DEFECT DETECTING METHOD AND SYSTEM

摘要

In detection of a defect in a part of an object having a surface which is substantially a surface of revolution, the surface of the inspected part is illuminated by light rays which are emitted through an annular portion coaxially disposed with the surface of the inspected part, and light rays reflected at the surface of the inspected part are received to form an image of the inspected part. The image is constituted of pixels corresponding to the respective portions of the surface of the inspected part. Signals having a value indicative of the brightness of the pixels are stored in relation to the respective positions of the pixels in the image. The stored signals are referred repeatedly to provide, as a set of signals, a predetermined number of the signals of the pixels positioned along an imaginary line extending radially through a central point in the image corresponding to the axis of the surface of the inspected part and positioned and distributed within a radial range extending along the imaginary line. Judgement whether or not there is a defect is made in accordance with comparison of tha signals of each set with a preset value, and with comparison between signals of two sets which are positioned along two of the imaginary lines which are proximate to each other.