| 摘要 |
PURPOSE:To avoid entry of atmosphere into a laser resonator and to remove contamination on the inner surface of a mirror readily even in a structure, from which the laser mirror cannot be removed, when the contamination of the laser mirror is removed, by removing the contamination by etching utilizing discharge from a discharge electrode provided in the laser resonator without detaching the laser mirror from the resonator. CONSTITUTION:When a total reflection mirror, which is attached to a laser resonator 1 or an output window (laser mirror M) is contaminated, a valve 2 is opened, and laser gas in the resonator 1 is exhausted by an exhausting pump (d). After the valve 2 is closed, a valve 3 is opened, and etching gas (e) is introduced in the resonator 1. As the etching gas, e.g., CCl4, CCl2F2, CF4, NF3 and the like are used. It is desirable that a pressure range of several Pa - several hundred Pa is used. Discharge is generated between a mesh electrode 6 facing the contaminated surface of the laser mirror M and the resonator 1. Then the gas in the vicinity of the mesh electrode 6 is converted into plasma, and the contamination of the laser mirror M is etched with ions. |
