Development of structured light 3D-scanner with high spatial resolution and its applications for additive manufacturing quality assurance.

Digital three-dimensional (3D) scanning is a cutting-edge metrology method that can digitally reconstruct surface topography with high precision and accuracy. Such metrology can help traditional manufacturing processes evolve into a smart manufacturing paradigm, which can ensure product quality by automated sensing and control. However, due to limitations with the spatial resolution, scanning speed, and size of the focusing area, commercially available systems cannot be directly used for in-process monitoring in smart manufacturing. For example, a metal 3D printer requires a scanner with second-level sensing, micron-level spatial resolution, and a centimeter-scale scanning region. Among the 3D scanning technologies, structured light 3D scanning can meet the scanning speed criteria but not the spatial resolution and scanning region criteria. This work addresses these challenges by reducing the field of view of a structured light scanner system while increasing the image sensor pixel resolution. Improvements to spatial resolution and accuracy are achieved by establishing hardware selection criteria, integrating the proper hardware, designing a scale-appropriate calibration target, and developing noise reduction procedures during calibration. An additively manufactured Ti-6Al-4V part was used to validate the effectiveness of the proposed 3D scanner. The scanning result shows that both melt pool geometry and overall shape can be clearly captured. In the end, the scanning accuracies of the proposed scanner and a professional-grade commercial scanner are validated with a nanometer-level accuracy white light interferometer using high-density point cloud data. Compared to the commercial scanner, the proposed scanner improves the spatial resolution from 48 to 5 μm and the accuracy from 108.5 to 0.5 μm. Compared to the white light interferometer, the proposed scanner improves the scanning and processing speed from 2 to 20 s. [ABSTRACT FROM AUTHOR]