Variable-resolution video moire error map system for inspection of continuously manufactured objects

Joel H. Blatt; Scott Christian Cahall; Jeffery A. Hooker

doi:10.1117/12.145546

28 May 1993 Variable-resolution video moire error map system for inspection of continuously manufactured objects

Joel H. Blatt, Scott Christian Cahall, Jeffery A. Hooker

Proceedings Volume 1821, Industrial Applications of Optical Inspection, Metrology, and Sensing; (1993) https://doi.org/10.1117/12.145546
Event: Applications in Optical Science and Engineering, 1992, Boston, MA, United States

Abstract

Moire techniques can be a powerful tool to determine deviation of a manufactured shape from a desired shape. In a traditional moire system, distorted gratings on an object are viewed through an undistorted grating. The moire contours that result represent equal depth contours over the entire viewed surface. By generating the moire patterns in video, it is possible to view the distorted gratings on a test object through a set of gratings that has been distorted by a similar but perfect object. The output is then a set of moire contours that corresponds to the differences between the two surfaces. This difference or error map eliminates much of the unnecessary information generated in traditional moire inspection and thus becomes a valuable tool for comparisons between an imperfect test object and a manufacturing standard. We have developed a variable resolution video system for creating this error map using a Michelson interferometer to generate the gratings. We have successfully applied this system to damage detection on a long, continuous lengths of pipe by having two side-by-side cameras looking at different sections of pipe and also by having one camera's view filtered with a video-taped recording of an undamaged section of the pipe.

Citation Download Citation

Joel H. Blatt, Scott Christian Cahall, and Jeffery A. Hooker "Variable-resolution video moire error map system for inspection of continuously manufactured objects", Proc. SPIE 1821, Industrial Applications of Optical Inspection, Metrology, and Sensing, (28 May 1993); https://doi.org/10.1117/12.145546

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