Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1990-08-08
1991-12-03
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
250237G, G01B 1124
Patent
active
050695487
ABSTRACT:
An apparatus and method for providing high resolution non-contact absolute contour measurements of an object with moire interferometry. The invention utilizes a projection moire system in which the entire projection system is translated to perform a field shift. The field shift produces a phase shift that is proportional to the height of the object. A coarse three dimensional map of the surface is first obtained from the phase shift. This is combined with high resolution relative measurements of the phase to obtain an absolute Z map of the surface. The invention does not suffer from the 2.pi. ambiguity problem and is suitable for prismatic discontinuous structures. In addition, the present invention is applicable to industrial environments and requires a relatively inexpensive optical system. Further, the field shifting technique is applicable to fast parallel process computers thereby allowing for fast absolute contour generation of prismatic parts.
REFERENCES:
patent: 4212073 (1980-07-01), Balasubramanian
patent: 4794550 (1988-12-01), Greivenkamp, Jr.
Article entitled: "Adaptation of a Parallel Architecture Computer to Phase Shifted Moire Interferometry", By: Albert J. Boehnlein, Kevin G. Harding, Ref.: SPIE vol. 728, Optics, Illumination and Image Sensing for Machine Vision, 1986.
Article entitled: "Moire Interometry for Industrial Inspection", By: Kevin Harding, Ref.: Lasers & Applications, Nov., 1983.
Article entitle: "Heterodyne and Quasi Heterodyne Holographic Interferometry", By: R. Dandiker & R. Thalmann, Ref.: Optical Engineering, Sep./Oct. 1985, Vol. 24, No. 5.
Article entitled: "Digital Phase Shifting Interferometry: a Simple Error-Compensating Phase Calculation Algorithm", By: P. Hariharan, B. F. Oreb, and T. Eiju, Ref.: Applied Optics, vol. 26, No. 13/Jul. 1987.
Article entitled: "Interferometric Measurement of the Roughness of Machined Parts", By: Katherine Creath and James C. Wyant.
Article entitled: "3-D Machine Vision for Automatic Measurements of Complex Shapes", By: G. T. Reid, R. C. Rixon and S. J. Marshall.
Article entitled: "Fringe Shifting in Various Moire Methods", By: F. P. Chiang, Ref.: Exp. Mech. 8(12), 554-560, Dec. 1968.
Article entitled: "Small Angle Moire Contouring", By: Kevin G. Harding, Mark Michniewicz, Albert Boehnlein, Ref.: SPIE Cambridge 87 Meeting, Cambridge, Mass.
Article entitled: "Fringe Pattern Anslysis", By: Albert Boehnlein, Kevin Harding Ref.: SPIE, Aug. 8-9, 1989, vol. 1163.
Evans F. L.
Industrial Technology Institute
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