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26 May 2011 Dual-wavelength holographic shape measurement with iterative phase unwrapping
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In order to measure the shape of a large number of identical components in a manufacturing industry we propose a method where digital holography is used to capture an image of the object and then the shape of the object is achieved by using information from the CAD-model. The holographic recording of the object is done using dual wavelengths giving a synthetic wavelength of about 400 μm. This gives a phase map where the phase intervals represent a depth distance on the object of about 0.2 mm. To find the shape of the object the phase map has to be unwrapped. Since the surface contains discontinuities we use information from the CAD-model of the measured object and unwrap the phase iteratively. The result becomes a digital point representation of the measured surface that can either be used just as a description of the object shape or as a way to describe how well the object has been manufactured compared to the CAD-model. The measurement process that is proposed is adapted for on-line purposes; hence it is fast and reliable.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sara Rosendahl, Per Bergström, Per Gren, and Mikael Sjödahl "Dual-wavelength holographic shape measurement with iterative phase unwrapping", Proc. SPIE 8082, Optical Measurement Systems for Industrial Inspection VII, 80820B (26 May 2011);

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