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Optical Engineering

Enhanced 3-D reconstruction of surfaces using multicolor gratings
Author(s): Bernard R. Gilbert; Joel H. Blatt
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Paper Abstract

Most optical topolography systems use a single-wavelength laser for projection, using a swept spot, a moving line, or a projected grating. In a typical projected grating system, the gratings are shifted and a series of images is used to recover the 3-D shape of the target. When the series of images is analyzed in the normal phase shift manner, the resulting 2-D phase map typically has phase unwrapping problems due to noise and Nyquist limits. Surfaces with large vertical discontinuities present a problem for phase unwrapping 3-D shape recovery. We look at simultaneously projecting multiple wavelengths onto a surface to help avoid problems in unwrapping the 2-D phase map. Multicolor projection and shape recovery are demonstrated with a white-light Michelson interferometer and with a two-color Mach-Zehnder interferometer. Using multiple wavelengths, it is unnecessary to rotate the interferometer mirror to change the grating pitch and some operations can be done in parallel, which reduces scanning time. Limitations and improvements in the current system are discussed.

Paper Details

Date Published: 1 January 2000
PDF: 9 pages
Opt. Eng. 39(1) doi: 10.1117/1.602335
Published in: Optical Engineering Volume 39, Issue 1
Show Author Affiliations
Bernard R. Gilbert, Florida Institute of Technology (United States)
Joel H. Blatt, Florida Institute of Technology (United States)

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