| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent dust of spatters or the like from sticking to an optical system member and also to reduce the fluctuation of the focal position of the optical system member due to heat of an assist gas and a high output of laser beam during laser machining. SOLUTION: The laser beam LB oscillated into a laser machining head 9 part from a laser beam oscillator is condensed with a condensing lens 13 (optical system member). This condensing lens 13 is protected with a filter 25 in the airtight chamber 29 formed in the optical path of the laser beam. Even though the condensing lens 13 generates heat during laser machining, since the temperature within the airtight chamber 29 is regulated to cool the condensing lens 13 and the pressure within the airtight chamber 29 is regulated, the focal position of the condensing lens 13 is not deformed even though the pressure of the assist gas 19 fluctuates, whereby stable laser machining is obtained. Even though dust of spatters or the like invades into the laser machining head 9, the condensing lens 13 is protected with the filter 25.</p> |
