| 摘要 |
PURPOSE:To prevent the degradation of the laser power use efficiency and the damage of an equipment due to a reflected light by providing a stop mirror on the outside of the focus position of a mirror which forms the laser beam emitted from an oscillator to a prescribed beam shape. CONSTITUTION:A laser beam 1 is condensed to a very small beam sectional area in the focus of a composite optical system consisting of an integration mirror 3 and a stop mirror 7 and is expanded gradually after passing the focus position and is formed to the same shape as the beam obtained near the focus of the integration mirror 3, namely, the beam shape suitable for heat treatment in a certain position again. Consequently, a material 6 to be worked is set in this position. A reflecting plate 8 is set between a working nozzle 4 and the material 6 to be worked to face the material to be worked, and the inside surface of the plate 8 is covered with high-reflection factor materials, and therefore, a reflected light 10 is turned back to the surface of the material 6 to be worked again. Most of the laser optical power is absorbed by the material to be worked while multireflecting between the surface of the material 6 to be worked and the inside surface of the reflecting plate 8. |
