| 摘要 |
PURPOSE:To prevent the decrease of energy of laser light as a result of continuous use and to prevent the failure of an optical system by evacuating the laser light irradiating part on the surface of a metallic pipe to a lower pressure and introducing an inert gas to the reflection mirror part in a laser guiding means. CONSTITUTION:While the inside of the metallic pipe 8 is evacuated by a vacuum pump, the inert gas is introduced from an introducing pipe 14 into the reflection mirror part 5 in a cylindrical body 2 which is hermetically sealed at one end and has a laser incident hole at the other end. The inert gas is restricted by a laser exit hole 6 so that the periphery of the mirror 5 is filled by the inert gas, then the inert gas flows out of the hole 6 into the metallic pipe 8. The laser light 3 is made incident in this state on the laser guiding means 1 from which the laser light is passed through a stop 7 of the diameter corresponding to the beam diameter of the light 3 and is condensed by a lens 4. The laser light is then reflected by the mirror 5 and is emitted from the hole 6 of the diameter corresponding to the diameter of the incident end so as to irradiate the inside surface of the metallic pipe 8. A carriage 17 is moved and the entire inside surface of the metallic pipe 8 is irradiated with the laser while the means 1 is rotated by rotary sealing mechanism 9a, 9b under the irradiation of the laser light. |
