New laser rangefinder for three-dimensional shape measurement of specular objects

We describe a new laser rangefinder for measurement of the shapes of specular objects, in many industrial contexts, objects with both Lambertian surfaces and specular surfaces are often manipulated. However, ordinary laser rangefinders usually cannot be used to measure specular objects. We propose a laser rangefinder for the measurement of specular objects based on a new idea in which the incident angle of a light-stripe upon the image sensor is limited through the use of a special light device. The concept of this rangefinder involves the application of triangulation to specular objects, which enables measurement of the shape of specular objects as well as Lambertian objects. We designed and built a prototype light-stripe projection rangefinder based on these principles. Experiments using the rangefinder successfully demonstrate the rangefinder's accuracy. The proposed rangefinder is a promising tool for the performance of many common industrial tasks including measurement of the shapes of polished metal and the inspection of soldered joint surfaces. (C) 2001 Society of Photo-Optical Instrumentation Engineers.