| 摘要 |
PURPOSE: To accurately detect a pin hole of a small diameter of a light permeable film, by arranging an ultrasonic light source at the side of one face of the film and a photodetecting part having an image pickup device at the side of the other face of the film. CONSTITUTION: An ultrasonic light source 3 is arranged at the side of one face of a film 1, and a photodetecting part 4 having a built-in solid image pickup device 5 is set at the side of the other face of the film 1. Most of the ultraviolet rays from the light source 3 are reflected and absorbed by the film 1, not penetrating to the photodetecting part 4. Meanwhile, if a pin hole 2 is present on the film 1, the ultraviolet rays pass through the pin hole to reach the photodetecting part 4, are converted to an image signal by the device 5 and processed at a signal-processing device 6. As a result, the pin hole 2 is detected. Even women the film 1 shows a high permeability to visible lights, the ultraviolet rays are generally low in transmission and therefore the amount of ultraviolet rays passing through the pin hole 2 is greatly different from that of ultraviolet rays passing through other parts than the pin hole 2. The pin hole 2 is accordingly judged surely. |
