Non-contact spatially constrained optical scanning methods applied for depth, width and gap measurements

The thesis presents the non-contact laser projection based systems utilized for quantifying the feature dimensions like width, depth and air gaps. Laser diode, Charge coupled device (CCD) and post-processing software using image processing tools are the major components of the non-contact measurement systems. The study involves two methods where the first method comprises of active laser-based triangulation and morphological edge detection for depth and width measurement applications. The second method uses edge detection technique and Dynamic Field of View (DFOV) for gap detection and tracking. Using the developed techniques, the case studies are conducted with smooth plastic fenders with induced artificial deviations, MIG welding seam and different air gap deco finishes. Experimental validations are carried out by comparing the results with commercial systems like 3D scanner and commercial sensor. Also, the Gauge Repeatability and Reproducibility (GR&R) studies are produced to identify the gap measurement tool capabilities interms of accuracy and repeatability.Keywords. Optical Inspection, laser triangulation, edge morphology, laser speckle, gap measurement, Field of View, Gauge Repeatability and Reproducibility.