Optical ring-image 3-D profile sensor

The purpose of this paper is to develop a non-contact profile sensor which will be able to measure 3-D free form machined metal surface as well as 3-D model shapes made of clay or wood. The proposed profile sensor called "optical ring image sensor' has two major advantages. First, reflection light from a target surface in optical axis can be detected in all directions using a ring slit. Second, the radius of optical ring image is linearly proportional to the displacement of the surface in optical axis. In this paper, the principle and properties of the optical ring sensor are presented analytically and experimentally. Finally, it is concluded that this sensor makes it possible to measure the profiles within an accuracy of 1O,a m for the 3-D free form surface with steep angles up to ± 80 degrees.