| 摘要 |
PURPOSE:To remove stray light from a defect inspecting which inspects a transparent substrate by using a laser beam by providing a black-painted glass plate which absorbs the laser beam on the opposite side from the laser beam. CONSTITUTION:A mask substrate 1 is irradiated with the laser beam 3 and reflected light from the substrate 1 is received by a photodetector to inspect the defect of the substrate 1. In this case, the 1st glass 11-1 and the 2nd glass 11-2 which have their reverse surfaces painted in black are provided on the opposite side of the substrate from the laser beam 3. Then, transmitted light 3-1 from the substrate 1 is absorbed by the 1st glass 11-1 and part of it is reflected by 90 deg., made incident on the 2nd glass 11-2, and reflected in the opposite direction from the laser beam 3. At this time, the 1st glass 11-1 and the 2nd glass 11-2 absorb the majority of the incident light. Thus, stray light which is transmitted through the mask substrate 1 and reflected by the surface of a moving mechanism under the substrate 1, so the mask substrate 1 is inspected with high accuracy. |
