| 摘要 |
PURPOSE:To perform inspection surely and satisfactorily by applying the transmitted illuminating light which is about the same as the reflected light from the normal surface of an object to be inspected through the through-hole that said object possesses thereby performing inspection. CONSTITUTION:A reflection mirror 20 is diagonally provided by facing the side opposite from the incident side of lighting rays 6 with respect to an object 22 to be inspected having a through-hole 16 in such a manner that the rays from an illuminating device 19 reflects on the mirror 2 and treat transmitted illuminating rays 21 enter the through-hole 16. This is made into the constitution that can optically process the video signal level through the through-hole 16 picked up by an industrial telecamera 9 in a manner as to assume the video signal level of about the same degree as that of a normal metallic surface by means of the transmitted illuminating rays 21. |
