A stereoscopic digital speckle photography system for 3-D displacement field measurements |
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Authors: | Per Synnergren Mikael Sjdahl |
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Institution: | Division of Experimental Mechanics, Luleå University of Technology, S-971 87 Luleå, Sweden |
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Abstract: | Stereoscopic digital speckle photography offers a technique to measure object shapes and 3-D displacement fields in experimental mechanics. The system measures the displacement of a random white light speckle pattern, which somehow is present on the object surface, using digital correlation. This paper describes a general physical model for stereo imaging systems. A camera calibration algorithm, which takes the distortion in the lenses into account, is also presented and evaluated by real experiments. Standard deviations of small deformations as low as 1% of the pixel size for in-plane deformations and 6% of the pixel size for the out-of-plane component are reported. Using the calibration algorithm described, the main source of errors is random errors originating from the correlation algorithm. |
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Keywords: | Three-dimensional displacement measurements White-light speckle metrology Digital speckle photography Lens distortions Imaging systems |
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