| 摘要 |
PURPOSE:To prevent impurities from sticking to a window and to increase laser output by a method wherein a means is provided at an opening in a chamber for the prevention of adhesion to the window of impurities present in the chamber. CONSTITUTION:A unit of this design is provided with an opening 3c whereat laser is emitted upon charging of a laser material, a window 5 that may close the opening 3c leading to a gas laser unit chamber, and a impurities adhesion preventing means 20 installed on the opening 3c for the purpose of preventing impurities from sticking to the window 5. In an impurities adhesion preventing means 20 of this design, for example, a cylinder 21, with its center axis coinciding with the laser beam optical axis L, is installed on the opening 3c that is positioned within a chamber flange 3b, and a plurality of wall panels 23 are arranged on the inner wall 22 of the cylinder 21. With the unit being constructed as such, impurities travelling afloat from the direction of the chamber inner wall are allowed to adhere to the outer circumference of the cylinder 21 while impurities entering the cylinder 21 after traveling afloat toward the optical axis L are, because their velocity component along the optical axis L is smaller, soon to loose velocity and land on the wall panels 23 without reaching the window 5. |
