| 摘要 |
PURPOSE:To detect only a really defective position correctly by inserting a light scattering plate into an optical path for illumination light made incident on the surface of a sample to be observed. CONSTITUTION:Light radiated from a light source lamp 8 is made parallel light by a collimator lens 9. The parallel light is made scattered light through the transmissive light scattering plate, a ground glass plate e.g., and the scattered light is passed through a condenser lens 11 and then reflected in the direction of an objective lens 13 by a half mirror 12. The image of the light source is formed on a position near the focus position of the objective lens 13. Since an optical system obtained by inserting a transmissive light scattering plate 10 into a Kohler illumination or an optical system similar to the Kohler illumination is used, light can be irradiated also from an inclined direction in addition to the vertical direction to an observing surface 14, so that only a real defective position can be correctly detected when an image is picked up by a TV camera and its pattern defect is tested by picture processing. |
