| CPC B23K 26/0622 (2015.10) [B23K 26/0648 (2013.01); B23K 26/18 (2013.01); B23K 26/53 (2015.10); B23K 2103/54 (2018.08)] | 11 Claims |
|
1. A method for processing a transparent workpiece, the method comprising:
directing a pulsed laser beam into the transparent workpiece, wherein:
the pulsed laser beam comprises pulse bursts having 2 sub-pulses per pulse burst or more;
each pulse burst of the pulsed laser beam comprises a burst duration Tbd of 380 ns or greater; and
the pulsed laser beam forms a pulsed laser beam focal line in the transparent workpiece, the pulsed laser beam focal line inducing absorption in the transparent workpiece, the induced absorption producing a defect in the transparent workpiece; and
the pulsed laser beam focal line comprises:
a wavelength λ;
a spot size wo; and
a Rayleigh range ZR that is greater than
 where FD is a dimensionless divergence factor comprising a value of 10 or greater; and
translating at least one of the transparent workpiece and the pulsed laser beam relative to each other along an open contour line to form an open contour comprising a plurality of the defects in the transparent workpiece; and
directing an infrared laser beam into the transparent workpiece along the open contour line to induce thermal stress in the transparent workpiece and thereby initiate separation along the open contour line, wherein:
the open contour is linear and comprises a directionally homogenous break resistance that does not vary greater than 25% over any direction along a surface of the transparent workpiece, and
wherein a diameter of each defect of the plurality of defects of the open contour and a spacing between adjacent defects of the open contour are increased with an increase in burst duration Tbd.
|