Optical triangulation is a very old method of determining absolute distance to an object. In recent years laser range sensors utilizing this principle have seen growing use, particularly in the auto industry. More accurate versions are being employed for dimensional inspection operations where the sensor is often mounted on a coordinate measuring machine. Such a system offers the potential for rapid non-contact dimensional metrology. However, there are several factors which must be taken into account if accurate and reliable results are to be achieved.
This paper examines problems which can be encountered when using laser triangulation range sensors. Results of a study comparing such sensors with conventional touch probes are presented and suggestions for improved sensor designs are made. The problem of accurately locating edges and other steeply contoured surface features is given special attention.