| 摘要 |
PROBLEM TO BE SOLVED: To distinctly and easily detect a very fine defect in a translucent substrate. SOLUTION: This defect detecting device 1 of the present invention is provided with an illumination systems 2-5 for irradiating the first face of a translucent substrate 0 with light, a light absorbing filter 11 for absorbing the light from the systems reflected in the first face of the substrate 0, a lens 8 for making incident light transmitted to the second face of the substrate 0 by the light from the illumination system to image-form an image thereof, an image picking-up means 6 for converting the image-formed image into an image data, and a monitor 9 for enlarging the image to display it. When a defect exists in the substrate 0, light from the illumination system is irregularly reflected in a defect position, light quantity to a corresponding picture element on the image picking-up means 6 corresponding to the position is changed and magnified on the monitor 9 to be reflected. Since the light reflected from the substrate 0 is absorbed by the filter 11 in this case, the image image-formed in the image picking-up means 6 is brought into a dark field to make the defect distinct on the monitor 9.
|
