| 摘要 |
PURPOSE:To produce a large perforated bodies having constant quality. CONSTITUTION:The plural perforated bodies 1 are housed into a cage 2 and are immersed into the liquid 4 in an immersion vessel 3. A laser beam source 6 is horizontally movably disposed below this immersion vessel 3 and, in the meantime, a detector 7 for detecting a laser beam from this laser beam source 6 past the perforated bodies 1 is arranged above the perforated bodies 2. Detection of crack is executed by making the laser beam incident on the perforated bodies 1 from the bottom end faces thereof in such a manner that the laser beam transmits the inside of the perforated bodies 1 and detecting the transmission quantity of the laser beam by this detector 7. The crack is detected by a change in this transmission quantity. The laser beam is irregularly reflected when the crack is generated in the perforated bodies 1. The crack of the gels (perforated bodies 1) is detected by detecting the sharp change in the transmission quantity of the laser beam. The cracked perforated bodies 1 put in a cage 2 are pulled up out of the liquid 4 by a motor 5 when the crack is detected. |
