JPH0510665B

PURPOSE:To intersept leakage of a laser beam out of a device even if trouble happens in the on-off circuit of the laser beam by intersepting the path of the laser beam when a process kit is taken out of the device. CONSTITUTION:A shutter plate 11 for opening or closing a scanning opening 2a is slidably fitted to the underface of the base 2 of a main device body, the pins 2b, 2c of the base 2 are freely fitted to the long holes 11c, 11d of the plate 11, and the plate 11 is energized in the direction of closing the opening 2a with springs 12a, 12b. When a kit 10 is inserted, the 2 protuberances 13, 14 formed on the top of the kit 10 are engaged with the legs 11a, 11b of the plate 11, and it is displaced in the direction of arrow C to open the opening 2a. When the kit 10 is taken off, the springs 12a, 12b move the plate 11 in the direction reverse to the direction C to intersept the path of laser beam. As a result, outward leakage of the laser beam can be intersepted even if trouble happens in the laser on-off circuit.