Simultaneous measurement of internal and external profiles using a ring beam device

Abstract

A ring beam device consisting of a conical mirror and a LD is available to form a disk-like beam sheet. We have shown measurement result of an inner diameter of pipes and holes and have developed a compact inner profile measuring instrument up to now. The ring beam device and a miniature CCD camera are incorporated in a glass tube. Validity of this instrument was shown by checking the inner profile of the references. In response to this trial, there appeared a strong request that not only an internal but also external inspection should be measured. Surely the pattern projection method conventionally used in 3D profile measurement may be useful for high speed and high precision measurement of various objects, but it is not always appropriate to measure an object with steeply inclined surface profile such as a bevel gear. In this paper, we propose a method for measurement of the external profile in addition to the internal profile. In our arrangement, one pair of concaved conical mirrors is used for the external profile measurement. When combined with our inner profile measurement method, simultaneous measurement of the inner and outer profiles becomes possible. A measurement result on a bevel gear showed availability of our proposal. We are aiming to realize simultaneous measurement of the internal and external profiles.