Non-destructive Measurement of Inner Radius of a Transparent Circular Pipe

Abstract

This paper shows a geometric optical measurement method newly developed for the purpose of measuring the inner radius of a transparent circular pipe. When the parallel laser beams run through a transparent circular pipe, two penetrated ones is observed comparatively clear : one of these is called the tangential mode and the other is the 1 order reflection mode. In this method the refraction of light is applied, but there is no need to use the index of refraction of the circular pipe material by using these two modes. In addition, it is possible to measure the inner radius at any axial position of a pipe. The value of inner radius for one transparent circular pipe is given with the mean value of 50 measured values. It is estimated from the experimental results that the total accuracy of this method is (mean value ± 0.001 mm). Therefore, the new measurement method is useful for measurement of the inner radius of a transparent circular pipe.