Non-contact laser inspection for the inner wall surface of a pipe

Abstract

A non-contact laser sensor based on the ring optical cutting image method to measure the size and profile of the inner wall of a pipe is developed. The sensor consists of a laser diode light source, an optical ring pattern generator and a CCD camera. The optical ring pattern from the optical ring pattern generator is projected onto the inner wall of the pipe, which is then viewed by the CCD camera. Reasonable parameters according to the theory of light scattering and reflection are chosen to simulate and optimize the measurement system. The adaptive weighted average value filter and the subpixel technique on several-step computing and half Gaussian fitting are deployed to obtain the edge and the centre of the ring image in order to filter the noise of the image and raise the resolution of the measurement system. The experimental results show that the principle is correct and the techniques are realizable.