Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1995-12-08
1997-03-18
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
250237G, 25055922, G01B 1124
Patent
active
056127863
ABSTRACT:
A method for measuring the contours (30) of a three-dimensional object (4); and a method for calibrating an optical system (2, 8). The object (4) is placed into the field of view of the optical system (2, 8). The optical system (2, 8) is activated to obtain a set of data giving a phase (x.sub.t) at each of a plurality of pixels corresponding to the object (4). The phases (x.sub.t) are unwrapped, e.g., by a method of ordered phase unwrapping. The unwrapped phases are converted into a set of three-dimensional coordinates (x.sub.s, y.sub.s, z.sub.s) of the object (4) for each of the pixels. These coordinates (x.sub.s, y.sub.s, z.sub.s) can be portrayed on a display of a computer (10). The method for calibrating the optical system (2, 8) shares several common steps with the above method. In addition, coordinates of a test calibration fixture (38, 46) are first mechanically measured. Following optical measurement of the calibration fixture (38, 46), an optimization procedure is used to minimize the difference between the mechanically measured coordinates (x.sub.m, y.sub.m, z.sub.m) and the coordinates (x.sub.s, y.sub.s, z.sub.s) calculated from the optical measurements. The optimization procedure in the calibration method fixes the intrinsic and extrinsic parameters of the optical system (2, 8). A blending method can be used to increase the dynamic range of the measured intensity. Phase shifting is performed by either a method of temporal phase shifting or a method of spatial phase shifting.
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Huber Edward D.
Kwon Osuk Y.
Shough Dean M.
Welling Rebecca L.
Williams Rick A.
Evans F. L.
Lockheed Missiles & Space Company Inc.
Radlo Edward J.
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