| 摘要 |
PURPOSE:To enable surface machining treatment having high accuracy to a work and to extend the service life of a nozzle part by arranging an inner part nozzle member having beam introducing passage widened to the work in the nozzle part and fins for cooling at outer peripheral part and an outer part nozzle member surrounding the inner part nozzle member. CONSTITUTION:Laser beam L is gradually widened along the beam L introducing passage 56 after condensing the beam to position of a focus F at the upper end part where is the narrowest part of the beam L introducing passage 56 in the inner part nozzle member 46 and radiated on the work W under defocussed state. In this case, the beam L reflected with the work W is absorbed with the inner wall of the above introducing passage 56 to a large part of the energy to effectively restrain influence into the optical system or nozzle part 10. On the other hand, as the inner part nozzle member 46 having the fins 58 for cooling is arranged at outer peripheral part to the outer part nozzle member 44, the heat caused by the above reflected beam L can be suitably radiated with the above fins 58. By this method, the nozzle part 10 having stable characteristic and enable high accurate machining treatment and extending long service life can be obtained. |
