| 摘要 |
PURPOSE:To obtain an inexpensive device of simple constitution which performs decision processing fast by extracting only a defect position of a substrate to be tested by using a hologram disk. CONSTITUTION:A standard substrate 1 is placed on an XY stage 3 and laser light from a laser oscillator 17 is made incident through a half-mirror 18 and a concave lens 20; and reflected light and light which is reflected by a half- mirror 19 and passed through a concave lens 21 are made incident on a hologram disk 13, so that interference fringes showing a pattern part are recorded on the hologram disk 13. Then the substrate 2 to be tested is mounted and a pattern image of the substrate 2 are projected on the hologram disk 13 by the same method. Then the image is picked up by an image pickup device 6 and inputted to a binary signal converting circuit 22 to generate a signal consisting of a white part, a dim light part, and a black part and a black and a white part signal are extracted by a sampling circuit 23 and outputted to a decision circuit 16 to decide that the substrate 2 is defective.
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