LASER BEAM MACHINING DEVICE

PURPOSE:To modify with less troubles and in shorter time the bottom face of a groove and the side faces of the surface adjacent thereto by providing a concave lens to widen out a laser beam on the tip part of an irradiating nozzle inserted into the groove of a material to be machined. CONSTITUTION:The groove 2 is formed to have an opening on the upper face of the material 1 to be machined consisting of a metallic material which is movable at a prescribed speed in a perpendicularly intersecting space direction X. An irradiating nozzle 7 of a laser beam 10 is provided freely ascendable and descendable at the inside of the groove 2, and a lens 8 to make the beam 10 made incident onto the nozzle 7 a paralleled beam is provided. Also a concave lens 9 to widen out at the specified angle the beam 10 which is made a paralleled beam by the lens 8 and to irradiate simultaneously the bottom face 2c of the groove 2 and both side faces 2a, 2b adjacent thereto is provided on the tip part of the nozzle 7. Then when the nozzle 7 is moved in the direction Y with reciprocating movement of the material 1 at specified speed in the direction X, the beam 10 which was widen out by the lens 9 irradiates simultaneously on the faces 2a-2c and the modified layer is formed.