| 摘要 |
PROBLEM TO BE SOLVED: To deplete a workpiece that strongly absorbs light which contains air, water, oxygen and hydrocarbon and which is not more than a specified value from the beam path of a laser by sealing the beam path from an outer atmosphere into an enclosure and repeatedly evacuating and back-filling the enclosure with inert gas. SOLUTION: The beam path of a laser operating at not more than 200 nm is sealed into an enclosure 4 from an outer atmosphere. A gas inlet port 10 and an evacuation port 12 are closed, a pump port 16 is opened and the enclosure 4 is evacuated by using a vacuum pump until it becomes prescribed residual pressure. Then, the pump port 16 is closed, the inlet port 10 is opened and the enclosure 4 is filled with inert gas until the enclosure 4 becomes not less than atmospheric pressure. Then, the inlet port 10 is closed again, the pump port 16 is opened and the evacuation and the back-fill of inert gas are repeated. The flow of inert gas is established in the enclosure during the operation of the laser, an absorption workpiece is shut out and the homogenous transmission path for laser beam can be maintained. |
