| 摘要 |
PURPOSE:To reduce the probability of error detection, which is due to stray light, of a foreign matter and to detect a foreign matter having a small gap in high probability. CONSTITUTION:A light beam from a light source 7 is converted into a sheet light beam L2 via lens systems 8, 9 and the light beam L2 slantly irradiates an area 10 on a pellicle 1, while a light beam from a light source 11 is converted into a sheet light beam L4 via lens systems 12. 13 and the light beam L4 vertically irradiates the area 10 on the pellicle 1. Scattered light from a defect such as a foreign matter in the area 10 is condensed by a light receiving lens 14, and an image of the defect is formed on an image pickup face of a one dimensional image pickup element 15 by the condensed light. A foreign matter having a small gap is detected by scattered light of the light beam L4. |
