Amplitude-modulated continuous-wave laser scanner employing adaptive gain control for avoidance of receiver saturation

With the rise of Industry 4.0, smart factory is fast becoming a key concept in infrastructure. To realize the autonomous production system, it is necessary to ensure the parts are properly manufactured. 3D scanners are expected to play a vital role in quality assessment in smart factories. Especially, amplitude-modulated continuous-wave laser scanners benefit from high accuracy and high sensitivity which are suitable for industrial inspection. However, due to the limited dynamic range of receiver electronics, such laser scanners fail to obtain the data points in 3D measurement of highly reflective objects. This impairment deteriorates the performance of conversion of 3D point clouds to solid data for shape inspection, 3D modeling, reverse engineering etc. We coped with receiver saturation by adopting a high-speed polarizationindependent variable optical attenuator in our laser scanner. With such a lase scanner, we have succeeded in prevention of data loss due to receiver saturation.