Polychromatic optical strain gauge
First Claim
1. A method for measuring strain of an object comprising:
- providing said object with a diffraction grating,illuminating said grating with radiation including at least two frequencies to produce an interference pattern corresponding to said frequencies,detecting at least a portion of the interference pattern corresponding to one of said frequencies, andanalyzing said interference pattern to determine strain.
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Accused Products
Abstract
A method and apparatus for measuring strain of an object is provided. The object to be measured is provided with a diffraction grating which is illuminated with radiation including at least two frequencies to produce an interference pattern. At least a portion of the interference pattern corresponding to at least one of the frequencies is detected and analyzed to determine strain. In some embodiments, the frequency of a portion of the diffraction pattern is detected, for example, by a human eye and the detected frequency compared with known frequencies to determine strain. In other embodiments, the relative angular position of portions of the pattern corresponding to different frequencies is detected. Since the relative angular position and intensity is affected by strain but not by certain rigid body rotations, strain measurement free of body rotation error may be made.
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Citations
33 Claims
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1. A method for measuring strain of an object comprising:
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providing said object with a diffraction grating, illuminating said grating with radiation including at least two frequencies to produce an interference pattern corresponding to said frequencies, detecting at least a portion of the interference pattern corresponding to one of said frequencies, and analyzing said interference pattern to determine strain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. Apparatus for measuring strain of an object comprising:
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a diffraction grating fixed to said object, a source of radiation including two frequencies for illuminating said grating and producing an interference pattern, a detector means for detecting at least a portion of said interference pattern corresponding to at least one of said frequencies, and analysis means for analyzing said portion of said pattern for determining said strain. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification