Shape measurement using high-density phase-shifted projected fringes

C. Gregory Hull-Allen; Paul E. Glenn; John D. Glenn

doi:10.1117/12.294444

10 December 1997 Shape measurement using high-density phase-shifted projected fringes

C. Gregory Hull-Allen, Paul E. Glenn, John D. Glenn

Proceedings Volume 3204, Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III; (1997) https://doi.org/10.1117/12.294444
Event: Intelligent Systems and Advanced Manufacturing, 1997, Pittsburgh, PA, United States

Abstract

Rapid, three-dimensional profilometry with resolution similar to that of mechanical coordinate measuring machines has long been a goal of vision system developers. Some success has been had using structured light projectors, flying spot scanners and the like. However, these techniques are limited by restrictions on the height variation and stability of the target object. This paper describes a phase measuring projected fringe interferometer that overcomes many of these problems. Using data from a high speed mega pixel class camera viewing high precision spatial modulation of a periodic illumination pattern on the target, new software unwraps the surface phase information and rapidly computes a true three dimensional surface. An important capability of the software is to avoid errors due to islands of missing data or high slope regions on the target. Interchangeable camera lenses permit measurements of a wide range of object sizes with a height resolution ratio on the order of 20 microns per meter of test piece size. The current application of the instrument is measurement of structural deflections of hypersonic aircraft structural components. In previous work, the technique has successfully measured the profile of coins and jet engine turbine blades and the curvature of a human spine. We summarize the special qualities of this instrument that make it well suited to such a wide range of measurements. Finally, we discuss some preliminary experimental results and compare them with typical accuracy requirements.

Citation Download Citation

C. Gregory Hull-Allen, Paul E. Glenn, and John D. Glenn "Shape measurement using high-density phase-shifted projected fringes", Proc. SPIE 3204, Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III, (10 December 1997); https://doi.org/10.1117/12.294444

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