3D laser measurements on scattering and translucent surfaces

Laser based scanning methods have proven to be a valuable tool for a variety of 3D measurement applications. However, just as touch probes do not measure soft or flexible parts well, laser based methods have encountered problems with surfaces which are very rough or translucent. Either type of surface tends to spread the laser light out over an extended region, creating an uncertainty blob which can lead to false measurements. This paper discusses the types of errors associated with these light scattering surfaces, and efforts to minimize these effects through tight control of the viewing optics. Specific data is presented from tests performed with a laser based measurement probe on a variety of surfaces from smooth metal to translucent plastics.