| 摘要 |
A system for detecting imperfections of one planar surface (17) of a disc-shaped glass master (1) and rotating the glass master (1) beneath an illumination source (9) and a video camera (15) or other device for receiving light from the illumination source (9) that reflects from the surface (17) under study. The camera (15) is oriented to receive illumination reflected only from an imperfectly flat portion of the surface (17) being inspected. The camera (15) has optics with a depth of focus less than the thickness of the glass master (1). The signal received by the camera (15) is processed by a template algorithm to compare the light level received with that from an assumed flat portion of the disc (1). If a significant discrepancy is found between the light reflected from different radii, the disc (1) is rejected. |
