| 摘要 |
PURPOSE:To ensure the judgment of a defective part and dust simply, by scanning the surface of a material to be checked by laser light, and storing the output signals from light receiving elements into memories. CONSTITUTION:A surface 10 of a material to be checked is sequentially scanned by laser light in the directions of (x) and (y). The output signals from light receiving elements are converted into digital values by an A/D converter in a time division mode, and the results are stored in a memory. When a signal 11, which indicates the defect at a position (n) and (m), is received, the part is cleaned by a rubber-like body or other cleaning tools. Then the laser light is projected again, and the result is stored in another memory. Then both memories are compared. When a defect signal 11' is present at a later address (n) and (m) corresponding to the memory address (n) and (m) of the defect signal 11, which is stored at first, it is judged that said defect signal is caused by the true defective part. When the defect signal is not present at the later memory address (n) and (m), it is judged that the signal is caused by the dust. Thus the defective part and the dust are judged positively and simply. |
