Method and optical assembly for high-angle laser processing of transparent workpieces

Abstract

The method for machining a transparent workpiece comprises guiding a laser beam directed along a beam path through an aspherical optical element and a transparent workpiece. The laser beam is irradiated at 1 / e of the laser beam. 2 The aspheric optical element is impacted radially offset from a centerline axis of the aspheric optical element at an offset distance of 30% or greater of a diameter. The beam path and the transparent workpiece are tilted relative to each other such that the beam path has a beam path angle at the impact surface that is less than 90° relative to the impact surface, and the portion of the laser beam directed into the transparent workpiece is a laser beam focal line having an internal focal line angle of less than 80° relative to the impact surface, such that defects having a defect angle of less than 80° are formed by induced absorption within the transparent workpiece.

Description

[0001] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Serial No. 63 / 076,031, filed on September 9, 2020, which is incorporated herein by reference in its entirety. background Technical Field

[0003] The present description relates generally to apparatus and methods for laser processing a transparent workpiece, and more particularly to a laser beam including a laser beam focal line that is quasi-non-diffracting when refracted into the transparent workpiece at high angles. Background Art

[0005] The field of laser processing of materials encompasses a wide variety of applications involving cutting, drilling, milling, welding, melting, etc. of different types of materials. Of particular interest among these processes is the cutting or separation of different types of transparent substrates in the production of materials such as glass, sapphire, or fused quartz, which can be used to produce thin-film transistors (TFTs) or display materials for electronic devices.

[0006] From a process development and cost perspective, there are many opportunities for improvement in cutting and separating glass substrates. It would be very interesting to have a method for separating glass substrates that is faster, cleaner, cheaper, more repeatable and more reliable than the methods currently implemented in the market. Many methods for separating glass substrates result in square separated edges that are susceptible to breakage and are typically processed to have bevels or are processed to be rounded to minimize the possibility of breakage. Currently, non-square edges are typically achieved using mechanical means (such as mechanical grinding and polishing). However, the processes described generate glass dust and particles that must be cleaned by additional process steps involving cleaning or chemical treatments. Therefore, there is a need for an alternative improved method for separating glass substrates that replaces conventional edge finishing processes with a particle-free and high-throughput process. Summary of the Invention

[0007] According to a first aspect of the present disclosure, a method for machining a transparent workpiece includes: directing a laser beam directed along a beam path and output by a beam source through an aspherical optical element and into an impact surface of the transparent workpiece. The laser beam is directed at 1 / e 2The aspheric optical element is radially offset from the centerline axis of the aspheric optical element by an offset distance of 30% or more of the diameter. The laser beam downstream of the aspheric optical element has a non-uniform radial intensity. The beam path and the transparent workpiece are tilted relative to each other so that the beam path has a beam path angle of less than 90° relative to the impact surface at the impact surface. In addition, the portion of the laser beam directed into the transparent workpiece is a laser beam focal line, and induced absorption is generated to produce defects in the transparent workpiece, the laser beam focal line including a wavelength λ, a spot size w o and greater than Rayleigh range Z R , where F D is a dimensionless divergence factor having a value of 10 or greater, and an internal focal line angle of less than 80° relative to the impact surface, such that the defect has a defect angle of less than 80° relative to the impact surface within the transparent workpiece.

[0008] A second aspect of the present disclosure includes the method of the first aspect, wherein the laser beam is emitted at 1 / e of the laser beam. 2 An offset distance of 50% or more of the diameter impacts the aspheric optical element radially offset from the centerline axis of the aspheric optical element.

[0009] A third aspect of the present disclosure includes the method of the first or second aspect, wherein the laser beam is emitted at 1 / e 2 An offset distance of 75% or greater of the diameter impinges upon the aspheric optical element radially offset from a centerline axis of the aspheric optical element.

[0010] A fourth aspect of the present disclosure includes the method of any of the preceding aspects, wherein a portion of the laser beam comprising a majority of the intensity of the laser beam impacts the impact surface at one or more ray propagation angles, each greater than the beam path angle.

[0011] A fifth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the aspheric optical element includes a refractive axicon, a reflective axicon, a negative axicon, or a diffractive optical device.

[0012] A sixth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the internal focal line angle is less than 80° to 50°.

[0013] A seventh aspect of the present disclosure includes the method of any of the preceding aspects, wherein the internal focal line angle is 75° to 50°.

[0014] An eighth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the internal focal line angle is 70° to 50°.

[0015] A ninth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the internal focal line angle is 75° or less relative to the impact surface, and the transparent workpiece has a thickness of 700 μm or greater.

[0016] A tenth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the internal focal line angle is 65° or less relative to the impact surface, and the transparent workpiece has a thickness of 500 μm or greater.

[0017] An eleventh aspect of the present disclosure includes the method of any of the preceding aspects, further comprising translating at least one of the transparent workpiece and the laser beam relative to each other along a contour line to form a contour having a plurality of defects.

[0018] A twelfth aspect of the present disclosure includes the method of the eleventh aspect, wherein the laser beam focal line extends from the impact surface of the transparent workpiece to the edge surface of the transparent workpiece, so that the plurality of defects each extend from the impact surface of the transparent workpiece to the edge surface of the transparent workpiece.

[0019] A thirteenth aspect of the present disclosure includes the method of the eleventh or twelfth aspect, wherein the contour line is a curved contour line, the profile is a curved profile, and the method further comprises: rotating the laser beam while translating at least one of the transparent workpiece and the laser beam relative to each other along the curved contour line, so that each defect of the plurality of defects is oriented radially inward or radially outward relative to the curved contour line.

[0020] A fourteenth aspect of the present disclosure includes the method of the thirteenth aspect, wherein the curved contour line is a closed curved contour line, and the curved profile is a closed curved profile.

[0021] A fifteenth aspect of the present disclosure includes the method of any one of the eleventh to fourteenth aspects, further comprising applying stress to the contour to separate the transparent workpiece along the contour.

[0022] A sixteenth aspect of the present disclosure includes the method of the fifteenth aspect, wherein the stress includes thermal stress, mechanical stress, or a combination thereof.

[0023] A seventeenth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the laser beam includes a pulsed laser beam output by a beam source that generates a pulse train including 2 sub-pulses or more per pulse train.

[0024] An eighteenth aspect of the present disclosure includes the method of any one of the preceding aspects, wherein the dimensionless divergence factor F D Is a value from 10 to 2000.

[0025] A nineteenth aspect of the present disclosure includes the method of any one of the preceding aspects, wherein a spacing between adjacent defects is 50 μm or less.

[0026] A twentieth aspect of the present disclosure includes the method of any of the preceding aspects, wherein the transparent workpiece is an alkali aluminosilicate glass material.

[0027] According to a twenty-first aspect of the present disclosure, a method for processing a transparent workpiece includes: directing a laser beam directed along a beam path and output by a beam source through a multi-optical axicon assembly including a truncated cone optical element and a lens axicon and into an impact surface of the transparent workpiece. The lens axicon is positioned downstream of the truncated cone optical element. The beam path and the transparent workpiece are tilted relative to each other so that the beam path includes a beam path angle of less than 90° relative to the impact surface at the impact surface. In addition, the portion of the laser beam directed into the transparent workpiece includes a laser beam focal line, and generates induced absorption to generate defects in the transparent workpiece, the laser beam focal line including a wavelength λ, a spot size w o and greater than Rayleigh range Z R , where F D A dimensionless divergence factor comprises a value of 10 or greater, and an internal focal line angle less than 80° relative to the impact surface, such that the defect comprises a defect angle less than 80° relative to the impact surface within the transparent workpiece.

[0028] A twenty-second aspect of the present disclosure includes the method of the twenty-first aspect, wherein the lens axicon includes a negative spherical aberration phase.

[0029] A twenty-third aspect of the present disclosure includes the method of aspect twenty-first or aspect twenty-second, wherein the lens axicon comprises an input surface having a central convex reflector and an output surface having a reflective convex aperture.

[0030] A twenty-fourth aspect of the present disclosure includes the method of any one of aspects twenty-first to twenty-third, wherein a transmission fiber extends between the beam source and the input surface of the frusto-conical optical element.

[0031] A twenty-fifth aspect of the present disclosure includes the method of aspect twenty-third, wherein the central convex reflector comprises a shielding diameter and the reflective convex aperture comprises a reflective ring surrounding a central aperture having an aperture diameter.

[0032] Aspect twenty-six of the present disclosure includes the method of any one of aspects twenty-one to twenty-fifth, wherein the truncated cone optical element includes an input surface having an input surface diameter, an output surface having an output surface diameter greater than the input surface diameter, an outer surface extending from the input surface to the output surface, and a reflective cone extending into the output surface.

[0033] A twenty-seventh aspect of the present disclosure includes the method of the twenty-sixth aspect, wherein the reflective cone includes a reflective cone surface parallel to an outer surface of the truncated cone optical element.

[0034] A twenty-eighth aspect of the present disclosure includes the method of the twenty-seventh aspect, wherein the reflective cone comprises a base diameter, and a diameter of the laser beam upstream of the truncated cone optical element is less than or equal to the base diameter of the reflective cone of the truncated cone optical element.

[0035] A twenty-ninth aspect of the present disclosure includes the method of any one of aspects twenty-first to twenty-eighth, wherein the frustum optical element collimates the laser beam.

[0036] A thirtieth aspect of the present disclosure includes the method of any one of aspects twenty-first to twenty-ninth, wherein the truncated cone optical element and the lens axicon are integrated into a monolithic lens system.

[0037] A thirty-first aspect of the present disclosure includes the method of any one of aspects 21 to 29, wherein a first alignment mechanism is coupled to a truncated cone optical element and is configured to translate the truncated cone optical element along a beam path, and a second alignment mechanism is coupled to a lens axis pyramid and is configured to translate the lens axis pyramid along a beam path.

[0038] A thirty-second aspect of the present disclosure includes the method of any one of aspects twenty-first to thirty-first, wherein the multiple optical axicon assembly further includes a split quarter-wave plate positioned between the truncated cone optical element and the lens axicon.

[0039] A thirty-third aspect of the present disclosure includes the method of aspect thirty-second, wherein the split quarter-wave plate includes a first plate portion and a second plate portion, the first plate portion includes a first fast axis and a first slow axis, and the second plate portion includes a second fast axis and a second slow axis, the first fast axis is orthogonal to the second fast axis, and the second fast axis is orthogonal to the second slow axis, and the first beam portion of the laser beam is polarized to a first polarization by passing through the first plate portion, and the second beam portion of the laser beam is polarized to a second polarization by passing through the second plate portion.

[0040] A thirty-fourth aspect of the present disclosure includes the method of any one of aspects twenty-first to thirty-third, wherein the internal focal line angle is less than 80° to 50°.

[0041] A thirty-fifth aspect of the present disclosure includes the method of any one of aspects twenty-first to thirty-fourth, further comprising: translating at least one of the transparent workpiece and the laser beam relative to each other along a contour line to form a contour having a plurality of defects.

[0042] The thirty-sixth aspect of the present disclosure includes the method of the thirty-fifth aspect, wherein the laser beam focal line extends from the impact surface of the transparent workpiece to the edge surface of the transparent workpiece, so that the multiple defects each extend from the impact surface of the transparent workpiece to the edge surface of the transparent workpiece.

[0043] A thirty-seventh aspect of the present disclosure includes the method of aspect thirty-fifth or thirty-sixth aspect, wherein the contour line includes a curved contour line, the profile includes a curved profile, and the method further includes: rotating the laser beam while translating at least one of the transparent workpiece and the laser beam relative to each other along the curved contour line, so that each of the multiple defects is oriented radially inward or radially outward relative to the curved contour line.

[0044] A thirty-eighth aspect of the present disclosure includes the method of the thirty-seventh aspect, wherein the curved contour line is a closed curved contour line, and the curved profile is a closed curved profile.

[0045] A thirty-ninth aspect of the present disclosure includes the method of any one of aspects thirty-fifth to thirty-eighth, further comprising applying stress to the contour to separate the transparent workpiece along the contour.

[0046] A fortieth aspect of the present disclosure includes the method of any one of aspects twenty-first to thirty-ninth, wherein the laser beam is a pulsed laser beam output by a beam source that generates a pulse train including 2 sub-pulses or more per pulse train.

[0047] The forty-first aspect of the present disclosure includes the method of any one of the twenty-first to fortieth aspects, wherein the dimensionless divergence factor F D Is a value from 10 to 2000.

[0048] A forty-second aspect of the present disclosure includes the method of any one of aspects twenty-first to forty-first, wherein a spacing between adjacent defects is 50 μm or less.

[0049] Additional features and advantages of the processes and systems described herein will be set forth in the detailed description that follows, and in part will become apparent to those skilled in the art from that description, or may be learned by practicing the embodiments described herein, including the following detailed description, claims, and drawings.

[0050] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The embodiments illustrated in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments may be understood when read in conjunction with the following drawings, in which like reference numerals designate like structures, and in which:

[0052] Figure 1A A perspective view schematically depicts an embodiment of a laser forming a profile of defects, each defect having a defect angle, in a transparent workpiece according to one or more embodiments described herein;

[0053] Figure 1B schematically depicts a side view of an embodiment of a laser forming a profile of defects, each defect having a defect angle, in a transparent workpiece according to one or more embodiments described herein;

[0054] Figure 2A Schematically depicts an optical assembly for laser processing a transparent workpiece according to one or more embodiments described herein, the optical assembly comprising a beam source, an aspheric optical element, and a lens assembly comprising a first lens and a second lens;

[0055] Figure 2B Schematically depicts a device according to one or more embodiments described herein. Figure 2A a cross section of the laser beam at a position along the beam path between the first lens and the second lens;

[0056] Figure 2C Schematically depicts a laser beam focal line in accordance with one or more embodiments described herein. Figure 2A a cross-sectional beam pattern at an impact surface of an example transparent workpiece formed by an optical assembly;

[0057] Figure 2D Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 2C The focal line of the laser beam is Figure 2C Example cross-sectional beam pattern at a depth of 250 μm within a transparent workpiece;

[0058] Figure 2ESchematically depicts a schematic diagram of a device according to one or more embodiments shown and described herein. Figure 2C and Figure 2D The focal line of the laser beam is Figure 2C and Figure 2D Example cross-sectional beam pattern at a depth of 450 μm within a transparent workpiece;

[0059] Figure 2F Schematically depicts the use of one or more embodiments shown and described herein. Figure 2A Example angled defects formed by the focal line of the laser beam;

[0060] Figure 2G Depicts a method for using a Figure 2A An intensity distribution of a focal line of a laser beam formed by an optical component and directed at a normal incidence angle into a transparent workpiece;

[0061] Figure 2H Depicts a method for using a Figure 2A An intensity distribution of a focal line of a laser beam formed by an optical component and directed at an oblique incident angle into a transparent workpiece;

[0062] Figure 2I A diagrammatic representation of a method for using a Figure 2A Irradiance of the focal line of the laser beam formed by the optical components as a function of the propagation distance within the transparent workpiece;

[0063] Figure 3A schematically depicts an optical assembly for laser processing a transparent workpiece according to one or more embodiments described herein, the optical assembly comprising an offset beam source, an aspheric optical element, and a lens assembly;

[0064] Figure 3B Schematically depicts an embodiment according to one or more embodiments described herein. Figure 3A a cross-section of the laser beam at a position along the beam path between the first lens and the second lens, wherein in this embodiment, the beam source is offset from the aspheric optical element such that the beam source is radially offset from the aspheric optical element by a first offset distance;

[0065] Figure 3C Schematically depicts an embodiment according to one or more embodiments described herein. Figure 3A The cross section of the laser beam at a position along the beam path between the first lens and the second lens, in this embodiment, the beam source is offset from the aspherical optical element so that the beam source is greater than Figure 3B The first offset distance and the second offset distance are radially offset from the aspheric optical element;

[0066] Figure 3D Schematically depicts a method for using a Figure 3A A side view of an embodiment of an optical element for laser forming a profile of an angled defect in a transparent workpiece;

[0067] Figure 3E Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 3A Cross-sectional beam diagrams of the laser beam focal line at different depths of an example transparent workpiece;

[0068] Figure 3F Schematically depicts the use of one or more embodiments shown and described herein. Figure 3A Example angled defects formed by the focal line of the laser beam;

[0069] Figure 3G Depicts a method for using a Figure 3A An intensity distribution of a focal line of a laser beam formed by an optical component and directed at a normal incidence angle into a transparent workpiece;

[0070] Figure 3H Depicts a method for using a Figure 3A An intensity distribution of a focal line of a laser beam formed by an optical component and directed at an oblique incident angle into a transparent workpiece;

[0071] Figure 3I A diagrammatic representation of a method for using a Figure 3A Irradiance of the focal line of the laser beam formed by the optical components as a function of the propagation distance within the transparent workpiece;

[0072] Figure 4A schematically depicts an optical assembly for laser processing a transparent workpiece according to one or more embodiments described herein, the optical assembly comprising a beam source, a multi-axicon assembly, and a lens assembly;

[0073] Figure 4B Schematically depicts a device according to one or more embodiments described herein. Figure 4A Multi-optical axis pyramid assembly;

[0074] Figure 4C schematically depicts a partial view of an optical assembly for laser processing a transparent workpiece according to one or more embodiments described herein, the optical assembly including a multi-axicon assembly;

[0075] Figure 5ASchematically depicts a cross-sectional beam diagram of a laser beam focal line using a laser beam according to one or more embodiments described herein. Figure 2A The optical assembly is formed and directed into the example transparent workpiece at a depth of 0.1 mm at an angle of 35° relative to the beam path;

[0076] Figure 5B Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 5A Cross-sectional beam diagram of the laser beam focal line at a depth of 1.9 mm within the example transparent workpiece;

[0077] Figure 5C Schematically depicts a cross-sectional beam diagram of a laser beam focal line using a laser beam according to one or more embodiments described herein. Figure 4A a frustum optical element of a multiple optical axicon assembly formed without a lens axicon and directed into the example transparent workpiece at a depth of 0.1 mm at an angle of 35° relative to the beam path;

[0078] Figure 5D Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 5C Cross-sectional beam diagram of the laser beam focal line at a depth of 1.9 mm within the example transparent workpiece;

[0079] Figure 5E Schematically depicts a cross-sectional beam diagram of a laser beam focal line using a laser beam according to one or more embodiments described herein. Figure 4A The lens axicon of the multi-optical axicon assembly is formed without using a truncated cone optical element and is directed into the example transparent workpiece at a depth of 0.1 mm at an angle of 35° relative to the beam path;

[0080] Figure 5F Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 5E Cross-sectional beam diagram of the laser beam focal line at a depth of 1.9 mm within the example transparent workpiece;

[0081] Figure 5G Schematically depicts a cross-sectional beam diagram of a laser beam focal line using a laser beam according to one or more embodiments described herein. Figure 4A A multi-axis pyramid assembly is formed and directed into the example transparent workpiece at a depth of 0.1 mm at an angle of 35° relative to the beam path;

[0082] Figure 5H Schematically depicts a schematic diagram of a device according to one or more embodiments described herein. Figure 5G Cross-sectional beam diagram of the laser beam focal line at a depth of 1.9 mm within the transparent workpiece;

[0083] Figure 6A Schematically depicts a device according to one or more embodiments described herein. Figure 4A Split quarter waveplate;

[0084] Figure 6B Schematically depicts a cross-sectional beam diagram of a laser beam focal line using a laser beam according to one or more embodiments described herein. Figure 4A The multi-axis pyramid component together with Figure 6A The split quarter wave plate is formed;

[0085] Figure 7A graphically depicts relative intensity of laser pulses within an exemplary pulse train versus time according to one or more embodiments described herein;

[0086] Figure 7B graphically depicts relative intensity of laser pulses within another exemplary pulse train versus time according to one or more embodiments described herein;

[0087] Figure 8A schematically depicts a side view of a transparent workpiece having a profile of an angled defect according to one or more embodiments described herein;

[0088] Figure 8B Schematically depicts a diagram of a process according to one or more embodiments described herein. Figure 8A a side view of two separate articles formed from a transparent workpiece, each separate article comprising an angled edge;

[0089] Figure 9A schematically depicts a side view of a transparent workpiece having a closed curved profile with an angled defect according to one or more embodiments described herein;

[0090] Figure 9B Schematically depicts a schematic diagram of a circuit according to one or more embodiments shown and described herein. Figure 9A a side view of a release article formed from a transparent workpiece, the release article comprising a tapered hole having angled edges;

[0091] Figure 10A schematically depicts a side view of a transparent workpiece having a profile of a defect extending from an impact surface to an edge surface and a profile of a defect extending from an opposing surface to the edge surface according to one or more embodiments shown and described herein; and

[0092] Figure 10B Schematically depicts a schematic diagram of a circuit according to one or more embodiments shown and described herein. Figure 10A A side view of a release article formed from a transparent workpiece, the release article including a beveled edge. DETAILED DESCRIPTION

[0093] Reference will now be made in detail to embodiments of a process for laser processing a transparent workpiece, such as a glass workpiece, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to indicate the same or similar parts. According to one or more embodiments described herein, a transparent workpiece can be laser processed to form a profile in the transparent workpiece, the profile comprising a series of defects along a desired separation line for separating the transparent workpiece into two or more separate articles. Each of the defects comprises a defect angle greater than 10° relative to normal incidence, such that after separating the transparent workpiece along the profile, the resulting separated articles comprise angled edges having edge angles greater than 10° relative to normal incidence. Defects in the transparent workpiece can be formed using a low diffraction beam, such as a quasi-non-diffraction beam, focused into the focal line of the laser beam.

[0094] Using current methods, when the beam is directed into a transparent workpiece at an increased angle relative to normal incidence (e.g., an angle greater than 10° from normal incidence), the distortion and aberrations of the extended focused laser beam (e.g., a quasi-undiffracted beam) increase, and therefore, it is difficult to form a series of high-angle defects to facilitate separation of the transparent workpiece into separated products with angled edges. For example, using previous laser processing techniques, aberrations are introduced into the beam when the laser beam enters a transparent workpiece with an angled, curved, or stepped surface. For a Bessel beam, these aberrations cause the peak beam intensity to drop significantly as the beam travels inside the transparent workpiece, thereby reducing the quality of high-angle defects or even preventing their formation. Although not intending to be limited by theory, in conventional angled cutting, the peak beam intensity drops due to the splitting of the central lobe of a standard Bessel beam into multiple lobes, and therefore the peak intensity of any of the split lobes is less than the peak intensity of the central lobe of an aberration-free Bessel beam. Although again not intending to be limited by theory, aberrations also cause the Rayleigh range of the beam to drop. Therefore, improved methods of laser processing transparent workpieces are desired. Accordingly, the methods and optical assemblies described herein use an arrangement of one or more aspheric optical elements, such as radially offset aspheric optical elements and a multi-axis pyramid assembly, to form an angled laser beam focal line in a transparent workpiece that maintains minimal divergence along the length of the laser beam focal line to profile high-angle defects and facilitate the formation of separated articles having angled edges as described herein with particular reference to the accompanying drawings.

[0095] As used herein, "laser processing" includes directing a laser beam onto and / or into a transparent workpiece. In some embodiments, laser processing further includes translating the laser beam relative to the transparent workpiece, for example, along a contour line or other path. Examples of laser processing include using a laser beam to form a contour comprising a series of defects extending into the transparent workpiece, and using an infrared laser beam to heat the transparent workpiece. Laser processing can separate the transparent workpiece along one or more desired separation lines. However, in some embodiments, additional non-laser steps (such as applying a mechanical force) can be used to separate the transparent workpiece along one or more desired separation lines.

[0096] As used herein, a "beam spot" refers to a cross-section of a laser beam (e.g., a beam cross-section) at the impact location of the laser beam at the impact surface of a transparent workpiece (i.e., the surface of the transparent workpiece on which the laser beam first impinges). The beam spot is the cross-section at the impact location. In the embodiments described herein, the beam spot is sometimes referred to as being "axisymmetric" or "non-axisymmetric." As used herein, axisymmetric refers to a shape that is symmetrical or appears the same for any arbitrary angle of rotation made about a central axis, and "non-axisymmetric" refers to a shape that is asymmetrical for any arbitrary angle of rotation made about a central axis. The axis of rotation (e.g., the central axis) is most often taken to be the optical axis (propagation axis) of the laser beam, which is an axis extending in the direction of beam propagation, which is referred to herein as the z-direction.

[0097] As used herein, "upstream" and "downstream" refer to the relative positioning of two locations or components along a beam path relative to a beam source. For example, if a first component is closer to the laser source than the second component along a path traversed by the laser beam, the first component is upstream of the second component.

[0098] As used herein, "laser beam focal line" refers to a pattern of interacting (e.g., intersecting) rays of a laser beam that form a focal region elongated in the direction of beam propagation. In conventional laser processing, the laser beam is tightly focused to a focal point. The focal point is the point of maximum intensity of the laser beam and is located at the focal plane in a transparent workpiece. In contrast, in the elongated focal region of a focal line, the area of ​​maximum intensity of the laser beam extends beyond the point to a line aligned with the direction of beam propagation. A focal line is formed by converging intersecting (e.g., intersecting) rays to form a continuous series of focal points aligned with the direction of beam propagation. The laser beam focal lines described herein are formed using a quasi-non-diffracting beam, as mathematically defined in detail below.

[0099] As used herein, a "contour line" corresponds to a set of intersection points of the laser beam with the incident surface of the transparent workpiece resulting from relative motion between the laser beam and the transparent workpiece. The shape of the contour line can be linear, angled, polygonal, or curved. The contour line can be closed (i.e., defining an enclosed area on the surface of the transparent workpiece) or open (i.e., not defining an enclosed area on the surface of the transparent workpiece). The contour line represents a boundary along which separation of the transparent workpiece into two or more parts is facilitated. Separation occurs simultaneously or with the assistance of external thermal or mechanical energy.

[0100] As used herein, a "profile" refers to a set of defects formed in a transparent workpiece by a laser beam through relative motion of the laser beam and the transparent workpiece along the profile. The defects are spaced apart along the profile and may be entirely contained within the interior of the transparent workpiece or extend through one or more surfaces into the interior of the transparent workpiece. Defects may also extend through the entire thickness of the transparent workpiece. Separation of the transparent workpiece occurs by connecting the defects, such as, for example, by propagation of a crack.

[0101] As used herein, a "defect" refers to an area of ​​a transparent workpiece that has been modified by a laser beam. A defect comprises an area of ​​the transparent workpiece having a modified refractive index relative to the surrounding unmodified areas of the transparent workpiece. Common defects include structurally modified areas in the transparent workpiece produced by the focal line of the laser beam, such as void spaces, cracks, scratches, flaws, holes, perforations, densification, or other deformations. In various embodiments herein, a defect may also be referred to as a defect line or damage track. The defect or damage track is formed by the interaction of the focal line of the laser beam with the transparent workpiece. As described more fully below, the focal line of the laser beam is produced by a pulsed laser. A defect at a specific location along a contour line is formed by the focal line produced by a single laser pulse at that specific location, a pulse train of sub-pulses at that specific location, or a plurality of laser pulses at that specific location. The relative motion of the laser beam and the transparent workpiece along the contour line results in the formation of multiple defects in the contour.

[0102] As used herein, the phrase "transparent workpiece" refers to a workpiece formed of glass, glass ceramic, or other transparent material, wherein the term "transparent" as used herein means that the material has a linear optical absorption of less than 20% per millimeter of material depth, such as less than 10% per millimeter of material depth for a specified pulsed laser wavelength, or less than 1% per millimeter of material depth for a specified pulsed laser wavelength. Unless otherwise specified, the material has a linear optical absorption of less than about 20% per millimeter of material depth. The transparent workpiece can have a depth (e.g., thickness) of from about 50 micrometers (μm) to about 10 mm (e.g., from about 100 μm to about 5 mm, or from about 0.5 mm to about 3 mm). The transparent workpiece can include a glass workpiece formed of a glass composition such as borosilicate glass, soda-lime glass, aluminosilicate glass, alkali aluminosilicate, alkaline earth aluminosilicate glass, alkaline earth boroaluminosilicate glass, fused silica, or a crystalline material (e.g., sapphire, silicon, gallium arsenide), or a combination thereof. In some embodiments, the transparent workpiece can be strengthened by thermal tempering before or after laser processing the transparent workpiece. In some embodiments, the glass can be ion exchangeable, such that before or after laser processing the transparent workpiece, the glass composition can undergo ion exchange to achieve glass strengthening. For example, the transparent workpiece can include ion exchanged glass and ion exchangeable glass, such as Corning®, available from Corning Incorporated in Corning, New York. (Corning ) glasses (e.g., No. 2318, No. 2319, and No. 2320). In addition, these ion-exchangeable glasses can have a coefficient of thermal expansion (CTE) of from about 6 ppm / °C to about 10 ppm / °C. Other example transparent workpieces can include display glasses commonly used as substrates for thin film transistor (TFT) fabrication for liquid crystal or OLED displays, such as EAGLE, available from Corning Incorporated in Corning, New York. and Corning LOTUS TM Glass. These display glasses may have a coefficient of thermal expansion (CTE) of from about 3 ppm / ° C. to about 4 ppm / ° C. Additionally, the transparent workpiece may include other compositions transparent to the wavelength of the laser, for example, glass ceramics or crystals such as sapphire or zinc selenide.

[0103] In an ion exchange process, ions in a surface layer of a transparent workpiece are replaced with larger ions of the same valence or oxidation state, for example, by partially or completely immersing the transparent workpiece in an ion exchange bath. The replacement of smaller ions with larger ions causes a compressive stress layer to extend from one or more surfaces of the transparent workpiece to a depth within the transparent workpiece, referred to as the depth of the layer. The compressive stress is balanced by a layer of tensile stress (referred to as the central tension), resulting in a net stress of zero in the glass sheet. The compressive stress developed at the surface of the glass sheet strengthens the glass and resists mechanical damage, thereby mitigating catastrophic failure of the glass sheet due to defects that do not extend through the depth of the layer. In some embodiments, smaller sodium ions in the surface layer of the transparent workpiece are exchanged for larger potassium ions. In some embodiments, the ions in the surface layer and the larger ions are monovalent alkali metal cations, such as Li+ (when present in the glass), Na+, K+, Rb+, and Cs+. Alternatively, the monovalent cations in the surface layer can be replaced with monovalent cations other than alkali metal cations, such as Ag+, Tl+, Cu+, and the like.

[0104] As used herein, the term "quasi-non-diffracting beam" is used to describe a laser beam having a low beam divergence, as described mathematically below. In particular, this laser beam is used to form the outline of a defect in the embodiments described herein. The laser beam has an intensity distribution I(X, Y, Z), where Z is the beam propagation direction of the laser beam, and X and Y are directions orthogonal to the beam propagation direction, as depicted in the accompanying figures. The X-direction and the Y-direction may also be referred to as cross-sectional directions, and the XY plane may be referred to as a cross-sectional plane. The coordinates and directions X, Y, and Z are also referred to as x, y, and z, respectively, herein. The intensity distribution of the laser beam in the cross-sectional plane may be referred to as a cross-sectional intensity distribution.

[0105] A quasi-non-diffracting laser beam can be formed by impinging a diffracted laser beam (such as a Gaussian beam) into, onto, or through a phase-changing optical element, such as an adaptive phase-changing optical element (e.g., a spatial light modulator, an adaptive phase plate, a deformable mirror, etc.), a static phase-changing optical element (e.g., a static phase plate, a diffractive optical element, or an aspheric optical element (such as an axicon), etc.) to modify the phase of the beam, reduce the beam divergence, and increase the Rayleigh range (as mathematically defined below). Example quasi-non-diffracting beams include Gauss-Bessel beams, Airy beams, Weber beams, and Bessel beams. Furthermore, optical assemblies including phase-changing optical elements are described in more detail below.

[0106] Without intending to be limited by theory, beam divergence refers to the magnification of the beam cross section in the direction of beam propagation (i.e., the Z direction). An example of the beam cross section discussed herein is a beam projected onto a transparent workpiece 160 ( Figure 1A ) on a laser beam 112. Diffraction is one factor that causes the laser beam to diverge. Other factors include focusing or defocusing caused by the optical system that forms the laser beam, or refraction and scattering at interfaces. The laser beam used to form the defect profile is formed by the laser beam focal line. The laser beam focal line has low divergence and weak scattering. The divergence of the laser beam is determined by the Rayleigh range Z R Characterize the Rayleigh range Z R The variance σ of the intensity distribution of the laser beam 2 and the beam spread factor M 2 In the following discussion, the formulas will be presented using the Cartesian coordinate system. Corresponding expressions for other coordinate systems are available using mathematical techniques known to those skilled in the art. Additional information on beam divergence can be found in A.E. Siegman, “New Developments in Laser Resonators,” SPIE Seminar Series, Vol. 1224, p. 2 (1990), and in R. Borghi and M. Santarsiero, “M. 2 factor of Bessel-Gauss beams 2factors), the disclosures of which are incorporated herein by reference in their entirety. Additional information can also be found in the international standards ISO 11146-1:2005(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 1: Stigmatic and simple astigmatic beams”, ISO 11146-2:2005(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 2: General astigmatic beams” and ISO 11146-3:2004(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 2: General astigmatic beams”. beamwidths, divergence angles and beam propagation ratios—Part 3: Intrinsic and geometrical laser beam classification, propagation and details of test methods”, the disclosures of which are incorporated herein by reference in their entirety.

[0107] refer to Figure 1A and Figure 1B2 , the pulsed laser beam 112 used to form the defect further has an intensity distribution I(X, Y, Z), where Z is the beam propagation direction of the pulsed laser beam 112, and X and Y are directions orthogonal to the propagation direction, as shown. The X-direction and the Y-direction may also be referred to as cross-sectional directions, and the XY plane may be referred to as the cross-sectional plane. The intensity distribution of the pulsed laser beam 112 on the cross-sectional plane may be referred to as the cross-sectional intensity distribution.

[0108] The pulsed laser beam 112 at the beam spot 114 or other cross-section may include a quasi-non-diffracting beam (e.g., a beam having a low beam divergence as mathematically defined below) by propagating the pulsed laser beam 112 (e.g., using a beam source 110 to output a pulsed laser beam 112 such as a Gaussian beam) through an aspheric optical element 120, as described below with respect to Figure 2A . Beam divergence refers to the magnification of the beam cross section in the beam propagation direction (i.e., the Z direction). As used herein, the phrase "beam cross section" refers to a cross section of the pulsed laser beam 112 along a plane perpendicular to the beam propagation direction of the pulsed laser beam 112 (e.g., along the XY plane). An example beam cross section discussed herein is a beam spot 114 of the pulsed laser beam 112 projected onto a transparent workpiece 160.

[0109] The length of the laser beam focal line generated from the quasi-non-diffracting beam is determined by the Rayleigh range of the quasi-non-diffracting beam. In particular, the quasi-non-diffracting beam defines a laser beam focal line 113 having a first endpoint and a second endpoint, each endpoint being defined by a position where the quasi-non-diffracting beam has propagated a distance from the beam waist equal to the Rayleigh range of the quasi-non-diffracting beam. The length of the laser beam focal line corresponds to twice the Rayleigh range of the quasi-non-diffracting beam. A detailed description of the formation of quasi-non-diffracting beams and determining their length, including generalizing the description of such beams to asymmetric (such as non-axisymmetric) beam cross-sectional profiles, is provided in U.S. Provisional Application Serial No. 62 / 402,337 and Netherlands Patent Application No. 2017998, which are incorporated herein by reference in their entirety.

[0110] The Rayleigh range corresponds to the distance (as defined in ISO 11146-1:2005(E), Section 3.12, relative to the position of the beam waist) over which the variance of the laser beam (relative to the variance at the beam waist) doubles, and is a measure of the divergence of the laser beam's cross-sectional area. The Rayleigh range can also be viewed as the distance along the beam axis at which the peak light intensity observed in the beam cross-sectional profile decays to half its value observed in the beam cross-sectional profile at the beam waist (position of maximum intensity). Laser beams with large Rayleigh ranges have low divergence and expand more slowly with distance in the beam propagation direction than laser beams with small Rayleigh ranges.

[0111] The beam cross section is characterized by shape and size. The size of the beam cross section is characterized by the spot size of the beam. For a Gaussian beam, the spot size is often defined as the point at which the beam intensity decreases to 1 / e of its maximum value. 2 The maximum intensity of a Gaussian beam occurs at the center of the intensity distribution (x=0 and y=0 (Cartesian) or r=0 (cylindrical)), and the radial extent used to determine the spot size is measured relative to the center.

[0112] Beams with a Gaussian intensity profile may be less preferred for laser processing to form defects 172 because they are highly diffracting and diverge significantly over short propagation distances (low Rayleigh range) when focused to a spot size small enough (such as a spot size in the micron range, such as about 1-5 μm or about 1-10 μm) to enable the available laser pulse energy to modify materials such as glass. In order to achieve low divergence (high Rayleigh range), it is desirable to control or optimize the intensity profile of the pulsed laser beam to reduce diffraction. The pulsed laser beam can be non-diffracting or weakly diffracting. Weakly diffracting laser beams include quasi-non-diffracting laser beams. Representative weakly diffracting laser beams include Bessel beams, Gauss-Bessel beams, Airy beams, Weber beams, and Mathieu beams.

[0113] Non-diffracting or quasi-non-diffracting beams often have complex intensity profiles, such as those that decrease non-monotonically with respect to radius. By analogy with Gaussian beams, for any beam (even one that is not axisymmetric), the effective spot size w o,eff Defined as the shortest radial distance in any direction from the radial position of maximum intensity (r = 0) at which the intensity decreases to 1 / e of the maximum intensity 2 In addition, for the axisymmetric beam w o,eff is the radial distance from the radial position of maximum intensity (r = 0) where the intensity decreases to 1 / e of the maximum intensity 2 In equation (1), the effective spot size w based on the non-axisymmetric beam can be expressed aso,eff Rayleigh range Z R The criteria for specifying a non-diffracted beam or a quasi-non-diffracted beam for forming the damage region are as follows:

[0114]

[0115] Among them F D is a dimensionless divergence factor having a value of at least 10, at least 50, at least 100, at least 250, at least 500, at least 1000, in the range of 10 to 2000, in the range of 50 to 1500, or in the range of 100 to 1000. For a non-diffracting or quasi-non-diffracting beam, the distance (Rayleigh range) at which the effective spot size doubles (Z in Equation (1) R ) is F D Multiply by the distance expected when using a typical Gaussian beam profile. Dimensionless divergence factor F D Provides a criterion for determining whether a laser beam is quasi-non-diffracting. As used herein, if at a value F D ≥10, the characteristics of the laser beam satisfy equation (1), and the pulsed laser beam 112 is considered to be quasi-non-diffracting. D As the value of α increases, the pulsed laser beam 112 approaches a more perfectly undiffracting state.

[0116] Additional information on the Rayleigh range, beam divergence, intensity distribution, axisymmetric and non-axisymmetric beams, and spot size used herein can also be found in the International Standards ISO 11146-1:2005(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 1: Stigmatic and simple astigmatic beams”, ISO 11146-2:2005(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 2: General astigmatic beams”, and ISO 11146-3:2005(E) entitled “Lasers and laser-related equipment—Test methods for laser beam widths, divergence angles and beam propagation ratios—Part 2: General astigmatic beams”. No. 11146-3:2004(E) entitled “Lasers and laser-related equipment—Test methods for laser beamwidths, divergence angles and beam propagation ratios—Part 3: Intrinsic and geometrical laser beam classification, propagation and details of test methods,” the disclosures of which are incorporated herein by reference in their entirety.

[0117] Now refer to Figure 1A and Figure 1B , an example transparent workpiece 160 is schematically depicted as being laser processed according to the methods described herein. Specifically, Figure 1A and Figure 1BThe laser beam 112 output by the beam source 110 and directed along the beam path 111 is schematically depicted with a beam propagation angle θ Bprop The laser beam 112 is directed into the transparent workpiece 160 such that the portion of the laser beam 112 directed into the transparent workpiece 160 includes a laser beam focal line 113 that is not orthogonal to an impact surface 162 of the transparent workpiece 160 and instead includes an internal beam angle θ that is less than 90° relative to the impact surface 162. Bi The laser beam 112 forms a beam spot 114 that is projected onto an impact surface 162 of a transparent workpiece 160 , which further includes an opposing surface 164 and an edge surface 166 extending between the impact surface 162 and the opposing surface 164 .

[0118] The laser beam focal line 113 generates induced absorption in the transparent workpiece 160 to produce a defect 172 in the transparent workpiece 160. Because the laser beam focal line 113 includes an internal beam angle θ Bi , so the defect 172 formed by induced absorption includes an internal beam angle θ equal to or approximately equal to Bi The defect angle θ D In other words, the defects 172 formed in the embodiments described herein comprise angled defects, where "angled" refers to an angular deviation from the direction normal to the impact surface 162 at the impact location 115. The laser beam focal line 113 is correspondingly angled. Furthermore, while Figure 1A and Figure 1B 160 , the laser beam focal line 113 is depicted as extending from the impact surface 162 to the opposing surface 164, but this merely illustrates one possible arrangement of the laser beam focal line 113 in and near the transparent workpiece 160. Specifically, it should be understood that a portion of the laser beam focal line 113 may extend outside of the transparent workpiece 160, e.g., beyond the impact surface 162, beyond the opposing surface 164, beyond the edge surface 166, or a combination thereof. Furthermore, when a portion of the laser beam focal line 113 extends outside of the transparent workpiece 160, the outer portion of the laser beam focal line 113 includes an outer focal line angle that, according to Snell's law, is less than the inner beam angle θ relative to the impact surface 162. bi Furthermore, it should be understood that the laser beam focal line 113 may begin at a location within the transparent workpiece 160 (e.g., between the impact surface 162 and the opposing surface 164) and end at a location within the transparent workpiece 160 (e.g., between the impact surface 162 and the opposing surface 164).

[0119] Figure 2A 、 Figure 3A and Figure 4A An optical assembly configured to produce a laser beam focal line 113 is depicted. Figure 2AA conventional optical assembly 100 is depicted that uses an aspheric optical element 120 aligned with a beam path 111 to produce a laser beam 112 that is quasi-non-diffracting when it strikes an impact surface 162 of a transparent workpiece 160. However, when using Figure 2A The conventional optical assembly 100 impacts the impact surface 162 at an angle such that refraction of the laser beam 112 causes the laser beam focal line 113 to have an internal beam angle θ of less than 80° relative to the impact surface 162. bi When the laser beam focal line 113 loses its quasi-non-diffraction property (as mathematically defined above) within the transparent workpiece 160 due to increased aberrations (such as astigmatism). Figure 3A ) and 100”( Figure 4A ) is designed to modify the laser beam 112 so that when the laser beam focal line 113 has an internal beam angle θ less than 80° relative to the impact surface 162 bi When , the laser beam focal line 113 exhibits quasi-non-diffraction characteristics in the transparent workpiece 160. Figure 3A Optical assembly 100 ′ is depicted wherein beam source 110 is radially offset from the other optical components of optical assembly 100 ′ such that laser beam 112 (ie, input beam) output by beam source 110 is radially offset from aspheric optical element 120 . Figure 4A An optical assembly 100" is depicted that includes a multiple optical axicon assembly 140 having a truncated cone optical element 142 and a lens axicon 150. As described in detail below, Figure 3A and Figure 4A The optical assembly 100 ′, 100 ″ can be used to form a laser beam focal line 113 having an internal beam angle θ of less than 80° relative to the impact surface 162 Bi The laser beam focal line 113 has a quasi-non-diffraction characteristic in the transparent workpiece 160 and has minimal astigmatic aberration.

[0120] Now refer to Figure 1B , the beam propagation angle θ is measured relative to the impact surface 162 Bprop , internal beam angle θ Bi and defect angle θ D Each of the beam propagation angle θ Bprop includes the average angle of the rays of the laser beam 112 that impact the impact surface 162 measured relative to the impact surface 162. Figure 1B As shown in FIG, the laser beam 112 impacting the impact surface 162 includes a maximum beam propagation angle θ Bmax and minimum beam propagation angle θ Bmin , maximum beam propagation angle θ Bmaxis the angle of the ray of the laser beam 112 having the largest angle relative to the impact surface 162 at the impact surface 162, and the minimum beam propagation angle θ Bmin is the angle of the ray of the laser beam 112 that has the smallest angle relative to the impact surface 162 at the impact surface 162. In addition, the laser beam 112 includes a beam path angle θ Bpath (ie, the angle of the beam path 111), the beam path angle θ Bpath is the average angle of the rays of the laser beam 112 striking the impact surface 162 relative to the impact surface 162 in the context of the rays approaching the impact surface 162 of the transparent workpiece with a uniform radial distribution. In some embodiments, for example, Figure 1B In the depicted embodiment, the laser beam 112 at the impact surface 162 includes uniform azimuthal intensity, and thus, the beam path angle θ Bpath and beam propagation angle θ Bprop is the same angle. However, in other embodiments, for example, Figure 3A-Figure 3I In the depicted embodiment, the laser beam 112 includes a non-uniform azimuthal intensity at the impact surface 162, and thus, the beam path angle θ Bpath and beam propagation angle θ Bprop It's a different angle.

[0121] Reference again Figure 1A and Figure 1B , the laser beam 112 can be focused into the laser beam focal line 113 using a lens 132. Figure 1A and Figure 1B A single lens 132 is depicted in FIG, but some embodiments may include a lens assembly 130 to focus the laser beam 112 into the laser beam focal line 113, the lens assembly 130 including a first lens 131 and a second lens 132 and a repeat thereof ( Figure 2A 、 Figure 3A 、 Figure 4A ).like Figure 1B As depicted in FIG, the laser beam 112 may include a ring shape when striking the lens 132. However, in other embodiments, such as Figure 3A-3F In the embodiment shown in FIG, the laser beam 112 may include a partial annular shape, such as a crescent shape, as shown in FIG. Figure 3C . The length of the laser beam focal line 113 can be in the range of about 0.1 mm to about 100 mm, or in the range of about 0.1 mm to about 10 mm. Various embodiments can be configured to have a laser beam focal line 113 having a length l of about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.7 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, or about 5 mm, for example, from about 0.5 mm to about 5 mm.

[0122] In operation, Figure 1A and Figure 1B The laser processing depicted in FIG further includes translating at least one of the laser beam focal line 113 and the transparent workpiece 160 relative to each other in the translation direction 101 along the contour line 165 (i.e., the desired separation line) to form a plurality of defects 172. The plurality of defects 172 form a contour 170 that can be used to separate the transparent workpiece 160 into a plurality of separated products 260', 360', 460' ( Figure 6B 、 Figure 7B 、 Figure 8B In some embodiments, the defect 172 may extend through the depth (ie, thickness) of the transparent workpiece 160, for example. Figure 1A In other embodiments, the defect may extend from the impact surface 162 to the edge surface 166, from the opposing surface 164 to the edge surface 166, or both (e.g., Figure 8A Defects 472a, 472b shown in ).

[0123] Figure 2A 、 Figure 3A and Figure 4A The optical components 100, 100', 100" each include a beam source 110. The transparent workpiece 160 can be positioned so that the laser beam 112 output by the beam source 110 is emitted, for example, when passing through the aspheric optical element 120 (at Figure 2A and Figure 3A ) or multi-optical axicon assembly 140 ( Figure 4A ) and then irradiating the transparent workpiece 160. The beam source 110 may include any known or yet-to-be-developed beam source 110 configured to output a laser beam 112 (e.g., a pulsed laser beam or a continuous wave laser beam). In some embodiments, the beam source 110 may output a laser beam 112 having a wavelength of, for example, 1064 nm, 1030 nm, 532 nm, 530 nm, 355 nm, 343 nm, 266 nm, or 215 nm. The laser beam 112 used to form the defect 172 in the transparent workpiece 160 may be well-suited for materials that are transparent to the selected laser wavelength, and the transparent workpiece 160 may be positioned such that the laser beam 112 output by the beam source 110 irradiates the transparent workpiece 160. Furthermore, a beam path 111 may extend from the beam source 110 to the transparent workpiece 160 such that when the beam source 110 outputs the laser beam 112, the laser beam 112 travels along the beam path 111.

[0124] In addition, Figure 2A 、 Figure 3A and Figure 4AIn the depicted embodiment, lens assembly 130 includes a first lens 131 and a second lens 132. In operation, first lens 131 collimates laser beam 112 within a collimating space 134 between first lens 131 and second lens 132, and second lens 132 focuses laser beam 112 onto, for example, a transparent workpiece 160, which may be positioned at imaging plane 104 of second lens 132. In some embodiments, first lens 131 and second lens 132 each comprise a plano-convex lens. When first lens 131 and second lens 132 each comprise a plano-convex lens, the curvature of first lens 131 and second lens 132 may each be oriented toward collimating space 134. In other embodiments, first lens 131 may comprise another collimating lens, and second lens 132 may comprise a meniscus lens, an aspheric lens, or other higher-order corrected focusing lens. In operation, the lens assembly 130 can control the positioning of the laser beam focal line 113 along the beam path 111 (eg, to control the positioning of the laser beam focal line 113 within the depth of the transparent workpiece 160 ).

[0125] Although Figure 2A 、 Figure 3A and Figure 4A 130, but other embodiments of the lens assembly 130 may include two or more lens groups, each lens group including a first lens 131 positioned upstream of the second lens 132. In embodiments including two or more lens groups 132, the second lens 132 positioned furthest downstream of the lens assembly 130 may focus the laser beam 112 into the transparent workpiece 160. For example, the lens assembly 130 may include Figure 2A 、 Figure 3A 、 Figure 4A , an 8F lens assembly including two groups of first lens 131 and second lens 132, or any other known or yet to be developed lens assembly 130 for focusing the laser beam 112 into the laser beam focal line 113. In addition, it should be understood that some embodiments may not include the lens assembly 130, and instead, the aspheric optical element 120 ( Figure 2A 、 Figure 3A ) or multi-axis pyramid assembly 140 ( Figure 4A ) The laser beam 112 can be focused into a laser beam focal line 113 and into the transparent workpiece 160 .

[0126] exist Figure 2A and Figure 3AIn the depicted embodiments of optical assemblies 100 and 100', an aspheric optical element 120 is positioned within a beam path 111 between a beam source 110 and a transparent workpiece 160. The aspheric optical element 120 can include any optical element including an aspheric shape. In some embodiments, the aspheric optical element 120 can include a conical wavefront generating optical element, such as an axicon lens, e.g., a negative index axicon lens, a positive index axicon lens, a reflective axicon lens, a diffractive axicon lens, etc. In some embodiments, when the aspheric optical element 120 comprises an axicon, the axicon 122 can have a laser output surface 126 (i.e., a conical surface) having an angle of about 1.2°, such as about 0.5° to about 5°, or about 1° to about 1.5°, or even about 0.5° to about 20°, measured relative to a laser input surface 124 (e.g., a flat surface) at which the laser beam 112 enters the axicon lens. Furthermore, the laser output surface 126 terminates at a conical tip 128. Furthermore, the aspheric optical element 120 comprises a centerline axis 122 extending from the laser input surface 124 to the laser output surface 126 and terminating at the conical tip 128.

[0127] exist Figure 2A , the conical tip 128 of the aspheric optical element 120 is aligned with the beam path 111, and the aspheric optical element 120 shapes the incident laser beam 112 (e.g., an incident Gaussian beam) into a quasi-non-diffracting beam, which is in turn directed through a first lens 131 and a second lens 132 that focuses the laser beam 112 into a laser beam focal line 113. In other words, when the laser beam 112 strikes the laser input surface 124 of the aspheric optical element 120, the centerline axis 122 of the aspheric optical element 120 and the cross-sectional center of the laser beam 112 are aligned. Figure 2B The cross-sectional intensity of the laser beam 112 downstream of the aspheric optical element 120 is depicted. As described above, the laser beam 112 is quasi-non-diffracting downstream of the aspheric optical element 120 and Figure 2B While not intending to be limited by theory, when the laser beam focal line 113 is at a beam propagation angle θ of 90° relative to the impact surface 162, the laser beam focal line 113 may have an azimuthally uniform intensity. Bprop (ie, normal to the impact surface 162 ) directed into the transparent workpiece 160 and when the laser beam focal line 113 includes an internal beam angle θ of 90° relative to the impact surface 162 Bi (i.e., perpendicular to the impact surface 162), Figure 2A The laser beam focal line 113 formed by the optical assembly 100 retains a quasi-non-diffraction characteristic through the depth of the transparent workpiece 160 .

[0128] However, when using Figure 2A The laser beam 112 formed by the optical component 100 has a beam propagation angle θ Bprop (After refraction of the laser beam 112 at the impact surface 162, the beam propagates at an angle θ Bprop A laser beam focal line 113 is formed, and the laser beam focal line 113 has an inner beam angle θ less than 80°. Bi , for example, 75° or less) impacting the impact surface 162 of the transparent workpiece 160, the laser beam focal line 113 creates astigmatic aberrations within the transparent workpiece 160. These astigmatic aberrations are introduced into the laser beam focal line 113 by the interaction of the laser beam 112 with the impact surface 162. In other words, the refraction of each ray of the laser beam 112 directed into the transparent workpiece 160 at a sufficiently non-orthogonal angle causes astigmatism such that the laser beam 112 loses its quasi-non-diffraction property and it becomes increasingly difficult to create sufficient damage within the transparent workpiece 160 to form the defect 172 of the profile 170. While not intending to be limited by theory, these astigmatic aberrations are a result of the cone of energy being refracted through the transparent workpiece 160 to create the deformed line focusing. While still not intending to be limited by theory, using Figure 2A The optical assembly 100 has an internal beam angle θ less than 80°. Bi The astigmatic aberration of the laser beam focal line 113 reduces the energy intensity of the laser beam focal line 113 along its length so that the induced absorption no longer produces the defect 172 at the depth of the transparent workpiece 160. Specifically, the increased astigmatic aberration reduces the percentage of the laser power of the laser beam focal line 113 contained in the central lobe and, therefore, reduces the peak beam intensity of the laser beam focal line 113 at increasing depths within the transparent workpiece 160. The peak beam intensity decreases with increasing astigmatic aberration within the transparent workpiece 160.

[0129] Now refer to Figure 2C-2E , depicting the use of Figure 2A The cross-sectional beam diagram of the laser beam focal line 113 formed by the optical assembly 100 is shown in FIG. Bprop is directed into the transparent workpiece 160 such that, after refraction at the impact surface 162, the laser beam focal line 113 includes an internal beam angle θ of 80°. Bi . Specifically, Figure 2C-2E The cross-sectional beam diagram shows the laser beam focal line 113 at the impact surface 162 ( Figure 2C ), at a depth of 250 μm in the transparent workpiece 160 ( Figure 2D ) and at a depth of 450 μm within the transparent workpiece 160 ( Figure 2E ) energy density. Figure 2C-2EAs shown in , the astigmatism aberration increases with increasing depth in the transparent workpiece 160, thereby reducing the energy density of the central lobe. Therefore, at a certain depth in the transparent workpiece 160, the energy density of the central lobe decreases below a threshold energy density, so that the defect 172 is not formed at this depth. For example, Figure 2F Describes the use of Figure 2A The optical component 100 is formed with a defect angle θ of 60° D Example defect 172, and as Figure 2F As shown in FIG, as the increasing astigmatism destroys the quasi-non-diffraction property of the laser beam focal line 113, the defect 172 extends only to a short distance in the depth of the transparent workpiece 160. In addition, when the internal beam angle θ of the laser beam focal line 113 is Bi Astigmatic aberration increases at a faster rate at increasing depths in the transparent workpiece 160 as it decreases relative to the impact surface 162. To further illustrate, Figure 2G Describes the use Figure 2A The laser beam focal line 113 formed by the optical component 100 is formed at a beam propagation angle θ of 90°. Bprop (ie, normal) is directed into the transparent workpiece 160 as it propagates in the transparent workpiece 160, and Figure 2H Describes the use Figure 2A The optical assembly 100 forms a laser beam focal line 113 when the laser beam propagation angle θ is tilted. Bprop The intensity distribution of the light as it propagates in the transparent workpiece 160 when it is directed into the transparent workpiece. Figure 2H As shown, the tilted beam propagation angle θ Bprop This results in an increase in astigmatic aberration at increasing depths in the transparent workpiece 160 , thereby reducing the peak intensity of the laser beam focal line 113 .

[0130] Now refer to Figure 2I , graph 20 shows the use of Figure 2A The laser beam focal line 113 formed by the optical component 100 is formed at a beam propagation angle θ of 90°. Bprop (Line 22) is directed into the transparent workpiece 160 and when the beam propagation angle θ is tilted Bprop When (line 24) is directed into the transparent workpiece 160, the irradiance of the laser beam focal line 113 as a function of the propagation distance within the transparent workpiece 160 as it propagates in the transparent workpiece 160. As shown in graph 20, after a propagation distance of 250 μm, the irradiance is the same as that at a beam propagation angle θ of 90°. Bprop Compared to the laser beam focal line 113 of the line 22 directed into the transparent workpiece 160 , the irradiance of the laser beam focal line 113 (line 24 ) formed obliquely is reduced by more than 50%.

[0131] Now refer to Figure 3A , the laser beam 112 (i.e., input beam) output by the beam source 110 is offset from the aspheric optical element 120 in the radial direction (e.g., along the radius of the laser beam 112, orthogonal to the beam propagation direction). Figure 3B and Figure 3C , when the laser beam 112 strikes the aspheric optical element 120 that is radially offset relative to the centerline axis 122 of the aspheric optical element 120, the laser beam 112 includes a non-uniform radial intensity downstream of the offset aspheric optical element 120. Furthermore, the cross-section (e.g., the non-uniform radial intensity) of the laser beam 112 can be rotated by rotating the aspheric optical element 120 about the optical axis 102.

[0132] Without intending to be bound by theory, this non-uniform radial intensity is generated because misalignment of the laser beam 112 relative to the centerline axis 122 of the aspheric optical element causes a redistribution of the laser energy incident on the aspheric optical element 120 as it passes through the aspheric optical element 120. Generally, such perturbations would be expected to be non-ideal, as offsetting the input beam or the aspheric optical element 120 disrupts the azimuthal symmetry of the rays of the laser beam 112. Thus, it is expected that the quality of the laser beam focal line 113 would be degraded by offsetting the aspheric optical element 120 from the beam path 111. With this understanding, those skilled in the art will typically take great care to minimize such radial perturbations, thereby optimally centering the input beam, the aspheric optical element (e.g., the axicon), and the downstream lens relative to one another. This applies when the quasi-undiffracted beam is incident normally on a transparent substrate, in which case the optical system and substrate properties are azimuthally symmetric about the beam propagation direction. However, in the case of cutting a tilted or angled transparent substrate, the azimuthal optical symmetry of the system is broken and the alignment described above is no longer optimal. While this radial offset perturbation of the laser beam 112 can reduce the total energy of the laser beam 112, some or all of the non-uniform radial intensity created by this perturbation increases the energy density once refracted into the tilted transparent workpiece 160, compared to the uniform radial intensity of the same laser beam 112 in the case where the aspheric optical element 120 is not offset. In other words, while not intending to be limited by theory, the energy density in the central lobe of the portion of the laser beam 112 refracted into the transparent workpiece 160 is not as high as that in the central lobe of the portion of the laser beam 112 refracted into the transparent workpiece 160. Figure 2C-2E In contrast, the laser beam focal line 113 formed by the inhomogeneous beam forms the smallest astigmatic aberration.

[0133] In fact, the radial displacement of the laser beam 112 with respect to the aspheric optical element 120 changes the laser beam 112 so that the laser beam 112 is quasi-non-diffracting even once refracted into the transparent workpiece 160, so that the laser beam focal line 113 has an internal beam angle θ of less than 80°. Bi For example, the internal beam angle θ Bi It can be 80° to 50°, such as 80° to 55°, 75° to 55°, 70° to 55°, etc., for example, 79°, 78°, 77°, 76°, 75°, 74°, 73°, 72°, 71°, 70°, 69°, 68°, 67°, 66°, 65°, 64°, 63°, 62°, 61°, 60°, 59°, 58°, 57°, 56°, 55°, 54°, 53°, 52°, 51°, etc.

[0134] Reference again Figure 3A , the laser beam 112 is radially offset from the aspheric optical element 120 by an offset distance a. Specifically, when the laser beam 112 impinges on the laser input surface 124 of the aspheric optical element 120, the offset distance a is the distance between the centerline axis 122 of the aspheric optical element 120 and the center of the cross section of the laser beam 112 in the XY plane. The relative offset between the aspheric optical element 120 and the laser beam 112 can be achieved by shifting the beam source 110 along the XY plane. The amount of offset required to fully destroy the symmetry of the laser beam 112 is a function of the diameter of the laser beam 112, wherein smaller input laser beam diameters require smaller offsets to fully destroy the symmetry. The amount of offset (i.e., the offset distance) should be a significant percentage of the input Gaussian beam diameter. A Gaussian beam is typically 2 Diameter is used to characterize the 1 / e 2 The diameter represents the radial distance from the beam center at which the beam intensity decays to 13.5% of its maximum intensity value (= 1 / e 2 For best results, if the optical apertures of the aspheric optical element 120 and downstream optics are large enough to accommodate the radial shift, the amount of radial offset of the beam center from the axicon center should be 1 / e 2 At least 30% of the beam diameter, but more preferably 1 / e 2 At least 50% of the beam diameter, and can even be 1 / e 2 In some embodiments, the laser beam 112 strikes the aspheric optical element 120 radially offset from the centerline axis 122 of the aspheric optical element 120 by an offset distance of 1 / e of the laser beam 112. 230% or greater of the diameter, for example, 35% or greater, 40% or greater, 45% or greater, 50% or greater, 55% or greater, 60% or greater, 65% or greater, 70% or greater, 75% or greater, 80% or greater, 85% or greater, 90% or greater, 95% or greater, 100% or greater, 105% or greater, 110% or greater, 120% or greater, etc.

[0135] The direction of the deflection of the laser beam 112 is determined by the plane of incidence, which is the plane containing both the optical axis of the angled beam and the surface normal. The direction of the radial deflection of the laser beam 112 is within this plane of incidence. This radial deflection will break the symmetry of the observed ring, but whether the observer sees it as an asymmetry about the "horizontal" or "vertical" axis depends solely on the observer's orientation or viewing angle. The direction of the radial deflection can be such that a large portion of the light passes through the optical assembly 100' in a manner that minimizes the average angle of incidence of the rays relative to the surface normal. This will minimize the aberrations imposed on the laser beam 112. For example, referring to Figure 3D , preferably a radial offset is performed so that at θ Bmax There is more light intensity at angles near θ Bmin There is less light intensity at angles near . In some cases, the cross section of the laser beam illuminating the aspheric optical element can be elliptical. That is, 1 / e of the input beam 2 The diameter can be larger if measured in one direction (e.g., the x-axis) and smaller if measured in the orthogonal direction (e.g., the y-axis). In this case, the amount of beam shift required to affect the asymmetry is based on 1 / e in the direction containing the plane of incidence. 2 diameter.

[0136] refer to Figure 2B 、 Figure 3B and Figure 3C , a horizontal line can be drawn that bisects each image through the optical axis of the optical components 100, 100' (the center of each annulus, along the beam path 111). For an input beam that is perfectly centered on the aspheric optical element 120, the annular power distribution is completely symmetrical and the integrated power on each side of the bisector will be equal. As the input beam is offset vertically, the annular power distribution becomes increasingly asymmetric about the bisector. In order to achieve significant benefits in generating defects 172 in the transparent workpiece 160 at high angles of incidence, the amount of radial offset of the input beam should be large enough so that the difference in integrated power on each side of the bisector is at least 50%, for example, at least 75% and up to 100%. It will be understood that the above reference to Figure 3A 、 Figure 3B and Figure 3CThe description of the bisector drawn in the image as "horizontal" does not mean that the optical assembly 100' is truly horizontal or vertical.

[0137] It is generally desirable to perform as small a radial offset as possible, which still allows defects 172 to be formed through the full depth of the material of the transparent workpiece 160 at a given substrate tilt angle. The larger the radial offset, the more asymmetric the beam cross-section will become at the transparent workpiece 160. This asymmetric cross-section will result in variations in the spatial distribution of stresses applied by each defect 172. The more asymmetric the beam cross-section, the more the stress distribution will tend to produce cracks oriented in a particular direction that may be different from the direction of the intended part profile 170 to be cut. Therefore, there is a trade-off between radially offsetting the laser beam 112 to affect stronger defects 172 through the entire thickness of the glass transparent workpiece 160 and keeping the radial offset small enough so that the profile 170 orientation does not result in an inability to connect adjacent defects 172 and separate the transparent workpiece 160 along the profile 170. For example, for a θ of nearly 80° (near normal incidence) with a thin transparent workpiece 160 (such as 400 μm thick), the radial offset θ may be adjusted to a desired value. Bi , we might expect only 1 / e 2 However, if the thickness of the transparent workpiece 160 is increased to 700 μm, the input beam deflection is increased to 1 / e 2 50% of the radius may be preferable, and if θ Bi A change to 70° (further away from normal incidence) further increases the input beam offset to 1 / e 2 75% of the radius may be preferred. For example, embodiments are contemplated in which the internal focal angle relative to the impact surface 162 is 75° or less and the transparent workpiece 160 comprises a thickness of 700 μm or greater, and embodiments are contemplated in which the internal focal angle relative to the impact surface 162 is 65° or less and the transparent workpiece 160 comprises a thickness of 500 μm or greater.

[0138] In some embodiments, the offset distance a may be from about 100 μm to about 3000 mm, for example, 200 μm, 500 μm, 1000 μm, 2500 μm, etc. In some embodiments, the offset distance a may be from about 200 μm to about 500 μm, or from about 500 μm to about 2000 μm, etc. In some embodiments, the offset distance a may include a cross-sectional diameter (i.e., 1 / e) of the laser beam 112 at a contact location between the laser beam 112 and the aspheric optical element 120 (e.g., at the laser input surface 124 of the aspheric optical element 120). 2 Width) 30% to 50%, or 50% to 75%, or 50% to 100%. Now refer to Figure 3B and Figure 3C, depicts a schematic cross-section of the laser beam 112 downstream of the offset aspheric optical element 120 at a location along the beam path 111 between the first lens 131 and the second lens 132. Figure 3B In the embodiment, the laser beam 112 is offset from the aspheric optical element 120 by a first offset distance, and Figure 3C In FIG. 1 , the laser beam 112 is offset from the aspheric optical element 120 by a second offset distance that is greater than the first offset distance. Figure 3A and Figure 3B As shown in , increasing the offset distance increases the asymmetry of the radial intensity of the laser beam 112 downstream of the offset aspheric optical element 120.

[0139] Now refer to Figure 3D , depicting the use of Figure 3A A side view of the optical assembly 100' forming a laser beam 112 with a laser beam focal line 113 having an internal beam angle θ of less than 80° relative to the impact surface 162. Bi .like Figure 3D As depicted in FIG, the beam path 111 and the transparent workpiece 160 are tilted relative to each other so that the beam path angle θ Bpath and beam propagation angle θ Bprop are all less than 90°. Specifically, the beam path angle θ Bpath and beam propagation angle θ Bprop The internal beam angle θ of the laser beam focal line 113 is Bi The laser beam 112 includes a first group of light rays 116 and a second group of light rays 118, and because the laser beam 112 downstream of the aspheric optical element 120 includes a non-uniform radial intensity, the first group of light rays 116 includes a greater energy intensity than the second group of light rays 118. In addition, as Figure 3D As shown in FIG, the first group of light rays 116 including most of the energy intensity of the laser beam 112 are all smaller than the beam path angle θ. Bpath The ray propagation angle impacts the impact surface.

[0140] Now refer to Figure 3E , depicting the use of Figure 3A The cross-sectional beam diagram of the laser beam focal line 113 formed by the optical assembly 100' is shown in FIG. Bpath and beam propagation angle θ Bprop is directed into the transparent workpiece 160 such that, after refraction at the impact surface 162, the laser beam focal line 113 includes an internal beam angle θ of 60°. Bi . Figure 3EThe cross-sectional beam diagram shows the energy density of the laser beam focal line 113 at several depth positions Z in the transparent workpiece defined by the equation Z=N(Dz). Specifically, Figure 3E The cross-sectional beam diagram of shows the energy density of the laser beam focal line 113 at depth positions Z=N (Dz), where N=0, N=1, N=2, N=3, N=4, and N=5, respectively.

[0141] like Figure 3E As shown in Figure 2A Unlike a non-shifted (i.e., non-biased) beam of the embodiment of the present invention, where astigmatism increases significantly at increasing depths in the transparent workpiece 160, the laser beam focal line 113 has minimally increased astigmatism and exhibits quasi-non-diffraction characteristics. Although there are some off-axis aberrations, the central lobe of the laser beam focal line 113 remains largely unchanged and maintains sufficient energy through the length of the laser beam focal line to produce induced absorption and form the defect 172, thereby facilitating the formation of an angled defect 172 having a significant length. In addition, Figure 3F Depicted with Figure 3A The optical component 100' is formed with a defect angle θ of 60° D Example defect 172, and as Figure 3F As shown in , the defect 172 extends the depth of the transparent workpiece 160 .

[0142] To further illustrate, Figure 3G Describes the use Figure 3A The laser beam focal line 113 formed by the optical component 100 is formed at a beam propagation angle θ of 90°. Bprop (ie, normal) is directed into the transparent workpiece 160 as it propagates in the transparent workpiece 160, and Figure 2H Describes the use Figure 3A The optical assembly 100 forms a laser beam focal line 113 when the laser beam propagation angle θ is tilted. Bprop The intensity distribution of the light as it propagates in the transparent workpiece 160 when it is directed into the transparent workpiece. Figure 2H As shown, the tilted beam propagation angle θ Bprop This results in astigmatic aberrations being minimized to no increase at increasing depths in the transparent workpiece 160 , thereby preserving the peak intensity of the laser beam focal line 113 through the depth of the transparent workpiece.

[0143] Now refer to Figure 3I , graph 40 shows the use of Figure 3A The laser beam focal line 113 formed by the optical component 100 is formed at a beam propagation angle θ of 90°. Bprop (Line 42) is directed into the transparent workpiece 160 and when the beam propagation angle θ is tilted BpropWhen the laser beam focal line 113 (line 44) is directed into the transparent workpiece 160, the irradiance of the laser beam focal line 113 as a function of the propagation distance within the transparent workpiece 160 as it propagates in the transparent workpiece 160. As shown in the graph 40, after a propagation distance of 250 μm, the irradiance of the laser beam focal line 113 (line 24) formed obliquely is reduced by 21% compared to the laser beam focal line 113 (line 22) formed normally at a propagation distance of 250 μm. Figure 3I The curve diagram 40 and Figure 2I The curve of Figure 20 is compared with the use of Figure 2A The angled laser beam focal line formed by the optical assembly 100 is compared to that formed by using Figure 3A The optical assembly 100 ′ forms an angled laser beam with improved irradiance at increased depth of the focal line.

[0144] Now refer to Figures 4A-4C , depicting an optical assembly 100". Figure 4A As shown, the optical assembly 100" includes a multi-axis pyramid assembly 140 (at Figure 4B and Figure 4C ). The multi-optical axicon assembly 140 includes a lens axicon 150 positioned downstream of a truncated cone optical element 142. Figure 4A , the beam source 110 is optically coupled to the multi-axicon assembly 140. In some embodiments, a delivery fiber 192 can extend between and optically couple the beam source 110 and the truncated cone optical element 142, for example, the input surface 144 of the truncated cone optical element 142. The delivery fiber 192 can steer the laser beam 112 and allow the beam source 110 to be located at any position relative to the multi-axicon assembly 140. In other embodiments, the beam source 110 can be optically coupled to the multi-axicon assembly 140 through free space, which may or may not include additional intervening optical components such as lenses, mirrors, etc.

[0145] Although Figure 4A and Figure 4B, the truncated cone optical element 142 and the lens axicon 150 are depicted as two separate optical components, but in some embodiments, the truncated cone optical element 142 and the lens axicon 150 are integrated into a monolith such that the multi-optical axicon assembly 140 comprises a monolithic lens system. In other embodiments, the multi-optical axicon assembly 140 can be modular to support additional shaping optics and facilitate independent movement of each of the truncated cone optical element 142 and the lens axicon 150, for example, using one or more alignment mechanisms 190 configured to change the separation distance between the truncated cone optical element 142 and the lens axicon 150. Figure 4A , a first alignment mechanism 190a can be coupled to the truncated cone optical element 142, and a second alignment mechanism 190b can be coupled to the lens axicon 150. The first alignment mechanism 190a is configured to translate the truncated cone optical element 142 along the beam path 111 (e.g., toward or away from the lens axicon 150), and the second alignment mechanism 190b is configured to translate the lens axicon 150 along the beam path 111 (e.g., toward or away from the lens axicon 150).

[0146] Now refer to Figure 4B , depicts the lens axicon 150 and the truncated cone optical element 142 of the multi-optical axicon assembly 140 in more detail. The truncated cone optical element 142 includes an optical element having an input surface diameter D FI The input surface 144 has an output surface diameter D FO 146, an outer surface 145 extending from input surface 144 to output surface 146, and a reflective cone 148 extending into output surface 146 and including a reflective cone surface 149. The truncated cone optical element 142 may include a crystalline material, a polymer material, a glass material, etc., for example, quartz, fused silica, barium fluoride, calcium fluoride, zinc selenide, BK7 optical glass, etc. The truncated cone optical element 142 may be formed by a process including diamond turning, molding, and polishing.

[0147] In some embodiments, the input surface 144, the output surface 146, or both are coated with an anti-reflection material, such as a dielectric anti-reflection material arranged in a quarter-wave stack. In addition, the reflective cone surface 149 includes a reflective material, such as a metal such as gold, aluminum, copper, or a dielectric reflective material. The reflective cone 148 includes a base diameter D FC and a reflective cone surface 149 parallel to the outer surface 145. Figure 4B As shown in FIG, the truncated cone optical element 142 comprises a truncated cone shape such that the output surface diameter D FO Larger than the input surface diameter D FIFor example, the output surface diameter D FO 0.5mm to 100mm, such as 1mm, 2mm, 4mm, 10mm, 25mm, 50mm, etc., and the output surface diameter D FO Specific base diameter D FC 1.1 to 100 times larger. The truncated cone optical element 142 includes a center line 143, and the reflective cone 148 is radially symmetric about the center line 143. In some embodiments, the base diameter D of the reflective cone 148 is FC is greater than or equal to the diameter of the laser beam 112 upstream of the frustoconical optical element 142. Furthermore, both the outer surface 145 and the reflective cone surface 149 may be at an angle of 45° with respect to the beam path 111.

[0148] Still refer to Figure 4B The lens axicon 150 includes an input surface 152, an output surface 154, and a center line 151. The lens axicon 150 is radially symmetric about the center line 151. Figure 4B As shown in FIG, the centerline 151 of the lens axicon 150 is aligned with the centerline 143 of the truncated cone optical element 142. The input surface 152 includes a central convex reflector 153, and the output surface 154 includes a reflective convex aperture 155. The central convex reflector 153 includes a shadowing diameter D O and is radially symmetrical about the centerline 151. In addition, the reflective convex aperture 155 includes a portion around the aperture having an aperture diameter D A The central aperture 158 of the reflective ring 156. Figure 4B In the embodiment depicted, the shielding diameter D O With aperture D A Same, however, in some embodiments, the shielding diameter D O Larger than aperture D A , and in some embodiments, the shielding diameter D O Smaller than aperture D A Furthermore, in some embodiments, lens axicon 150 includes a negative spherical aberration phase.

[0149] Now refer to Figure 4CIn operation, laser beam 112 enters truncated-conical optical element 142 through input surface 144, strikes reflection cone 148, and is reflected by reflection cone surface 149 of reflection cone 148 toward outer surface 145. Next, rays of laser beam 112 undergo total internal reflection at outer surface 145, which directs laser beam 112 toward output surface 146, where it exits truncated-conical optical element 142. The process of directing laser beam 112 through truncated-conical optical element 142 collimates laser beam 112 such that when laser beam 112 reaches lens axicon 150, it is collimated. In other words, truncated-conical optical element 142 converts an input Gaussian plane wave (i.e., laser beam 112 upstream of truncated-conical optical element 142) into a collimated annular beam (i.e., laser beam 112 between truncated-conical optical element 142 and lens axicon 150). Without the truncated optical element 142 to control the diameter of the collimated annular beam that strikes the lens axicon 150 (e.g., the laser beam 112 upon exiting the truncated optical element 142), some of the power of the laser beam would be lost due to shadowing and vignetting by the central convex reflector 153 of the lens axicon 150. For example, without the truncated optical element 142, the laser beam 112 may lose 25% to 50% of its laser power at the lens axicon 150, e.g., 33% of its laser power.

[0150] Still refer to Figure 4C , the laser beam 112 propagates (as a collimated ring) from the frustum optical element 142 into the lens axicon 150 and then reflects off the reflective convex aperture 155 and the central convex reflector 153 before exiting the lens axicon 150 as a quasi-undiffracted beam. However, unlike using Figure 2A The quasi-non-diffracted beam formed by the optical component 100 is different when passing through Figure 4A After the multi-axis pyramid assembly 140 of the optical assembly 100 ″ is formed, the laser beam 112 retains its quasi-non-diffraction properties once refracted into the transparent workpiece 160, so that the laser beam focal line 113 may include an internal beam angle θ less than 80° relative to the impact surface 162 of the transparent workpiece 160 Bi , and the laser can form a defect angle θ of less than 80° in the transparent workpiece 160 relative to the impact surface 162 D Indeed, after passing through the multi-axicon assembly 140, the laser beam 112 is susceptible to the formation of astigmatic aberrations once refracted into the transparent workpiece 160 at an oblique angle.

[0151] Now refer to Figures 5A-5H , shows a cross-sectional beam diagram of a laser beam focal line formed using various optical components in an example transparent workpiece tilted 35° relative to the beam path 111. First, Figure 5A and Figure 5B The cross-sectional beam diagram shows the energy density of the laser beam focal line, which is generated using Figure 2A The optical assembly 100 is formed and at a depth of 0.1 mm ( Figure 5A ) and at a depth of 1.9 mm within the example transparent workpiece ( Figure 5B ) is directed into the example transparent workpiece tilted 35° relative to the beam path 111. Figure 5A As shown in , the laser beam focal line has negligible distortion (e.g., astigmatism) at a depth of 0.1 mm, but these astigmatism increases at increasing depths. For example, at depths greater than 0.3 mm, the astigmatism overwhelms the central lobe, and thus, while not intending to be limited by theory, the light intensity at the central lobe is too low to form a defect and / or the energy of the astigmatism causes undesirable damage that extends from the defect into the bulk of the example transparent workpiece. Furthermore, Figure 5B It is shown that at a depth of 1.9 mm within the transparent workpiece 160, the laser beam focal line has significant astigmatic aberration.

[0152] then, Figure 5C and Figure 5D The cross-sectional beam diagram shows the energy density of the laser beam focal line, which is generated using Figure 4A The truncated cone optical element 142 of the multi-optical axicon assembly 140 of the optical assembly 100" is formed without using the lens axicon 150, and at a depth of 0.1 mm ( Figure 5C ) and at a depth of 1.9 mm inside the transparent workpiece ( Figure 5D ) is directed into the example transparent workpiece tilted 35° relative to the beam path 111. Figure 5C As shown in , the laser beam focal line has negligible distortion (e.g., astigmatism) at a depth of 0.1 mm, but these astigmatism aberrations increase at increasing depths. For example, at depths greater than 0.3 mm, the astigmatism aberrations dominate the central lobe. Figure 5D It is shown that at a depth of 1.9 mm within the transparent workpiece, the laser beam focal line has significant astigmatic aberration.

[0153] Figure 5E and Figure 5F The cross-sectional beam diagram shows the energy density of the laser beam focal line, which is generated using Figure 4A The lens axicon 150 of the multi-optical axicon assembly 140 of the optical assembly 100" is formed without using the truncated cone optical element 142 and at a depth of 0.1 mm ( Figure 5E ) and at a depth of 1.9 mm within the example transparent workpiece ( Figure 5F) is directed into the example transparent workpiece tilted 35° relative to the beam path 111. Figure 5E As shown in , the laser beam focal line has negligible distortion (e.g., astigmatic aberrations) at a depth of 0.1 mm, and these astigmatic aberrations increase only minimally at increasing depths. While not intending to be bound by theory, the accumulated negative spherical aberration of the lens axicon 150 causes the laser beam to be resilient to astigmatic aberrations at high angles. In practice, Figure 5F It is shown that at a depth of 1.9 mm within the transparent workpiece 160, the laser beam focal line has minimal increase in astigmatic aberration, maintains high energy density in the central lobe, and maintains its quasi-non-diffraction characteristics. However, because Figure 5E and Figure 5F The cross-sectional beam pattern is formed without the use of the truncated cone optical element 142, so the laser beam loses some laser power at the lens axicon 150 because the beam is not first shaped to correspond to the dimensions of the lens axicon 150. As described above, including the truncated cone optical element 142 with the lens axicon 150 minimizes this laser power loss.

[0154] For example, Figure 5G and Figure 5H The cross-sectional beam diagram shows the energy density of the laser beam focal line, which is obtained using Figure 4A The optical assembly 100" is formed by both the truncated cone optical element 142 of the multi-optical axicon assembly 140 and the lens axicon 150, and at a depth of 0.1 mm ( Figure 5G ) and at a depth of 1.9 mm inside the transparent workpiece ( Figure 5H ) is directed into the example transparent workpiece tilted 35° relative to the beam path 111. Figure 5G As shown in , the laser beam focal line has negligible distortions (eg, astigmatic aberrations) at a depth of 0.1 mm, and these astigmatic aberrations only minimally increase at increasing depths due to the accumulated negative spherical aberration of the lens axicon 150 . Figure 5F It is shown that at a depth of 1.9 mm within the transparent workpiece 160, the laser beam focal line has minimal increase in astigmatic aberration, maintains high energy density in the central lobe, and maintains its quasi-non-diffractive properties. In addition, due to the presence of the truncated cone optical element 142, minimal laser power is lost at the lens axicon 150. Therefore, when the laser beam 112 is refracted into the transparent workpiece 160, both the truncated cone optical element 142 and the lens axicon 150 are used to modify the laser beam to minimize both astigmatic aberration and energy loss.

[0155] Now refer to Figure 6A , Figure 4AThe multiple optical axicon assembly 140 can also include a split quarter-wave plate 180 positioned between the truncated cone optical element 142 and the lens axicon 150. The split quarter-wave plate 180 includes a first plate portion 182 having a first fast axis 186a and a first slow axis 188a. The split quarter-wave plate 180 also includes a second plate portion 184 having a second fast axis 186b and a second slow axis 188b. The first fast axis 186a is orthogonal to the second fast axis 186b, and the first slow axis 188a is orthogonal to the second slow axis 188b. When the laser beam 112 passes through the split quarter-wave plate 180, the first plate portion 182 having a first fast axis 186a and a first slow axis 188a polarizes a first beam portion of the laser beam 112 to a first polarization (e.g., a particular horizontal, vertical, or circular polarization), and the second plate portion 184 having a second fast axis 186b polarizes a second beam portion of the laser beam 112 to a second polarization (e.g., another particular horizontal, vertical, or circular polarization). Polarizing the first beam portion to the first polarization and polarizing the second beam portion to a second polarization orthogonal to the second beam wavelength portion decoheres the first beam portion from the second beam portion.

[0156] Furthermore, the first polarization is orthogonal to the second polarization, such that the first beam portion and the second beam portion combine incoherently downstream of the split quarter-wave plate 180, such that the beam spot 114 formed on the impact surface 162 of the transparent workpiece 160 is non-axisymmetric. While not intending to be limited by theory, two laser beam portions having orthogonal polarizations (e.g., vertical and horizontal, right-handed circular and left-handed circular) do not interfere, and when each laser beam portion is projected onto the transparent workpiece 160, each beam portion combines incoherently and collectively forms the non-axisymmetric beam spot 114 (e.g., elliptical). As an illustrative example, the first polarization and the second polarization each include positions on the Poincare sphere that are approximately 180° apart, such that they are orthogonal. It should be understood that the incoherent combination between the first beam portion and the second beam portion can occur with any two orthogonal polarizations.

[0157] Now refer to Figure 6B , depicts a cross-sectional beam pattern of a laser beam focal line 113 formed using a multi-axic assembly 140 including a split quarter-wave plate 180. Specifically, Figure 6B The cross-sectional beam diagram of FIG. 1 shows the energy density of the laser beam focal line 113 within the transparent workpiece 160. Figure 6BAs shown in , the energy density is non-axisymmetric and has an elliptical shape with a major axis and a minor axis. This elliptical shape facilitates the formation of a defect 172 having a central defect region formed at the intersection of the major and minor axes and one or more radial arms formed in the direction of the major axis. In operation, the laser beam focal line 113 is oriented such that the major axis of the beam spot 114 extends along the contour line 165, thereby forming defects 172 having radial arms extending along the contour line 165. By controlling the laser beam focal line 113 so that the direction of the radial arms of each defect 172 extends along the contour line 165, better control of crack propagation can be achieved.

[0158] Reference again Figures 1A-6B In operation, the laser beam 112 can be translated relative to the transparent workpiece 160 (e.g., in the translation direction 101) along the contour line 165 to form a plurality of defects 172 of the contour 170. The laser beam 112 is directed or positioned into the transparent workpiece 160 to generate induced absorption within the transparent workpiece 160 and accumulate sufficient energy to break chemical bonds in the transparent workpiece 160 at spaced locations along the contour line 165 to form the defects 172, each of the defects 172 including a defect angle θ of less than 80° relative to the impact surface 162. D According to one or more embodiments, the transparent workpiece 160 may be aligned with the alignment mechanism 190 by movement of the transparent workpiece 160 (eg, movement of the alignment mechanism 190 coupled to the transparent workpiece 160, such as Figure 3A ), movement of the laser beam 112 (eg, movement of the laser beam focal line 113), or movement of both the transparent workpiece 160 and the laser beam focal line 113 to translate the laser beam 112 across the transparent workpiece 160.

[0159] Defects 172 can be spaced approximately 0.1 μm to about 500 μm apart from one another along profile 170, for example, about 1 μm to about 200 μm, about 2 μm to about 100 μm, about 5 μm to about 20 μm, etc. For example, for a TFT / display glass composition, a suitable spacing between defects 172 can be about 0.1 μm to about 50 μm, such as about 5 μm to about 15 μm, about 5 μm to about 12 μm, about 7 μm to about 15 μm, or about 7 μm to about 12 μm. In some embodiments, the spacing between adjacent defects 172 can be about 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, etc.

[0160] like Figure 1A and Figure 1BAs shown in FIG, a plurality of defects 172 of the profile 170 extend into the transparent workpiece 160 and establish a path for crack propagation for separating the transparent workpiece 160 into separate parts along the profile 170. Forming the profile 170 includes translating the laser beam 112 relative to the transparent workpiece 160 (e.g., in a translation direction 101) along the profile line 165 to form the plurality of defects 172 of the profile 170. According to one or more embodiments, the plurality of defects 172 of the profile 170 can be formed by movement of the transparent workpiece 160, movement of the laser beam 112 (e.g., movement of the laser beam focal line 113), or movement of both the transparent workpiece 160 and the laser beam 112 (e.g., using one or more alignment mechanisms 190 ( Figure 3A ), such as a translation stage, a gantry arm, etc., to translate the laser beam 112 across the transparent workpiece 160. By translating the laser beam focal line 113 relative to the transparent workpiece 160, a plurality of defects 172 can be formed in the transparent workpiece 160, wherein each defect 172 of the plurality of defects 172 includes a defect angle θ of less than 10° relative to the impact surface 162. D .

[0161] A suitable laser wavelength for forming the defect 172 is a wavelength at which the combined loss of linear absorption and scattering of the transparent workpiece 160 is sufficiently low. In embodiments, the combined loss of linear absorption and scattering of the transparent workpiece 160 at the wavelength is less than 20% / mm, or less than 15% / mm, or less than 10% / mm, or less than 5% / mm, or less than 1% / mm, where the dimension " / mm" refers to the distance per millimeter within the transparent workpiece 160 in the beam propagation direction (e.g., the Z direction) of the laser beam 112. Representative wavelengths for many glass workpieces include Nd 3+ fundamental and harmonic wavelengths (e.g., Nd having a fundamental wavelength close to 1064 nm and higher order harmonic wavelengths close to 532 nm, 355 nm, and 266 nm) 3+ :YAG or Nd 3+ Other wavelengths in the ultraviolet, visible, and infrared portions of the spectrum that meet the linear absorption and scattering loss requirements for a given substrate material combination may also be used.

[0162] In operation, the laser beam 112 output by the beam source 110 can produce multiphoton absorption (MPA) in the transparent workpiece 160. MPA is the simultaneous absorption of two or more photons of the same or different frequencies, which excites a molecule from one state (usually the ground state) to a higher energy electronic state (i.e., ionization). The energy difference between the lower state and the higher state of the molecule involved is equal to the sum of the energies of the photons involved. MPA (also known as induced absorption) can be, for example, a second-order or third-order (or higher-order) process that is several orders of magnitude weaker than linear absorption. It differs from linear absorption in that, for example, the intensity of second-order induced absorption can be proportional to the square of the light intensity, and therefore it is a nonlinear optical process.

[0163] The perforation step of forming the profile 170 ( Figure 1A and Figure 1B ) A beam source 110 (e.g., a pulsed beam source such as an ultrashort pulse laser) can be used in combination with an aspheric optical element 120, a first lens 131, and a second lens 132 to illuminate a transparent workpiece 160 and generate a laser beam focal line 113. The laser beam focal line 113 includes a quasi-non-diffracting beam (such as a Gauss-Bessel beam or a Bessel beam as defined above) and can fully or partially perforate the transparent workpiece 160 to form defects 172 in the transparent workpiece 160 (the defects 172 each include a defect angle θ of less than 80° relative to the impact surface 162). D ), which can form the profile 170. In embodiments where the laser beam 112 comprises a pulsed laser beam, the pulse duration of each pulse is in a range of about 1 femtosecond to about 200 picoseconds, such as about 1 picosecond to about 100 picoseconds, 5 picoseconds to about 20 picoseconds, etc., and the repetition rate of each pulse can be in a range of about 1 kHz to 4 MHz, such as about 10 kHz to about 3 MHz, or about 10 kHz to about 650 kHz.

[0164] Now refer to Figure 7A and Figure 7BIn addition to single-pulse operation at the aforementioned various pulse repetition rates, in embodiments including pulsed laser beams, pulses can also be generated in bursts 500 of two sub-pulses 500A or more sub-pulses (such as, for example, 3 sub-pulses, 4 sub-pulses, 5 sub-pulses, 10 sub-pulses, 15 sub-pulses, 20 sub-pulses, or more sub-pulses per burst, such as 1 to 30 sub-pulses per burst 500, or 5 to 20 sub-pulses per burst 500). While not intending to be limited by theory, a burst is a short, rapid group of sub-pulses that produces optical energy interactions with the material (i.e., MPA in the material of the transparent workpiece 160) on a timescale that is not easily achievable using single-pulse operation. While also not intending to be limited by theory, energy within a burst (i.e., a group of pulses) is conserved. As an illustrative example, for a pulse train having an energy of 100 μJ / train and 2 sub-pulses, the energy of 100 μJ / train is distributed between the 2 pulses to produce an average energy of 50 μJ per sub-pulse, and for a pulse train having an energy of 100 μJ / train and 10 sub-pulses, the energy of 100 μJ / train is distributed between the 10 sub-pulses to produce an average energy of 10 μJ per sub-pulse. Furthermore, the energy distribution between the sub-pulses of a pulse train need not be uniform. In fact, in some instances, the energy distribution between the sub-pulses of a pulse train follows an exponential decay pattern, where the first sub-pulse of the pulse train contains the most energy, the second sub-pulse of the pulse train contains slightly less energy, the third sub-pulse of the pulse train contains even less energy, and so on. However, other energy distributions within each pulse train are possible, where the exact energy of each sub-pulse can be tailored to achieve varying degrees of modification of the transparent workpiece 160.

[0165] While not intending to be limited by theory, when defects 172 of one or more profiles 170 are formed using a pulse train having at least two sub-pulses, the force required to separate the transparent workpiece 160 along the profile 170 (i.e., the maximum resistance to fracture) is reduced compared to the maximum resistance to fracture of a profile 170 having the same spacing between adjacent defects 172 formed in the same transparent workpiece 160 using a single-pulse laser. For example, the maximum resistance to fracture of a profile 170 formed using a single pulse is at least twice the maximum resistance to fracture of a profile 170 formed using a pulse train having two or more sub-pulses. Furthermore, the difference in maximum resistance to fracture between a profile 170 formed using a single pulse and a profile 170 formed using a pulse train having two sub-pulses is greater than the difference in maximum resistance to fracture between a profile 170 formed using a pulse train having two sub-pulses and a profile 170 formed using a pulse train having three sub-pulses. Thus, a pulse train can be used to form a profile 170 that is easier to separate than a profile 170 formed using a single-pulse laser.

[0166] Still refer to Figure 7A and Figure 7B , the sub-pulses 500A within the pulse train 500 can be separated by a duration that is in the range of about 1 nanosecond to about 50 nanoseconds, for example, about 10 nanoseconds to about 30 nanoseconds, such as about 20 nanoseconds. In other embodiments, the sub-pulses 500A within the pulse train 500 can be separated by a duration that is up to 100 picoseconds (e.g., 0.1 picoseconds, 5 picoseconds, 10 picoseconds, 15 picoseconds, 18 picoseconds, 20 picoseconds, 22 picoseconds, 25 picoseconds, 30 picoseconds, 50 picoseconds, 75 picoseconds, or any range therebetween). For a given laser, the time interval T between adjacent sub-pulses 500A within the pulse train 500 is p ( Figure 4B ) can be relatively uniform (e.g., within about 10% of each other). For example, in some embodiments, each sub-pulse 500A within the pulse train 500 is separated in time from the subsequent sub-pulse by approximately 20 nanoseconds (50 MHz). Furthermore, the time between each pulse train 500 can be about 0.25 microseconds to about 1000 microseconds, e.g., about 1 microsecond to about 10 microseconds, or about 3 microseconds to about 8 microseconds.

[0167] In some of the exemplary embodiments of the beam source 110 described herein, for the beam source 110 outputting a laser beam 112 comprising a pulse train repetition rate of approximately 200 kHz, the time interval T b ( Figure 7B ) is about 5 microseconds. The laser pulse train repetition rate is related to the time T between the first pulse in a pulse train and the first pulse in the subsequent pulse train. b About (laser pulse train repetition rate = 1 / T b ). In some embodiments, the laser pulse train repetition rate may be in the range of about 1 kHz to about 4 MHz. In embodiments, the laser pulse train repetition rate may be, for example, in the range of about 10 kHz to 650 kHz. The time T between the first pulse in each pulse train and the first pulse in the subsequent pulse train is b It can be about 0.25 microseconds (4 MHz burst repetition rate) to about 1000 microseconds (1 kHz burst repetition rate), for example about 0.5 microseconds (2 MHz burst repetition rate) to about 40 microseconds (25 kHz burst repetition rate), or about 2 microseconds (500 kHz burst repetition rate) to about 20 microseconds (50 kHz burst repetition rate). The exact timing, pulse duration, and burst repetition rate can vary depending on the laser design, but short pulses (T d <20 picoseconds, and in some embodiments, T d ≤15 picoseconds) works well.

[0168] The pulse train repetition rate can be in the range of about 1 kHz to about 2 MHz, such as about 1 kHz to about 200 kHz. Bursting or generating a pulse train 500 is a type of laser operation in which the emission of sub-pulses 500A is not in a uniform and steady stream, but rather in a cluster of compact pulse trains 500. The pulse train laser beam can have a wavelength selected based on the material of the transparent workpiece 160 being operated on, so that the material of the transparent workpiece 160 is substantially transparent at the wavelength. The average laser power per train measured at the material can be at least about 40 μJ per mm of material thickness. For example, in an embodiment, the average laser power per pulse train can be about 40 μJ / mm to about 2500 μJ / mm, or about 500 μJ / mm to about 2250 μJ / mm. In a specific example, for a 0.5 mm to 0.7 mm thick Corning EAGLE For transparent workpieces, a pulse train of about 300 μJ to about 600 μJ can cut and / or separate the workpiece, which corresponds to an exemplary range of about 428 μJ / mm to about 1200 μJ / mm (i.e., for a 0.7 mm EAGLE Glass is 300μJ / 0.7mm, for 0.5mm EAGLE Glass is 600μJ / 0.5mm).

[0169] The energy required to modify the transparent workpiece 160 is the pulse energy, which can be described in terms of the burst energy (i.e., the energy contained within a burst 500, where each burst 500 comprises a series of sub-pulses 500A), or in terms of the energy contained within a single laser pulse (where many pulses may comprise a burst). The pulse energy (e.g., burst energy) can be from about 25 μJ to about 750 μJ, for example, from about 50 μJ to about 500 μJ, or from about 50 μJ to about 250 μJ. For some glass compositions, the pulse energy (e.g., burst energy) can be from about 100 μJ to about 250 μJ. However, for display or TFT glass compositions, the pulse energy (e.g., burst energy) can be higher (e.g., from about 300 μJ to about 500 μJ, or from about 400 μJ to about 600 μJ, depending on the specific glass composition of the transparent workpiece 160).

[0170] While not intending to be limited by theory, using a laser beam 112 comprising a pulsed laser beam capable of generating a pulse train is advantageous for cutting or modifying a transparent material, such as glass (e.g., transparent workpiece 160). Compared to using single pulses separated in time by the repetition rate of a single pulse laser, using a train sequence that spreads the pulse energy within a rapid sequence of pulses within the train allows for a time scale of high-intensity interaction with the material that is greater than that achievable using a single pulse laser. Using a pulse train (as opposed to single pulse operation) increases the size (e.g., cross-sectional size) of the defects 172, which facilitates connecting adjacent defects 172 when separating the transparent workpiece 160 along one or more contours 170, thereby minimizing unintended crack formation. Furthermore, the use of a pulse train to form defects 172 increases the randomness of the crack orientations extending outward from each defect 172 into the bulk material of the transparent workpiece 160, such that individual cracks extending outward from defects 172 do not affect or otherwise deviate from the separation of profile 170, thereby causing the separation of defects 172 to follow profile 170 and minimizing the formation of unintended cracks.

[0171] Reference again Figures 1A-6B In some embodiments, the transparent workpiece 160 may be further acted upon in a subsequent separation step to cause separation of the transparent workpiece 160 along the contour 170 to form a separated transparent article comprising an angled edge ( Figures 8A-10B ). A subsequent separation step may include using mechanical force, thermal stress-induced force, or chemical etchants to propagate a crack along the profile 170. A heat source such as an infrared laser beam may be used to generate thermal stress and thereby separate the transparent workpiece 160 along the profile 170. Separating the transparent workpiece 160 may include directing an infrared laser beam at the profile 170 to induce thermal stress to propagate a crack along the profile 170. In some embodiments, the infrared laser beam may be used to initiate separation, and the separation may then be completed mechanically. Without being limited by theory, the infrared laser is a controlled heat source that rapidly increases the temperature of the transparent workpiece 160 at or near the profile 170. This rapid heating may build compressive stress in the transparent workpiece 160 on or near the profile 170. Because the area of ​​the heated glass surface is relatively small compared to the total surface area of ​​the transparent workpiece 160, the heated area cools relatively quickly. The resulting temperature gradient induces tensile stress in transparent workpiece 160 sufficient to propagate a crack along profile 170 and through the depth of transparent workpiece 160, thereby causing transparent workpiece 160 to completely separate along profile 170. Without being bound by theory, it is believed that the tensile stress may be caused by expansion of the glass (i.e., varying density) in portions of the workpiece having higher local temperatures.

[0172] Suitable infrared lasers for generating thermal stress in glass will typically have a wavelength that is readily absorbed by glass, typically having a wavelength in the range of 1.2 μm to 13 μm, for example, in the range of 4 μm to 12 μm. In addition, the power of the infrared laser beam can be from about 10 W to about 1000 W, for example, 100 W, 250 W, 500 W, 750 W, etc. In addition, the 1 / e 2 The beam diameter may be about 20 mm or less, for example, 15 mm, 12 mm, 10 mm, 8 mm, 5 mm, 2 mm or less. In operation, the larger 1 / e 2 The beam diameter can facilitate faster laser processing and higher power, while the smaller 1 / e 2 The beam diameter can facilitate high-precision separation by limiting damage to portions of the transparent workpiece 160 near the contour 170. Example infrared lasers include carbon dioxide lasers ("CO2 lasers"), carbon monoxide lasers ("CO lasers"), solid-state lasers, laser diodes, or combinations thereof.

[0173] In other embodiments, depending on the type, depth, and material properties (e.g., absorption, CTE, stress, composition, etc.), stress present in the transparent workpiece 160 may cause spontaneous separation along the profile 170 without requiring further heating or mechanical separation steps. For example, when the transparent workpiece 160 comprises a strengthened glass substrate (e.g., an ion-exchanged or thermally tempered glass substrate), the formation of the profile 170 may induce a crack to propagate along the profile 170 to separate the transparent workpiece 160.

[0174] Now refer to Figures 8A-10B , schematically illustrates example transparent workpieces 260, 360, 460 and resulting separated articles 260', 360', 460' formed from these transparent workpieces using the methods and systems described herein. As an example, Figure 8A A schematic side view of a transparent workpiece 260 is depicted having a plurality of defects 272, each of the plurality of defects 272 having a defect angle of less than 80° relative to the impact surface of the transparent workpiece 260. The plurality of defects 272 (i.e., the outline of these defects 272) can be separated to form one or more separated articles 260', each separated article 260' including an angled edge 261, such as Figure 8B As shown in .

[0175] As another example, Figure 9AA schematic side view of a transparent workpiece 360 ​​is depicted including a plurality of defects 372, including a first defect 372a and a second defect 372b. The plurality of defects 372 include a curved profile formed along a curved profile line. The first defect 372a and the second defect 372b both extend radially inward, for example, from the impact surface 362 (i.e., Figure 9A ) extends to the opposing surface 164 (ie, Figure 9B Thus, at the impact surface 362, the first defect 372a and the second defect 372b are spaced apart by a first distance D S1 The first defect 372a and the second defect 372b are spaced apart from each other at the opposite surface 364 by a distance smaller than the first spacing distance D. S1 The second spacing distance D S2 In the embodiment where the curved contour line is circular, the first separation distance D S1 is the diameter of the closed contour line at the impact surface, and the second separation distance D S2 is the diameter of the closed contour line at the opposite surface. Figure 9B As shown in FIG, the closed outline of defect 372 can be separated to form a separated article 360' having a tapered hole 363 defined by angled edge 361. For example, the closed outline of defect 372 can be separated using a chemical etching process to form a separated article 360' having tapered hole 363. For example, the closed outline of defect 372 can be chemically etched using an etchant comprising 5% HF and 10% HNO3. Without intending to be limited by theory, each of the defects in the closed outline of defect 372 acts as a preferred path for the chemical etchant and, therefore, promotes faster chemical etching than chemically etching only the unaltered surface of transparent workpiece 360. As an example, the tapered hole 363 formed using the embodiments described herein can be used in a liquid lens.

[0176] Still refer to Figure 9A and Figure 9B The curved profile of defect 372 can be formed by rotating laser beam 112 about beam path 111 while translating transparent workpiece 160 and laser beam 112 relative to each other, such that defect 372 retains a radially inward direction relative to the curved contour along the curved profile. Furthermore, it should be understood that while defect 372 is depicted as being oriented radially inward relative to the curved contour, in other embodiments, defect 372 can be oriented radially outward, for example, by rotating laser beam 112 about beam path 111.

[0177] As another example, Figure 10AA schematic side view of a transparent workpiece 460 including a plurality of defects 472 including a first defect 472a and a second defect 472b is depicted. The first defect 472a extends from the impact surface 462 to the edge surface 466 of the transparent workpiece 160, and the second defect 472b extends from the opposing surface 464 to the edge surface 466. The first defect 472a can be formed by directing the laser beam focal line 113 at an angle from the impact surface 462 to the edge surface 466, and the second defect 472b can be formed by directing the laser beam focal line 113 at an angle from the opposing surface 464 to the edge surface 466. Furthermore, the first defect 472a can be part of a plurality of first defects 472b forming a first profile, and the second defect 472b can be part of a plurality of second defects 472b forming a second profile. In operation, a first profile of the first defect 472a and a second profile of the second defect 472b can be separated using the embodiments described herein to form a first profile as shown in FIG. Figure 10B A separation article 460' having a beveled edge 468 is depicted in FIG.

[0178] For purposes of describing and defining the present technology, it is noted that reference herein to a variable being a "function" of a parameter or another variable is not intended to imply that the variable is a function of only the listed parameter or variable. Rather, reference herein to a variable being a "function" of a listed parameter is intended to be open-ended, such that the variable may be a function of a single parameter or multiple parameters.

[0179] As used herein, the term "about" means that amounts, dimensions, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or larger or smaller as needed, thereby reflecting tolerances, conversion factors, rounding, measurement errors, etc. and other factors known to those skilled in the art. When the term "about" is used in describing a value or an endpoint of a range, the specific value or endpoint referred to is included. Regardless of whether the numerical value or the endpoint of the range in the specification is recorded with "about", two embodiments are described: one modified by "about" and one not modified by "about". It will also be understood that the endpoints of each range are important relative to the other endpoint and are independent of the other endpoint.

[0180] Directional terms as used herein (eg, up, down, right, left, front, back, top, bottom) are made only with reference to the drawings as drawn and are not intended to imply absolute orientations.

[0181] Unless otherwise expressly stated, any method described herein is not to be construed as requiring that its steps be performed in a specific order, nor as requiring any particular orientation of an apparatus. Thus, in the absence of a method claim that actually recites an order of steps to be followed, or an apparatus claim that actually recites an order or orientation of individual components, or in the absence of other specific indications in the claims or description that the steps are to be limited to a specific order, or in the absence of a specific order or orientation of components of an apparatus, no order or orientation is intended to be inferred in any respect. This applies to any possible non-explicit basis for interpretation, including: matters of logic with respect to arrangement of steps, flow of operations, order of components, or orientation of components; ordinary meaning inferred from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0182] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an element" includes aspects having two or more such elements unless the context clearly dictates otherwise.

[0183] It will be apparent to those skilled in the art that various modifications and variations may be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Therefore, it is intended that the specification covers various modifications and variations of the embodiments described herein as long as such modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. A method for processing a transparent workpiece (160), the method comprising: A laser beam (112) directed along a beam path (111) and output by a beam source (110) is directed through an aspheric optical element (120) and into an impact surface (162) of the transparent workpiece (160), wherein: The laser beam (112) is 1 / e of the laser beam (112) 2 impacting the aspheric optical element (120) radially offset from a centerline axis (122) of the aspheric optical element (120) at an offset distance of 30% or greater of the diameter; The laser beam (112) downstream of the aspheric optical element (120) includes a non-uniform radial intensity; The beam path (111) and the transparent workpiece (160) are inclined relative to each other such that the beam path (111) includes a beam path angle at the impact surface (162) that is less than 90° relative to the impact surface (162); and The portion of the laser beam (112) directed into the transparent workpiece (160) includes a laser beam focal line (113), and generates induced absorption to produce a defect (172) within the transparent workpiece (160), the laser beam focal line (113) including: wavelength λ; Spot size w o ; Rayleigh range Z R , the Rayleigh range Z R Greater than Among them F D is a dimensionless divergence factor including a value of 10 or greater; and An internal focal line angle is less than 80 degrees relative to the impact surface (162), such that the defect (172) comprises a defect angle within the transparent workpiece (160) that is less than 80 degrees relative to the impact surface (162).

2. The method according to claim 1, wherein The laser beam (112) is 1 / e of the laser beam (112) 2 An offset distance of 75% or greater of the diameter impacts the aspheric optical element (120) radially offset from the centerline axis (122) of the aspheric optical element (120).

3. The method according to claim 1, wherein A portion of the laser beam (112) comprising a majority of the intensity of the laser beam impinges on the impingement surface (162) at one or more ray propagation angles that are each greater than the beam path angle.

4. The method according to claim 1, wherein The internal focal angle is less than 80° to 50°.

5. The method of claim 1, further comprising: At least one of the transparent workpiece (160) and the laser beam (112) is translated relative to each other along a contour line (165) to form a contour (170) including a plurality of defects (172).

6. The method according to claim 5, wherein The contour line (165) comprises a curved contour line, the contour (170) comprises a curved contour, and the method further comprises rotating the laser beam (112) while translating at least one of the transparent workpiece (160) and the laser beam (112) relative to each other along the curved contour line such that each defect (172) of the plurality of defects (172) is oriented radially inward or radially outward relative to the curved contour line.

7. A method for processing a transparent workpiece (160), the method comprising: A laser beam (112) directed along a beam path (111) and output by a beam source (110) is directed through a multi-optical axicon assembly (140) comprising a truncated cone optical element (142) and a lens axicon (150) and into an impact surface (162) of the transparent workpiece (160), wherein: The lens axicon (150) is positioned downstream of the frustum optical element (142); and The beam path (111) and the transparent workpiece (160) are inclined relative to each other such that the beam path (111) includes a beam path angle at the impact surface (162) that is less than 90° relative to the impact surface (162); and The portion of the laser beam (112) directed into the transparent workpiece (160) includes a laser beam focal line (113), and generates induced absorption to produce a defect (172) within the transparent workpiece (160), the laser beam focal line (113) including: wavelength λ; Spot size w o ; Rayleigh range Z R , the Rayleigh range Z R Greater than Among them F D is a dimensionless divergence factor including a value of 10 or greater; and An internal focal line angle is less than 80 degrees relative to the impact surface (162), such that the defect (172) comprises a defect angle within the transparent workpiece (160) that is less than 80 degrees relative to the impact surface (162).

8. The method according to claim 7, wherein The lens axicon (150) includes a negative spherical aberration phase.

9. The method according to claim 7, wherein: The lens axicon (150) includes an input surface (152) having a central convex reflector (153) and an output surface (154) having a reflective convex aperture (155); The central convex reflector (153) includes a shielding diameter; and The reflective convex aperture (155) includes a reflective ring (156) surrounding a central aperture (158) having an aperture diameter.

10. The method according to claim 7, wherein: The truncated cone optical element comprises: an input surface (144) comprising an input surface diameter; comprising an output surface (146) having an output surface diameter greater than the input surface diameter; an outer surface (145) extending from the input surface (144) to the output surface (146); and a reflective cone (148) extending into the output surface (146); wherein: The reflective cone (148) includes a reflective cone surface (149) parallel to the outer surface (145) of the truncated cone optical element (142); The reflective cone (148) includes a base diameter; and The diameter of the laser beam (112) upstream of the truncated cone optical element (142) is smaller than or equal to the base diameter of the reflection cone (148) of the truncated cone optical element (142).

11. The method according to claim 7, wherein The multiple optical axicon assembly (140) further includes a split quarter wave plate (180) positioned between the truncated cone optical element (142) and the lens axicon (150).

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