locked moiré fringe analysis for automated contouring of diffuse surfaces

Thesis (M.S.)--University of Rochester. College of Engineering and Applied Science. Institute of Optics, 1978. This thesis was digitized by the Institute of Optics in 2014 and was determined to have lapsed into the public domain. If you are the author and have questions about the digitization of your work, please contact Kari Brick, Graduate Program Coordinator for the Institute of Optics, at kbrick@ur.rochester.edu. Other contact information for the Institute is available at http://www.optics.rochester.eduPhase-Locked moiré systems have the advantage of rapid data acquisition and accuracy of better than one twentieth of the fringe spacing. In conventional moiré systems data acquisition is performed by making a photographic plate and taking measurements from the plate either visually or with a microdensitometer. This is slow and the accuracy is about one-quarter of the fringe spacing. The phase-locked system is more accurate and permits a more favorable trade off between accuracy and working depth. The equations governing moiré contouring are examined and compared with the results from interferometric methods. It is found that surface contouring with straight line gratings is equivalent to interferometric contouring in a Twyman-Green type system when certain relations are noted. This equivalence allows many of the current A.C. interferoI metric techniques to be applied to moiré contouring. The design and operation of a phase-locked Moiré system based on phase-locked interferometry is presented