Transparent material processing with an ultrashort pulse laser

• US 8,389,891 B2
• Filed: 10/16/2009
• Issued: 03/05/2013
• Est. Priority Date: 09/08/2005
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Bovatsek, James, Arai, Alan Y., Yoshino, Fumiyo
• Primary Examiner(s): Evans, Geoffrey S
• Application Number:
  US12/580,739
• Publication Number:
  US 20100086741A1
• Time in Patent Office: 1,236 Days
• Field of Search: 219/121.67, 219/121.69, 219/121.72, 438/463
• US Class Current: 219/121.69
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0617 and with spots spaced along the common axis
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/244 Overlap seam welding
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B23K 26/53 for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
• CPC Class Codes: B28D 5/0011 with preliminary treatment, e.g. weakening by scoring
• CPC Class Codes: B29C 59/16 by wave energy or particle radiation , e.g. infrared heating B29C59/007 takes precedence
• CPC Class Codes: B29C 65/00 Joining or sealing of preformed parts , e.g. welding of plastics materials; Apparatus therefor general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326
• CPC Class Codes: B29C 65/14 using wave energy , i.e. electromagnetic radiation, or particle radiation using mechanical waves B29C65/06; using ultrasonic waves B29C65/08; pressing means transparent to electromagnetic radiation B29C66/81267
• CPC Class Codes: B29C 65/1616 Near infrared radiation [NIR], e.g. by YAG lasers
• CPC Class Codes: B29C 65/1635 at least passing through one of the parts to be joined, i.e. laser transmission welding
• CPC Class Codes: B29C 65/1638 focusing the laser beam on the interface
• CPC Class Codes: B29C 65/1658 scanning once, e.g. contour laser welding
• CPC Class Codes: B29C 65/1664 making use of several radiators
• CPC Class Codes: B29C 65/1674 making use of laser diodes B29C65/167 takes precedence
• CPC Class Codes: B29C 65/1696 making use of masks
• CPC Class Codes: B29C 65/38 Impulse heating
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/30223 : said melt initiators being rib-like
• CPC Class Codes: B29C 66/322 : Providing cavities in the joined article to collect the burr
• CPC Class Codes: B29C 66/3282 : for reinforcing the joint
• CPC Class Codes: B29C 66/41 : Joining substantially flat articles B29C66/47 and subgroups take precedence; Making flat seams in tubular or hollow articles B29C66/51 and subgroups take precedence
• CPC Class Codes: B29C 66/43 : Joining a relatively small portion of the surface of said articles B29C66/45 takes precedence
• CPC Class Codes: B29C 66/71 : characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73366 : both parts to be joined being transparent or translucent to visible light
• CPC Class Codes: B29C 66/7352 : Thickness, e.g. very thin
• CPC Class Codes: B29C 66/73921 : characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/836 : Moving relative to and tangentially to the parts to be joined, e.g. transversely to the displacement of the parts to be joined, e.g. using a X-Y table B29C66/65 takes precedence
• CPC Class Codes: B29C 66/91641 : the heat or the thermal flux being non-constant over time
• CPC Class Codes: B29C 66/919 : characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/934 : by controlling or regulating the speed
• CPC Class Codes: B29C 66/939 : characterised by specific speed values or ranges
• CPC Class Codes: B29C 66/944 : by controlling or regulating the time
• CPC Class Codes: B29C 66/949 : characterised by specific time values or ranges
• CPC Class Codes: B29K 2033/12 : Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0026 : Transparent
• CPC Class Codes: B81B 1/00 : Devices without movable or flexible elements, e.g. microcapillary devices
• CPC Class Codes: B81C 1/00119 : Arrangement of basic structures like cavities or channels, e.g. suitable for microfluidic systems
• CPC Class Codes: C03B 23/20 : Uniting glass pieces by fusing without substantial reshaping
• CPC Class Codes: C03B 23/203 : Uniting glass sheets C03B23/24 takes precedence
• CPC Class Codes: C03B 33/0222 : Scoring using a focussed radiation beam, e.g. laser
• CPC Class Codes: C03C 23/0025 : by a laser beam
• CPC Class Codes: Y10T 428/13 : Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/15 : Sheet, web, or layer weakened to permit separation through thickness
• CPC Class Codes: Y10T 428/24479 : including variation in thickness
• CPC Class Codes: Y10T 428/24802 : Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

Methods for ultrashort pulse laser processing of optically transparent materials. A method for scribing transparent materials uses ultrashort laser pulses to create multiple scribe features with a single pass of the laser beam across the material, with at least one of the scribe features being formed below the surface of the material. This enables clean breaking of transparent materials at a higher speed than conventional techniques. Slightly modifying the ultrashort pulse laser processing conditions produces sub-surface marks. When properly arranged, these marks are clearly visible with side-illumination and not clearly visible without side-illumination. In addition, a method for welding transparent materials uses ultrashort laser pulses to create a bond through localized heating. The ultrashort pulse duration causes nonlinear absorption of the laser radiation, and the high repetition rate of the laser causes pulse-to-pulse accumulation of heat within the materials. The laser is focused near the interface of the materials, generating a high energy fluence at the region to be welded. This minimizes damage to the rest of the material and enables fine weld lines.

Claims

1. A method of scribing a transparent material, comprising:

using a single pass of a focused beam of ultrashort laser pulses to create a surface groove in said material and at least one modified region within the bulk of said material, wherein said surface groove and said at least one modified region are each formed by interaction of said focused beam with said material, said surface groove in said material and said at least one modified region within the bulk being formed along the beam propagation direction, and wherein said surface groove and said at least one modified region are discontinuous and separated in depth.

2. The method according to claim 1, wherein a location of said surface groove and said at least one modified region are separated by a determined distance.

3. The method according to claim 1, wherein said ultrashort pulses are generated at a repetition rate sufficiently high such that an interaction between a laser pulse and a modified region creates additional regions of material modification within the material.

4. The method according to claim 1, wherein said focused beam comprises a non-circular spot distribution.

5. The method according to claim 1, wherein said transparent material comprises sapphire.

6. The method according to claim 1, wherein the intensity of the focused beam results in non-linear absorption within a region defined by a three-dimensional intensity distribution that includes a beam waist.

7. A method for scribing a transparent material, comprising:

using a single pass of a focused beam of ultrashort laser pulses to create a plurality of modified regions within the bulk of said material, wherein said method comprises focusing said beam to a beam waist within the bulk of said material, wherein an intensity of said focused beam is sufficient to cause first material modification at a first location within the material in the beam propagation direction, and is sufficient to cause second material modification at a second location at a greater distance along said beam propagation direction within the material at or near said beam waist, wherein first and second modified regions resulting from said first and second material modifications are formed along said beam propagation direction as discontinuous first and second regions separated in depth.

8. The method according to claim 7, wherein the intensity of the focused beam results in non-linear absorption within a region defined by a three-dimensional intensity distribution that includes the focused beam waist.

9. The method according to claim 7, wherein said first location is at or near the surface of the material.

10. The method according to claim 7, wherein said second location at or near the beam waist is separated from the first location by a determined distance.

11. The method according to claim 7, wherein said ultrashort pulses are generated at a repetition rate sufficiently high such that an interaction between a laser pulse and a modified region creates additional regions of material modification within the material.

12. The method according to claim 7, wherein said focused beam comprises a non-circular spot distribution.

13. The method according to claim 7, wherein said transparent material comprises sapphire.

14. A transparent material scribed at two or more locations in a depth direction thereof with a single pass of a focused beam of ultrashort laser pulses, wherein said scribed locations comprise a surface groove scribed in said material and at least one scribe feature formed in the bulk of said material, and wherein said surface groove and said at least one scribe feature are formed along said beam propagation direction, said surface groove and said at least one scribe feature being discontinuous and separated in depth.

15. The apparatus according to claim 14, wherein said transparent material comprises sapphire.

16. A method of scribing a transparent material, comprising:

irradiating said material in a single pass with ultrashort laser pulses to modify said material at two or more locations in a depthwise direction thereof, wherein at least a portion of said irradiating is carried out with a diffractive optical element that generates multiple regions of high optical intensity at different depthwise locations along the propagation axis of the input beam, said diffractive optical element receiving an input beam and generating multiple laser modified discontinuous regions separated in depth.

17. The method of claim 16, wherein a surface groove is formed in said material, and at least one modified region is formed within the bulk of said material.