Patent ID: 9108268
Filing Date: 2015-08-18
Classification: B23K

Abstract:
1. A laser processing apparatus comprising: a chuck table for holding a workpiece; a laser beam applier for applying a pulsed laser beam to said workpiece held on said chuck table, said laser beam applying means including a pulsed laser oscillator for oscillating the pulsed laser beam, a repetition frequency adjuster for adjusting the repetition frequency of said pulsed laser beam to be oscillated by said pulsed laser oscillator, and an objective lens focuser for focusing said pulsed laser beam oscillated by said pulsed laser oscillator onto said workpiece held on said chuck table; a varifocal lens provided between said pulsed laser oscillator and said focusing objective lens, said varifocal lens having a piezoelectric device to change its focal length according to the period of radio-frequency waves produced by said piezoelectric device; radio-frequency current frequency adjuster for adjusting the frequency of a radio-frequency current to be applied to said piezoelectric device; and a controller for controlling said repetition frequency adjuster and said radio-frequency current frequency adjuster; said controller controlling said repetition frequency adjuster and said radio-frequency current frequency adjuster so as to produce a phase difference between the repetition frequency of said pulsed laser beam to be oscillated by said pulsed laser oscillator and the frequency of said radio-frequency current to be applied to said piezoelectric device of said varifocal lens.