Analysis and Modeling of Surface Waviness Inspection with Light Reflection, Part 1: Laser Beam Scanning Method

Abstract

The laser beam scanning method for inspecting a reflective surface has been studied with analytical derivations and numerical modeling. Specular reflection off the surface was assumed and mathematical relations consistent with analytic geometry were used to trace the laser beam and predict its screen projection. It was found that deviation of the screen projection is proportional to the surface slope along the projection direction at the reflecting point and the distance from the point to the screen. The 3-D modeling was validated with 2-D analytical relationship as a special case and was tested with a profiled SMC (sheet molding compound) panel. The screen projections of reflected laser scans off surfaces with typical features of interest are predicted and the effects of waviness orientation are investigated.