Three-dimensional imaging technique using optical diffraction

Sheng Tan; Douglas P. Hart

doi:10.1117/12.455262

11 February 2002 Three-dimensional imaging technique using optical diffraction

Sheng Tan, Douglas P. Hart

Proceedings Volume 4567, Machine Vision and Three-Dimensional Imaging Systems for Inspection and Metrology II; (2002) https://doi.org/10.1117/12.455262
Event: Intelligent Systems and Advanced Manufacturing, 2001, Boston, MA, United States

Abstract

This paper presents a novel fast and simple technique to measure three-dimensional (3D) objects. An integrated 3D camera is built, which features a motorized off-axis rotating aperture. A regular spot pattern projection adds texture onto smooth 3D objects. When rotating, the off-axis aperture translates depth information into blurred image diameter. The displacement of each spot between two arbitrary aperture positions reveals depth. A pseudo- correlation algorithm based on optical diffraction is proposed to measure spot displacement fast and accurately. When subtracting two consecutive images of a roughly Gaussian-shaped displaced spot, the normalized subtraction intensity peak height is directly proportional to the spot displacement. The peak height to displacement calibration curve is specifically defined by optical parameters of the imaging system. Proper combination of off-axis aperture location and magnification ratio determines the size of the measurement range. Experiment observations show that the calibration curve is highly smooth and sensitive to the spot displacement at sub-pixel level. Real-time processing is possible with only order of image size arithmetic operations. The proposed technique holds potential for various industrial machine vision applications.

Citation Download Citation

Sheng Tan and Douglas P. Hart "Three-dimensional imaging technique using optical diffraction", Proc. SPIE 4567, Machine Vision and Three-Dimensional Imaging Systems for Inspection and Metrology II, (11 February 2002); https://doi.org/10.1117/12.455262

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