Enhancement in Dynamic Range of Amplitude-Modulated Continuous-Wave Laser Scanner Having a Coaxial Configuration

• Published in: IEEE transactions on instrumentation and measurement 2021, Vol.70, p.1-10
• Main Authors: Zhang, Chao, Set, Sze Yun, Yamashita, Shinji
• Format: Article
• Language: English
• Subjects: Amplitudes; Attenuation; Automatic control; Automatic gain control; Avalanche photodiodes; Continuous wave lasers; Data loss; Dynamic range; erbium-doped fiber amplifiers (EDFAs); gain control; High definition; Inspection; isolators; laser radar; Lasers; Measurement by laser beam; Optical attenuators; optical reflection; Optical scanners; Optical sensors; Pellicle; Photodiodes; Receivers; Scanners; shape measurement; Three dimensional models; Three-dimensional displays
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2020.3011768

A laser scanner is a powerful tool for 3-D geometry measurement. The amplitude-modulated continuous-wave (CW) laser scanner, which benefits from high accuracy measurement operating in the intermediate range, is suitable for high-precision 3-D industrial inspection. However, due to the limited dynamic range, laser scanners suffer from data loss and deterioration. This poses challenges for 3-D modeling, conversion of 3-D point cloud data to 3-D solid data, and so on. We chose the operation wavelength in the 1530-nm region. The dynamic range of an amplitude-modulated CW laser scanner was enhanced by the implementation of a combination of a low-noise and high-gain optical preamplifier and p-i-n photodiodes, a pellicle beamsplitter, and automatic gain control using a polarization-independent high-speed variable optical attenuator based on electrooptic ceramics in the receiver. In these manners, receiver sensitivity of -72 dBm was achieved and receiver dynamic range of around 37 dB was realized. We expect that our results contribute to high-definition industrial inspection for Industry 4.0.