Development of Optical Ring Image Sensor for 3D Profile Measurement of Machined Metal Surface. Light Scattering Simulation of Metal Surface and Its Verification.

Many optical methods have been developed in non-contact 3D profile measuring fields, but these methods can not be used to measure the profile of a metal surface well, due to the influence of the specular reflection, steep slope and the roughness. In this paper a new optical displacement sensor called optical ring image sensor is presented. In order to verify the possibility applying this sensor to measure the profile shape of a metal surface, the light scattering characteristics of the metal surface are analyzed using computer simulation, and then the light intensity distribution detected by a CCD line sensor is investigated based on the theory of Kirchhoff diffraction. Furthermore, an experimental system of the sensor is constructed and the measuring experiments are carried out for a metal workpiece (S55C) with Rq=0.33μm. The experimental and theoretical results show that the sensor can be applied to measure the profile shape of a metal surface such as mold and die.