Improved line of light measurements on shiny and transparent surfaces

The use of laser line systems for cross sectional measurement on production parts is a method that has been in use for over 30 years with few changes in the equipment. A primary limitation of using a laser line triangulation methods has always been the inability to obtain good measurements on shiny or transparent surfaces. Not only is the return signal poor from such surfaces, but the presence of multiple reflections can cause problems. This paper will explore new methods to obtain better measurements on very shiny, mirror like surfaces as well as transparent materials such as plastic and glass. The paper will quantify what improvements may be expected with the improved methods possible today, as well as identify the remaining limitations of these methods. The results will be compared against the results obtained using methods other than line of light triangulation and discuss the comparisons in performance achieved.