| 摘要 |
PURPOSE:To facilitate the control of the equipment along with a handier construction thereof, by inspecting light leaked at a defect with one matrix-like image sensing element shielding light over an opening to detect the defect on a conductive layer of a through hole. CONSTITUTION:A through hole (TH) 34 is shielded with a rod 35 and is irradiated by an illumination light 42. When any defect exists in a conductive layer 33 of the TH 34, an image on the right from the center axis of the TH 34 is reflected on the surface (r) of a prism 36 and the image on the left is reflected on the surface S while the image passing straight through the TH 34 passes straight through the prism 36 to form images at parts b1, b2 and b0 of a image sensing element. The image signals are passed through a binary coding circuit 39 and the image a' formed (a) of the TH 34 unshielded is memorized into an image memory 40 and images b0'-b2' formed at the parts b0-b2 done into a memory 41 thereby enabling highly accurate detection of a defect of the TH 34. |
