| 摘要 |
PURPOSE:To reduce absorption scattering due to impurities and to improve a laser output by arranging means for removing impurities staying to the vicinity of a discharge unit from the vicinity of a laser optical member in a laser head. CONSTITUTION:Since an excimer laser uses fluorine gas having high reactivity as one of laser gases, fluoride of impurity is generated in a laser head 2. An electrode material is sputtered by discharging, a large quantity of fine metal particles are generated. In order to remove the impurities, laser gas is introduced to a gas processor 9 by the head 2 in which the laser gas 1 is sealed, fluoride is removed from the gas, and only rare gas of high purity is merely returned into the head 2 from rare gas guide holes 10, 11. As a result, reaction product of the gas and metal particles in a laser light path are suppressed to a minimum limit to prevent a decrease in the output of a laser light. |
