Diameter measurement by laser at the submicron accuracy level

Abstract

One important consequence of the Quality Revolution that is currently taking place in all sectors of advanced manufacturing industry is the requirement for more systematic and precise measurement. This is a pre-requisite for controlling tolerances on manufactured components and for ensuring that products leaving the factory meet the required specifications. The dramatic increase in computer power coupled with the demands of the space age nanotechnology and customer sophistication have meant that instrumentation is being constantly pushed to the limits in terms of accuracy tolerance and speed. Diameter measurements are carried out on a daily basis in many sectors of manufacturing industry. Due to the emphasis on factors such as speed accuracy and repeatability the current trend is to move away from conventional measurement techniques (metre rule measuring tape Vernier callipers) towards non-contact techniques. One of such techniques involves the use of the laser. This paper discusses at the design of a laser tracer data initiation capture and processing unit that permits diameter measurements to be made on-line and has the capability of carrying out up to 500 measurements per second. The system is non-contact with a measurement range of 2. 0000 mm and a resolution of 0. 5 im. It is demonstraated that by using two of these devices diameters of up to 220. 000 mm can be measured. This is done by incorporating a translational table that provides the