Abstract
Many trials have been proposed to measure inner diameter of pipes and/or holes. However most of them are classified into contact methods with any kind of stylus. In this paper, inner profile measurement method of pipes is described using a ring beam device which consists of a conical mirror and a LD. The beam from the LD is directed to the top of the conical mirror which is precisely fabricated and polished in angle so as to form a ring beam for optical sections of the inner surface. This optically sectioned profile is analyzed to calculate the inner diameter and/or profile. In the experimental, pipes and holes of engine blocks are tested to measure the inner profile as well as to find defects of inner surfaces.
