| 摘要 |
PURPOSE:To simplify the title detection and decision by radiating a laser beam to an action film, calculating a ratio of the action film left at the bottom of a pin hole to the thickness of the action film by a specific expression from the variation of the transmission light quantity and deciding a flaw. CONSTITUTION:A laser beam 4 whose intensity makes a Gaussian distribution is projected vertically to the surface of an action film 1, and a transmission light is received by the reverse side of the film 1. Subsequently, a signal voltage ratio S of the light quantity P2 transmitted through a part where a pin hole 3 exists, to the light quantity P1 transmitted through a part where the pin hole does not exist is detected. Next, the ratio S is decided to be equal to the increase (k) of the transparency of the film 1 by the pin hole, and from an action film transparency T of no flaw measured in advance, the ratio of thickness delta2 of a film of the bottom of the pin hole 3 to the thickness delta1 of the film 1 by an expression logkT/logT=delta1/delta2=n, and when it is smaller than a prescribed number N, the pin hole 3 is decided to be a flaw. |
