Submicrometric evaluation of workpiece surfaces in precision manufacturing

Today one of the leading technologies in coordinate measurement systems is optical measurement systems. Although they were discovered nearly 30 years ago, it is a technology that improves with a fascinating acceleration. So in order to evaluate the results of new technology, a comparison has been made with a well developed contact measurement system which already has standards. This thesis probably might be mentioned as a small step in standardization of optical systems. Many measurements have been done in order to compare the roughness properties of specimens that have different surface profiles (periodic and random), materials (aluminum and steel), machining styles, machining velocities and reflection abilities. It is observed that, two devices give comparable results if the surface has a good reflection value and not been very fine machined, especially for periodic profiles. Also the surface should not be ruined or scratched. It is observed that, the problem with the fine machined specimens that has periodic profiles is that the contact system can not detect the extreme values of the surface and give a result of dominant fine profile. On the other hand, optical system can detect very extreme values of the profile so that the results are getting scattered. Consequently, it is experienced that there is an inadequacy of contact stylus compared to a light beam because of its geometrical form. It is obvious that, the production of a stylus that can reach the thickness of a light beam is not possible using current technology.