| 摘要 |
PROBLEM TO BE SOLVED: To prevent a crack from reaching the surface by splitting a laser beam into a plurality of sub-beams and focusing them to a microarea in a member to be machined. SOLUTION: A single laser beam 11 from a laser light source 1 enters into a beam splitting means 2 to produce two sub-beams 12A, 12B entering into a focus optical system 3. A member 10 to be machined is mounted on a holding base 4 disposed oppositely to the focus optical system 3. The focus optical system 3 focuses the sub-beams 12A, 12B to a microarea 13 in a member to be machined. Absorption takes place by optical nonlinear phenomenon when the density of laser light exceeds a some threshold in the microarea 13 or the vicinity thereof. The absorption causes optical damage or breakdown of optical insulation and the microarea 13 in the member 10 to be machined is denatured such that it can be viewed from the outside. Consequently, the member 10 to be machined can be marked internally. |
