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

The laser scanner is a powerful tool for 3D geometry measurement. The amplitude-modulated continuous-wave laser scanner, which benefits from high accuracy measurement operating in the intermediate range, is suitable for high-precision 3D industrial inspection. However, due to the limited dynamic range, laser scanners suffer from data loss and deterioration. This poses challenges for 3D modelling, conversion of 3D point cloud data to 3D solid data etc. We chose the operation wavelength at 1530-nm region. The dynamic range of an amplitude-modulated continuous-wave laser scanner was enhanced by implementation of a combination of a low-noise and high-gain optical preamplifier and PIN photodiodes, a pellicle beamsplitter, and an automatic gain control using a polarization-independent high-speed variable optical attenuator based on electro-optic 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.