JPS57193876A - Detection for flaw and defect due to multiple taking-in of television picture - Google Patents

Abstract

PURPOSE:To detect flaws and defects with a high sensitivity by a low-output laser, by taking in many television pictures during one cycle of vertical scanning of illumination and totalizing results for every one picture to discriminate whether flaws and defects exist or not. CONSTITUTION:The image of a material 7 to be checked is picked up on a television 8 by a polygon 2 which scans horizontally a laser source 1, a K-Q lens 3 which makes beams parallel and reduces the beam diameter, a galvanolens 4 which scans vertically, a cylinder lens 5 which makes the vertical scanning parallel, and a half mirror 6 which allows the two-dimensional scanning to transmit through and reflects the scattered light from flaws to an ITV. In the detection of flaws due to the television picture signal, since flaws are detected as the scattered light by the dark field method, the image pickup tube utilizes the lag characteristics of about 50msec; and for example, if 32 pictures of the image which is divided to 32 equally to be illuminated are taken in and are superposed to obtain one picture, it is discriminated whether flaws exist on the face to be checked or not. Thus, the vertical scanning period is longer in accordance with the check speed, and the device is inexpensive, and the life is extended.