| 摘要 |
PURPOSE:To obtain a spiral slit with high accuracy by forming two irradiation points on a cylindrical work and moving and cutting the work so that the irradiation points draw spiral locusci and eliminating a part between both cutting parts. CONSTITUTION:When a laser beam is made incident on a split lens body 45, it is split into two and made to almost equal split laser beams 22c and 22d which are converged and the two irradiation points 22a and 22b are formed on the work 11 and through holes are provided thereon. At the same time, since the work 11 is rotated and moved in order, the irradiation points 22a and 22b move relatively while cutting the side wall of the work 11 and the spiral slit 13 is completed. At this time, the respective irradiation points 22a and 22b machine both side edges of the slit 13 at the same time and eliminates the part between both the side edges. Then, when a machining starting point is deviated by 180 deg. and the machining is performed in the same may, two spiral slits 13 and 14 are obtained. |
