Laser processing apparatus
A laser processing apparatus including a laser beam branching mechanism provided between a laser oscillator and a focusing unit. The laser beam branching mechanism includes a spread angle adjusting unit for adjusting the spread angle of a laser beam and a branching unit for branching the laser beam into a plurality of laser beams. The branching unit includes a half-wave plate, a first polarization beam splitter for separating the laser beam into P polarized light and S polarized light, a first mirror for reflecting the P polarized light, a second mirror for reflecting the S polarized light, and a second polarization beam splitter for leading the P polarized light reflected by the first mirror and the S polarized light reflected by the second mirror to different optical paths extending in the same direction.
1. A laser processing apparatus comprising:
a chuck table for holding a workpiece;
laser beam applying means for applying a laser beam to the workpiece held on the chuck table, the laser beam applying means including laser beam oscillating means for oscillating a laser beam, focusing means for focusing the laser beam oscillated by the laser beam oscillating means and applying the laser beam focused to the workpiece held on the chuck table, and a laser beam branching mechanism provided between the laser beam oscillating means and the focusing means for branching the laser beam oscillated by the laser beam oscillating means into a plurality of laser beams; and
feeding means for relatively moving the chuck table and the laser beam applying means in a feeding direction;
the laser beam branching mechanism including spread angle adjusting means for adjusting the spread angle of the laser beam oscillated by the laser beam oscillating means and a branching unit for branching the laser beam passed through the spread angle adjusting means into the plurality of laser beams;
the branching unit including a half-wave plate, a first polarization beam splitter for separating the laser beam passed through the half-wave plate into P polarized light and S polarized light, a first mirror for reflecting the P polarized light obtained by the first polarization beam splitter, a second mirror for reflecting the S polarized light obtained by the first polarization beam splitter, and a second polarization beam splitter for leading the P polarized light reflected by the first mirror and the S polarized light reflected by the second mirror to different optical paths extending in the same direction;
the first mirror and the second mirror being arranged so that the P polarized light and the S polarized light traveling in the same direction from the second polarization beam splitter are spaced a slight distance from each other;
whereby the spread angle of the laser beam oscillated by the laser beam oscillating means is adjusted by the spread angle adjusting means to thereby adjust the spacing between the focal points of the plurality of laser beams formed by the P polarized light and the S polarized light to be focused by the focusing means.
2. The laser processing apparatus according to claim 1 , wherein the branching unit includes a plurality of branching units, the P polarized light and the S polarized light passed through the upstream one of the plurality of branching units being 45° rotated in polarization plane by the half-wave plate of the next one of the plurality of branching units, the P polarized light in the next branching unit being further branched into P polarized light and S polarized light to be introduced into the focusing means, the S polarized light in the next branching unit being further branched into P polarized light and S polarized light to be introduced into the focusing means.