| 摘要 |
PURPOSE:To prevent the detection of a minute defect formed onto a mask, and to simplify the mask detector by conducting illumination by a diffused light by using a diffusion filter for the mask pattern. CONSTITUTION:Beams emitted from a light source 2 are collected by a condenser lens 3, and beams changed into the diffused lights by the diffusion filter 13 are illuminated to the mask to be inspected 1. The transmitted light of the mask 1 is passed through an imaging lens 4, and imaged onto the imaging surface of a photosensor 5. Accordingly, voltage to proper reference voltage is compared and changed into binary because the output voltage of the sensor corresponding to a minute transparent section in an opaque wide region is slightly smaller than a large transparent section and the voltage of a minute opaque section in a transparent wide region is slightly larger than a large opaque section. Consequently, the minute defect section cannot be detected. |
