PURPOSE: To eliminate the need for a light shielding cover for enclosing the entire part of a device and to provide a reduction in cost and an improvement in productivity by providing specifically a shielding plate for laser light on the outside circumferential side of a laser lens holder through which an assist gas is passed.
CONSTITUTION: Many groove parts 14 are provided in the axial direction on the inside circumference on the bottom end side of a lens holder 13, and a lens 7 is inserted and held therein. A pressurized assist gas passes through the parts 14 and is fed to a work piece 9 side. Laser light 2 passes the lens 7, and spreads in four ways after irradiating the work piece 9. The 1st light shielding pieces 15a of a rectangular strip shape are juxtaposed at specified intervals along the axial line on the outside circumferential side of the holder 13, and the 2nd light shielding pieces 15b of a rectangular strip shape are similarly provided on the outside circumference of the pieces 15a so as to enclose said pieces. Clearance 17 is formed in the spacings between the pieces 15a, and the light shielding plate 15 consists of the group of the pieces 15a, 15b. The retainers 16 for the plates 15 enclosing the outside of the pieces 15b support freely slidably the pieces 15a, 15b of which the bottom ends contact with the work piece 9. Then the gaps between the holder 13 and the work piece 9 are hermetically closed by the plate 15, and the reflected light of the light 2 reflects repeatedly on the plate 15 without leaking to the outside. Gas vents are provided to the pieces 15b.
YAMAGUCHI HIROSHI
HONGOU MIKIO
MIZUKOSHI KATSUROU
SHIMASE AKIRA
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