13 May 2013 3D shape measurements of fast moving rough surfaces by two tilted interference fringe systems
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Shape measurement of moving, especially rotating objects is an important task in the field of process control. The Laser Doppler Distance Sensor was invented for this purpose. It is realized by two tilted interference fringe systems and enables the simultaneous measurement of the surface velocity and profile. The distance is coded in the phase difference between the generated interference signals of two photo detectors. In order to achieve a distance uncertainty of below 1μm a steep calibration function is necessary. This can be achieved by increasing the tilting angle. However, due to the speckle effect at rough surfaces, random envelopes and phase jumps occur disturbing the phase difference estimation with increasing tilting angle. This problem was overcome recently by employing a receiving optics matching reducing the distance uncertainty by about one magnitude. By evaluating the Doppler frequencies of the two fringe systems the surface velocity and thereby the objects mean diameter can be calculated as well as angular misalignment of the sensor can be detected.
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Robert Kuschmierz, Robert Kuschmierz, Philipp Günther, Philipp Günther, Jürgen W. Czarske, Jürgen W. Czarske, } "3D shape measurements of fast moving rough surfaces by two tilted interference fringe systems", Proc. SPIE 8788, Optical Measurement Systems for Industrial Inspection VIII, 87881T (13 May 2013); doi: 10.1117/12.2020168; https://doi.org/10.1117/12.2020168

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