METHOD OF CLOSED FORM RELEASE FOR BRITTLE MATERIALS USING BURST ULTRAFAST LASER PULSES

• US 20150136743A1
• Filed: 11/11/2014
• Published: 05/21/2015
• Est. Priority Date: 11/19/2013
• Status: Active Grant

• Current Assignee: Rofin-Sinar Technologies LLC (Coherent Corp.)
• Original Assignee: Rofin-Sinar Technologies Incorporated (Coherent Corp.)
• Inventors: HOSSEINI, S. ABBAS
• Granted Patent: US 11,053,156 B2
• Time in Patent Office: Days
• US Class Current: 219/121.61
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/38 by boring or cutting
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: C03B 33/0222 Scoring using a focussed radiation beam, e.g. laser
• CPC Class Codes: C03B 33/04 Cutting or splitting in curves, especially for making spectacle lenses
• CPC Class Codes: C03B 33/091 using at least one focussed radiation beam, e.g. laser beam C03B33/0955 takes precedence
• CPC Class Codes: C03B 33/0955 using a focussed radiation beam, e.g. laser

Abstract

A method for machining and releasing closed forms from a transparent, brittle substrate includes using a burst of ultrafast laser pulses to drill patterns of orifices in the substrate. Orifices are formed by photoacoustic compression and they extend completely or partially in the transparent substrate. A scribed line of spaced apart orifices in the transparent substrate comprise a closed form pattern in the substrate. A heat source is applied in a region about said scribed line of spaced apart orifices until the closed form pattern releases from the transparent substrate.

Claims

1. A method for machining and releasing closed forms from a transparent substrate, comprising the following steps:

providing a transparent substrate;

providing ultrafast laser pulses beam comprising a burst of laser pulses;

providing a laser beam delivery system capable of focusing said laser beam onto said transparent substrate and enabling relative patterned movement between said laser beam and said transparent substrate;

focusing said laser beam relative to said substrate to form a beam waist external to said transparent substrate, wherein said laser pulses incident on said surface of said substrate are focused such that sufficient energy density is maintained within said transparent substrate to form a continuous laser filament therethrough without causing optical breakdown;

propagating a plurality of orifices, each orifice is propagated about said filament that traverses completely or partially through a said transparent substrate by photoacoustic compression;

directing said laser filament in said transparent substrate creating a closed form pattern in said transparent substrate comprising a scribed line of spaced apart orifices drilled into said transparent substrate; and

,

applying a heat source to said region of said closed form pattern in said transparent substrate comprising a scribed line of spaced apart orifices drilled into said transparent substrate until said closed form pattern releases from said transparent substrate.

11. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 1, wherein:

said orifices are spaced 2-10 μ

m center to center.

2. A method for machining and releasing closed forms from a transparent substrate, comprising the following steps:

propagating a plurality of orifices and scribing a line comprised of said propagated orifices, each of said orifices drilled by photoacoustic compression resulting from a laser beam having ultrafast laser pulses comprising a burst of laser pulses in said transparent substrate;

said scribed line creates a closed form bounded within said scribed line and a cullet outside said scribed line;

said orifices being spaced apart from each other;

heating said closed form bounded within said scribed line of said orifices of said transparent substrate and heating said transparent substrate outside of said closed form until said closed form is separated from said transparent substrate.

3. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 2, wherein:

said step of heating said closed form bounded within said scribed line of said orifices of said transparent substrate includes applying heat along said scribed line of orifices until said closed form is separated from said transparent substrate.

4. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 3, wherein:

said step of heating includes relative motion between said heat source and said substrate.

5. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 4, wherein:

said step of heating is performed with a laser source.

6. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 5, wherein:

said laser source is a CO₂ laser.

7. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 4, wherein:

said step of heating is performed with a flame.

8. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 4, wherein:

said step of heating is performed with a heat gun.

9. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 5, wherein:

said CO₂ laser spot size on said substrate is in a diametrical range of 100 um to 10 mm.

10. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 5, wherein:

said CO₂ laser spot size on said substrate is 8 mm, 6 mm of said laser spot resides on said transparent substrate outside of said scribed line of said orifices of said transparent substrate and 2 mm of said laser spot resides on said closed form, said transparent substrate outside of said orifices being heated more than said closed form.

12. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 2, wherein:

said orifices are spaced 2-10 μ

m center to center.

13. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 2, wherein:

said orifices extend partially through said transparent substrate.

14. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 2, wherein:

said orifices extend completely through said transparent substrate.

15. A method for machining and releasing closed forms from a transparent substrate, comprising the following steps:

propagating a plurality of orifices and scribing a line comprised of said propagated orifices, each of said orifices drilled by photoacoustic compression using a laser beam having ultrafast laser pulses comprising a burst of laser pulses in said transparent substrate;

said scribed line creates a closed form bounded within said scribed line and a body outside said scribed line;

said orifices being spaced apart from each other;

heating and destroying said closed form bounded within said scribed line of said orifices of said transparent substrate.

16. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, wherein:

said step of heating is performed with a CO₂ laser source.

17. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, wherein:

said step of heating is performed with a heat gun.

18. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, wherein:

said step of heating is performed with a flame.

19. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, further comprising the step of:

cooling said closed form with a cold source.

20. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, wherein said cold source may be selected from the group of a cold fluid, and dry ice.

21. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 15, further comprising the step of:

applying mechanical pressure to said closed form to separate said closed form within said scribed line of orifices.

22. A method for machining a transparent substrate, comprising the following steps:

propagating a plurality of orifices and scribing a line comprised of said propagated orifices, each of said orifices drilled by photoacoustic compression resulting from a laser beam having ultrafast laser pulses comprising a burst of laser pulses in said transparent substrate;

said orifices being spaced apart from each other;

heating said scribed line of said orifices of said transparent substrate and heating said transparent substrate on a first side of said scribed line of said orifices and on a second side of said orifices until said transparent substrate is separated into first and second portions thereof.

23. The method for machining a transparent substrate as claimed in claim 22 wherein said substrate is tubularly shaped.

24. A method for machining and releasing closed forms from a transparent substrate, comprising the following steps:

scribing, using photoacoustic compression to drill a first plurality of orifices in said transparent substrate, an inner circular pattern comprising said first plurality of orifices;

scribing, using photoacoustic compression to drill a second plurality of orifices in said transparent substrate, an outer circular pattern comprising said second plurality of orifices;

heating a first portion of said transparent substrate within said inner circular pattern comprising said first plurality of orifices;

heating a second portion of said transparent substrate around the location of said outer circular pattern comprising said second plurality of orifices;

separating said first portion of said transparent substrate within said inner circular pattern comprising said first plurality orifices from the remainder of said transparent substrate; and

,

separating a second portion of said transparent substrate within said outer circular pattern comprising said second plurality of orifices from the remainder of said transparent substrate.

25. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 24 wherein said step of heating said first portion of said transparent substrate is performed with a heat source selected from the group of a laser, a flame and a heat gun and wherein said step of heating said second portion of said transparent substrate is performed with a heat source selected from the group of a laser, a flame and a heat gun.

26. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 24, further comprising the steps of:

cooling said first and second portions of said transparent substrate to facilitate separation of said first and second portions of said transparent substrate.

27. The method for machining and releasing closed forms from a transparent substrate as claimed in claim 24 wherein said first and second plurality of orifices are drilled completely through said transparent substrate.