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Proceedings Paper

Comprehensive ranging disambiguation for amplitude-modulated continuous-wave laser scanner
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Paper Abstract

Amplitude-modulated continuous-wave laser scanner with focusing optics can realize extremely high-precision 3D measurement. Since amplitude-modulated continuous-wave scheme employs periodical modulation, the longitudinal resolution and the maximum unambiguous range are in a trade-off. Our system utilizes dual-frequency modulation compromise such trade-off. However, such an attractive laser scanner suffers from ranging ambiguity due to aliasing, which is the systematic error inherent in amplitude-modulated continuous-wave scheme. We have removed the ranging ambiguity by aliasing synthesis. Secondly, the acquired 3D point clouds contain phase jumping at the maximum unambiguous range. With leveraging the relationship between the intensity and spatial information, the phase jumping was unwrapped to recover the spatial continuity. Thirdly, the 3D point clouds in the defocused region of the amplitude-modulated continuous-wave laser scanner distort since the depth-of-focus of focusing optics is generally cm order. The 3D point clouds in the defocused area are contaminated by aliasing which can also be regarded as a ranging ambiguity problem. We have experimentally restored the 3D point clouds by aliasing synthesis with the assistance of intensity information. The ranging area can be elongated by at least ten times of the depth-of-focus with such data processing. With the above-all mentioned configuration and data processing, we have compromised the ranging ambiguity inherent in the amplitude-modulated continuous-wave laser scanner comprehensively. We expect that our results contribute to high-precision industrial inspection for Industry 4.0.

Paper Details

Date Published: 1 April 2020
PDF: 8 pages
Proc. SPIE 11352, Optics and Photonics for Advanced Dimensional Metrology, 113521D (1 April 2020);
Show Author Affiliations
Chao Zhang, The Univ. of Tokyo (Japan)
Sifan Liu, The Univ. of Tokyo (Japan)
Zheyuan Zhang, The Univ. of Tokyo (Japan)
Neisei Hayashi, Tokyo Institute of Technology (Japan)
Lei Jin, The Univ. of Tokyo (Japan)
Sze Yun Set, The Univ. of Tokyo (Japan)
Shinji Yamashita, The Univ. of Tokyo (Japan)

Published in SPIE Proceedings Vol. 11352:
Optics and Photonics for Advanced Dimensional Metrology
Peter J. de Groot; Richard K. Leach; Pascal Picart, Editor(s)

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