Laser Light-Based Technique for Detection and Assessment of Localized Defects in Reflective Automotive Surfaces

Surface quality plays an important role on aesthetic appeal of any exterior component of a vehicle. As such, smooth and defect-free are some of the critical characteristics of an automotive surface. Numerous manufacturing-related factors such as production environment, substrate material, coating material, handling is known to generate defects to inherently decrease the overall quality of the external surface. Many of these defects tend to be localized while spreading over large areas of the surface. However, the vast majority of available systems are unable to unequivocally quantify surface defects, and, in most cases, the surface quality assessment is performed in a relative and rather qualitative manner. To address this, the main goal of the present study was to develop a new laser light-based technique capable to detect and quantify the localized defects that are present on the surface of reflective components for automotive exteriors. For this purpose, the setup of the proposed prototypical system was validated through a blend of optical simulations and experiments performed on concave and convex defects with determined geometries and with sizes placed in the sub-millimeter range. This type of knowledge is essential in understanding how the collimated fascicle of light is being redirected after interacting with localized surface defects. Future extensions of this work will target the more general case of globally spread defects of an undetermined shape that are - for instance - characteristic to painted automotive bodies.