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21 June 2019 Absolute angle measurement using dual-wavelength laser speckle for robotic manufacturing
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A non-contact optical technique employing dual-wavelength laser speckle is investigated for absolute angle measurement. The approach uses the separation of the speckle patterns formed by two closely spaced illumination wavelengths to determine the angle of a surface. Autocorrelation is performed on a single exposure containing both speckle patterns to find their relative displacement, which is directly related to the absolute surface angle. This absolute angle determination offers an advantage over previous techniques using laser speckle that require a reference image. The underlying theory linking the speckle pattern displacement and the surface angle is presented, along with a proof-of-concept sensor. Experimental results from the sensor confirm the validity of the theory, with measurements demonstrating a mean difference from applied angles of 0.136°.
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sam J. Gibson, Thomas O. H. Charrett, and Ralph P. Tatam "Absolute angle measurement using dual-wavelength laser speckle for robotic manufacturing", Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 110560K (21 June 2019);

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