Inner Profile Measurement and Flaw Inspection of Pipes and Tubes

摘要

Inner profile measurement is an important matter in such fields as mechanical engineering including car and aircraft industries, and heavy industry relating to jet engines and power plant. In addition, we can find many applications in medicine and/or surgery related field. Here we describe recent development of our measurement principle for inner diameter and profile of pipes and/or tubes. The key device in this technique is a ring beam device which consists of a conical mirror and a laser diode (LD). And the fundamental principle is based on optical sectioning without using any contact type stylus. The optically sectioned profile of an inner wall of a pipe-like object is analyzed to give the inner profile in addition to the inner diameter. This optical instrument with simple and small configuration has been under development for practical uses. In our experimental works up to now, the availability of this instrument has been evaluated in many cases. This ring beam device consisting of a conical mirror and a LD is assembled in a glass pipe and the beam emitted from the LD is deformed, after reflected by the top of the conical mirror, into a disk-like circular light sheet. We show measurement result of pipes, and, at the same time, report a few examples that are developed for practical purposes. Both the ring beam device and a miniaturized CCD camera are fabricated into a glass tube for easier practical applications. We have already reported the fundamental principle of this measurement system and showed some applications. Here we report our trial to extend our technique to checking defects and flaws on the inner wall of pipe-like objects.