Laser processing of slots and holes
The present invention relates to a process for cutting and separating interior contours in thin substrates of transparent materials, in particular glass. The method involves the utilization of an ultra-short pulse laser to form perforation or holes in the substrate, that may be followed by use of a CO 2 laser beam to promote full separation about the perforated line.
1. A method of forming a glass article, comprising:
I. focusing a pulsed first laser beam into a laser beam focal line;
II. directing the laser beam focal line into a glass substrate at a plurality of locations along a closed inner contour defining an inner glass piece, the laser beam focal line generating an induced absorption within the glass substrate such that the laser beam focal line produces a defect line extending through a thickness of the glass substrate at each location of the plurality of locations;
III. heating the glass substrate, thereby inducing a stress in the glass substrate that separates the inner glass piece from the glass substrate along the closed inner contour; and
IV. heating the inner glass piece after the separation with a second laser beam such that the inner glass piece softens and drops from the glass substrate.
2. The method according to claim 1 , wherein step III comprises heating the glass substrate in a heating chamber.
3. The method according to claim 1 , wherein step III comprises tracing an infrared third laser beam over the closed inner contour.
4. The method according to claim 3 , wherein a wavelength of the infrared third laser beam is in a range from about 9 micrometers to about 11 micrometers.
5. The method according to claim 4 wherein the infrared third laser beam is a defocused laser beam.
6. The method according to claim 5 , wherein the infrared third laser beam is a CO 2 laser beam.
7. The method according to claim 1 , wherein a spacing between adjacent defect lines of the first plurality of defect lines is in a range from about 0.1 micrometer to about 15 micrometers.
8. The method according to claim 1 , wherein the closed inner contour is a circle.
9. The method according to claim 1 , further comprising cutting release lines between an edge of the glass substrate and an outer contour outside the inner contour.
10. The method according to claim 1 , wherein a surface roughness R a of a cut edge of the glass substrate along the inner contour is less than about 0.5 micrometers.
11. The method according to claim 10 , wherein subsurface damage perpendicular to the cut edge extends less than 75 micrometers into the glass substrate.
12. The method according to claim 1 , wherein the subsurface damage is less than about 25 micrometers.
13. The method according to claim 1 , wherein the plurality of defect lines extend perpendicular to the major surfaces of the glass substrate.
14. The method according to claim 1 , wherein the pulsed first laser beam is focused by a focusing lens and the pulsed first laser beam irradiates the focusing lens in the form of an annulus.
15. A method of forming a glass article, comprising:
I. focusing a pulsed first laser beam into a laser beam focal line;
II. directing the laser beam focal line into a glass substrate at a plurality of locations along a closed inner contour defining an inner glass piece, the laser beam focal line generating an induced absorption within the glass substrate such that the laser beam focal line produces a defect line extending through a thickness of the glass substrate at each location of the plurality of locations;
III. tracing a defocused infrared laser beam over the closed inner contour, thereby inducing a stress in the glass substrate that separates the inner glass piece from the glass substrate; and
IV. heating the inner glass piece after the separation with a CO 2 laser beam such that the inner glass piece softens and drops from the glass substrate.
16. The method according to claim 15 , wherein a wavelength of the defocused laser beam is in a range from about 9 micrometers to about 11 micrometers.
17. The method according to claim 15 , wherein a spacing between adjacent defect lines of the first plurality of defect lines is in a range from about 0.1 micrometer to about 15 micrometers.
18. The method according to claim 15 , wherein the pulsed first laser beam is focused by a focusing lens and the pulsed first laser beam irradiates the focusing lens in the form of an annulus.