Laser formed chamfers for glass sheets

Abstract

A sheet comprising glass is provided comprising a first surface extending in a first plane and a second surface opposite the first surface extending in a second plane parallel to the first plane. A first direction extends normal to the first and second planes, and a second direction extends perpendicularly to the first direction. The sheet comprises perforations extending between the first and second surfaces, the perforations defining a section retained within a frame of the sheet. Perforations form an internal edge with a non-linear profile having an apex. A first corner joins the edge and the first surface. A second corner joins the edge and the second surface. The edge extends further in the second direction at the apex than at the first and second corners. A compressive region is positioned along the edge and the first and second surfaces. Material is under compressive stress in the compressive region.

Description

SP24-277-3LASER FORMED CHAMFERS FOR GLASS SHEETS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 752981 filed on February 3, 2025, the content of which is relied upon and incorporated herein by reference in its entirety.FIELD

[0002] Embodiments relate generally to systems and methods for the use of laser perforation to form edges in glass products and approaches for increasing the strength and contact angles of edges that are formed.BACKGROUND

[0003] Glass cutting and edge finishing play a key role in many glass products such as display glass, cover glass, and the like. In particular, square edges of glass sheets are prone to breakage and, accordingly, are often processed to have bevels or to be rounded to minimize the chance of breakage. Currently, non-square edges are often fabricated using mechanical means, such as mechanical grinding and polishing. However, these approaches generate glass dust and particles that must be cleaned by additional process steps involving washing or chemical treatments. Additionally, mechanical polishing of inner-contours (such as a hole-cutout) is often highly difficult or even impossible, and often thin sections, such as those having a thickness less than or equal to about 200 micrometers, may be damaged by the polishing process.BRIEF SUMMARY

[0004] In various embodiments described herein, systems and methods may be provided using laser perforation to form edges in glass products and approaches for increasing the strength and contact angles of edges that are formed. Laser-based machining methods allow glass to be processed with improved edge quality, reduced particulate generation, and higher speeds compared to conventional cutting techniques.

[0005] Carbon dioxide (CO2) laser beams, Bessel beams, and filamentation technologies enable processing of glass with square edges. A pseudo-nondiffracting beam such as a Gaussian-Bessel beam (hereafter referred to simply as a “Bessel” beam) may be formed using a pulsed ultrafast laser. These Bessel beams may have a wavelength that the glass sheet is transparentto (e.g., about 515 nanometers, about 532 nanometers, about 800 nanometers, aboutSP24-277-31030 nanometers, about 1064 nanometers), thereby allowing the Bessel beams to make modifications within the glass that extend through the full thickness of the glass sheet. Bessel beams may be created with a focal volume having a diameter and a length, with the diameter typically being less than about 5 micrometers and with the length typically being between about 1 millimeter and about 15 millimeters. Under these conditions, the low-intensity laser light outside a focal region of a Bessel beam may pass through a glass sheet without significant absorption, but the high-intensity light in the focal region is absorbed due to nonlinear absorption processes. Bessel beams may be larger than about 5 micrometers in diameter, but the Bessel beams typically do not possess a sufficient energy density to modify glass at these larger diameters.

[0006] The result of laser modification with a Bessel beam is that each laser shot damages a long, thin line through the entire thickness of the sheet. The sheet may then be placed on a mechanical stage under the laser beam. One or more laser shots may be used to form a single laser damage spot (e.g., a perforation), and the sheet may be translated in a transverse direction using the mechanical stage. After the sheet has been translated, further laser shots may be used to form another laser damage spot such that a controllable pitch is accomplished between laser damage spots (e.g., between about 1 micrometer and about 20 micrometers). Damage at each spot connects to the previous spots, and a weakened damage plane forms in the glass sample. After perforation, when an external force is applied to the glass sheet via mechanical or thermal means (e.g., through the use of a CO2 laser), the perforated section often breaks on the weakened plane with a controlled edge.

[0007] Methods and systems are provided herein to simultaneously chamfer and cut sheets using a laser beam so that resulting products with chamfered or shaped edges may be formed. If a chamfered part contacts another object, the slope of the chamfered edge reduces the probability that an impact event will cause cracking or chipping. In many applications, it may be desirable to maximize the slope of the chamfered edges. This slope may be expressed as the contact angle 6C, which is the angle subtended between the surface normal of a chamfered part at a side surface and a line tangent to the chamfered edge at its surface connection point with the side surface. Example contact angles 6ci, 0C2 are illustrated in FIG. 1 and described in greater detail below in reference to FIG. 1. Using approaches described herein, sections may be formed from sheets with the sections having edges with increased contact angles, with a maximum contact angle (as defined below) of about 12.5 degrees or more or even 20 degrees or more being possible.SP24-277-3

[0008] Angled Bessel beams may be used to create chamfered glass edges. However, angled Bessel beams are only capable creating chamfers with flat, faceted edges (such as C-chamfers). If a curved non-diffracting beam such as an Airy beam, a curving Bessel beam, a caustic beam, or another similar beam is substituted for a straight Bessel beam, then a curved damage plane may form in the sheet and may result in a chamfered edge profde after part release. But current curving Bessel beams are typically limited in the maximum curvatures that they may provide, and Airy beams often experience high aberrations during non-paraxial propagation when the propagation angle is about 15 degrees or more. Here the use of either a new beam (termed a “caustic beam”) or a curving Bessel beam may allow simultaneous laser cutting and chamfering of glass sheets with high contact angles of about 12.5 degrees or more, about 15 degrees or more, or even 20 degrees or more. However, Airy beams, existing curving Bessel beams, angled Bessel beams, and other types of beams may be used in other embodiments, such as when high contact angles (e.g., of about 12.5 degrees or more) or in other situations.

[0009] Caustic and curving Bessel beams may both be used to laser perforate sheets to accomplish high contact angles in resulting chamfers. These sheets may comprise glass (e.g., a glass ceramic). In various embodiments described herein, modifications are made to caustic beamforming systems and / or curving Bessel beamforming systems to achieve efficient high angle laser chamfering.

[0010] Caustic beam phase profiles may be used so that, under non-paraxial conditions, the profiles generally are maintained with a limited number of aberrations. Caustic beamforming systems may include a prism phase that may be applied to the caustic beam profile, with this prism phase being configured to minimize the angles of the light rays compared to the optical axis and to reduce the resolution requirements of any phase mask(s) that are used to form the beam. A prism phase may be formed using a physical prism, optical elements, or other elements. Caustic beamforming systems may also include another polynomial phase configured to flatten the beam’s intensity profile over its length and to improve cutting performance. For example, a polynomial phase may be used that is defined by an additive combination of polynomials of an order of 0 to 5 using transverse coordinates as their variables (e.g. aR5+bR4+cR3+dR2+eR+f where a, c, b, d, e, and f are constants and where R is the radial coordinate defined by R=(x2+y2)05transverse to the beam). Additionally, caustic beamforming systems may apply a caustic beam phase to a laser beam with an intensity adjusted to a rectangular or oval transverse shape with a flat-top profile (rather than a circular Gaussian shape), thereby generating a resulting caustic beam having greatly improved contrast betweenSP24-277-3its main and side lobes and an elliptical focal spot shape. With the rectangular or oval transverse shape, the laser beam may define an aspect ratio at or before application of any phases. This aspect ratio may be a height of the laser beam in a plane divided by the width of the laser beam in the plane, with the plane being orthogonal to a lengthwise direction of the laser beam. The width and the height of the laser beam are not equal in some embodiments so that the aspect ratio is not equal to one. When these oval or rectangular intensity profiles are combined with burst lasers, sidelobe absorption may be greatly reduced and cracks from the cutting process may be guided to be parallel to the cutting direction. These modifications enable caustic beams to cut glass or a glass ceramic with larger contact angles of about 15 degrees or more or even about 20 degrees or more. These larger contract angles may be accomplished while still preserving the ability to easily and cleanly separate sections defined by contours that have been perforated within a sheet. The contour separation may be readily accomplished by applying stress through mechanical bending, or by applying thermal stress with an infrared laser such as a carbon dioxide laser.

[0011] Curving Bessel beamforming systems may also achieve increased contact angles. With certain systems described herein such as 4f systems, two separate portions or halves of a beam may be created, and these separate portions or halves may be combined to form a full beam having a relatively symmetrical shape. Furthermore, an optical delay element (e.g., in the form of a small piece of glass or another material) may be introduced to one half of the curving Bessel beam to move the half closer to the other half, thereby allowing low-intensity regions at a center of the curving Bessel beam to be avoided. A split quarter wave plate may also be used in curving Bessel beamforming systems to simultaneously decohere both halves of the curving Bessel beam from each other and to shape their focal spots into elliptical shapes to control the cracking direction to be parallel to the cutting direction. These modifications enable curving Bessel beams to cut glass with a larger contact angle of at least about 15 degrees, at least about 20 degrees, etc., and this may be accomplished while still preserving the ability to separate sections that have been perforated from a sheet. The split quarter wave plate may include four quadrants with each quadrant having a fast axis rotated by about 90 degrees relative to neighboring quadrants, and a polarization of the laser beam may be circular when the laser beam enters the split quarter wave plate.

[0012] Additionally, while most laser processing beams are rotationally symmetric about the propagation axis, several key non-diffracting and other beam shapes for laser processing exist. For example, near-net bullnose and chamfered edges may be accomplished with a single pass of a laser beam. Furthermore, other techniques may be used such as angled Bessel beams,SP24-277-3multi-segmented Bessel beams, Airy beams, curving Bessel beams, and caustic beams to form unique beam shapes. For each beam-type, a diffractive optical element produces a non-symmetric, quasi -nondiffracting beam that is focused into the bulk of the material. The design of these beams is such that a chamfered or curved cut face is produced, reducing or eliminating the need for further edge grinding to a final edge shape and also providing other potential advantages. To achieve this, the beams may be aligned rotationally relative to the edge being cut so that the appropriate alignment is obtained. Furthermore, for complex shapes such as rounded device screens, the orientation may need to change rapidly to maintain rapid cutting. Current options for this include rotating parts, rotating a sizable portion of the optical system, or rapidly changing the beam on an active shaping element. However, rotation of a substantial portion of the optical system and / or a substantial number of system components is often slow, complicated, and limited in a practical process system size, and this rotation may be particularly difficult where components are rotated more than 45 degrees.

[0013] In various embodiments described herein, optical methods and rotatable optical assemblies may be provided for shaped beam rotation utilizing prisms. Rotatable optical assemblies and optical methods may be used to create laser beams with spatial-temporal pulse shapes to enable features such as shaped edges with contour tangent profiles or complex hole shapes, and the rotatable optical assemblies and optical methods may create these features at a high production rate.

[0014] Advanced beam shaping for laser processing has allowed for novel processes, such as shaped beams in a laser process configured to create C-style chamfered edges and shaped beams in an Airy laser process, which provide for a pre-contoured cut from a laser beam. One challenge with these beams is that they are not symmetric and, if needed to be used in different orientations, they often must be rotated relative to the part being processed. In various optical methods described herein, a single rotatable optical element may be rotated. This rotatable optical element may be provided with a compact size, allowing it to be easily rotated due to its compact size. Additionally, rotatable optical elements may amplify a rotational speed of beam profiles by a factor of two or more, allowing for faster, shorter movements and increased processing speeds and manufacturing efficiency.

[0015] In some embodiments, a multi-axis processing system may be provided capable of rapidly processing complex perforations or other modifications within sheets. Both complex external contours and complex internal contours may be formed in sheets. In some cases, an incoming beam may be provided with a small linear offset relative to an optical axis of a prism or another optical element, and this may allow for rapid rotation of the focused beam around aSP24-277-3rotational axis in a circle while maintaining the orientation relative to the circle tangent. This may allow for rapid creation of internal circular features in the part with a predefined internal edge shape. Where internal features are generated, edge shapes that are produced may be positioned between one section of a sheet and a remainder of the sheet, with the internal features forming a contour path. The section may eventually be separated from the remainder of the sheet at the contour path formed by the internal features upon the application of physical bending, thermal stresses (e.g., from a CO2 laser), chemical etching, and / or upon the completion of other processes.

[0016] Laser perforated sheets may also be subjected to ion-exchange processing to enhance the edge strength and / or other properties of the sheet and any sections within the sheet. Multiple internal edges may be laser patterned within a large glass sheet so that one or more removable sections are formed within the sheet, but the sections may be retained within the sheet during ion-exchange processing. Perforations that are formed may act as conduits for ionexchange, strengthening the individual part contours. Coating processes, like black matrix printing, may also be done before any sections are removed from the sheet. After this processing is performed, sections may be removed from other portions of a sheet. By performing more processing on sheets before removable sections are removed from sheets, this processing may be performed with greater cost-efficiency.

[0017] One challenge with performing more processing on sheets before removable sections are removed from sheets is that, after ion-exchange, a phenomenon of “pop-out” of the internal sections may occur when these large, perforated sheets are processed downstream and inadvertently flexed. “Pop-out” refers to the displacement or tilt of the internal parts relative to the frame of the larger sheet, such that one or more locations of an internal part protrude above or below the plane of the surrounding frame. The magnitude of such displacement may be microns, hundreds of microns, or in extreme cases over one millimeter, even such that the internal part may be completely free of the surrounding frame. Pop-out may occur less in smaller perforated glass sheets (e.g., those that are less than about 300 millimeters by 300 millimeters in size). Challenges with pop-out may be more prominent where the sheet size is large (e.g., greater than about 500 millimeters in length or width) or when the sheet is thin (e.g., less than about 1.1 millimeters).

[0018] In various embodiments described herein, internal edges that are formed may create an edge locking geometry that mitigates pop-out, and removable sections may be more easily retained within sheets so that ion-exchange processing and other processing may be performed with a reduced risk of pop-out. For example, internal edges may be provided with non-linearSP24-277-3profiles and / or various complex geometries. The combination of chamfer formation and ionexchange processing may enable a more robust large sheet process, and additionally final parts may be provided that are inherently edge chamfered without the need for later mechanical finishing or with a reduced need for mechanical finishing. By preventing the removable sections from protruding out of the plane relative to other portions of the sheet until the sections are intended to be removed, problems may be avoided with downstream printing or coating processes, where consistent surface height is often required to ensure accuracy of the printing process.

[0019] In various embodiments described herein, sheets may be provided having removable sections therein, and the sheets may be subjected to ion-exchange processes while the removable sections remain within the sheets. Furthermore, other processing steps like washing and coating may be performed before any removable sections are removed from the sheets. By doing so, processing steps of ion-exchange, washing, coating, and the like may be performed with greater cost-efficiency. Before removable sections are removed, compressive regions may be formed through ion-exchange at the locations of the internal edges, with these compressive regions extending entirely through the thickness of sheets. Once the sections are removed, the ion-exchange material may remain present in a compressive region positioned at these edges.

[0020] Since pop-out is inherently caused by motion of an internal removable section relative to its surrounding frame, a structured laser perforation such as a perforated chamfer created before ion-exchange may serve to geometrically lock the removable sections within a sheet. By forming these laser perforations before ion-exchange processing, the laser perforations may serve as effective conduits during ion-exchange, allowing ion-exchange material to extend into the openings formed by laser perforations so that the ion-exchange material may be diffused at internal edges that are formed, thereby allowing compressive regions to be formed. This may enable sections to have high strength edges. In addition to forming laser perforated chamfers within the larger sheet using Airy beams, caustic beams, or curving Bessel beams, laser perforated chamfers made with multi-spot Gaussian beams also work effectively when these chamfers are formed before ion-exchange processes, with the multi -spot Gaussian beams enabling edge shapes to be formed that beneficially protect against pop-out. Laser perforated chamfers made with multi-spot Gaussian beams may be formed using techniques described in “Protecting the edge: Ultrafast laser modified C-shape glass edges” in the Journal of Laser Applications, Volume 34, Issue 1, dated February 2022, by Daniel Flamm,SP24-277-3Myriam Kaiser, Marvin Feil, Max Kahmann, Michael Lang, Jonas Kleiner, and Tim Hesse, which is incorporated by reference herein for all purposes.

[0021] By using laser formed edges to secure removable sections within a sheet, sections may inherently be formed with edges that are both ion-exchanged and chamfered. Chamfers are often desired for reliability and for robustness against edge impact in downstream handling. For some products, the use of laser formed edges to secure removable sections within a sheet may eliminate the need for a mechanical polishing or chamfering step after removal of sections, reducing cost. However, mechanical polishing and chamfering may be performed after removal of sections in some embodiments. For example, ion-exchanged and chamfered sections may be lightly polished with a process like brush polishing, removing between about 10 micrometers and about 20 micrometers of material per edge. When a small amount of postsingulation polishing is performed, final sections that are formed may have a significant chamfer as well as remaining compressive regions where ion-exchange material is present. By retaining compressive regions, edge strengths of about 800 megapascals or more may be enabled that allow the sections to pass head-impact testing that may be required in the automotive industry.

[0022] Chamfered edges may be created with an apex distance. Chamfered edges may extend between two opposing surfaces of a sheet or a section, and the apex distance is the maximum lateral distance that the chamfered edge extends out relative to a comer where one of the opposing surfaces meets the chamfered edge. Chamfered edges may be created with an apex distance of about 25 micrometers or more, about 30 micrometers or more, about 35 micrometers or more, about 40 micrometers or more, about 45 micrometers or more, or even 50 micrometers or more. Previous processes (e.g., brush polishing a square edge that had gone through the same laser perforation and ion-exchange process steps) were not capable of creating such a large chamfer by themselves without completely removing material that has been diffused during ion-exchange, which results in a reduction of the edge strength of the final part.

[0023] Additionally, lasers used in various embodiments described herein may be an ultrafast laser configured to create perforations within sheets at high processing speeds. The approaches described herein may exhibit low particulate generation and be a high-throughput process, providing advantages over other conventional edge finishing processes.

[0024] Various products may be formed using the approaches described herein. The approaches described herein may be used to create products like instrument cluster displays (ICDs) or center stack displays (CSDs). By performing ion-exchange processing, products thatSP24-277-3are formed may pass head impact testing, and ion-exchange processing may also help to eliminate cracking failure that may occur when multi-layer coated through-glass via dies are singulated.

[0025] In an example embodiment, a method for forming a chamfered edge in a sheet is provided. The method comprises generating a laser beam, with the laser beam being a caustic laser beam or a curving Bessel beam. The method also comprises directing the laser beam to the sheet to form the chamfered edge leading from a first surface of the sheet to an opposite second surface of the sheet, with the sheet comprising glass. The chamfered edge extends between the first surface and the second surface of the sheet. A first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the chamfered edge immediately adjacent to the first surface. A second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the chamfered edge immediately adjacent to the second surface. The first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the chamfered edge from the first surface to the second surface is at least about 25 degrees.

[0026] In some embodiments, the first contact angle and the second contact angle may both be at least about 15 degrees or more such that the change in direction for the chamfered edge from the first surface to the second surface is at least about 30 degrees. Additionally, in some embodiments, the first contact angle and the second contact angle may both be at least about 20 degrees or more such that the change in direction for the chamfered edge from the first surface to the second surface is at least about 40 degrees.

[0027] In some embodiments, the laser beam may be the caustic laser beam, and the method may further comprise directing the laser beam through one or more elements, with the one or more elements being configured to apply a first phase in the form of a prism phase to the laser beam. The first phase may reduce angles of light rays within the laser beam relative to an optical axis relative to when the first phase is not applied and / or reduce resolution requirements of a phase mask relative to when the first phase is not applied. In some embodiments, the one or more elements may be configured to apply a second phase to the laser beam, and the second phase may be configured to flatten an intensity profile of the laser beam in a lengthwise direction of the laser beam relative to when the second phase is not applied.

[0028] In some embodiments, the laser beam may define an aspect ratio at or before application of any phases. The aspect ratio is a height of the laser beam in a plane divided by a width of the laser beam in the plane. The plane may be orthogonal to a lengthwise direction of the laser beam, and the aspect ratio is not equal to one.SP24-277-3

[0029] In some embodiments, the laser beam may be the curving Bessel beam, and the method may further comprise using a binary phase mask to form a first half of the laser beam that is symmetric to a second half of the laser beam. Additionally, in some embodiments, the method may also comprise positioning an optical delay element relative to the curving Bessel beam so that about half of the curving Bessel beam travels through the optical delay element while a remaining portion of the curving Bessel beam does not travel through the optical delay element. In some embodiments, the optical delay element may spatially offset the half of the curving Bessel beam relative to the remaining portion of the curving Bessel beam along a length of the curving Bessel beam. In some embodiments, the method may also comprise positioning a polarization mask relative to the curving Bessel beam. Additionally, in some embodiments, the polarization mask may comprise a split quarter wave plate. In some embodiments, the split quarter wave plate may comprise four quadrants with each quadrant having a fast axis rotated by about 90 degrees relative to neighboring quadrants. Furthermore, in some embodiments, a polarization of the laser beam may be circular when the laser beam enters the split quarter wave plate.

[0030] In some embodiments, the laser beam may be generated in bursts, with each of the bursts comprising a plurality of pulses. Additionally, in some embodiments, each burst may comprise at least five pulses and a time delay may be provided between each pulse of the at least five pulses. In some embodiments, the time delay may be at least about 12 nanoseconds.

[0031] In another example embodiment, a substrate may be provided that is made by a process. The process comprises generating a laser beam, with the laser beam being a caustic laser beam or a curving Bessel beam. The process also comprises directing the laser beam to a sheet to form a chamfered edge leading from a first surface of the sheet to an opposite second surface of the sheet, with the sheet comprising glass. The chamfered edge extends between the first surface and the second surface of the sheet. A first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the chamfered edge immediately adjacent to the first surface, and a second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the chamfered edge immediately adjacent to the second surface. The first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the chamfered edge from the first surface to the second surface is at least about 25 degrees.

[0032] In another example embodiments, a glass or glass ceramic sheet is provided comprising a frame and a section having a first surface and a second surface opposing the first surface, with the section being retained within the frame of the sheet. The sheet also comprisesSP24-277-3perforations extending from the first surface to the second surface and positioned between the section and the frame. The section has a chamfered edge adjacent to the perforations. A first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the chamfered edge immediately adjacent to the first surface, and a second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the chamfered edge immediately adjacent to the second surface. The first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the chamfered edge from the first surface to the second surface is at least about 25 degrees.

[0033] In some embodiments, the perforations may be at least partially formed using a caustic laser beam or a curving Bessel beam. Furthermore, in some embodiments, the first contact angle and the second contact angle may both be at least about 20 degrees or more such that the change in direction for the chamfered edge from the first surface to the second surface is at least about 40 degrees.

[0034] In another example embodiment, a substrate is provided comprising a first surface, a second surface opposing the first surface, and a chamfered edge extending between the first surface and the second surface. A first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the chamfered edge immediately adjacent to the first surface, and a second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the chamfered edge immediately adjacent to the second surface. The first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the chamfered edge from the first surface to the second surface is at least about 25 degrees.

[0035] In some embodiments, the chamfered edge may be at least partially formed using a caustic laser beam or a curving Bessel beam. In some embodiments, the first contact angle and the second contact angle may both be at least about 20 degrees or more such that the change in direction for the chamfered edge from the first surface to the second surface is at least about 40 degrees.

[0036] In another example embodiment, a method for forming a chamfered edge in a sheet is provided. The method comprises generating a laser beam and directing the laser beam to the sheet to form the chamfered edge, with the chamfered edge extending between a first surface and a second surface of the sheet. A first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the chamfered edge immediately adjacent to the first surface, and a second contact angle is defined between a third line normalSP24-277-3to the second surface and a fourth line tangent to a portion of the chamfered edge immediately adjacent to the second surface. The first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the chamfered edge from the first surface to the second surface is at least about 25 degrees, and the sheet comprises glass.

[0037] In some embodiments, the first contact angle and the second contact angle may both be at least about 20 degrees or more such that the change in direction for the chamfered edge from the first surface to the second surface is at least about 40 degrees.

[0038] In another example embodiment, a laser system for imparting a modification at a sheet is provided. The laser system comprises the sheet, a first optical element having a first surface and a second surface, and a laser configured to generate a laser beam directed towards the first surface of the first optical element with a first beam profile. The first optical element is configured to cause the laser beam to travel to the second surface so that the laser beam has a second beam profile when exiting at the second surface and such that the laser beam with the second beam profile is directed at the sheet and imparts the modification at the sheet. The laser system also comprises a rotary actuator configured to cause rotation of the first optical element. The rotary actuator is configured to rotate the first optical element by a first angle, the second beam profile is rotated by a second angle relative to the first beam profile when the first optical element is rotated by the first angle, and the second angle is at least about 1.5 times more than the first angle.

[0039] In some embodiments, the second angle may be at least about 2 times more than the first angle. Additionally, in some embodiments, the modification may be at least one of a crack, an index modification, a trench, a void, a densification, a change in chemical bonding in the sheet, melting, or a color center in the sheet. Furthermore, in some embodiments, the modification may define an internal feature in the sheet, and the internal feature may have a cross-sectional edge shape that is symmetrical about an optical axis.

[0040] In some embodiments, the cross-sectional edge shape may be a curved shape, a parabolic shape, a polygonal shape, or a shape comprising multiple linear segments.

[0041] In some embodiments, the laser beam may be used to form a plurality of internal features in the sheet.

[0042] In some embodiments, the laser system may also comprise a spatial shaping system configured to receive the laser beam to adjust a beam profile of the laser beam. Furthermore, in some embodiments, the first beam profile may be formed using the spatial shaping system. In some embodiments, the spatial shaping system may comprise at least one of a fixed diffractive optical element, a phase plate, or another optical system configured to impart aSP24-277-3rotationally non-symmetric amplitude or phase profile on the laser beam. Additionally, in some embodiments, the spatial shaping system comprises a spatial light modulator. In some embodiments, the laser system may also comprise one or more preparatory optical elements configured to direct the laser beam to the spatial shaping system.

[0043] In some embodiments, the laser system may also comprise a second optical element configured to adjust the laser beam after the laser beam has exited at the second surface of the first optical element. Furthermore, in some embodiments, the second optical element may be configured to focus the laser beam.

[0044] In some embodiments, the laser system may also comprise a polarization controlling element configured to adjust a polarization of the laser beam. In some embodiments, the laser beam may be an Airy beam, a caustic beam, a Bessel beam, a multisegment beam, or a multi-spot Gaussian beam. In some embodiments, the sheet may comprise glass. In some embodiments, the first optical element may define a first optical axis, the laser beam may be received at the first surface of the first optical element at a second optical axis, and a small linear offset may be present between the first optical axis and the second optical axis. In some embodiments, the laser beam may be generated in bursts, and each of the bursts may comprise a plurality of pulses. In some embodiments, the first optical element may be a Dove prism or a k-mirror assembly.

[0045] In another example embodiment, a method of modifying a sheet to form an internal feature in the sheet is provided. The method comprises generating a laser beam and directing the laser beam to a first optical element comprising a first surface and a second surface. The laser beam is directed to the first optical element so that the laser beam is received at the first surface with a first beam profile, so that the laser beam exits at the second surface with a second beam profile, and so that the laser beam is directed to the sheet after exiting the first optical element to generate the internal feature in the sheet. The method also comprises rotating the first optical element by a first angle while directing the laser beam to the first optical element, thereby generating the internal feature in the sheet. The second beam profile is rotated by a second angle relative to the first beam profile when the first optical element is rotated by the first angle, and the second angle is at least about 1.5 times more than the first angle.

[0046] In some embodiments, the method may also include adjusting a position of the sheet relative to the first optical element after the internal feature is formed, generating a second laser beam, directing the second laser beam to the first optical element, and rotating the first optical element to generate a second internal feature in the sheet. In some embodiments, the laser beamSP24-277-3may be an Airy beam, a caustic beam, a Bessel beam, a multi-segment beam, or a multi-spot Gaussian beam.

[0047] In another example embodiment, a modified sheet is provided that is made by a process. The process comprises generating a laser beam and directing the laser beam to a first optical element comprising a first surface and a second surface. The laser beam is directed to the first optical element so that the laser beam is received at the first surface with a first beam profile, so that the laser beam exits at the second surface with a second beam profile, and so that the laser beam is directed from the second surface towards the sheet to generate an internal feature in the sheet. The process also comprises rotating the first optical element by a first angle while directing the laser beam to the first optical element, thereby generating the internal feature in the sheet. The second beam profile is rotated by a second angle relative to the first beam profile when the first optical element is rotated by the first angle, and the second angle is at least about 1.5 times more than the first angle.

[0048] In some embodiments, the process may also comprise adjusting a position of the sheet relative to the first optical element after the internal feature is formed, generating a second laser beam, directing the second laser beam to the first optical element, and rotating the first optical element to generate a second internal feature in the sheet. In some embodiments, the laser beam may be an Airy beam, a caustic beam, a Bessel beam, a multi-segment beam, or a multi-spot Gaussian beam.

[0049] In another example embodiment, a sheet is provided comprising a first surface extending in a first plane and a second surface opposite the first surface extending in a second plane parallel to the first plane. A first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction. The sheet also comprises perforations extending between the first surface and the second surface, and the perforations define a section of the sheet retained within a frame of the sheet. The perforations form an edge in the sheet, the edge is an internal edge in the sheet, and the edge has a nonlinear profile having an apex. A first comer joins the edge and the first surface, and a second comer joins the edge and the second surface. The edge extends further in the second direction at the apex than at the first comer and the second comer. The sheet comprises a compressive region positioned along the first surface, the second surface, and the edge, and the compressive region is a region within the sheet where material is under compressive stress. The sheet also comprises glass.

[0050] In some embodiments, the compressive region may be formed through ionexchange with ion-exchange material diffusing into the sheet to create the compressive region.SP24-277-3In some embodiments, the compressive region may extend entirely from the first surface to the second surface at one or more locations on the sheet. In some embodiments, the sheet may comprise one or more coatings present on the sheet, and the one or more coatings may comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer. In some embodiments, a depth of layer of the compressive region at the edge may be about 5 micrometers or more.

[0051] In another example embodiment, a substrate is provided comprising a first surface extending in a first plane and a second surface opposite the first surface extending in a second plane parallel to the first plane. A first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction. The substrate also comprises an edge extending between the first surface and the second surface, and the edge is formed from laser perforations extending from the first surface and the second surface. The edge has a non-linear profile having an apex. A first comer joins the edge and the first surface, and a second comer joins the edge and the second surface. The edge extends further in the second direction at the apex than at the first comer and the second comer. The substrate comprises a compressive region positioned along the first surface, the second surface, and the edge, and the compressive region is a region within the substrate where material is under compressive stress. Th substrate also comprises glass.

[0052] In some embodiments, the compressive region may be formed through ionexchange with ion-exchange material diffusing into the substrate to form the compressive region. In some embodiments, the ion-exchange material in the compressive region may comprise potassium or sodium. In some embodiments, a surface concentration of the ionexchange material at the edge may be less than a surface concentration of the ion-exchange material at the first surface. In some embodiments, the edge may comprise a curved shape or a plurality of flat surfaces. In some embodiments, the edge may define an apex distance that is equal to or greater than a depth of layer of the compressive region at the first surface, with the apex distance being a maximum distance that the apex extends out in the second direction relative to the first comer.

[0053] In some embodiments, a depth of layer of the compressive region at the edge may be about 5 micrometers or more. Additionally, in some embodiments, the depth of layer of the compressive region at the edge may be less than a depth of layer of the compressive region at the first surface. In some embodiments, the depth of layer for the compressive region at the edge may be at least about 5 micrometers less than the depth of layer for the compressive region at the first surface.SP24-277-3

[0054] In some embodiments, a roughness average at the first surface, the second surface, or the edge may be less than or equal to 100 nanometers. In some embodiments, the substrate may also comprise one or more coatings present on the substrate. The one or more coatings may comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer.

[0055] In some embodiments, a first contact angle may be defined between a first line normal to the first surface and a second line tangent to a portion of the edge immediately adjacent to the first surface, and a second contact angle may be defined between a third line normal to the second surface and a fourth line tangent to a portion of the edge immediately adjacent to the second surface. The first contact angle and the second contact angle may both be at least about 10 degrees or more such that a change in direction for the edge from the first surface to the second surface is at least about 20 degrees.

[0056] In some embodiments, the first contact angle and the second contact angle may both be least about 12.5 degrees or more such that the change in direction for the edge from the first surface to the second surface is at least about 25 degrees. Additionally, in some embodiments, the first contact angle and the second contact angle may both be at least about 20 degrees or more such that the change in direction for the edge from the first surface to the second surface is at least about 40 degrees.

[0057] In another example embodiment, a method for making a substrate is provided. The method comprises forming laser perforations in a sheet. The laser perforations define the substrate having an edge within the sheet, and the edge is an internal edge within the sheet. The substrate defines a first surface extending in a first plane, and a second surface opposite the first surface extending in a second plane parallel to the first plane. The edge extends between the first surface and the second surface. A first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction. The edge has a non-linear profile having an apex. A first comer joins the edge and the first surface, a second comer joins the edge and the second surface, and the edge extends further in the second direction at the apex than at the first comer and the second comer. The method also comprises creating a compressive region in the sheet, with the compressive region positioned along the first surface, the second surface, and the edge. The method also comprises releasing the substrate from other portions of the sheet. The substrate also comprises glass.

[0058] In some embodiments, the compressive region may be created by performing ionexchange with the sheet, and, during ion-exchange, ion-exchange material may be diffused into the sheet to form the compressive region. Additionally, in some embodiments, the laserSP24-277-3perforations may extend fully through a depth of the sheet. In some embodiments, the method may also comprise coating the sheet or the substrate with one or more coatings, and the one or more coatings may comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer. In some embodiments, the method may also comprise polishing the edge of the substrate, and the edge may be polished either before the substrate is released from the other portions of the sheet or after the substrate is released from the other portions of the sheet.

[0059] In some embodiments, after polishing of the edge, the compressive region may remain positioned around the edge. In some embodiments, a depth of layer of the compressive region at the edge may be at least about 5 micrometers less than a depth of layer of the compressive region at the first surface.

[0060] In some embodiments, a first contact angle may be defined between a first line normal to the first surface and a second line tangent to a portion of the edge immediately adjacent to the first surface, and a second contact angle may be defined between a third line normal to the second surface and a fourth line tangent to a portion of the edge immediately adjacent to the second surface. The first contact angle and the second contact angle may both be at least about 12.5 degrees or more such that a change in direction for the edge from the first surface to the second surface is at least about 25 degrees. In some embodiments, the laser perforations may be formed using at least one of a multi-segment angled Bessel beam profile, a caustic beam profile, an Airy beam profile, a curving Bessel beam profile, or a multi-spot Gaussian beam.

[0061] In another example embodiment, a substrate formed by a process is provided. The process comprises forming laser perforations in a sheet. The laser perforations define the substrate having an edge within the sheet, and the edge is an internal edge within the sheet. The substrate defines a first surface extending in a first plane and a second surface opposite the first surface extending in a second plane parallel to the first plane. The edge extends between the first surface and the second surface. A first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction. The edge has a non-linear profile having an apex. A first comer joins the edge and the first surface, and a second comer joins the edge and the second surface. The edge extends further in the second direction at the apex than at the first comer and the second comer. The process also comprises creating a compressive region in the sheet, with the compressive region positioned along the first surface, the second surface, and the edge. The process also comprises releasing the substrate from other portions of the sheet, and the substrate comprises glass.SP24-277-3

[0062] In some embodiments, the compressive region may be created by performing ionexchange with the sheet. During ion-exchange, ion-exchange material may be diffused into the sheet to form the compressive region.BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0064] FIG. 1 is a schematic view illustrating an example optical assembly allowing the relationship between angles in a curving beam to be seen, in accordance with some embodiments discussed herein;

[0065] FIG. 2 is a plot illustrating the objective numerical aperture (“NA”) value that may be used to obtain various contact angles formed at edges by an optical assembly similar to the one illustrated in FIG. 1, in accordance with some embodiments discussed herein;

[0066] FIG. 3A is an image illustrating an example Airy beam formed using a 0.4 NA ideal lens propagated through Fresnel diffraction, in accordance with some embodiments discussed herein;

[0067] FIG. 3B is an image illustrating an example Airy beam formed using a 0.4 NA ideal lens propagated through Rayleigh-Sommerfeld (“RS”) diffraction, in accordance with some embodiments discussed herein;

[0068] FIG. 3C is an image illustrating an example Airy beam formed using a 0.8 NA ideal lens propagated through Fresnel diffraction, in accordance with some embodiments discussed herein;

[0069] FIG. 3D is an image illustrating an example Airy beam formed using a 0.8 NA ideal lens propagated through RS diffraction, in accordance with some embodiments discussed herein;

[0070] FIG. 4A is an image illustrating an example caustic beam formed using a 0.8 NA ideal lens propagated using through RS diffraction, in accordance with some embodiments discussed herein;

[0071] FIG. 4B is a plot illustrating a phase across a mask used to create the caustic beam of FIG. 4A, with two plotlines included showing the resulting phase when a prism phase was used and when a prism phase was not used, in accordance with some embodiments discussed herein;SP24-277-3

[0072] FIG. 4C is a plot illustrating a maximum focal spot intensity at different z-coordinates, which is the direction the beam propagates in and generally perpendicular to the glass sheet to be processed, in accordance with some embodiments discussed herein;

[0073] FIG. 5A is a plot illustrating different phase values within an example phase mask that may be used for a caustic beam, in accordance with some embodiments discussed herein;

[0074] FIG. 5B is a plot illustrating first plotline showing a ratio of the side lobe intensity to the focal spot intensity as a function of the aspect ratio and second plotline showing a focal spot width to height ratio as a function of the aspect ratio, in accordance with some embodiments discussed herein;

[0075] FIG. 6 illustrates images of example main lobes and side lobes formed from caustic beams with different aspect ratios, in accordance with some embodiments discussed herein;

[0076] FIG. 7A is a plot illustrating a trajectory of a focal spot of a curving Bessel beam, in accordance with some embodiments discussed herein;

[0077] FIG. 7B is a plot illustrating a trajectory of a focal spot of a curving Bessel beam formed by reflecting a latter half of the beam across its apex, in accordance with some embodiments discussed herein;

[0078] FIG. 8A is a plot illustrating an example curving Bessel beam centered at the origin and using the maximum acceleration possible, in accordance with some embodiments discussed herein;

[0079] FIG. 8B is a plot illustrating an example curving Bessel beam centered at the origin whose total deflection is lowered by fitting a parabola near the origin, in accordance with some embodiments discussed herein;

[0080] FIG. 9A is an image illustrating a curving Bessel beam with a contact angle of about 25 degrees where one beam half has been shifted towards the other beam half to avoid the creation of low-intensity regions at a center of the curving Bessel beam, in accordance with some embodiments discussed herein;

[0081] FIG. 9B is a plot illustrating different phase values within an example phase mask used to create the beam of FIG. 9A, in accordance with some embodiments discussed herein;

[0082] FIG. 10 is a plot illustrating the maximum focal intensity as a function of the z-coordinate where a destructive combination of beam halves is used, where a constructive combination of beam halves is used, and where an incoherent combination of beam halves is used, in accordance with some embodiments discussed herein;

[0083] FIGS. 11A-11C are images illustrating example polarization masks for curving Bessel beam formation, in accordance with some embodiments discussed herein;SP24-277-3

[0084] FIG. 12 is an image illustrating an example focal spot shape resulting from use of the final polarization mask of FIG. 11C, in accordance with some embodiments discussed herein;

[0085] FIG. 13 is a schematic view illustrating an example optical system for caustic beam formation, in accordance with some embodiments discussed herein;

[0086] FIG. 14 is a schematic view illustrating an example optical system for curving Bessel beam formation, in accordance with some embodiments discussed herein;

[0087] FIG. 15A is a side profile view illustrating an example section cleaved using a caustic beam, in accordance with some embodiments discussed herein;

[0088] FIG. 15B is a front face view illustrating the edge of the section of FIG. 15A, looking at the edge straight on, in accordance with some embodiments discussed herein;

[0089] FIG. 16A is a side profile view illustrating an example section cleaved using a curving Bessel beam, in accordance with some embodiments discussed herein;

[0090] FIG. 16B is a front face view illustrating the edge of the section of FIG. 16A, looking at the edge straight on, in accordance with some embodiments discussed herein;

[0091] FIG. 17 is a block diagram illustrating an example optical system for creation and rotation of a laser beam, in accordance with some embodiments discussed herein;

[0092] FIG. 18A is a schematic view illustrating a laser system comprising a rotation optical element in the form of a Dove prism, in accordance with some embodiments discussed herein;

[0093] FIG. 18B is a schematic view illustrating a rotation optical element in the form of a k-mirror assembly, in accordance with some embodiments discussed herein;

[0094] FIG. 19 is a plot illustrating a longitudinal profile for an Airy beam for different Y -coordinates, in accordance with some embodiments discussed herein;

[0095] FIG. 20 is a plot illustrating a longitudinal profile for an Airy beam for different X-coordinates, in accordance with some embodiments discussed herein;

[0096] FIG. 21 is a plot illustrating an intensity profile at various positions along a propagation axis (the z-axis), in accordance with some embodiments discussed herein;

[0097] FIG. 22 is a plot illustrating a longitudinal profile for an Airy beam for different Y -coordinates where the profile has been rotated 180 degrees relative to the plot in FIG. 19, in accordance with some embodiments discussed herein;

[0098] FIG. 23 is a plot illustrating a longitudinal profile for an Airy beam for different X-coordinates where the profile has been rotated 180 degrees relative to the plot in FIG. 20, in accordance with some embodiments discussed herein;SP24-277-3

[0099] FIG. 24 is a plot illustrating an intensity profile at various positions along a propagation axis (the z-axis) where the profile has been rotated 180 degrees relative to the plot in FIG. 21, in accordance with some embodiments discussed herein;

[0100] FIG. 25 is an image illustrating an example perforated edge formed using an Airy beam, in accordance with some embodiments discussed herein;

[0101] FIG. 26A is a schematic view illustrating various example beam profiles swept about an optical axis to form internal features in sheets, in accordance with some embodiments discussed herein;

[0102] FIG. 26B is a schematic view illustrating various example beam profiles swept about an optical axis to form internal features in sheets, in accordance with some embodiments discussed herein;

[0103] FIGS. 27A-27B are schematic views illustrating an example process flow for forming internal features in a sheet through laser perforation and then singulating sections within the sheet, in accordance with some embodiments discussed herein;

[0104] FIG. 28 is a schematic view illustrating a section positioned within a frame of a sheet, in accordance with some embodiments discussed herein;

[0105] FIG. 29 is a schematic view illustrating the section experiencing pop-out relative to the surrounding frame of the sheet, in accordance with some embodiments discussed herein;

[0106] FIG. 30 is a height map illustrating various locations in sheets where the sheets are experiencing pop-out at the edges of the sections, in accordance with some embodiments discussed herein;

[0107] FIG. 31 is a schematic view illustrating an example section separated from remaining portions of a sheet via straight perforations;

[0108] FIG. 32 is a schematic view illustrating an example section separated from remaining portions of a sheet via non-linear perforations, in accordance with some embodiments discussed herein;

[0109] FIG. 33 is a schematic view illustrating an example Bessel beam optical assembly, in accordance with some embodiments discussed herein;

[0110] FIG. 34 is a plot illustrating an example intensity profile for a Bessel beam as a function of a focus position, in accordance with some embodiments discussed herein;

[0111] FIG. 35 is an image illustrating an example Bessel beam cross section, in accordance with some embodiments discussed herein;

[0112] FIG. 36 is a schematic view illustrating an example Bessel beam optical assembly, in accordance with some embodiments discussed herein;SP24-277-3

[0113] FIG. 37 is atop view illustrating perforations formed within a sheet using a Bessel beam optical assembly similar to the one illustrated in FIG. 36, in accordance with some embodiments discussed herein;

[0114] FIG. 38 is a front face view illustrating a cut edge formed within a sheet using a Bessel beam optical assembly similar to the one illustrated in FIG. 36, in accordance with some embodiments discussed herein;

[0115] FIG. 39A is a side profile view illustrating a cut edge of an example section of a sheet where a C-style chamfered edge formed through laser perforation using a multi-segment angled Bessel beam is shown, in accordance with some embodiments discussed herein;

[0116] FIG. 39B is a side profde view illustrating a cut edge of an example section of a sheet where a curved chamfered edge formed through laser perforation using a curved laser beam is shown, in accordance with some embodiments discussed herein;

[0117] FIG. 40A is an image illustrating an example bullnose laser edge chamfer, in accordance with some embodiments discussed herein;

[0118] FIG. 40B is an image illustrating an example C-style chamfered edge, in accordance with some embodiments discussed herein;

[0119] FIG. 41A illustrates images of a cross section intensity profile of a scan at different focus locations, in accordance with some embodiments discussed herein;

[0120] FIG. 4 IB is a plot illustrating the peak grayscale intensity as a function of focus position, in accordance with some embodiments discussed herein;

[0121] FIG. 41C is a spot movement plot illustrating the peak location as a function of the focus position, in accordance with some embodiments discussed herein;

[0122] FIG. 4 ID illustrates images of a cross section intensity profile of a scan at different focus locations, in accordance with some embodiments discussed herein;

[0123] FIG. 4 IE is a plot illustrating the peak grayscale intensity as a function of focus position, in accordance with some embodiments discussed herein;

[0124] FIG. 4 IF is a spot movement plot illustrating the peak location as a function of the focus position, in accordance with some embodiments discussed herein;

[0125] FIG. 42A is a schematic view illustrating an example process flow for formation and singulation of sections within a sheet, in accordance with some embodiments discussed herein;

[0126] FIG. 42B is a plot illustrating edge strengths for edges of various example sheets formed using different approaches, in accordance with some embodiments discussed herein;SP24-277-3

[0127] FIG. 43 illustrates various scanning electron micrograph images with an increased concentration of potassium ions from ion-exchange being shown around the exterior surfaces of the samples, in accordance with some embodiments discussed herein;

[0128] FIG. 44 is a schematic, top view of an interior section formed within a sheet, with this sheet being usable in a ball-on-ring test to assess the force and deflection required to effect release of the interior section, in accordance with some embodiments discussed herein;

[0129] FIG. 45 is a schematic, side view of an example setup that may be used on the sheet of FIG. 44 for the ball-on-ring test, in accordance with some embodiments discussed herein;

[0130] FIG. 46 is a plot illustrating the peak load as a function of the section diameter where sheets have different thicknesses, in accordance with some embodiments discussed herein;

[0131] FIG. 47 is a plot illustrating the peak load as a function of the section diameter where different chamfer approaches were used, in accordance with some embodiments discussed herein;

[0132] FIG. 48 is a plot illustrating the peak load as a function of the section diameter where different chamfer approaches were used, in accordance with some embodiments discussed herein;

[0133] FIG. 49A is a schematic view illustrating an example section comprising a compressive region having a depth of layer (DOL) when the section has not been prechamfered, in accordance with some embodiments discussed herein;

[0134] FIG. 49B is a schematic view illustrating the section of FIG. 49A after brush polishing and how the DOL is removed during brush polishing, in accordance with some embodiments discussed herein;

[0135] FIG. 49C is a schematic view illustrating an example section comprising a compressive region having a DOL when the section has been pre -chamfered, in accordance with some embodiments discussed herein;

[0136] FIG. 49D is a schematic view illustrating the section of FIG. 49C after brush polishing and how some DOL remains at edges even after brush polishing is performed, in accordance with some embodiments discussed herein;

[0137] FIG. 50 is a block diagram illustrating various components within an example laser system, in accordance with some embodiments discussed herein;

[0138] FIG. 51 is a flow chart illustrating an example method for modifying a sheet to form an internal feature such as a perforation or internal edges in the sheet, in accordance with some embodiments discussed herein;SP24-277-3

[0139] FIG. 52 is a flow chart illustrating an example method for forming and singulating sections of a sheet so that the sections are made with high cost-efficiency and so that the sheet has a high edge strength, in accordance with some embodiments discussed herein; and

[0140] FIG. 53 is a flow chart illustrating an example method for forming a chamfered edge in a sheet, in accordance with some embodiments discussed herein.DETAILED DESCRIPTION

[0141] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. Additionally, any connections or attachments may be direct or indirect connections or attachments unless specifically noted otherwise. As used here, the terms “beam” and “laser beam” are intended to be used synonymously. As used herein, “ion-exchange material” may include certain ions (e.g., potassium ions, sodium ions, etc.) that are diffused into the substrate during the ion exchange process. Additionally, certain perforations described herein may be provided in the form of long thin lines of laser modified material that extend through the full thickness of a sheet.

[0142] Laser chamfering using non-diffracting laser beams offers many benefits over mechanical edge finishing. These benefits may include increased speed, precision, and cleanliness. However, laser chamfering using non-diffracting laser beams is often limited in the chamfer geometries it may create. The focal regions of non-diffracting laser beams tend to travel roughly parallel to the average direction of a local bundle of rays passing through them, so the maximum angles that the laser beam focal regions make relative to their optical axes (equivalent to the chamfer contact angle) are limited by the maximum angle of the light rays forming the laser beam. In practice, this means that the focusing power (termed numerical aperture (NA)) of the objective lens used to form the chamfering beam and the refraction of light at the surface of the section combine to limit the maximum deflection that the laser beam may produce.

[0143] This concept is illustrated in FIG. 1, which is a schematic view illustrating an example optical assembly 100 allowing the relationship between angles in a curving beam to be seen. The optical assembly 100 includes a lens 102 and the sheet 108, but the optical assembly 100 may include other components such as a laser and other optical elements. The lens 102 is configured to focus a laser beam to generate a focused beam profile as the laser beam is directed to the sheet 108. A first edge 104A and a second edge 104B are shown for the beam profile after travelling through the lens 102 but before travelling through the sheet 108.SP24-277-3The first edge 104A defines a focus angle of 9f, and this focus angle 9f may be defined by the equation 9f = sin~ (NA'), where NA represents the objective numerical aperture value for the lens 102. The second edge 104B may possess a similar focus angle. The objective numerical aperture value is indicative of the focusing power for the lens 102.

[0144] Upon the laser beam reaching the sheet 108, refraction may reduce the focus angle 9f to the refracted focus angle 9fr, with 9fr= sin~ (nairsin 9f / ng) and wherenairis the refractive index of air and ngis the refractive index of the sheet 108. A first edge 106A and a second edge 106B are shown for the beam profile while the laser beam travels through the sheet 108.

[0145] The curving beam has a beam profile 110, with the beam profile 110 showing the focal region of the laser beam within the sheet 108. The focal region may be proximate to a point of maximum intensity in each transverse slice of a laser beam. The curving beam profile 110 defines a contact angle 9ciat the entry surface 105 of the sheet 108 where the laser beam first enters the sheet 108. The contact angle 9cimay be somewhat lower than the refracted focus angle 9fr. The contact angle 9ciis measured between a surface normal 105A at the entry surface 105 and a line 105B tangent to the curving beam profile 110 immediately adjacent to the entry surface 105 of the sheet 108 where the laser beam first enters the sheet 108. Similarly, the curving beam profile 110 defines aC2 at the exit surface 105C of the sheet 108 where the laser beam exits the sheet 108. The contact angleC2 is measured between a surface normal 105D at the exit surface 105C and a line 105E tangent to the curving beam profile 110 immediately adjacent to the exit surface 105C. The contact angles 9ci,C2 may be equal to each other in some embodiments, but these contact angles 9ci,C2 may be different from each other in other embodiments. References to contact angles 9Cherein may refer to the contact angle 9ciand / or the contact angleC2. The contact angle 9ci,C2 may both be about 12.5 degrees or more, about 15 degrees or more, about 17.5 degrees or more, or even about 20 degrees or more. Thus, where the contact angles 9ci,C2 are equal to each other, the curving beam profile 110 may experience a change in direction (cibetween the surfaces 105, 105C of about 25 degrees or more, about 30 degrees or more, about 35 degrees or more, or even about 40 degrees or more.

[0146] The sheet 108 may comprise glass in some embodiments. This glass and other glass described herein may be a glass made by Coming Incorporated such as its Gorilla® glass or its Lotus™ NXT glass, but other types of glass may be used as well including glass made by companies other than Coming Incorporated.SP24-277-3

[0147] As the objective numerical aperture value increases, this results in increased 9f and 9fr, which tends to lead to an increase in the contact angles 6ci, 0C2. The relationship between the objective numerical aperture value and the maximum achievable contact angles 6ci, 0c2 are illustrated in the plot 212 in FIG. 2, although the maximum achievable contact angle may be somewhat lower in practice. The contact angles 6Cmay be formed by an optical assembly similar to the one illustrated in FIG. 1, with the contact angles 6Cbeing formed at an entry surface similar to the entry surface 105 of FIG. 1 or at an exit surface similar to the exit surface 105C of FIG. 1. As shown in FIG. 2, the maximum achievable contact angle increases as the objective numerical aperture value increases, with the maximum achievable contact angle topping out at around 45 degrees. For certain beam types, the contact angle 6Cmay increase more rapidly as the objective numerical aperture value reaches higher levels ranging between 0.8 and 1.0. Airy laser beams, caustic laser beams, curving Bessel laser beams, and angled Bessel laser beams all exhibit relationships between the contact angle 6Cand the objective numerical aperture value that are similar to the relationship shown in the plot 212.

[0148] Despite the aforementioned limitations for laser chamfering using non-diffracting laser beams, laser chamfering is useful to increase the impact resistance of parts. If a chamfered part contacts another part or a vertical post, contact occurs on the chamfered edge of the chamfered part, which protects the comers of the chamfered part from cracking or chipping. In many applications, it may be desirable to maximize the contact angles 6C, and increasing the objective numerical aperture value NA of the focusing objective is the primary way to accomplish this when laser chamfering using non-diffracting laser beams. Other approaches of laser chamfering using diffracting beams (using sequential Gaussian foci) exist, but these approaches often require further processing such as carbon dioxide (CO2) laser processing or etching to release parts. These other approaches also often retain uneven (step-like) edge profiles after release.

[0149] In various embodiments described herein, caustic beams and certain curving Bessel beams may be used to provide high angle chamfering using non-diffracting beams. As explained further herein, these types of laser beams may be beneficial over other laser beams such as Airy beams and other curving Bessel beams.

[0150] As shown in FIG. 2, Airy beams may reach high chamfer angles in theory when higher objective numerical aperture values of about 0.5 or more are used. However, aberrations are often present within the Airy beams due to the breakdown of the paraxial approximation.SP24-277-3The paraxial approximation is a small-angle approximation which states that sin(0) ~ 0, and this paraxial approximation is only considered valid for angles less than about 10 degrees.

[0151] To analyze the effect of the paraxial approximation on the Airy beams, two different simulation techniques were used. The first, termed Fresnel diffraction, relies on the paraxial approximation and propagates beams as if the paraxial approximation was always true. Fresnel diffraction therefore masks any effects of the paraxial approximation on beam propagation. The second simulation technique, termed Rayleigh-Sommerfeld (RS) diffraction, does not rely on the paraxial approximation. Consequently, RS diffraction tends to show effects of the paraxial approximation on beam propagation for Airy beams. By comparing Airy beams formed using low and high objective numerical aperture values NA under both Fresnel and RS propagation, the effects of the paraxial approximation may be better understood for Airy beams.

[0152] FIGS. 3A-3D illustrate Airy beams formed using either Fresnel or RS diffraction using an ideal lens having a particular objective numerical aperture value. FIG. 3 A is an image 314A illustrating an example Airy beam formed using a 0.4 NA ideal lens propagated through Fresnel diffraction, FIG. 3B is an image 314B illustrating an example Airy beam formed using a 0.4 NA ideal lens propagated through RS diffraction, FIG. 3C is an image 314C illustrating an example Airy beam formed using a 0.8 NA ideal lens propagated through Fresnel diffraction, and FIG. 3D is an image 314D illustrating an example Airy beam formed using a 0.8 NA ideal lens propagated through RS diffraction.

[0153] Comparing FIGS. 3A and 3B, only minor effects from the paraxial approximation are seen at the lower NA value of 0.4. FIG. 3A shows the full length of the Airy beam without errors from the paraxial approximation. By contrast, in FIG. 3B, the start and end of the Airy beam have lost some intensity compared to the Airy beam in FIG. 3A. For example, the intensity is lower in FIG. 3B where the Z-coordinate ranges between -450 and -350 micrometers and between 350 and 450 micrometers relative to the intensity at similar ranges in FIG. 3A. However, the errors from the paraxial approximation are still minor at the lower 0.4 NA value.

[0154] However, when the NA value is raised to the higher value of 0.8 in FIGS. 3C and 3D, more severe aberrations become visible in FIG. 3D as compared to FIG. 3C. FIG. 3C illustrates the full length of the Airy beam without errors from the paraxial approximation. By contrast, in FIG. 3D, severe aberrations become visible for the 0.8 NA beam under RS diffraction. In FIG. 3D, the start and end of the Airy beam have both lost some intensity compared to the Airy beam in FIG. 3C. For example, the intensity is substantially lower in FIG.SP24-277-33D where the Z-coordinate ranges between -450 and -250 micrometers and between 250 and 450 micrometers relative to the intensity at similar ranges in FIG. 3C. The aberrations formed when using RS diffraction and a 0.8 NA beam tend to show that Airy beams are less suitable for chamfering using high NA values, making these Airy beams less useful for cutting applications.

[0155] Caustic beams were also investigated. These caustic beams curve with a similar trajectory to Airy beams but do not utilize the paraxial approximation in their formation. Caustic beams are typically formed using the phase Pr= el(-m<pwhere ( / ) is the spherical coordinate along the beam curving direction and m is a scaling factor that determines the length of the beam. However, this phase Pi contains high slopes requiring high mask resolution. The phase Pi also translates to high angle rays following the phase mask requiring large -aperture lenses, and caustic beams formed using only the phase Pi are more likely to be aberrated by real -world objectives.

[0156] To reduce the slope of the phase Pi and to center the laser beam on the optical axis, a centering prism phase may be added to the phase Pi so that a modified phase P2is formed. This phase P2 may be obtained using the formula P2where ko is the wavenumber of the light used to create the beam, x is the spatial coordinate, and 0pis the prism angle. By reducing the slope of the phase and center of the beam on the optical axis, the maximum ray angles in the beam may be reduced and aberrations from real-world objectives may be reduced.

[0157] The phase P2 may also be modified to flatten the intensity profile of a caustic beam in the lengthwise direction. An Airy beam made using an input beam with a Gaussian intensity profile, a circular intensity profile, or an elliptical flat-top intensity profile also has an intensity that varies along a length of the Airy beam. However, when Airy beams are made using square or rectangular top-hat input beams, Airy beams generally remain flat with little variance in intensity along a length of the Airy beam. Unlike Airy beams, caustic beams often have focal intensities that vary significantly through their lengths even when formed using top-hat square or rectangular intensity profiles, typically reaching a maximum in the center of the beam and falling off towards the front or back of the beam. The low intensities near the front and back of the caustic beam reduce the usable length of the caustic beam during cutting, thereby reducing the contact angles 0ccaustic beams may achieve. The addition of a polynomial phase (previously described) may flatten the caustic beam intensity profile in a lengthwise direction of the laser beam and extend its usable cutting range. The phase P2 used to form the causticSP24-277-3beam then becomes a modified phase P3, with P3=<a is a scaling factor and R is the radial coordinate normalized to a maximum of 1 across the beam aperture.

[0158] FIG. 4A illustrates an image 416A illustrating the caustic beam propagated using RS diffraction with an NA value of 0.8. This caustic beam exhibits strong intensity throughout the focal volume of the caustic beam.

[0159] FIG. 4B is a plot 416B illustrating a resulting phase across the mask used to create the caustic beam of FIG. 4A with two plotlines included to show the resulting phase when a prism phase was used and when a prism phase was not used. The plotline 417A illustrates the phase in radians without the prism phase at various X-coordinates across a mask, and plotline 417B illustrates the phase in radians with the prism phase at various X-coordinates across a mask. The additional prism phase may result in significantly lower slopes for the phase at various X-coordinates across a mask, and this may ease mask resolution requirements and reduce optical aberrations from real-world focusing lenses.

[0160] FIG. 4C is a plot 416C illustrating a maximum focal spot intensity at different z-coordinates, and the z-coordinates may roughly correspond to positions along the beam profile 110 of FIG. 1 with z=0 corresponding to a center of a sheet. The plotline 417C illustrates the maximum focal spot intensity in watts per square centimeter (W / cm2) without the additional polynomial phase at various Z-coordinates for caustic beams, and plotline 417D illustrates the maximum focal spot intensity in watts per square centimeter (W / cm2) with the additional polynomial phase at various Z-coordinates for caustic beams. Relative to the plotline 417C where no additional polynomial phase is used, the plotline 417D where an additional polynomial phase is used has a flattened curve that enables the cutting range of the laser beam to be extended. The contact angle 3C(which may correspond to the angle where the beam intensity reaches about 80 percent of its maximum intensity in some embodiments) where no additional polynomial phase is used is about 30 degrees, and the contact angle 3Cfor the caustic beam with an additional polynomial phase is about 35 degrees. The prism phase was also evaluated in simulations with an ideal focusing lens and sufficient resolution, but the prism phase did not have a significant impact on the plotlines 417C, 417D.

[0161] Sidelobe absorption is often a significant problem when cutting glass using Airy beams and caustic beams due to the relatively low intensity contrast between the focal region and side lobe regions of these beams. Absorption in the sidelobes may reduce the power available to the main lobe for cutting deep within the sheets. Additionally, sidelobe absorptionSP24-277-3may cause cracking perpendicular to the cutting direction, which may reduce the strength of the part after cutting. Sidelobe absorption may also damage and roughen the surface of a sheet, reducing a laser damage threshold in the roughened area. Due to the focal spot shapes of Airy beams and caustic beams, the sidelobes of each laser beam (or burst) may overlap with the sidelobes of the previous shot, and this may cause severe damage to sheets in overlap areas.

[0162] Shot-to-shot sidelobe overlap and intensity contrast between side lobes and main lobes may be improved by altering a spatial extent of the Airy beam. These issues may also be addressed by using oval or rectangular top-hat shaped intensity profiles rather than round or square intensity profiles. Additionally, when using an oval or rectangular shaped intensity profile, an elliptical focal spot shape may be generated, and this may force crack growth in a direction parallel to the cutting process.

[0163] FIGS. 5A-5B and 6 illustrate the effect of using a rectangular input beam to generate caustic beams. FIG. 5A is a plot 518A illustrating different phase values within an example phase mask that may be used for a caustic beam. In the plot 518A, the phase is shown at various X-coordinates and Y -coordinates for the phase mask, and the color bar to the right of the plot 518A illustrates the phase values corresponding to colors in the plot 518A, with the phase values provided in radians. Caustic beam generation systems typically include a circular Gaussian beam centered on a phase mask. However, here, caustic beam generation systems consist of a beam having the profile indicated by the rectangular shape 519. Altering an aspect ratio of this rectangular shape 519 changes the focal spot of caustic beams without affecting the nondiffracting nature of the caustic beams.

[0164] FIG. 5B is a plot 518B having an aspect ratio on the x-axis. The plotline 521 A corresponds to the y-axis shown on the left side of the plot 518B, with the plotline 521 A illustrating an intensity ratio on the y-axis . This intensity ratio is a ratio of the side lobe intensity (Max (ISL)) to the focal spot intensity Max(lML)). The intensity ratio is around 0.46 when the aspect ratio is around 0.15. However, the intensity ratio then drops at a high rate, moving down to around 0.25 when the aspect ratio increases to around 0.16. Thus, the side lobes have a maximum brightness that is about 25% of the maximum brightness for the main lobe. When the aspect ratio is increased to around 0.25, the intensity ratio increases a significant amount to 0.6. As the aspect ratio is increased from 0.25 to around 1.0, the intensity ratio remains around 0.60.

[0165] The plotline 52 IB of FIG. 5B corresponds to the y-axis shown on the right side of the plot 518B, with the plotline 52 IB illustrating a focal spot width to height ratio. The focal spot width to height ratio is generally at higher levels above about 0.8 when the aspect ratio isSP24-277-3less than 0.2. As the aspect ratio is increased from 0.1 to 0.2, the focal spot width to height ratio drops significantly from around 1.2 to around 0.75. However, as the aspect ratio is increased from 0.2 to 1.0, the focal spot width to height ratio drops at a significantly lower rate, with the focal spot width to height ratio only being slightly less than 0.75 at an aspect ratio of 1.0. Narrowing the input beam (moving left in the plot 518B) increases the focal spot width to height ratio so that the focal spot is wider than it is tall, forcing crack formation parallel to the cutting plane.

[0166] Additionally, FIG. 6 illustrates images of example main lobes and side lobes formed from caustic beams with different aspect ratios. The image 620A illustrates the caustic beam focal spots where the aspect ratio is 1, the image 620B illustrates the caustic beam focal spots where the aspect ratio is 0.2, the image 620C illustrates the caustic beam focal spots where the aspect ratio is 0.16, and the image 620D illustrates the caustic beam focal spots where the aspect ratio is 0.1.

[0167] In the image 620A, a main lobe 621 A and side lobes 623 A are illustrated. In the image 620B, a main lobe 62 IB and side lobes 623B are illustrated. In the image 620C, a main lobe 621C and side lobes 623C are illustrated. Finally, in image 620D, amain lobe 621D and side lobes 623D are illustrated. As used herein, side lobes may be either positioned to the side or directly below the main lobes. The main lobes 621A-621D each have a greater intensity or brightness relative to the other side lobes 623A-623D.

[0168] Caustic beam focal spots with low side-lobe intensity and elliptical shapes are shown in images 620C and 620D of FIG. 6. As the input beam becomes more rectangular, the horizontal extent of sidelobes is reduced, with sidelobes being positioned more narrowly underneath the main lobe. For example, in the image 620A, the side lobes 623A extend a significant distance in the horizontal directions relative to the main lobe 621 A. When the aspect ratio is reduced, the side lobes are positioned more narrowly underneath the main lobe. For example, in the image 620D where the smallest aspect ratio is used, the side lobes 623D are positioned almost entirely underneath the main lobe 62 ID.

[0169] Combining an elliptical focal spot shape with a laser which fires bursts of pulses may decrease the intensity of the beam and further reduce sidelobe absorption while preserving sufficient total energy in the beam for laser cutting. In some embodiments, bursts may each include 5 or more pulses with a time delay between the pulses within a burst. This time delay may be about 12 nanoseconds in some embodiments between the pulses in the burst. By contrast, reducing the energy of the beam may reduce sidelobe absorption, but this reduction may leave an insufficient amount of total energy in the beam for laser cutting. Additionally,SP24-277-3laser shots with multiple pulses in each burst may generate large cracks that enable cutting with large pitches and no shot-to-shot sidelobe overlap.

[0170] In addition to the other beams discussed herein, curving Bessel beams may be used to obtain chamfered edges with higher contact angles of about 15 degrees or more or even about 20 degrees or more. Curving Bessel beams are non-diffracting beams with Bessel-like foci that follow a shaped trajectory as the beams propagate. Curving Bessel beams are capable of cutting glass with a chamfered edge in a similar manner to Airy beams and caustic beams. Curving Bessel beams have a maximum angle constraint related to the NA of the focusing objective similar to Airy beams and caustic beams. However, curving Bessel beams have an additional constraint on the maximum lateral acceleration in the position of their focal spots, which may severely reduce the maximum contact angle 3Cthat curving Bessel beams may achieve. This constraint is equal to:Y > z * \f" z)\ [1] where y is a constant related to the focusing power of the beam, z is distance from the beam’s origin, f(z describes the beam’s path, andf"(z) describes the second derivative along the beams path, y is invariant in our case. This equation may be solved for f" z) and integrated twice to find the f (z) having maximal acceleration (and therefore the maximum curvature and maximum contact angle). This results in the following equation:(z) = y * ((z + c) * ln(z + c) — b) [2] where b is a constant used to shift the beam’s apex to its center point (chosen so that the equation f (z) = 0 is satisfied where z=L / 2 and where L is the beam’s target length) and c is a small constant chosen to prevent infinite acceleration at the origin. These constraints limit the contact angle achievable by a curving Bessel beam. Ideally, we would like to manipulate the beam such that it achieves an angle as close to that of a caustic beam as possible. A curving Bessel beam created that follows the trajectory given in Equation (2) may achieve this. However, such a beam does not have reflective symmetry across its apex as seen in FIG. 7A.

[0171] FIG. 7A illustrates a plot 722A showing a trajectory of a focal spot of a curving Bessel beam made using Equation (2) above. In the plot 722A, the x-axis shows the z-coordinates, which are positions along the optical axis stated in terms of percentages ranging from 0 to 100 percent. Furthermore, in the plot 722A, the y-axis shows the x-coordinates, which are positions along the axis of acceleration stated in terms of percentages ranging from 0 to 100 percent. A focal line 725 extends down the middle of the plot 722A at a Z-coordinate of about 50 percent. A first half 1K of the plotline is illustrated to the left of the focal line 725 whileSP24-277-3a second half 727B of the plotline is illustrated to the right of the focal line 725. A lack of reflective symmetry across the focal line 725 may result in an asymmetric chamfer, with the first half 727A being significantly different from the second half 727B.

[0172] FIG. 7B is a plot 722B illustrating a trajectory of a focal spot of a curving Bessel beam formed by reflecting a second half 727D of the beam made using equation 2 above across its apex at the focal line 725. In the plot 722B, the x-axis shows the z-coordinates, which are positions along the optical axis stated in terms of percentages ranging from 0 to 100 percent. Furthermore, in the plot 722B, the y-axis shows the x-coordinates, which are positions along the axis of acceleration stated in terms of percentages ranging from 0 to 100 percent. Similar to the plot 722A of FIG. 7A, a first half 727C of the plotline is illustrated to the left of the focal line 725 while a second half 727D of the plotline is illustrated to the right of the focal line 725. By reflecting the second half 727D of the beam across the focal line 725, the first half 727C is symmetrical to the second half 727D. While plot 722B is symmetric about the focal line 725, this reduces the overall curvature of the beam by making the constraint from equation (1) significantly more onerous. Indeed, a curving Bessel beam made using this method and a 0.8 NA lens has a maximum contact angle of about 12 degrees, and this is far below what caustic beams are capable of achieving.

[0173] Another method to form a symmetric beam is to form only half of a beam after a focal line and then reflect the beam across the focus line at the origin. Such a beam may be formed by using Equation (2) and setting b=0. In this case, the beam apex is at z 0. allowing acceleration up to the full limit given in Equation (1) to be used to form the beam.

[0174] A plot 824A illustrating the trajectory of such a curving Bessel beam is shown in FIG. 8A, with the curving Bessel beam centered at the origin and using the maximum acceleration possible. The curving Bessel beam formed with b=0 has an extremely high acceleration near the origin dictated by the value chosen for c, giving it a less desirable shape. For the curving Bessel beam illustrated in the plot 824A, the c value was set to 0.1. However, the c value may possess a wide variety of other values.

[0175] The shape may be improved by starting the beam’s trajectory on a parabolic path near the origin and transitioning to the trajectory given by Equation (2) at z=p. The modified trajectory is given in the following equation:SP24-277-3<<< > p [3]

[0176] FIG. 8B illustrates a resulting beam formed using Equation 3, with the plot 824B in FIG. 8B illustrating an example curving Bessel beam centered at the origin with the total deflection being lowered by fitting a parabola near the origin. The beam in FIG. 8B has an improved shape relative to the beam of FIG. 8A. The maximum angle that the beam may reach may be tuned via selection of the variable p and may be chosen to fit the experimental system.

[0177] To reflect a beam across a line at the origin, a phase mask for the beam may be changed to a binary mask using the following equation:> < < < >where <PCBB is the phase of the curving Bessel beam limited to the range [0, 2n), with the range including 0 and with the range extending up to but not including 2n, and where (Pbinary is the phase of the binary mask. In a binary mask of height n, the + / - 1 orders of diffraction have equal power and are oriented such that the -1 order is reflected across a line at the origin with respect to the +1 order, causing the trajectories shown in FIGS. 8 A and 8B to form fully symmetric chamfering beams. Experimentally, the first half of the curving Bessel beam may form downstream proximate to the conjugate plane of the 4f system and the other half may be formed upstream proximate to the conjugate plane of the 4f system. A curving Bessel beam with a length sufficient to cut glass may be created by matching the input beam size to the phase mask used. However, a low-intensity region may be present near the center of the beam due to the significant shortfall between the intensity of a Gaussian beam (which is flat near the center) and the intensity needed to keep a constant intensity through the focus of the beam.

[0178] In practice, the low-intensity region often leaves an unperforated section near the center of a sheet (e.g., a glass sheet), and this greatly reduces the effectiveness of the cutting process. To prevent the formation of the low-intensity region, one of the two halves of the curving Bessel beam may be modified to alter its focal position such that the point Zf= 0 occurs at a different absolute value of z for the modified and unmodified beam halves. Thus, the modified and unmodified beam halves may effectively be moved closer to each other. AlteringSP24-277-3the beam’s focal position may be accomplished by emitting a portion of the beam through a thick glass plate . By emitting the beam through the thick glass plate, the focal point of the beam may be shifted. In some embodiments, this may shift the focal point of the beam by roughly half (by a factor of ngiass - null) the plate’s thickness. However, the beam’s focal position may be adjusted in other ways.

[0179] FIG. 9A is a plot 926A illustrating a curving Bessel beam with a contact angle of about 25 degrees. Similar to the examples described above, the curving Bessel beam was created by forming two separate beams, with the two beams meeting at an z-coordinate of about 500 micrometers. To form the curving Bessel beam, a piece of glass was placed in the path of one of the beams to effectively move the two beams closer together. By moving these beams closer together, low-intensity regions at a center of the curving Bessel beam (e.g., around the z-coordinate of about 500 micrometers) may be avoided. Otherwise, the low-intensity region may be present near the center of the beam due to the significant shortfall between the intensity of a Gaussian beam (which is flat near the center) and the intensity needed to maintain a constant intensity through the focus of the beam.

[0180] FIG. 9B is a plot 926B illustrating different phase values within an example phase mask that may be used to create the curving Bessel beam of FIG. 9A. In the phase mask of FIG. 9B, all phase values in the phase mask were either 0 or n. Two additional modifications were made to the curving Bessel beam to improve beam quality and cutting performance. One was made to create an elliptical focal spot shape to force the crack direction to be parallel to the cutting direction. Another modification was made to eliminate interference between the two beam halves where they meet, with this modification being implemented by rotating polarizations of the beam halves so that the polarizations were orthogonal to each other (this modification may be implemented simultaneously with crack propagation control (CPC) by using a split quarter wave plate in some embodiments).

[0181] A method called crack propagation control (CPC) is commonly used to create elliptical focal spots in Bessel beams. In the CPC method, the polarization of half of a Bessel beam is rotated by 90 degrees. This causes the two halves of the beam to combine incoherently, which causes an elliptical focal spot to form. Another method that achieves a similar focal spot shape is to block a portion of the beam, but this method reduces system power throughput.

[0182] If half the curving Bessel beam is shifted to connect the two sides in the center, the beams from each side interfere with each other. The resulting interference depends on the relative phase between the two beams, and this relative phase is random when a thick glass plate is used to delay one beam. The relative phase depends on the thickness of the plate relativeSP24-277-3to an integer number of laser wavelengths. Rotating the polarization of one half of the beam to be orthogonal to the other half causes the two beams to combine incoherently and prevents interference from occurring.

[0183] FIG. 10 illustrates a plot 1028 showing the maximum focal intensity in the beam vs. z-coordinate in beams where beams are combined in a destructive combination of beam halves, a constructive combination of beam halves, and an incoherent combination of beam halves. As noted previously, the z-coordinates correspond to positions along the optical axis. Plotline 1028A illustrates data for the destructive combination, plotline 1028B illustrates data for the constructive combination, and plotline 1028C illustrates data for the incoherent combination. The incoherently combined curving Bessel beam represented by plotline 1028C has a more consistent intensity profile through its length, which results in a higher quality cut and prevents the destructive case from occurring. In FIG. 10, one half of the beam was shifted by 150 micrometers to form the combinations.

[0184] Different types of polarization masks may be used to form curving Bessel beams with desirable properties. FIGS. 11A-11C are images illustrating both example polarization masks and a resulting curving Bessel beam formed by the polarization masks in the background image. These polarization masks have different combinations of polarization rotations so that curving Bessel beams having different properties may be formed. For example, different portions of the polarization masks may be subjected to polarization rotation to achieve control of the focal spot shape and to achieve an incoherent combination of adjacent beams using a single mask.

[0185] In the image 1130A, the intensity profile 1134A of the curving Bessel beam in the Fourier plane is illustrated in the background image. A circle 1132A is also illustrated that is representative of a focusing lens aperture. In the image 1130A, a polarization mask is also illustrated, with the polarization mask comprising a first half 1136A and a second half 1136B. The first half 1136A is positioned above the second half 1136B. In the polarization mask in image 1 BOA, the polarization for the first half 1136A is rotated by about 90 degrees while the polarization for the second half 1136B is not rotated. The combination of the first half 1136A and the second half 1136B in the polarization mask may ensure an incoherent combination of beam halves for the curving Bessel beam, but this combination does not effectively form a focal spot with an elliptical shape.

[0186] In the image 1 BOB, the intensity profile 1134B of the curving Bessel beam in the Fourier plane is illustrated in the background image. A circle 1132B is also illustrated that is representative of a focusing lens aperture. In the image 1130B, a polarization mask is alsoSP24-277-3illustrated, with the polarization mask comprising a first half 1136C and a second half 1136D. In the polarization mask of FIG. 1 IB, the first half 1136C is positioned to the left of the second half 1136D. In the polarization mask in image 1130B, the polarization for the first half 1136C is rotated by about 90 degrees while the polarization for the second half 1136D is not rotated. The combination of the first half 1136C and the second half 1136D in the polarization mask may assist in forming an elliptical focal spot, but this combination does not effectively ensure an incoherent combination of beam halves for the curving Bessel beam.

[0187] While the polarization masks of FIGS. 11A and 11B each are less effective in various ways, the polarization mask illustrated in the image 1130C of FIG. 11C may effectively ensure an incoherent combination of beam halves while also forming a focal spot with a strong elliptical shape. In the image 1130C, the intensity profile 1134C of the curving Bessel beam in the Fourier plane is illustrated in the background image. A circle 1132C is also illustrated that is representative of a focusing lens aperture. In the image 1130C, a polarization mask is also illustrated, with the polarization mask comprising a first quarter 1136E, a second quarter 1136F, a third quarter 1136G, and a fourth quarter 1136H. In the polarization mask in image 1130C, the polarization for the first quarter 1136E and the fourth quarter 1136H are both rotated by about 90 degrees while the polarization for the second quarter 1136F and the third quarter 1136G are not rotated. The combination of the quarters 1136E-1136H in the polarization mask may assist in forming an elliptical focal spot while simultaneously ensuring an incoherent combination of beam halves for the curving Bessel beam.

[0188] A prototype mask similar to the one illustrated in image 1130C of FIG. 11C may be made by cutting a quarter wave plate into four sections and flipping opposite corners to create a split quarter wave plate. When the split quarter wave plate is combined with an additional quarter wave plate so that the input polarization to the split quarter wave plate is circular, this may create a polarization state similar to the one illustrated in FIG. 11C. The resulting curving Bessel beam may have a focal spot shape similar to the shape illustrated in the image 1238 of FIG. 12, resulting in strong control of crack direction during the cutting process. The focal spot shape of FIG. 12 has a strong ellipticity.

[0189] Additionally, the binary phase mask in the plot 926B of FIG. 9B may be manufactured as a diffractive optic using orthogonally polarized feature elements in the 0 and 7i phase regions. For example, if orthogonal, linearly polarized regions are used, an input beam with circular polarization (e.g., via upstream quarter wave plate) may be separated simultaneously into the main and reflected beam components. The binary phase mask may also be formed using a metasurface optic designed with polarization-sensitive features. ASP24-277-3metasurface may also be generated to represent a non-binary design that is sampled using polarization-sensitive features to evenly distribute energy to each main and reflected beam.

[0190] Both caustic beams and curving Bessel beams suitable for high-angle chamfering are described herein. A phase mask for caustic beams may be similar to the one illustrated in FIG. 5A, and a phase mask for curving Bessel beams may be similar to the one illustrated in FIG. 9B. Phase masks used to create caustic beams and curving Bessel beams may be created using a spatial light modulator (SLM). The SLM is a device which may impart a phase between 0 and 2TI (in 256 steps) at each independent pixel to an incoming laser beam which is reflected off the SLM. The phase masks may have a 1152 pixel by 1920 pixel resolution with a pixel pitch of about 8 micrometers, but other resolutions and pixel pitches may be used for the phase masks.

[0191] FIG. 13 is a schematic view illustrating an example caustic beam optical system 1340 for caustic beam formation. For the case of the caustic beam, the beam 1342 is initially a Gaussian beam before reaching the elliptical shaping element 1344. The elliptical shaping element 1344 may reshape the beam 1342 into an elliptical Gaussian beam before it strikes the SLM 1346, and this may help to preserve power efficiency of the beam 1342 before reflection off the SLM 1346. The SLM 1346 may have a phase mask displayed thereon. The elliptical shaping element 1344 may be provided in the form of one or more lenses (e.g., cylindrical lens(es)) or anamorphic prism pairs, but the elliptical shaping element 1344 may be provided in other forms. However, the elliptical shaping element 1344 may be replaced with other optical elements which reshape the input beam intensity into other shapes (e.g., rectangular, square, circular, etc.). The beam 1342 is then reimaged by lenses 1348, 1350, with these lenses 1348, 1350 being provided in a 4f optical configuration. The beam 1342 is then focused by a lens 1352 having a high NA (e.g., an NA of about 0.6 or more), thereby generating a focused beam 1342A. The focused beam 1342A is directed to the sheet 1354 to generate a laser beam having the profile 1356 at the sheet 1354.

[0192] FIG. 14 is a schematic view illustrating an example curving Bessel beam optical system 1440 for curving Bessel beam formation. For the curving Bessel beam, a beam 1442 is initially provided as a simple Gaussian beam. The beam 1442 is reflected off the SLM 1446, and the SLM 1446 may have a phase mask displayed thereon. The beam 1442 is then reimaged by lenses 1448, 1450, with these lenses 1448, 1450 being provided in a 4f optical configuration. The curving Bessel beam optical system 1440 may be provided without any focusing lens similar to the lens 1352 of FIG. 13. Because no focusing lens similar to the lens 1352 is provided in the curving Bessel beam optical system 1440, the lens 1450 may have a high NASP24-277-3(e.g., an NA of about 0.6 or more). The magnification ratio of the lenses 1448, 1450 is typically close to 1:1, but the ratio for the curving Bessel beam optical system 1440 may be as low as 1:70 so that the beam 1442 is demagnified by a factor of up to 70. The lens 1450 generates a focused beam 1442A that is directed towards the sheet 1454. An optical delay element 1458 is positioned between the lens 1450 and the sheet 1454, with the optical delay element 1458 provided in the form of a piece comprising glass or another material. The optical delay element 1458 may be used to spatially offset one half of the focused beam 1442A relative to the other along a length of the focused beam 1442A as described herein (e.g., in reference to FIG. 9A). The focused beam 1442A is then directed to the sheet 1454 to generate the profde 1456 at the sheet 1454. While a split-quarter wave plate is not included in the illustrated curving Bessel beam optical system 1440, a split-quarter wave plate may be placed between the lenses 1448, 1450 when used.

[0193] High angle chamfering beams typically require objective numerical aperture values of above about 0.65 with long working distances to facilitate practical processes. Where objective numerical aperture values of above about 0.65 are used, aberrations may naturally tend to occur and there may be increased sensitivity to angular inputs. Light rays in high angle chamfering beams come in at relatively large angles, and most focusing objectives are designed for planewave inputs. The result is that some aberrations may develop as the chamfering beams pass through a real-world optical system. Additional aberrations which are incurred when refracting into a sheet (e.g., a glass sheet) also become stronger for higher angle beams.

[0194] There are various methods to correct these aberrations. These methods include reverse propagation, neural networks with forward propagation, phase retrieval algorithms, and in-situ corrections. For reverse propagation, a “perfect” beam is generated in simulation (typically using ideal lenses) and propagated into its focal region. The beam is then reversed and propagated backwards through a real -world optical system. The phase of the beam after propagating through all optical elements back to the location of the SLM is then used to replace the original phase mask for the beam. Aberrations from entering glass may also be fixed using this reverse propagation method by generating the perfect beam inside glass and refracting through the glass-air interface during reverse propagation. This reverse propagation method is highly effective but requires precise knowledge of the optical system and its components.

[0195] A method using neural networks with forward propagation may also be used to correct for aberrations. In this method, a perfect beam may be generated and then perturbed with various aberrations. These aberrations may typically be defined via Zemike coefficients. A computer and / or neural networks may then be trained to recognize the aberration phases thatSP24-277-3lead to certain defects in the final curving beam. A camera may be used to image the beam in the experimental system, and the computer and / or neural networks may be used to ascertain the phase function of the aberrations in the experimental beam. A reverse phase may be added to the original phase mask to fix the beam. Aberrations from entering the glass may be recorded by placing a glass sample in the focal region of the beam during the imaging step. In performing this method, care may be taken to prevent additional refraction out of the glass sheet via index matching fluid.

[0196] A method using phase retrieval algorithms may also be used to correct for aberrations. Phase retrieval algorithms such as the Gerchberg-Saxton algorithm or adjoint state method may be used. Phase retrieval algorithms may derive the phase of a beam via images of the beam in a focal plane. Experimental images of the beam may be fed into a phase retrieval algorithm to obtain the phase of the experimental beam. This phase of the experimental beam may then be compared to the desired phase, and a phase mask may be designed to correct for the aberrations in the experimental system. Aberrations from entering the glass may be recorded by placing a glass sample in the beam’s focal region during the imaging step. In performing this method, care may be taken to prevent additional refraction out of the glass sheet via index matching fluid.

[0197] Additional methods of in-situ corrections may also be used to correct for aberrations. These methods generally involve the use of a wavefront sensor, an interferometer, or an iterative correction to the beam. In the case of the wavefront sensor or interferometer, information about the beam may be used to determine its phase so that the determined phase may be compared against an ideal phase and corrected. Iterative schemes add different phases to the phase mask on the SLM and use a camera to record the resulting beam and move towards a higher quality beam. Machine learning algorithms may be used to guide selection of the corrective phase and to increase the speed the process.

[0198] Experiments were performed to create caustic beams and curving Bessel beams. For the caustic beams, the experimental system depicted in FIG. 13 was reproduced using an anamorphic prism pair to generate an elliptical beam. The system included a 0.83 NA aspheric focusing lens (e.g., an EO 22-758 lens) and a pulsed ultrafast laser. The pulsed ultrafast laser had a pulse width of about 8 picoseconds, a pulse energy of about 1.2 millijoules, a burst number of 8, a repetition rate of about 10 kilohertz, a wavelength of about 1030 nanometers, and a Gaussian spatial profile having a diameter of about 16 millimeters. However, different lasers may be used in other embodiments, and lasers may be operated with different properties. Due to limited commercially available lens options with suitable working distance and NA, theSP24-277-3lens purchased was designed for a wavelength of 587.6 nanometers, which led to significant aberrations being imparted to the beam upon propagation through the lens. The previously mentioned reverse-propagation method was used to correct for these aberrations. Additionally, in-situ corrections were used to correct residual aberrations that were present due to form departure in the lens.

[0199] After laser processing using this experimental system, a mechanical force was applied by hand to break the sheet along the perforation line. The resulting cleaved section is shown in FIGS. 15A-15B. FIG. 15A is a side profile view illustrating an example section 1560 cleaved using a caustic beam, and FIG. 15B is a front face view illustrating the edge of the section 1560 of FIG. 15A so that the quality of the cleaved edge maybe seen. The section 1560 has a thickness of about 700 micrometers between the first surface 1563A and the second surface 1563B. To form the chamfered edge in the section 1560, the section 1560 was positioned on a mechanical stage and was then translated under a beam generated by a laser. The beam was provided in bursts having eight pulses each. Each burst made a single curved perforation through the glass sheet. The movement speed of the mechanical stage and laser firing rate were controlled such that there was a pitch between adjacent perforations, with the pitch being about 10 micrometers.

[0200] The chamfered edge that was formed included a first portion 1562A, a second portion 1562B, and an apex 1562 between the first portion 1562 A and the second portion 1562B. The apex 1562 is generally a point where the first portion 1562A and the second portion 1562B meet in the illustrated section 1560 of FIGS. 15A-15B. The first portion 1562A of the chamfered edge meets the first surface 1563 A at the comer 1565 A, and the second portion 1562B of the chamfered edge meets the second surface 1563B at the comer 1565B. The second portion 1562B defines a contact angle 61 relative to a direction normal to the second surface 1563B, with this angle 61 being measured using a line that is approximately tangent to the second portion 1562B at the comer 1565B. This contact angle 61 is about 20 degrees in the illustrated embodiment. Thus, the angle defined between a plane formed by the second surface 1563B and the line that is approximately tangent to the second portion 1562B at the comer 1565B is about 110 degrees. The angle defined at the first surface 1563A was slightly lower than the angle defined at the second portion 1562B, and this was due to aberrations in the lens that were introduced by manufacturing errors in the lens and were not completely corrected before processing.

[0201] Experiments were also performed to create curving Bessel beams. The experimental system included a 0.6 NA aspheric focusing lens and a pulsed ultrafast laser. The pulsedSP24-277-3ultrafast laser had a pulse width of about 8 picoseconds, a pulse energy of about 1.2 millijoules, a burst number of 8, a repetition rate of about 10 kilohertz, a wavelength of about 1030 nanometers, and a Gaussian spatial profde having a diameter of about 8 millimeters. However, different lasers may be used in other embodiments, and lasers may be operated with different properties.

[0202] A sheet was placed on a mechanical stage and perforated in a line using the curving Bessel beam. The sheet had a thickness of about 700 micrometers between the first surface 1663 A and the second surface 1663B. The movement speed of the mechanical stage and the laser firing rate were controlled such that a pitch was maintained between adjacent perforations, with the pitch being about 10 micrometers.

[0203] After laser processing using this experimental system, a section of the sheet was separated using mechanical force. Images of the section after separation are shown in FIGS.16A-16B. FIG. 16A is a side profile view illustrating an example section 1664 cleaved using a curving Bessel beam. The section 1664 has a first surface 1663A and a second surface 1663B opposite the first surface 1663 A. The section 1664 also has a chamfered edge comprising a first portion 1666A, a second portion 1666B, and an apex 1666 positioned between the first portion 1666A and the second portion 1666B. The first portion 1666A of the chamfered edge meets the first surface 1663 A at the comer 1665 A, and the second portion 1666B of the chamfered edge meets the second surface 1663B at the comer 1665B.

[0204] The second portion 1666B extends at an angle 62 relative to a line 1669A normal to the second surface 1663B. This angle 62 is measured relative to a line 1669B tangent to the second portion 1666B at the comer 1665B. The angle 62 is about 15 degrees. This angle 62 is lower than the contact angle formed using the caustic beam due to the lower NA objective that was used to form the curving Bessel beam. However, use of a higher NA objectives may allow higher contact angles of about 20 degrees or more even where curving Bessel beams are used.

[0205] FIG. 16B is a front face view illustrating the edge of the section 1664 of FIG. 16A. Each vertical line visible in FIG. 16B is a perforation resulting from a single laser shot from a laser. The damage morphology looks similar to perforation cutting using a straight Bessel beam. An unperforated strip 1667 is present near the center of the chamfered edge. This unperforated strip 1667 is likely formed due to beam interference since no split quarter wave plate was used in forming the edge.

[0206] FIG. 17 is a block diagram illustrating an example optical system 1768 for creation and rotation of a laser beam. The optical system 1768 may be configured to subject a sheet toSP24-277-3laser processing so that the laser beam has a particular spatial-temporal shape. The optical system 1768 includes a laser 1770 configured to assist in generating a laser beam. This laser beam may be an Airy beam, a caustic beam, or a Bessel beam in some embodiments, but other laser beams may be formed in other embodiments. Other components (e.g., elements 1772, 1774, 1776, 1778) may also assist in shaping or otherwise modifying laser beams. The laser 1770 may be configured to generate a laser beam in a series of pulse bursts in other embodiments, with each of the bursts comprising a plurality of pulses and with a time delay provided between each of the pulses. The time delay may be at least about 12 nanoseconds in some embodiments, but a different time delay value may be used in other embodiments. The laser 1770 may be operated with properties that are similar to those used for other lasers described herein.

[0207] The optical system 1768 may include one or more preparatory optical element(s) 1772 in some embodiments. The preparatory optical element(s) 1772 may be configured to direct the laser beam from the laser 1770 to the spatial shaping system 1774, and the preparatory optical element(s) 1772 may accomplish this in various ways (e.g., through reflection, refraction, or through other approaches).

[0208] The spatial shaping system 1774 may be configured to receive the laser beam to adjust a beam profile of the laser beam. For example, the spatial shaping system 1774 may be configured to impart changes to the spatial and / or temporal profile of a laser beam. The spatial shaping system 1774 may be provided in various forms. For example, the spatial shaping system may be a passive shaping system in some embodiments. Where the spatial shaping system is a passive shaping system, the spatial shaping system may comprise at least one of a fixed diffractive optical element, a phase plate, or another optical system configured to impart a rotationally non-symmetric amplitude and / or phase profile on the laser beam. In other embodiments, the spatial shaping system may be an active shaping system. Where the spatial shaping system is an active shaping system, the spatial shaping system may comprise a spatial light modulator such as a liquid crystal element or a digital micromirror device. However, the spatial shaping system may possess other forms in other embodiments.

[0209] In some embodiments, the first beam profile for the laser beam received at the rotation optical element may be formed using the spatial shaping system 1774. In some embodiments, one or more additional optical element 1776 and one or more polarization control elements 1778 may also be included to help form the first beam profile for the laser beam received at the rotatable optical element 1780. The polarization control element(s) 1778 may be configured to adjust a polarization of the laser beam before the laser beam is receivedSP24-277-3at the rotatable optical element 1780, and the additional optical element(s) 1776 may be configured to impart other changes on the laser beam before the laser beam is received at the rotatable optical element 1780. Polarization control element(s) 1778 may include one or more of polarizers (e.g., linear polarizers or circular polarizers), wave plates (e.g., quarter-wave plates, split quarter-wave plates, half-wave plates, and the like), birefringent materials, and / or other elements.

[0210] The laser beam may be received at the rotatable optical element 1780, and the rotatable optical element 1780 may be rotated to rotate the laser profile about an axis. Examples of rotatable optical elements are described in greater detail herein. The rotatable optical element may be similar to the rotatable optical element 1892 of FIG. 18A in some embodiments. The rotatable optical element may be rotated while the laser beam is actively being directed to the rotatable optical element. By doing so, an internal feature may be formed in the sheet. As the rotatable optical element is rotated, the beam profile of the laser exiting the rotatable optical element may be rotated at a faster rate (e.g., 2 times faster) than the rotatable optical element itself.

[0211] One or more final optical elements 1782 are also provided, and these element(s) 1782 may be configured to adjust the laser beam after the laser beam has exited through the rotatable optical element 1780 but before the laser beam has reached the sheet 1784. In some embodiments, the final optical element(s) 1782 may be configured to focus the laser beam.

[0212] Final optical element(s) 1782 may include a focusing element and possibly other optical elements that may maintain the relative spatial and temporal properties of the beam or change these properties. These final optical element(s) 1782 produce a spatial-temporal beam profile in the sheet 1784 that is well controlled for a desired outcome, such as cutting an edge.

[0213] The sheet 1784 may comprise glass in some embodiments. A spatial -temporal beam eventually reaches the sheet 1784. Once in the sheet 1784, the spatial-temporal beam may modify the material within the sheet 1784 to form one of the modifications described herein. The modification may be a material permanent material modification, and the modification may have a three-dimensional form controlled by the shaping elements. Modifications may optionally include perforations (e.g., cracks), index modifications, voids, densification, or changes to chemical bonding in the material. The spatial -temporal beam could also produce transient modifications such as melting or color center creation with three -dimensions as determined by the shaped beam. Temporary or permanent modifications may be used as-is, or these modifications may be leveraged in an additional process to form the final part. For example, additional processes may include laser-induced cracking to provide a path forSP24-277-3separation through deflection or additional laser processes. Additionally or alternatively, additional processes may include etching based feature release (e.g., acid etching, caustic etching, and the like), application of transient chemical features to obtain increased sub-surface light absorption, or formation of vias (e.g., through glass vias). Other processes may also be used.

[0214] The sheet 1784 may be positioned on a motion control unit 1786, with the motion control unit 1786 being configured to move the sheet 1784 relative to other components of the optical system 1768 so that modifications may be formed at different locations within the sheet 1784. For example, one modification (e.g., a perforation) may be formed at one location in the sheet 1784, and the motion control unit 1786 may be configured to adjust the location of the sheet 1784 before additional modifications are formed at another location in the sheet 1784. For example, the motion control unit 1786 may be configured to reposition the sheet 1784 after one or more laser bursts or after one or more pulses within a burst. The motion control unit 1786 may comprise a linear actuator, a rotational actuator, a motor (e.g., a DC motor, an AC motor, a stepper motor, a servo motor, and the like), a programmable logic controller, sensors, and / or other components.

[0215] Optionally, elements may be provided that are configured to assist with temporal shaping in some embodiments. These elements may be provided at some point in the system path. In some embodiments, temporal shaping may be accomplished by using a laser with a “burst mode” of laser pulses. Additionally or alternatively, an active 4-f temporal shaping system may be used, with the active 4-f temporal shaping system serving as an optical element. These temporal shaping optical elements allow for temporal control coupled to the special beam profile for further tuning of the laser-material interaction.

[0216] While the elements in the optical system 1768 are illustrated in a particular order and arrangement in FIG. 17, the order and arrangement of the elements may be altered in other embodiments.

[0217] Rotatable optical elements may be provided in various forms, and FIG. 18A is a schematic view illustrating a laser system 1888 having a rotatable optical element 1892 in the form of a Dove prism, with the rotatable optical element 1892 configured to be rotated to adjust a beam profile for a laser beam. A laser 1889 may be included in the laser system 1888. The laser 1889 may generate a laser beam having a first beam profile 1890 A, and the laser 1889 may be configured to direct the laser beam towards the first surface 1892A of the rotatable optical element 1892 with the first beam profile 1890A. The laser 1889 may be configured to operate with properties that are similar to those used for other lasers described herein. AnSP24-277-3optical axis 1885 may be defined in the rotatable optical element 1892, with the optical axis 1885 extending between the first surface 1892 A and the second surface 1892B. The optical axis 1885 may extend in a line that roughly extends between the center of the first surface 1892A and the center of the second surface 1892B. In some embodiments, the laser beam may be received at the first surface 1892A at a small linear offset relative to the optical axis 1885. By doing so, rapid rotation of the focused beam around a rotational axis in a circle may be enabled while maintaining the orientation relative to the circle tangent.

[0218] The rotatable optical element 1892 includes a first surface 1892A and a second surface 1892B. The rotatable optical element 1892 is configured to receive the laser beam at the first surface 1892A, and the rotatable optical element 1892 is configured to allow the laser beam to travel through the rotatable optical element 1892 to the second surface 1892B so that the laser beam has a second beam profile 1890B when exiting the second surface 1892B. After exiting at the second surface 1892B, the laser beam may be received at a sheet 1897 so that modifications 1897A may be imparted at the sheet 1897. The modifications 1897A may be at least one of a perforation, an index modification, a trench, a void, a densification, a change in chemical bonding in the material, melting, color centers, or an internal feature in the sheet 1897. However, other modifications may be formed in the sheet 1897. In the illustrated embodiment of FIG. 18A, the modifications 1897A are internal features in the sheet 1897, and the internal features have a cross-sectional edge shape that is symmetrical about an optical axis similar to the examples illustrated in FIGS. 26A-26B. Different sections of the sheet may be separated from each other proximate to the location where the internal features are located. The sheet 1897 may comprise glass in some embodiments, but the sheet 1897 may comprise different materials in other embodiments. The modifications 1897A of FIG. 18A are not drawn to scale. The sheet 1897 may be positioned on a motion platform 1899 so that the sheet 1897 generally remains in a fixed position relative to the motion platform 1899 during operation, and the motion platform 1899 may be moved relative to other components of the laser system 1888 so that modifications may be formed at different locations within the sheet 1897.

[0219] The laser system 1888 also includes a rotary actuator 1895. The rotary actuator 1895 is configured to cause rotation of the rotatable optical element 1892. The rotary actuator 1895 may cause rotation of the rotatable optical element 1892 while a laser beam is actively being directed into the rotatable optical element 1892, and this may cause the beam profile for the laser beam to be rotated at the sheet 1897.

[0220] The rotary actuator 1895 is configured to rotate the rotatable optical element 1892 as indicated by the arrows 1894A, and the rotary actuator 1895 may rotate the rotatable opticalSP24-277-3element 1892 by a first angle. When the rotary actuator 1895 rotates the rotatable optical element 1892, the resulting second beam profile 1890B may be rotated relative to the first beam profile 1890A as indicated by the arrows 1894B, with the second beam profile 1890B being rotated by a second angle relative to the first beam profile 1890A. The beam profiles 1890A, 1890B are merely provided for the purposes of illustration, and beam profiles having different shapes may be used. The rotatable optical element 1892 may be configured so that the second angle is greater than the first angle. In other words, as the rotatable optical element 1892 is rotated, the second beam profile 1890B is rotated in even greater amounts. In some embodiments, the second angle may be at least about 1.5 times more than the first angle, at least about 1.75 times more than the first angle, at least about 2 times more than the first angle, at least about 2.25 times more than the first angle, or at least about 2.5 times more than the first angle. In some embodiments, the second angle may be between 1.95 times and 2.05 times more than the first angle. Even with this rotation, laser propagation may be maintained in line with the input.

[0221] The laser system 1888 does not include any additional elements between the rotatable optical element 1892 and the sheet 1897 or between the laser 1889 and the rotatable optical element 1892. However, in other embodiments, additional elements described herein may be present between the rotatable optical element 1892 and the sheet 1897.

[0222] As an alternative to the rotatable optical element 1892, which is provided in the form of a Dove prism, other rotatable optical elements may be used. For example, a k-mirror assembly may be used in some embodiments. While the Dove prism generally operates through refraction, a k-mirror assembly is a reflective equivalent of the Dove prism. A k-mirror assembly may be advantageous for high-powered lasers because a k-mirror assembly may be made with lower losses and high damage thresholds relative to a Dove prism. Additionally, k-mirror assemblies may introduce fewer aberrations to the beam compared to Dove prisms.

[0223] One example laser system 1801 using a k-mirror assembly 1810 is illustrated in FIG. 18B. The laser system 1801 comprises a laser 1889, which may be identical to the laser in the laser system 1888 of FIG. 18A. The laser 1889 may generate a laser beam having the first beam profile 1890A, and the laser 1889 may be configured to direct the laser beam along an initial path 1802 towards the k-mirror assembly 1810.

[0224] The illustrated k-mirror assembly 1810 comprises a first mirror 1812, a second mirror 1814, and a third mirror 1816. Additionally, in some embodiments, the k-mirror assembly 1810 may comprise a rotary actuator 1818, but the rotary actuator 1818 may be provided separately from the k-mirror assembly 1810 in other embodiments. The mirrors 1812,SP24-277-31814, 1816 may be angled such that the laser beam travels along an initial path 1802 that is parallel and / or colinear with the exit path 1808. While the mirrors 1812, 1816 extend at equal but opposite angles, the mirrors 1812, 1816 may extend at a variety of different angles. Furthermore, while the mirror 1814 extends in a plane that extends parallel to the initial path 1802 of the laser beam, the plane of the mirror 1814 may extend at other angles. The illustrated k-mirror assembly 1810 is merely exemplary, and k-mirror assemblies may be modified in other embodiments.

[0225] The laser beam travels along the initial path 1802 until it reaches the first mirror 1812 of the k-mirror assembly 1810, and the laser beam traveling along the initial path 1802 is reflected off of the first mirror 1812 so that the laser beam travels along the path 1804 towards the second mirror 1814. The laser beam traveling along the path 1804 is reflected off of the second mirror 1814 so that the laser beam travels along the path 1806 towards the third mirror 1816, and then the laser beam traveling along the path 1806 is reflected off of the third mirror 1816, effectively exiting the k-mirror assembly 1810 so that the laser beam travels along the exit path 1808. The laser beam traveling along the exit path 1808 may generate the second beam profile 1890B.

[0226] The rotary actuator 1818 allows the k-mirror assembly 1810 to be rotated about a rotational axis, and this rotational axis may be parallel with the initial path 1802 and the exit path 1808 of the laser beam. As the k-mirror assembly 1810 is rotated, the beam profile of the laser beam is also rotated. Similar to the Dove prism, rotation of the k-mirror assembly may allow the second beam profile 1890B to rotate at a faster rate than the k-mirror assembly 1810 itself. As the k-mirror assembly 1810 is rotated by a first angle (as indicated by the arrows 1820), the second beam profile 1890B may be rotated by a second angle (as indicated by the arrows 1822). In some embodiments, the second angle may be at least about 1.5 times more than the first angle, at least about 1.75 times more than the first angle, at least about 2 times more than the first angle, at least about 2.25 times more than the first angle, or at least about 2.5 times more than the first angle. Even with this rotation, laser propagation may be maintained in line with the input.

[0227] One rotatable optical element in the form of a Dove prism was tested with a spatially asymmetric Airy beam. FIGS. 19-21 illustrate the properties of a non-rotated Airy beam, and FIGS. 22-24 illustrate properties of an Airy beam that was rotated using a Dove prism. FIG.19 is a plot 1996 illustrating a longitudinal profile for an Airy beam for different Y -coordinates, and FIG. 20 is a plot 2096 illustrating a longitudinal profile for an Airy beam for different X-SP24-277-3coordinates. FIG. 21 is a plot 2196 illustrating an intensity profile at various positions along a propagation axis (in a Z-direction).

[0228] FIG. 22 is a plot 2296 illustrating a longitudinal profile for an Airy beam for different Y-coordinates where the profile has been rotated 180 degrees relative to the plot in FIG. 19, and FIG. 23 is a plot 2396 illustrating a longitudinal profile for an Airy beam for different X-coordinates where the profile has been rotated 180 degrees relative to the plot in FIG. 20. FIG. 24 is a plot 2496 illustrating an intensity profile at various positions along a propagation axis (in a Z-direction) where the profile has been rotated 180 degrees relative to the plot in FIG. 21.

[0229] To obtain the Airy beam having the properties of FIGS. 22-24, a laser system similar to the laser system 1888 was used so that a Dove prism was used. In the laser system, the Dove prism was rotated about 90 degrees, resulting in a rotation of the beam profile at the sheet of about 180 degrees. For example, the beam profile illustrated in FIG. 22 is rotated about 180 degrees relative to the beam profile illustrated in FIG. 19, and the position of the Airy beam maximum is effectively flipped for the y-coordinates in FIG. 22 relative to FIG. 19. Additionally, the beam profile illustrated in FIG. 23 is rotated about 180 degrees relative to the beam profile of FIG. 20, and the position of the Airy beam maximum is effectively flipped for the x-coordinates in FIG. 23 relative to FIG. 20. However, even with this rotation, the intensity of the beams are effectively the same in plot 2196 of FIG. 21 and plot 2496 of FIG. 24.

[0230] FIG. 25 is an image 2598 illustrating an example laser perforation profile 2598B of an Airy beam. The image 2598 shows a sheet 2598A, and a beam is used to separate a section 2598C of the sheet 2598A. The edge has a slight bullnose shape following the profile of the Airy beam illustrated in FIG. 25. With the laser perforation profile 2598B, the edge is formed with a first peak 2506 and a second peak 2508, with the distance 2504 between these two peaks being about 20 micrometers. This laser perforation profile 2598B was created using an Airy beam that was not optimized for cut quality, and other laser perforation profiles having an improved quality may be obtained using other techniques described herein.

[0231] Optical systems may be used to rotate a desired laser beam profile to track a specific orientation relative to the outline of a given part. These optical systems may also be used to create internal features by following a similar path with the beam orientation reversed. One example of note is the rapid creation of internal features.

[0232] In FIGS. 26A-26B, several examples of internal features that may be created in sheets are illustrated, with the internal features having edge profiles defined by laser profiles. In each of the schematics illustrated in FIGS. 26A-26B, an optical axis 2603 is illustrated, andSP24-277-3a respective beam profile is eventually rotated around the optical axis 2603 to form an internal feature.

[0233] In the schematic 2601 A, the beam profile 2605 A is shown relative to the optical axis 2603. The beam profile 2605 A has a concave curved shape, and the beam profile 2605 A is positioned in close proximity to the optical axis 2603 near the center of the beam profile 2605A. In the schematic 260 IB, a laser beam having the beam profile 2605A is used to form an internal feature in the sheet 2607. The beam profile 2605 A is rotated relative to the optical axis 2603 as indicated by the arrows 2609 to form the internal feature. The internal feature has a narrow central processed region that spreads towards the top and bottom of the sheet 2607.

[0234] In the schematic 2601C, the beam profile 2605B is shown relative to the optical axis 2603. The beam profile 2605B has a concave curved shape similar to the beam profile 2605A of FIG. 26A, but the beam profile 2605B is positioned farther away from the optical axis 2603 relative to the beam profile 2605A of FIG. 26A. In the schematic 260 ID, a laser beam having the beam profile 2605B is used to form an internal feature in the sheet 2607. The beam profile 2605B is rotated relative to the optical axis 2603 as indicated by the arrows 2609 to form the internal feature, and the internal feature has an hourglass shape having a wider minimum thickness relative to the shape formed in the schematic 260 IB.

[0235] In the schematic 260 IE, abeam profile 2605C is shown relative to the optical axis 2603. The beam profile 2605C has a convex curved shape, with the beam profile 2605C being closer to the optical axis 2603 at the edges of the beam profile 2605C than at the center of the beam profile 2605C. In the schematic 260 IF, a laser beam having the beam profile 2605C is used to form an internal feature in the sheet 2607. The beam profile 2605 C is rotated relative to the optical axis 2603 as indicated by the arrows 2609 to form the internal feature, and the internal feature has a wider thickness near the center of the sheet 2607 and a smaller thickness near the edges of the sheet 2607.

[0236] In the schematic 2601G, the beam profile 2605D is shown relative to the optical axis 2603. The beam profile 2605D has aplurality of linear segments. In the schematic 2601H, a laser beam having the beam profile 2605D is used to form an internal feature in the sheet 2607. The beam profile 2605D is configured to form a C-style chamfered edge. As used herein, a “C-style chamfered edge” is a multi-segment angled chamfered edge having a plurality of surfaces that are generally flat, and these edges may comprise three surfaces in some embodiments. The beam profile 2605 D is rotated relative to the optical axis 2603 as indicated by the arrows 2609 to form the internal feature, and the internal feature has a wider thickness near the center of the sheet 2607 and a smaller thickness near the edges of the sheet 2607.SP24-277-3

[0237] While various shapes are illustrated in FIGS. 26A-26B for the cross-sectional edge shapes of internal features, other cross-sectional edge shapes may be used such as a parabolic shape, a polygonal shape, or a shape comprising multiple linear segments. Other cross-sectional edge shapes may be used as well.

[0238] Chemical strengthening of glass, such as through ion-exchange, is a way of obtaining a higher strength and more reliable parts for cover glass used in displays or handheld devices. In ion-exchange, glass sections may be immersed in a salt bath, and this immersion allows larger ions to penetrate through the surface of a glass sheet to form a thin compressive layer near the surface of the sheet.

[0239] The creation of the internal features as illustrated in FIGS. 26A-26B may be beneficial for various applications, internal features may be used to create contour lines of a series of perforations so that a removable section may be formed within a sheet. However, internal features may also be used to enable strengthening of the glass at the full sheet level, before removing the internal sections, by allowing ion-exchange material to penetrate and diffuse within the internal features, thereby allowing compressive regions to be formed.

[0240] Depending on the specific use case, these internal features may be retained in a sheet. Where this is done, the internal features may enable ion-exchange material to easily penetrate at the internal features so that compressive regions may be formed. In some embodiments, internal features may be mechanically adjusted to form a larger hole, or the features may be wet etched (e.g., to form a shaped through-glass via). In addition to providing internal or externally contoured parts with shaped edge geometries, small circular features with initially shaped geometries (curved, chamfered, angled, and the like) may be used to improve an aspect ratio of post-etched through-glass vias or to encourage retention or drop-out of glass plugs. These glass plugs are small portions of the glass sheet that are perforated from other sheets when some internal features are formed. Rotation of a straight laser beam or shaped laser beam in combination with laser perforations (continuous laser firing during sample translation), may enable formation of rippled, scalloped, or other complex edge geometries at high speeds.

[0241] With previous solutions, a tradeoff was faced when attempting to ion-exchange. If one cuts a sheet into individual sections and separates those sections from the sheet before ionexchange, a high edge strength on each part may be achieved due to ion-exchange along the whole part edge, but this is achieved while also requiring more complex and less cost-efficient handling of all the individual parts. With this approach, individual part handling of the individual sections must be performed for all post-cut steps such as ion-exchange, washing, application of coatings (e.g., inks, other printed features, dielectric coatings such as anti-SP24-277-3reflective coatings, polymers, anti-fingerprint coatings, and the like). Individual part handling and coating is generally more costly than if the same processes are applied at the full sheet level.

[0242] In another alternative solution, ion-exchange processing may be performed at the full sheet level before perforations are formed. When ion-exchange processing is performed at the full sheet level, handling of the sheet may be simplified relative to when separated sections must be handled independently of each other. Additionally, when ion-exchange processing is performed at the full sheet level, coatings may be applied more simply on a larger format. However, since the individual sections must be cut out of the sheet after ion-exchange processing, the edge strength of the cut edges may be low due to the lack of ion-exchange material along the cut edges.

[0243] To address these trade-offs, the processes may be performed in a different order. Perforations may be formed within sheets before any ion-exchange processing is performed. However, the sections defined within the sheet by the perforations may be retained in the sheet. Sections may be considered to be retained within a sheet even when they are experiencing pop-out, with sections no longer being retained within the sheet only when the sections are completely removed from the sheet. The entire sheet including any removable sections may be subjected to ion-exchange and other processing before the removable sections are actually removed. This approach may provide increased efficiency in ion-exchange processes because the processing may be performed at the full sheet level so that handling of the sheet and the removable sections therein is made less difficult and more efficient and so that the other benefits of operating at the full sheet level are realized. However, the sheets and the removable sections therein may also have improved edge strengths as the ion exchange material may penetrate through laser perforations and therefore strengthen the full length of the edge. Edge strengths may be greater than about 500 megapascals or even greater than about 600 megapascals, and these edge strengths may be accomplished across a range of glass thicknesses (e.g., between about 0.2 and about 1.3 millimeters).

[0244] Scanning microprobe data of the potassium ion concentration at the edges of a glass sample were evaluated to ensure that ion-exchange material was effectively diffused with this new process flow, and the scanning microprobe data confirmed that the ion-exchange material penetrated the perforations thoroughly. Furthermore, a small amount of brush polishing (generally less than about 20 micrometers of material removed at edges) on the final singulated parts may be used to raise the edge strength to greater than about 800 megapascals while still maintaining a compressive region having ion-exchange material at all surfaces of the sectionsSP24-277-3that are formed because the depth of removal may be less than the DOL for the compressive region of ion-exchange material.

[0245] A process flow for forming sheet-perforated ion diffused edges is shown in FIGS.27A-27B. At stage 2702A, a sheet 2704 is provided and perforations 2706 (e.g., laser perforations) having the desired contour(s) are formed in the sheet 2704. Various contours having different shapes and sizes may be used. After the perforations 2706 are formed, sections 2708 may be formed in the sheet 2704 that are capable of being separated from another frame portion of the sheet 2704. However, the sections 2708 may remain within the sheet 2704 and may not be separated from the sheet 2704 until later in the process flow.

[0246] Perforation may create through-body defects in the glass sheet that guide crack propagation. When perforation is used to create internal contours, sections may be retained in the sheet. This allows for full sheet processing at the ion-exchange, washing, and coating stages. Retention of removable sections within the sheet may also allow for the final singulated sections to have an edge strength that realizes the benefits from ion exchange, with edge strength in excess of 500 megapascals. Furthermore, as described further herein, brush polishing may be performed after ion exchange to produce parts with edge strength in excess of 800 megapascals.

[0247] At stage 2702B, the sheet 2704 is exposed to an ion-exchange material, which may be provided in a bath 2710. The sheet 2704 may be placed in a bath 2710 so that ion-exchange material may be diffused into the sheet 2704. In particular, the ion-exchange material may be diffused into the sheet 2704, into the sections 2708, and may penetrate the perforations 2706 so that the edges of the section 2708 exposed to the ion-exchange material. Thus, the perforations 2706 may act as conduits for the ion-exchange material.

[0248] The bath 2710 may be a molten salt bath (or two or more molten salt baths) containing the larger ions to be exchanged with the smaller ions in the sheet 2704. It should be noted that aqueous salt baths may also be utilized. In addition, the composition of the bath(s) may comprise more than one type of larger ion (e.g., Na+ and K+) or a single larger ion. It will be appreciated by those skilled in the art that parameters for the ion exchange process, comprising, but not limited to, bath composition and temperature, immersion time, the number of immersions of the sheet 2704 in a salt bath (or baths), use of multiple salt baths, additional steps such as annealing, washing, and the like, may generally be determined by the composition of the sheet 2704 and the desired depth of layer and surface compressive strength of the sheet 2704 that results from strengthening. Exemplary molten bath compositions may comprise nitrates, sulfates, and chlorides of the larger alkali metal ion. Typical nitrates comprise KNO3,SP24-277-3NaNOs, L1NO3. NaSC>4, and combinations thereof. The temperature of the bath 2710 typically may be in a range from about 380 degrees Celsius up to about 500 degrees Celsius, while immersion times may range from about 15 minutes up to about 100 hours depending on the thickness of the sheet 2704, bath temperature and glass (or monovalent ion) diffusivity for the sheet 2704. However, temperatures and immersion times different from those described above may also be used.

[0249] In embodiments, the sheet 2704 may be immersed in a molten salt bath of 100% NaNOs, 100% KNO3, or a combination of NaNCfi and KNO3 having a temperature from about 370 degrees Celsius to about 500 degrees Celsius. In some embodiments, the sheet 2704 may be immersed in a molten mixed salt bath comprising from about 5% to about 90% KNO3 and from about 10% to about 95% NaNCh. In one or more embodiments, the sheet 2704 may be immersed in a second bath, after immersion in a first bath. The first and second baths may have different compositions and / or temperatures from one another. The immersion times in the first and second baths may vary. For example, immersion in the first bath may be longer than the immersion in the second bath. In embodiments, the sheet 2704 may be immersed in a molten, mixed salt bath comprising NaNCh and KNO3 (e.g., 49% / 51%, 50% / 50%, 51% / 49%) having a temperature less than about 420 degrees Celsius (e.g., about 400 degrees Celsius or about 380 degrees Celsius), for less than about 5 hours, or even about 4 hours or less.

[0250] Once the ion-exchange has been completed, the sheet 2704 may be removed from the bath 2710. Thus, the resulting sections 2708 that are formed from the sheet 2704 include a compressive region comprising ion-exchange material at exterior surfaces of the sections 2708.

[0251] Ion-exchange processes may be used to chemically strengthen glass substrates and other materials. The bath 2710 of ion-exchange material may comprise molten salt, and larger alkali ions from the bath 2710 may (commonly K+) diffuse into the sheet 2704 and replace smaller alkali ions. For example, the larger alkali ions may be potassium ions (K+), and these ions may be configured to replace the sodium ions (Na+) or other ions where the sheet 2704 comprises glass. However, the ions that are diffused into the substrate during ion-exchange and the ions that are replaced during ion-exchange may be different in other embodiments.

[0252] The penetration of the larger ions during ion-exchange introduces compressive stress into the surfaces and edges of the sheet, which may make the sheet much more resistant to surface damage and resulting cracking. The ions generally diffuse into any parts of the sheet that are in direct contact with the salt bath. The distance to which the ions diffuse into the sheet is typically characterized by the DOL. The penetration of the larger diffused ions cause the regions near the surfaces of the sheet to go into compression. Hence, for a sheet, the large flatSP24-277-3surfaces of a sheet become strengthened, as well as the exposed edges. A typical edge strength for such ion-exchanged sheets is about 600 megapascals, with the exact value depending on the material, amount of ion-exchange processing that has been completed, and the exact finish quality imparted to the glass edge.

[0253] Even though some processes, such as a laser perforation process, may be used to cut a sheet after the sheet has been subjected to ion-exchange processing, drawbacks exist with this approach. When sheets are perforated and / or cut after ion-exchange, any perforated edges that are formed during laser perforation processes are not be exposed to any salt bath during ion-exchange. Thus, ion-exchange material typically is not present at these newly perforated edges, making the edge strength at these newly perforated edges weaker. In some cases where ion-exchange processing is performed before laser perforation, the edge strength of newly perforated edges may be about four to five times weaker than parts that are first perforated and then subjected to ion-exchange.

[0254] Looking back at FIG. 27A, the sheet 2704 may be subjected to printing or other types of decoration at state 2702C. At stage 2702D within FIG. 27B, the sections 2708 may be singulated from the frame of the sheet 2704. This may be accomplished by using a laser or a mechanical scribe to form release lines 2712 in the frame of the sheet 2704 which allows the sheet to separate the sections 2708 from other portions of the sheet 2704. Since the sheet 2704 is ion exchanged, substantial internal stress (central tension) is present throughout the sheet, and this causes the glass sheet to quickly separate about the release lines 2712.

[0255] At stage 2702E, the sections 2708 are shown separated from the sheet 2704. Compressive regions comprising ion-exchange material may be present at edges of the sections 2708 so that the sections 2708 and the edges thereof have a greater strength. In some embodiments, the sections may be subjected to polishing after ion-exchange is completed.

[0256] After sheets are perforated to form sections therein, the sections may prematurely pop-out before the sections are intended to be separated from other portions of the sheets. Due to the stresses created by ion exchange, the cracks may propagate around the internal contours after ion exchange so that the sections become physically disconnected from the surrounding frame. When such a sheet is bent or vibrated, these sections may move slightly out of the plane of the sheet, causing them to tilt slightly and project out relative to the surrounding frame by some distance, such as by about 10 microns or more, by about 50 microns or more, or by about 500 microns or more. In extreme cases, the sections can fall completely out of the surrounding sheet. Pop-out arises more often and with greater magnitude as sheets are increased to largerSP24-277-3sizes, such as sheet sizes greater than about 475 millimeters by 750 millimeters or even greater than about 730 millimeters by 920 millimeters.

[0257] An example of pop-out is illustrated in the schematic views of FIG. 29, with FIG.28 showing a similar section 2804 before pop-out. In FIG. 28, a section 2804 is positioned within a frame 2802 of a sheet 2800. The sheet 2800 has laser perforated edges 2806 of the internal sections separating the section 2804 and the frame 2802. The sheet 2800 also has a thickness Tl, and this thickness T1 may remain relatively uniform across the entire sheet 2800. Among other things, the thickness Tl, the size of the section 2804, and the shape of the laser perforated edges 2806 may impact the force required to cause pop-out or release of the section 2804. Once perforated edges 2806 are formed in the sheet 2800, the section 2804 may remain in intimate contact with the frame 2802, so the section 2804 does not simply fall out of the parent sheet after laser perforated edges 2806 are formed due to friction between the section 2804 and the frame 2802 and the texture of the perforated edges 2806 of the section 2804 and the frame 2802. In various embodiments described herein, edges of sections formed within sheets may have an average surface roughness that is less than or equal to about 5 microns, or even less than or equal to about 1 micron. Where brush polishing is performed at a surface, the average surface roughness may be about 100 nanometers or less, about 20 nanometers or less, or even about 10 nanometers or less. After ion exchange, a larger gap may be formed proximate to the laser perforated edges 2806.

[0258] However, the section 2804 may experience pop-out if the forces acting on the section 2804 are greater than the friction forces holding the section 2804 in place. Pop-out may occur if the sheet 2800 is bent, if the sheet 2800 is subjected to vibration or other repeated motions, or if other forces act directly on the section 2804 or the frame 2802. Pop-out may also occur when salt is washed off of a sheet (e.g., after ion-exchange), such as when sheets are immersed in hot water during dip-rinse events, or when subjected to a thermal gradient, or when transported, or when washed. Other causes for pop-out may also exist.

[0259] FIG. 29 is a schematic view illustrating a section 2904 experiencing pop-out. In FIG. 29, the sheet 2900 includes a frame 2902 and the section 2904, with the section 2904 being separated from the frame 2902 by perforations 2906. The section 2904 projects out relative to the frame 2902 in the top right comer and in the bottom left comer of the section 2904 in FIG. 29, and the section 2904 is rotated relative to the frame 2902.

[0260] Pop-out is generally not a concern before ion-exchange processes are completed because the internal sections are still connected to the surrounding frame. However, pop-out tends to be more problematic after the ion-exchange processes are completed. Ion-exchangeSP24-277-3processing may create enough stress within a sheet to cause cracks to propagate around the edges of the internal sections. By itself, this crack propagation is not a problem, as cracks tend to follow the edges of the internal parts. However, subsequent bending or vibration of the sheet that happens during transportation of the sheet or during washing of the sheet may cause the internal sections to slip relative to the frame and protrude from the sheet.

[0261] FIG. 30 is a height map illustrating various locations in a sheet 3000 where the sheet 3000 is experiencing pop-out at the edges of the sections 3004. The sheet 3000 has six sections 3004 positioned within the sheet 3000, and the sheet 3000 has a size of about 475 millimeters by 750 millimeters. The sheet 3000 also includes a frame 3002 surrounding the sections 3004, and perforations 3006 separate the sections 3004 from the surrounding frame 3002. The sheet 3000 was laser perforated, ion-exchanged, dip-rinsed, and then transported to the height measurement system.

[0262] Where pop-out occurs, the internal sections typically protrude outwardly from the other portions of the sheet up to about 100 micrometers (or 0.1 millimeters). However, pop-out is even more prominent in certain locations for the example shown in FIG. 30. While the height at the edges of the sections 3004 is generally between about -0.05 millimeters and about 0.05 millimeters at most locations, the height at the edges of the sections 3004 falls outside of this range in regions 3008, 3010, and 3012. At region 3008, the height reaches about 0.23795 millimeters. At region 3010, the height reaches about -0.080 millimeters, and the height reaches about -0.0888 millimeters at region 3012. Such significant amounts of pop-out may be detrimental for the reasons noted herein.

[0263] FIG. 31 is a schematic view illustrating an example section 3104 positioned within a sheet 3100, with straight laser perforated edges 3106 separating the sheet 3100 from a surrounding frame 3102 of the sheet 3100. With the sheet 3100, vertical motion of the section 3104 is possible as indicated by the arrows Al. However, no gap is present (or a very small gap is present) between the section 3104 and the surrounding frame 3102, so the sheet 3100 must be subjected to bending or to other forces to overcome the friction forces between the section 3104 and the surrounding frame 3102 and to cause separation of the section 3104 from the frame 3102.

[0264] FIG. 32 is a schematic view illustrating an example section 3204 separated from a surrounding frame 3202 of a sheet 3200 via non-linear laser perforated edges 3206. The nonlinear laser perforated edges 3206 are curved in shape, but non-linear laser perforated edges may be provided with other shapes in other embodiments. With the sheet 3200, vertical motion of the section 3204 is possible as indicated by the arrows A2. However, no macroscopic gap isSP24-277-3present (or a very small gap is present) between the section 3204 and the surrounding frame 3202, so the section 3204 is retained within the frame 3202 of the sheet 3200. The sheet 3200 must be subjected to bending or to other forces to cause separation of the section 3204 from the frame 3202. Because of the shape of the non-linear laser perforated edges 3206, the amount of force required to cause pop-out of the section 3204 is higher than the amount of force required to cause pop-out of the section 3104.

[0265] The sheet 3200 includes a first surface 3214 and a second surface 3216 opposite the first surface 3214. Both surfaces 3214, 3216 extend parallel to the X-Y plane. Non-linear laser perforated edges 3206 extend between the first surface 3214 and the second surface 3216, with the non-linear laser perforated edges 3206 positioned between the section 3204 from the frame 3202 of the sheet 3200. These non-linear laser perforated edges 3206 form one or more internal edges. The non-linear laser perforated edges 3206 may be formed from various types of laser beams such as caustic laser beams, curving Bessel beams, or other laser beams. In the sheet 3200, a first direction D 1 extends parallel to the Z-axis, with the first direction D 1 being normal to the first plane and the second plane. A second direction D2 extends in parallel to the X-axis and perpendicularly to the first direction D 1.

[0266] The sheet 3200 has one or more internal edges 3218 formed therein proximate to the non-linear laser perforated edges 3206. The internal edge(s) 3218 have a non-linear profile having an apex 3212, and the internal edge(s) 3218 extend between the first comer 3208 and the second corner 3210. The first comer 3208 joins the first surface 3214 and the internal edge(s) 3218, and the second comer 3210joinsthe second surface 3216 and the internal edge(s) 3218. The internal edge(s) 3218 extends further in the second direction D2 at the apex 3212 than it does at the first comer 3208 and the second comer 3210. In FIG. 32, the apex 3212 extends a distance Bl further in the second direction D2 relative to the first comer 3208 or the second comer 3210 (whichever comer is farther away). This distance Bl may be referred to herein as the “apex distance.” In some embodiments, the apex distance B 1 may be at least about 3 micrometers, at least about 5 micrometers, at least about 10 micrometers, at least about 20 micrometers, at least about 40 micrometers, or even at least about 60 micrometers. The sheet 3200 includes material diffused through ion-exchange, with the diffused material positioned along the first surface 3214, the second surface 3216, and the internal edge(s) 3218. The apex distance B 1 may be greater than or equal to the DOL of ion-exchange material diffused on the surfaces of the section 3204. The internal edge(s) 3218 has a curved shape in FIG. 32, but internal edge(s) may be provided with a plurality of flat surfaces (e.g., C-style chamfered edges) or may have other shapes in other embodiments.SP24-277-3

[0267] A contact angle 03 is defined at the section 3204 between a line normal to the first surface 3214 and a portion of the edge surface 3218 immediately adjacent to the first comer 3208. The contact angle 03 may be at least about 10 degrees or more, about 12.5 degrees or more, about 15 degrees or more, about 17.5 degrees or more, or about 20 degrees or more in some embodiments. An angle similar to the contact angle 03 may be defined at the second comer 3210 between a line normal to the second surface 3216 and the portion of the edge surface 3218 immediately adjacent to the second surface 3216. The contact angle may be measured by obtaining the angle between a line normal to the surface 3214 and a line tangent to the edge surface 3218 at the comer 3208.

[0268] Similar to the sections illustrated in FIG. 43, the sheet 3200 and the section 3204 therein may include diffused material that has been diffused through ion-exchange, with the diffused material positioned along the first surface 3214, the second surface 3216, and the edge surface 3218. In some embodiments, potassium ions may be used during ion-exchange processes to result in a compressive region comprising potassium remaining in the sheet 3200. The diffused ion-exchange material may help form the compressive region that extends entirely from the first surface 3214 to the second surface 3216 at one or more locations on the sheet 3200. For example, the compressive region may extend all the way through the non-linear laser perforated edges 3206 between the surfaces 3214, 3216. The compressive region at the edge surface 3218 may have a DOL of about 5 micrometers or more in some embodiments. However, the DOL of the compressive region at the edge surface 3218 may be less than a DOL of the compressive region at the first surface 3214 if the edge surfaces have been subjected to polishing after ion-exchange processing. For example, the compressive region at the edge surface 3218 may be at least about 5 micrometers less than the DOL of the compressive region at the first surface 3214 in some embodiments. Additionally or alternatively, the surface concentration of ion-exchange material in the compressive region at the edge surface 3218 may be less than a surface concentration of the ion-exchange material in the compressive region at either of the first surface 3214 or the second surface 3216. The apex distance Bl may be equal to or greater than the DOL of the compressive region at the first surface 3214 or the second surface 3216.

[0269] Additionally or alternatively, one or more coatings may be present on the sheet 3200, and the coatings may comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer. The sheet 3200 may comprise glass in some embodiments, but the sheet 3200 may comprise other materials.SP24-277-3

[0270] The various surfaces 3214, 3216, 3218 of the sheet 3200 may also have a particular surface roughness. In some embodiments, if the edge surface 3218 has not been subjected to post-ion -exchange polishing, then the average surface roughness of the edge surface 3218 may be less than about 5 micrometers, as measured by the average surface roughness (Ra). When the edge surface 3214 has been subjected to polishing, the average surface roughness of the edge surface may be less than or equal to about 100 nanometers, about 20 nanometers, or even about 10 nanometers. However, the average surface roughness may be different in other embodiments.

[0271] Quasi-non diffracting beams are often referred to as “Bessel-like” laser beams, “Bessel” laser beams, or “focal lines.” When using laser to cut glass, high intensity short pulse laser light may be focused to at a spot diameter of about a few micrometers in order to modify a sheet, inducing refractive index changes, structural modifications, and / or microcracking in the sheet. For traditional Gaussian-like laser beams, diffraction often causes light to spread out quickly, meaning such a spot diameter may only be maintained over a propagation distance within the tens of micrometers. But Bessel-like beams allow the light to maintain this focused spot size over millimeters or more of propagation distance. This means the Bessel-like beams may quickly create controlled perforations, or long thin lines of laser modified material, each of which extend through the full thickness of the glass sheet.

[0272] To cut a glass sheet, perforations may be spaced closely together, typically at pitches that range from about 1 micrometer to about 50 micrometers. The perforations may be arranged to trace out the contour of a desired section within the sheet. The closely spaced perforations may be used to create and guide the cracks forming from laser damage imparted in the brittle material of the sheet. Consequently, the sheet may separate about the perforated contours. Since the perforations extend through the full thickness of the glass sheet, the cracks may be controlled reliably even in highly stressed material. Additionally, the fact that each shot of the laser beam induces a full through thickness modification means that the cutting speeds may be very high (e.g., greater than about 1 meter per second).

[0273] FIG. 33 is a schematic view illustrating an example Bessel beam optical assembly 3300. With this assembly 3300, an initial laser beam 3302A is directed towards a first optical element 3304 in the form of an axicon, thereby generating the modified beam 3302B. The modified beam 3302B is then directed from the first optical element 3304 to the second optical element 3306, thereby generating the modified beam 3302C. The modified beam 3302C is directed from the second optical element 3306 to the third optical element 3308, thereby generating the modified beam 3302D. The modified beam 3302D is then directed from theSP24-277-3third optical element 3308 to the sheet 3312, with the modified beam 3302D having a line focus 3310 as the modified beam 3302D reaches the sheet 3312. The line focus 3310 may be adjusted based on the optical elements 3304, 3306, 3308 that are used.

[0274] FIG. 34 is a plot 3400 illustrating an example intensity profile for a Bessel beam as a function of a focus position. The focus position is provided in units of millimeters, and the peak-on axis intensity is provided with a unit of analog to digital converter counts. As illustrated, the peak-on axis intensity remains at about 0 counts until a focus position of about 0.6 millimeters is reached. The peak-on axis intensity moves up to about 240 counts at a focus position of around 1.1 millimeters, and the peak-on axis intensity then decreases to about 0 counts at a focus position of about 2.0 millimeters.

[0275] FIG. 35 is an image 3500 illustrating an example Bessel beam cross section, with an x-position illustrated on the x-axis in micrometers and with a y-position illustrated on the y-axis in micrometers. The intensity of the Bessel beam is generally greatest at a center point, with the center point being at an x-position of about 5 micrometers and at a y-position of about 5 micrometers. While the center point in the image 3500 generally appears darker than some of the surrounding points, this is an illusion caused by the use of a grayscale image, and the intensity is actually at a maximum at this center point. However, the other changes in color at locations farther away from this center point are representative of small sidelobes where the Bessel beam had localized increases in intensity.

[0276] With Bessel beams, long thin laser modifications may be provided, and the Bessel beam may be good at guiding cracks within sheets. Furthermore, lasers used to form Bessel beams are readily available, and these lasers may form short pulse, high energy laser beams. FIG. 36 is a schematic view illustrating an example Bessel beam optical assembly 3600 comprising an axicon 3604. A laser beam 3602 is directed to the axicon 3604, which may direct a Bessel beam 3606 towards the sheet 3608. A focal line 3610 is also illustrated, and the focal line 3610 may have a length of greater than about 2 millimeters. With the Bessel beams, a spot diameter of about a few micrometers (e.g., about 0.2 micrometers to about 5 micrometers) may be maintained through the full thickness of the sheet 3608. Perforations may be formed using the assembly 3600 with a laser configured to generate laser beams in pulses having a pulse duration of about a picosecond.

[0277] FIG. 37 is a top view illustrating perforations 3704 formed within a sheet 3700 using a Bessel beam optical assembly similar to the one illustrated in FIG. 36. The sheet 3700 includes two different portions 3702 formed on opposing sides of the perforations 3704. One of these portions 3702 may be a removable section, and the other may be a frame that theSP24-277-3removable section may be separated from. As illustrated, the perforations 3704 may guide crack propagation, with cracks 3706 extending along the path formed by the perforations 3704.

[0278] FIG. 38 is a front face view illustrating a cut edge 3806 formed within a sheet 3800 using a Bessel beam optical assembly similar to the one illustrated in FIG. 36. The sheet 3800 defines a thickness T2 that is measured from a first surface 3802 of the sheet 3800 to an opposing second surface 3804 of the sheet 3800, with the thickness T2 being about 700 micrometers. However, the thickness T2 value may be different in other embodiments. The cut edge 3806 extends between the first surface 3802 and the second surface 3804. As may be seen on the cut edge 3806, perforations that are formed generally extend vertically in FIG. 38.

[0279] Traditionally, laser cutting has been used to form glass edges that are straight. If a chamfered edge is desired at the glass edge, then this is typically completed by mechanically grinding or polishing the glass edges after cutting using a grinding wheel having a shape configured to impart the desired edge shape.

[0280] In the case of perforation processing, a nominally straight Bessel-like beam may be changed to other beams to form a non-linear perforation. For example, a multi -segment angled Bessel beam (a quasi-nondiffracting style beam comprised of stitched, straight and angled Bessel beam facets) may be used to create a C-chamfer like shape, or a curving beam may be used to create a curved chamfer shape. Laser beams which exhibit curving focal regions include but are not limited to caustic beams, Airy beams, or curving Bessel beams. In the case of curving beam profiles, Airy beams may be used for lower contact angle chamfers (typically less than about 15 degrees), while caustic or curving Bessel beams may be used to create higher contact angle chamfers. Some examples of glass edges with non-linear perforations are shown in FIGS. 39A-39B. Perforation methods used to form these edges may retain many of the benefits of straight perforation cutting, such as the ability to cut arbitrary two-dimensional shapes, easy separation of sections, and low flaw sizes.

[0281] A cut edge of an example section 3900 of a sheet where C-style chamfered edges formed through laser perforation with a multi-segment angled Bessel beam are illustrated in the side profile view of FIG. 39A. The section 3900 includes an edge having an edge surface 3922, and the edge surface 3922 includes a first portion 3902, a second portion 3906, and an apex portion 3904 positioned between the first portion 3902 and the second portion 3906. The section 3900 also has a first surface 3908 and a second surface 3918 opposite the first surface 3908. Surfaces 3908, 3918 are parallel to each other. A comer 3920 joins the first surface 3908 with the edge surface 3922, and a comer 3924 joins the second surface 3918 with the edge surface 3922. The section 3900 comprises glass has a thickness of about 0.7 millimeters, withSP24-277-3this thickness measured as the minimum distance from the first surface 3908 to the second surface 3918.

[0282] The different portions of the edge surface 3922 extend at different angles. The apex portion 3904 generally extends as a flat surface with this surface extending at a 90 degree angle relative to the surfaces 3908, 3918. While the apex portion 3904 is flat in FIG. 39A, the apex portion 3904 may simply be a point or a tip that extends out the farthest relative to other portions of an edge surface, or an apex portion may be provided with another shape. The first portion 3902 extends at a contact angle 65 relative to a line normal to the first surface 3908, and the second portion 3906 extends at a contact angle 64 relative to a line normal to the second surface 3918. The angles 64, 65 may be equal to each other in some embodiments. In some embodiments, the angles 64, 65 may be about 10 degrees or more, about 12.5 degrees or more, about 15 degrees or more, about 17.5 degrees or more, or about 20 degrees or more. The contact angles may each be measured at one of the comers 3920, 3924.

[0283] To make a high-quality cut, it may be beneficial to pay special attention certain aspects of beam formation and to maintain certain conditions. If these conditions are not followed, then the glass separation may deviate from the intended chamfer shape. For example, in forming C-style chamfered edges, multi-segment angled Bessel beams may experience off-axis aberrations, and phase mask-based correction methods may be used to compensate for aberrations from lens systems and from rays entering the glass sheets at an angle. This may be accomplished by applying precise amounts of spherical aberration into the beam, with the aberration potentially being different near the top, middle, and bottom segment of the beam.

[0284] Additionally, multi-segment angled Bessel beams require both lateral and offset compensation for each beamlet to make each beamlet stitch together precisely with the glass substrate. This may be accomplished by introducing small angular and lateral offsets in the phase mask that are applied independently to each segment of the beam. The three -segment beams may also use a decoherence method to prevent the interference between each beamlet and adjacent beamlets at the locations which they intersect or slightly overlap, and this may be accomplished by altering the polarization of each beam segment (e.g., by using a cut waveplate that only affects the middle segment of the three-segment beam).

[0285] In order to generate multi-segment angled Bessel beams, various beam parameters may be used. Laser beams may be generated with a wavelength of about 1030 nanometers. Additionally, the laser beams may be generated in bursts of pulses, with 4 pulses per burst and with a pulse width of about 9 picoseconds. A pulse delay of 25 nanoseconds may be used between each pulse. Within each burst, about 160 microjoules of energy are delivered to theSP24-277-3sheet. Laser beam generated perforations may have a pitch of about 3 micrometers between adjacent perforations and perforations may have a spot diameter of about 3 micrometers. Additionally, the top, middle, and bottom beam segment lengths may have values similar to those shown in FIG. 41C. While certain beam parameters are described herein, other beam parameters may be used in order to generate multi-segment angled Bessel beams. While multisegment angled Bessel beams are beneficial in many respects, creating high angle chamfers having contact angles of about 20 degrees or more may be challenging with multi-segment angled Bessel beams. Additionally, the optical elements used to create these multi-segment angled Bessel beams may be challenging to fabricate. For example, fabricating a phase mask and the final objective to create multi-segment angled beams with high contact angles may be challenging.

[0286] FIG. 39B is a side profile view illustrating a cut edge of an example section 3910 of a sheet where a curved chamfered edge formed through laser perforation with an Airy laser beam is shown. The same section 3910 is shown on the right and left in FIG. 39B. The section 3910 includes an edge having an edge surface 3934, and the edge surface 3934 includes a first portion 3912, a second portion 3916, and an apex 3914 positioned between the first portion 3912 and the second portion 3916. The section 3910 also has a first surface 3926 and a second surface 3930 opposite the first surface 3926. Surfaces 3926, 3930 are parallel to each other. A comer 3928 joins the first surface 3926 with the edge surface 3934, and a comer 3932 joins the second surface 3930 with the edge surface 3934. The section 3910 comprises glass and has a thickness of about 0.55 millimeters, with this thickness measured as the minimum distance from the first surface 3926 to the second surface 3930.

[0287] Unlike the apex portion 3904 in FIG. 39A, the apex 3914 is simply a point in FIG.39B where the first portion 3912 and the second portion 3916 of the edge surface 3934 meet, but this apex 3914 may extend in a line that extends into and out of the page in FIG. 39B. The first portion 3912 extends at a contact angle 66 relative to a line normal to the first surface 3926, and the second portion 3916 extends at a contact angle 67 relative to a line normal to the second surface 3930. Contact angles 66, 67 may be measured at one of the comers 3928, 3932. The contact angles 66, 67 may be equal to each other in some embodiments. In some embodiments, the contact angles 66, 67 may be about 10 degrees or more, about 12.5 degrees or more, about 15 degrees or more, about 17.5 degrees or more, or about 20 degrees or more.

[0288] In order to generate Airy laser beams or laser beams that are Airy-like in nature, various beam parameters may be used. Laser beams may be generated with a wavelength of about 1030 nanometers. Additionally, the laser beams may be generated in bursts of pulses,SP24-277-3with 8 pulses per burst and with a pulse width of about 9 picoseconds. A pulse delay of 25 nanoseconds may be used between each pulse. Within each burst, about 230 microjoules of energy are delivered to the sheet. Laser beams generated perforations having a pitch of about 12 micrometers between adjacent perforations and a perforations having a spot diameter of about 3 micrometers. Additionally, the beams had a length of about 765 micrometers measured in air. However, other beam parameters may be used in order to generate Airy laser beams.

[0289] Certain beam formation aspects may be beneficial in forming curved chamfered edges using Airy beams. The incident beam on a phase mask may be applied as an elliptical shape, and this elliptical shape may have a major to minor axis ratio of about 8 to 1. By using this elliptical shape, the amplitude of the focused beam’s side-lobes may be reduced. Having a side lobe intensity that is too high may cause damage in sheets in unintended locations, and this side lobe laser damage may prevent the separation of removable sections from being guided fully by the laser damage from main lobe of the beam as intended.

[0290] Additionally, Airy laser beams may function more effectively in high-burst patterns. In these high-burst patterns, up to eight pulses or more may be present in each burst, and this may reduce the damage from the side lobes, including the first order side-lobe, which is the strongest side-lobe. Again, such side-lobe damage may potentially prevent the separation of removable sections from being guided fully by the laser damage from main lobe of the beam as intended.

[0291] As with multi-segment angled Bessel beams, Airy laser beams may also benefit from the use of phase mask-based correction methods. These phase mask-based correction methods may impart precise amounts of spherical aberration and may compensate off-axis aberrations from both the lens system and from the rays passing into the interface of the glass at an angle.

[0292] FIG. 40A is an image illustrating an example section 4000 having a bullnose laser edge chamfer 4002 that may be made with a multi-spot or multi-focus Gaussian beams (such as described in the publication “Protecting the edge: Ultrafast laser modified C-shape glass edges” noted above) formed within the section 4000. The section 4000 has a first surface 4004 and a second surface 4006 opposite the first surface 4004. The section 4000 defines a thickness T3, with the thickness T3 being measured between the surfaces 4004, 4006. The thickness T3 is about 550 micrometers, but different thicknesses may be used in other embodiments. Diffractive optics may be used to form the multi-spot Gaussian beams, allowing the bullnose shape to be formed for the edge chamfer 4002. The multi-spot Gaussian beams may enable other complex edge shapes and arbitrary two-dimensional part shapes to be accomplished.SP24-277-3However, when multi-spot Gaussian beams are used, crack control and separation of such high angle edges may be challenging compared to perforated edges, with acid or hydroxide etching often being required when multi-spot Gaussian beams are used. Furthermore, optical elements may be relatively complex to fabricate when multi-spot Gaussian beams are used.

[0293] FIG. 40B is an image illustrating an example section 4010 having an example C-style chamfered edge made from a multi -spot Gaussian beam. The section 4010 has a first surface 4018 and a second surface 4020 opposite the first surface 4018. The section 4010 defines a thickness T4, with the thickness T4 being measured between the surfaces 4018, 4020. The thickness T4 is about 550 micrometers, but different thicknesses may be used in other embodiments. Diffractive optics may be used to form the multi-spot Gaussian beams, allowing the C-style chamfered edge to be formed for the edge chamfer. The C-style chamfered edge generally comprises three surfaces, including surface 4012, surface 4014, and surface 4016.

[0294] To generate laser beams to generate C-style chamfered edges and curved chamfered edges, a programmable spatial light modulator (SLM) system may be used. A Gaussian beam emitted by a short pulse laser was shaped by a phase mask displayed on the SLM, and the phase mask required additional lenses to transform and demagnify the laser beam into a multisegment angled Bessel beam or an Airy beam in particular sheets. Laser beams were characterized by imaging them with a camera (e.g., a Charge -Coupled Device (CCD) camera or a complementary metal-oxide-semiconductor (CMOS) camera) and microscope objective lens, which was scanned through the focus of the laser beam to observe the cross-sectional profile of the beam as the focus position was changed.

[0295] Resulting cross-sectional images of a laser beam are illustrated in FIGS. 41A for a laser beam configured to generate C-style chamfered edges where the laser beam was used to cut a 0.7 millimeter thick sheet. The focus position was adjusted by about 10 micrometers between each of the individual cross-sectional images. The sequence of the images 4100 starts at the first image 4102 and proceeds from left to right in the rows on the left side of the line 4104 before moving to the next row on the left side of the line 4104. The sequence proceeds from the last image on the left side of the line 4104 to the first image on the right side of the line 4104, and the sequence then proceeds in a similar fashion.

[0296] The peak grayscale intensities of laser beams on the camera were calculated from the images in FIG. 41 A, and the calculated peak grayscale intensity was used to obtain the plot 4108 of FIG. 4 IB, which is a plot illustrating the peak grayscale intensity as a function of focus position for a laser beam. The plot 4108 shows the datapoints 4110 and the best fit line 4112.SP24-277-3The peak grayscale intensity remained around 10 counts when the focus position was below 200 micrometers and when the focus position was above about 825 micrometers. However, the peak grayscale intensity rose to levels of above 175 counts at focus positions between about 200 micrometers and about 825 micrometers. The best fit line 4112 had a maximum peak grayscale intensity of around 165 counts when the focus position was around 500 micrometers. When the grayscale intensity is about 100 counts or more, the laser beams have sufficient intensity to cut glass over a distance measured in air of about 550 micrometers, which corresponds to an ability for the beam to cut a glass thickness of about 700 micrometers.

[0297] The peak intensity location translates laterally as the focus position is changed, and the peak intensity location was also calculated from the images of FIG. 41 A. The results are illustrated in FIG. 41 C, which is a plot illustrating movement of a peak location when the focus position is changed. The plot 4114 shows datapoints 4116 corresponding to apeak x-coordinate and a best fit line 4118 for the peak x-coordinates as the focus position was changed. The plot 4114 also illustrates datapoints 4120 corresponding to a peak y-coordinate and a best fit line 4122 for the peak y-coordinates as the focus position was changed.

[0298] The best fit line 4118 generally has three different straight linear segments. A first segment has a length A3 and has a change A5 in focus position. A second segment has a length A6. This second segment generally remains at about the same peak location, so the length A6 corresponds to a change in the focus position. A third segment has a length A4 and has a change A7 in focus position. The length A3 and the length A4 are both about 209 micrometers. The length A5 and A7 are both about 200 micrometers. Furthermore, the length A6 is about 180 micrometers. However, these lengths A3-A7 may be different in other embodiments.

[0299] Additionally, resulting cross-sectional images of a laser beam are illustrated in FIGS. 4 ID for a laser beam configured to generate curved chamfered edges where the laser beam was used to cut a 1.1 millimeter thick sheet. The focus position was adjusted by about 10 micrometers between each of the individual cross-sectional images. The sequence of the images 4124 in FIG. 4 ID was similar to the sequence in FIG. 41A, with the sequence starting at the first image 4126, proceeding left to right in the rows to the left of the line 4128, and then proceeding from left to right in rows to the right of the line 4128.

[0300] The peak grayscale intensity of laser beams was calculated from the images in FIG.41D, and the calculated peak-on axis intensity was used to obtain the plot 4132 of FIG. 41E, which is a plot illustrating the peak grayscale intensity as a function of focus position. The plot 4132 shows the datapoints 4134 for the peak-on axis intensity and the corresponding best fit line 4138. The peak grayscale intensity remained around 10 counts when the focus positionSP24-277-3was below about 50 micrometers and when the focus position was above about 875 micrometers. However, the peak grayscale intensity rose to higher levels at certain focus positions between about 50 micrometers and about 875 micrometers, with the peak grayscale intensity reaching levels of above 200 counts around a focus position of 350 micrometers. The best fit line 4138 had a maximum peak grayscale intensity of around 190 counts when the focus position was around 400 micrometers. When the grayscale intensity is about 100 counts or more, the laser beams have sufficient intensity to cut glass over a distance measured in air of about 750 micrometers, which corresponds to an ability of the beam to cut a glass thickness of about 1100 micrometers.

[0301] The peak intensity location translates laterally as the focus position is changed, and the peak intensity location was also calculated from the images of FIG. 41D. The results are illustrated in FIG. 4 IF, which is a plot 4140 illustrating movement of a peak location in the x-direction and the y-direction as the focus position is changed in the z-direction. The plot 4140 illustrates data points 4142 corresponding to a peak x-coordinate at various focus positions in the z-direction, a best fit line 4144 associated with the data points 4142, and data points 4146 corresponding to a peak y-coordinate at various focus positions in the z-direction. Because the best fit line associated with the data points 4146 tracks the data points 4146 so closely, this best fit line cannot be easily seen.

[0302] While FIGS. 41D-41F illustrate results for an Airy laser beam used for cutting a 1.1 millimeter thick material, beams may be scaled upward or downward in size to cut thicker or thinner material, and beams may possess substantially the same cross-sectional profiles and other properties when scaled upward or downward.

[0303] An example process flow for formation and singulation of sections within a sheet is illustrated in the schematic view of FIG. 42A. At stage 4200A, a section 4206 is provided in a sheet, with a frame 4202 surrounding the section 4206. The frame 4202 is generally 60 millimeters by 80 millimeters in size, and the section 4206 is generally about 44 millimeters by 60 millimeters in size. However, the frame 4202 and the section 4206 may have different sizes in other embodiments. A perforated contour 4204 is formed within the sheet to separate the frame 4202 and the section 4206.

[0304] Between stage 4200A and stage 4200B, the sheet may be ion-exchanged. At stage 4200B, release lines 4208 may be formed in the frame 4202 so that the frame 4202 may easily be separated from the section 4206. At stage 4200C, the section 4206 is released from the remaining portions of the frame 4202 by separating the frame 4202 at the release lines 4208SP24-277-3and proximate to the perforated contour 4204. Once stage 4200 is completed, the section 4206 is completely separated from the remaining frame 4202.

[0305] Once this section 4206 was separated, the section 4206 was subjected to edge strength testing, and these test results are illustrated in FIG. 42B. FIG. 42B is a plot 4250 illustrating edge strengths for edges of various example sheets formed in various ways. Sections having edges formed in three different ways were tested. Sections having straight perforated edges are represented by the first set of data points in FIG. 42B. Sections having C-style chamfered edges which were removed from surrounding frames before ion-exchange processing are represented by the second set of data points in FIG. 42B. C-style chamfered edges that were processed with the technique illustrated in FIG. 42A (which were not removed from surrounding frames before ion-exchange processing) are represented by the third set of data points in FIG. 42B.

[0306] The plot 4250 shows when different sections failed based on the amount of stress applied to the sections. For example, the lines each have their lowest failure percent value at a lower bend strength value on the x-axis. However, as the stress increased and as one advances from left to right in the plot 4250, the failure percent shown on the y-axis increases. Where a given line within the plot 4250 is steeper, the process used to make the sections corresponding to that line are more consistent. Where a given line within the plot 4250 is less steep, the process used to make the sections corresponding to that line is less consistent as there is more spread in the failure. Each of the lines show generally consistent slopes, and the results indicate the edges strengths are nominally equivalent. This shows that the edge strengths obtained when ion-exchange processing occurs after perforations are formed in sheets but before removable sections are removed from sheets are comparable to edge strengths obtained when ionexchange processing occurs after removable sections are removed. The sections that were tested were ion-exchanged in the same bath. The same testing was done with curved chamfered edges, and these edges had similar edge strength results relative to those shown in FIG. 42B.

[0307] Since the compressive layer formed by the material diffused during the ionexchange process is important to provide strength to sheets and / or sections, scanning electron micrograph (SEM) images and elemental analysis via energy dispersive X-ray spectroscopy (EDS) may be deployed to determine if the ion-exchange material fully penetrates the perforations. Results indicated that the DOL for compressive regions positioned along straight perforations is indeed highly uniform. To see if this also holds true for the non-linear laser chamfered edges, similar tests were made with C-style chamfered edges, and curved chamferedSP24-277-3edges. The testing samples were ion-exchanged in a bath of potassium nitrate (KNO3) for around 3 hours at around 440 degrees Celsius.

[0308] The SEM results are illustrated in FIG. 43, with the figure illustrating various scanning electron micrograph images with material diffused through ion-exchange. Three samples are shown in FIG. 43, including a first sample 4316, a second sample 4330, and a third sample 4344.

[0309] The DOL of the compressive regions in FIG. 43 and in other embodiments described herein may be measured by determining how far ion-exchange material has diffused into the underlying sheet or section until the ion-exchange material reaches a background level in the sheet or the section, and the DOL may be measured through the use of SEM equipment or other imaging equipment. The DOL may be measured with Electron Probe Micro-Analysis (EPMA) or other mass spectroscopy methods. Ion-exchange material (e.g., potassium ions, sodium ions, etc.) reaches a background level when an increased level of ion-exchange material may not be detected relative to the level of ion-exchange material in a sheet or section that has not been ion-exchanged.

[0310] In the first sample 4316, the illustrated section has a thickness of about 0.55 millimeters, and the section has a similar shape and size to the section 4206 of FIG. 42A. The illustrated section has a first surface 4318 with a compressive region 4324 positioned at the first surface 4318, a second surface 4322 opposing the first surface 4318 with a compressive region 4328 positioned at the second surface 4322, and an edge surface 4320 extending between the first surface 4318 and the second surface 4322 with a compressive region 4326 positioned at the edge surface 4320. The edge surface 4320 was formed with an Airy beam. As illustrated, the DOL at each of the surfaces generally remains uniform, even at comers where each of the surfaces meet. The DOL is about 40 micrometers at all surfaces.

[0311] In the second sample 4330, the illustrated section has a thickness of about 0.55 millimeters, and the section had a similar shape and size to the section 4206 of FIG. 42A. The second sample 4330 is a control sample. The section used in the second sample 4330 was cut with the Airy beam but was removed from the remainder of the sheet before ion-exchange. The illustrated section in the second sample 4330 has a first surface 4332 with a compressive region 4338 positioned at the first surface 4332, a second surface 4336 opposing the first surface 4332 with a compressive region 4342 positioned at the second surface 4336, and an edge surface 4334 extending between the first surface 4332 and the second surface 4336 with a compressive region 4340 positioned at the edge surface 4334. The edge surface 4334 was formed with an Airy laser beam. As illustrated, the DOL at each of the surfaces generally remains uniform,SP24-277-3even at comers where each of the surfaces meet. The DOL is about 40 micrometers. The image for the second sample 4330 shows that the compressive region has not only fully covered both the top and bottom surfaces but also the entire laser formed glass edge. However, in the small, spalled region proximate to the comer between the edge surface 4334 and the first surface 4332, a reduced amount of ion-exchange material is present in the compressive region such that the DOL is smaller. This spalled region is an artifact of the pre-SEM sample preparation process, and this spalled region is not present during the laser perforation or ion-exchange process.

[0312] In the third sample 4344, the illustrated section has a thickness of about 0.7 millimeters, and the section had a similar shape and size to the section 4206 of FIG. 42A. The illustrated section has a first surface 4346 with a compressive region 4352 positioned at the first surface 4346, a second surface 4350 opposing the first surface 4346 with a compressive region 4356 positioned at the second surface 4350, and an edge surface 4348 extending between the first surface 4346 and the second surface 4350 with a compressive region 4354 positioned at the edge surface 4348. The edge surface 4348 was formed with a C-style chamfered edge. As illustrated, the DOL at each of the surfaces generally remains uniform, even at comers where each of the surfaces meet. The DOL is about 40 micrometers.

[0313] For the first sample 4316 and the third sample 4344, the ion-exchange material forming the compressive region has penetrated uniformly around the laser formed perforations and edges. While the ion-exchange material is not uniformly distributed in the third sample 4330, this was due to the pre-SEM sample preparation process as noted above, and this spalled region is not present during the laser perforation or ion-exchange process. Hence, ion-exchange processes may be effectively performed on sheets before sections have been separated from sheets, and this holds true regardless of whether C-style chamfered edges or curved chamfered edges. However, performing ion-exchange processes on sheets may be effective even when other chamfers are used such as multi-spot or multi focus Gaussian beam formed chamfers.

[0314] Ball-on-ring testing may be performed to evaluate a maximum amount of force applied to a laser perforated section contained in a sheet and a maximum amount of deflection for a laser perforated section in a sheet before the section releases from the sheet. A sheet that may be used in this ball-on-ring testing is illustrated in the schematic, top view of FIG. 44, and a schematic, side view of the ball-on-ring testing assembly is illustrated in FIG. 45.

[0315] The sheet 4400 includes an interior section 4404 possessing a circular shape. The sheet 4400 also includes a frame 4402 positioned outwardly from the interior section 4404, and perforations 4406 may be formed at locations between the interior section 4404 and the frameSP24-277-34402. These perforations 4406 may extend all the way from one surface of the sheet 4400 to the opposing surface of the sheet 4400. The interior section 4404 includes a diameter A8. The sheet 4400 also has a rectangular shape, with the sheet 4400 having a length A9 and a width A 10, and the sheet 4400 also has a relatively constant thickness All as shown in FIG. 45. Adjusting the diameter A8, the length A9, the width A10, and the thickness Al 1 may adjust the maximum force and maximum deflection results during ball-on-ring testing. In some embodiments, the length A9 and the width A10 may be around 160 millimeters, but other values may be used for the length A9 and the width A 10.

[0316] In FIG. 45, the perforations 4406 extend in a line that is perpendicular to the opposing surfaces of the sheet 4400. However, as described herein, the perforations 4406 may possess other non-linear shapes, or the perforations 4406 may be aligned in a different manner.

[0317] The ball-on-ring testing assembly also comprises a load ring 4408 and a contact ball 4410. The load ring 4408 is positioned so that it comes in contact with the frame 4402 at positions located radially outwardly from the interior section 4404, with the load ring 4408 statically supporting the frame 4402. The contact ball 4410 is positioned so that it comes in contact with the interior section 4404 proximate to a center of the interior section 4404. A force is applied with the contact ball 4410 on the interior section 4404 as indicated by the arrow D4. As this force is applied, the load ring 4408 provides a force opposing the force induced at the contact ball 4410 and deflection occurs in the sheet 4400 as indicated by the arrows D3. In particular, deflection may occur in larger levels at the interior section 4404 than at the frame 4402. During the ball-on-ring testing, the observed sheet deflection may continuously increase as the force applied at the contact ball 4410 is increased. As the force applied continues to increase, the sheet deflection may continue to increase until the interior section 4404 suddenly releases relative to the frame 4402, at which point the maximum applied force and maximum deflection may be recorded. The amount of force applied to the contact ball 4410 may be measured with a load cell. Additionally, the amount of deflection of the sheet and / or the interior section 4404 may be measured using various types of measurement equipment, enabling the deflection to be determined as a function of the amount of force applied. The ball-on-ring testing approach described herein creates a rotationally symmetric stress field that may be easily modeled.

[0318] Sheets having different properties were subjected to ball-on-ring testing to evaluate the maximum deflection and maximum force required for release of laser perforated sections from the sheets. In initial testing, a laser was used to make square edge perforated contours, and the testing results for this testing are illustrated in the plot of FIG. 46. Three different sheetSP24-277-3thicknesses were evaluated for this testing. The first sheet thickness was 0.7 millimeters, the second sheet thickness was 1.1 millimeters, and the third sheet thickness was 1.3 millimeters. Additionally, the sections provided in glass sheets were provided with circular shapes having different diameters to evaluate the impact of the section size. The diameter sizes that were tested included a 40 millimeter diameter, a 60 millimeter diameter, an 80 millimeter diameter, a 100 millimeter diameter, and a 120 millimeter diameter. Furthermore, the sheets comprised glass material.

[0319] In the plot of FIG. 46, the peak load is included as the variable on the Y -axis, with the peak load provided in Newtons. Furthermore, a section diameter is included at the variable on the X-axis, with the perforation diameter provided in millimeters. The data points 4602 each correspond to testing done on sheets having a thickness of 1.3 millimeters, the data points 4604 each correspond to testing done on sheets having a thickness of 1.1 millimeters, and the data points 4606 each correspond to testing done on sheets having a thickness of 0.7 millimeters.

[0320] As illustrated in the plot of FIG. 46, the section having smaller diameters required more force to separate from the sheet. The sections having the smallest diameter of around 40 millimeters are illustrated on the far left of the plot, and these sections had the highest peak load relative to other diameter sizes when other factors were left unchanged. The sections having the largest diameter of around 120 millimeters are illustrated on the far right in the plot, and these sections had the lowest peak load relative to other diameter sizes when other factors were left unchanged. The smaller diameters correlate to higher peak loads because smaller sections are physically stiffer than larger sections, and hence the smaller sections require more force to cause the section to deflect enough to pull the edges of the section inward and to create sufficient clearance for the section to release.

[0321] Also, a larger amount of force was required to release laser perforated sections when sheets having a larger thickness were used. The data points 4602 (each positioned proximate to the top of the plot 4600) each corresponded to sheets having a thickness of 1.3 millimeters, which was the highest thickness of the data points presented in the plot 4600. The data points 4602 each had the highest peak load relative to the other data points presented in the plot 4600. The data points 4606 (each positioned proximate to the bottom of the plot 4600) corresponded to sheets having a thickness of 0.7 millimeters, which was the lowest thickness of the data points presented in the plot 4600. The data points 4606 each had the lowest peak load relative to the other data points presented in the plot 4600. Thicker sheets are generally stiffer, and this may explain the larger amount of force required as the sheet thickness is increased. As theSP24-277-3thickness is adjusted, the measured peak load generally scales as the thickness raised to the third power (t3), correlating with mechanical beam theory.

[0322] Testing was also performed to evaluate the impact of using lasers to create nonlinear perforations relative to using basic linear perforations. FIG. 47 is a plot 4700 illustrating the peak load as a function of the section diameter where these two different chamfer approaches were used. In the plot 4700, data was obtained using a glass sheet having athickness of about 0.7 millimeters, and the sections used in the glass sheet had different diameters. The x-axis of the plot illustrates different testing conditions for the various datapoints. Datapoints 4702 used basic straight perforations and a section having a 40 millimeter diameter. Datapoints 4704 used non-linear perforations to create a C-style chamfered edge and a section having a 42 millimeter diameter. Datapoints 4706 used basic straight perforations and a section having an 80 millimeter diameter. Datapoints 4708 used laser formed perforations to create a C-style chamfered edge and a section having an 82 millimeter diameter. The laser formed perforations used for datapoints 4704, 4708 created C-style chamfered edges similar to those described in other embodiments herein.

[0323] While datapoints 4702 and the datapoints 4704 were obtained using similar section diameters of 40 millimeters and 42 millimeters respectfully, the datapoints 4704 had an average peak load of about 53.8446 Newtons while the datapoints 4702 had a peak load of about 19.1813 Newtons. Thus, the peak load for the datapoints 4704 was about 2.8 times higher than the peak load for the datapoints 4702. The datapoints 4702 included four datapoints, with the datapoints having peak loads of 19.304 Newtons, 19.016 Newtons, 19.151 Newtons, and 19.254 Newtons. The datapoints 4704 included five datapoints, with the datapoints having peak loads of 56.782 Newtons, 54.931 Newtons, 55.481 Newtons, 51.858 Newtons, and 50.171 Newtons. If anything, the larger diameter used to obtain the datapoints 4704 relative to the datapoints 4702 would have led to a reduction in the peak load if all other variables were kept constant.

[0324] While datapoints 4706 and the datapoints 4708 were obtained using similar section diameters of 80 millimeters and 82 millimeters respectfully, the datapoints 4708 had a peak load of about 32.1938 Newtons while the datapoints 4706 had a peak load of about 10.1484 Newtons. Thus, the peak load for the datapoints 4708 was about 3.2 times higher than the peak load for the datapoints 4706. The datapoints 4706 included five datapoints, with the datapoints having peak loads of 10.144 Newtons, 10.338 Newtons, 10.683 Newtons, 9.647 Newtons, and 9.93 Newtons. The datapoints 4708 included six datapoints, with the datapoints having peak loads of 32.214 Newtons, 32.842 Newtons, 33.239 Newtons, 31.575 Newtons, 30.323SP24-277-3Newtons, and 32.97 Newtons. If anything, the larger diameter used to obtain the datapoints 4708 relative to the datapoints 4706 would have led to a reduction in the peak load if all other variables were kept constant. Thus, the C-style chamfered edges greatly increased the peak load required to generate release of laser perforated sections relative to the straight perforated edges, showing that the laser formed non-linear perforations improved the robustness against pop-out.

[0325] Additional laser chamfers were made with an Airy laser beam, and FIG. 48 illustrates peak load for sheets perforated using Airy laser beams relative to other testing sheets that were perforated with straight perforations. In the plot 4800, the thickness was 0.7 millimeters for all datapoints. Furthermore, test results for different perforation types are shown.

[0326] Datapoints 4802 corresponded to a sheet having curved chamfered edges with a section diameter of about 40 millimeters, and the datapoints 4802 had an average peak load of about 41.6633 Newtons. Datapoints 4804 corresponded to a sheet having straight perforations with a section diameter of about 40 millimeters, and the datapoints 4804 had an average peak load of about 19.1813 Newtons. Datapoints 4806 corresponded to a sheet having C-style chamfered edges with a section diameter of about 42 millimeters, and the datapoints 4806 had an average peak load of about 53.8446 Newtons. Thus, the datapoints 4802 where curved chamfered edges were used had peak loads of about 2.17 times more than the datapoints 4804 where straight perforations were used, and the datapoints 4806 where C-style chamfered edges were used had peak loads of about 2.81 times more than the datapoints 4804 where straight perforations were used. The datapoints 4806 where C-style chamfered edges were used had peak loads of about 1.29 times more than the datapoints 4802 where curved chamfered edges were used. Thus, the curved chamfered edges and C-style chamfered edges significantly decreased the likelihood of section release occurring relative to when straight perforations were used, and C-style chamfered edges required about 29 percent more force before section release occurred relative to curved chamfered edges. While the results for curved and C-style chamfered edges were different, these differences were likely a function of small differences in the total apex amplitude of the specific curved chamfered edges and C-style chamfered edges chamfers that were tested, and these chamfers may have similar peak load values where the total apex amplitude for these chamfers are the same. In general, chamfers with large apex amplitudes or deeper chamfers are expected to require the most force to create enough deflection and clearance to pop-out.SP24-277-3

[0327] Datapoints 4808 corresponded to a sheet having curved chamfered edges with a section diameter of about 80 millimeters, and the datapoints 4808 had an average peak load of about 26.695 Newtons. Datapoints 4810 corresponded to a sheet having straight perforations with a section diameter of about 80 millimeters, and the datapoints 4810 had an average peak load of about 10.1484 Newtons. Datapoints 4812 corresponded to a sheet having C-style chamfered edges with a section diameter of about 82 millimeters, and the datapoints 4802 had an average peak load of about 32.1938 Newtons.

[0328] Thus, the datapoints 4808 where curved chamfered edges were used had peak loads of about 2.63 times more than the datapoints 4810 where straight perforations were used, and the datapoints 4812 where C-style chamfered edges were used had peak loads of about 3.17 times more than the datapoints 4810 where straight perforations were used. The datapoints 4812 where C-style chamfered edges were used had peak loads of about 1.21 times more than the datapoints 4808 where curved chamfered edges were used. Thus, the curved chamfered edges and C-style chamfered edges significantly decreased the likelihood of section release occurring relative to when straight perforations were used, and C-style chamfered edges required about 21 percent more force before section release occurred relative to curved chamfered edges. While the results for curved and C-style chamfered edges were different, these differences were likely a function of small differences in the total apex amplitude of the specific curved chamfered edges and C-style chamfered edges that were tested, and these chamfers may have similar peak load values where the total apex amplitude for these chamfers are the same.

[0329] Multi-spot Gaussian beams may also be used. Based on the larger apex height chamfer available for chamfers made using multi-spot Gaussian beams, these multi-spot Gaussian beams are expected to enable even greater pop-out robustness than the C-style chamfered edges and curved chamfered edges. Finite element modeling confirmed this general expectation and revealed that pop-out is reduced when larger chamfer apex distances for chamfers are increased and when other factors such as the contour geometry and the load condition are otherwise maintained.

[0330] Additionally, polishing (e.g., brush polishing) is often performed after a sheet or a section is subjected to ion-exchange processing, and pre-chamfering edges of a section before ion-exchange may be beneficial for various reasons. Where brush polishing is performed on a section having square edges that have been subjected to ion-exchange, the range of final edge profiles available is limited. While the brush polish process itself may be used to generate a wide range of edge profiles, if the brush polish process is used to remove large amounts ofSP24-277-3material at the comers, then brush polishing may completely remove the compressive regions at those comers. By performing laser chamfering before ion-exchange, ion exchange material may be retained at more consistent levels around the surfaces of a section even after any polishing is performed, and this is demonstrated in FIGS. 49A-49D.

[0331] FIG. 49A illustrates an example section 4900A having a compressive region, with the compressive region comprising ion-exchange material diffused at the surfaces of the section where the section 4900A has not been pre-chamfered before ion-exchange processes. The section 4900A has a first surface 4902A, a second surface 4902C opposite the first surface 4902A, and an edge surface 4902B extending between the first surface 4902A and the second surface 4902C. A compressive region is positioned at each of the surfaces 4902A-4902C. For example, a compressive region 4904A is positioned at the first surface 4902A, a compressive region 4904E is positioned at the second surface 4902C, and a compressive region 4904C is positioned at the edge surface 4902B. Additionally, a compressive region 4904B is positioned at the comer where the first surface 4902A and the edge surface 4902B meet, and a compressive region 4904D is positioned at the comer where the second surface 4902C and the edge surface 4902B meet. The compressive region generally possesses a DOL T5 at all surfaces and comers of the section 4900A, with the DOL T5 being about the same at the surfaces 4902A-4902C. However, the DOL T5 is slightly greater for the compressive region 4904B and the compressive region 4904D at the comers since there are multiple surfaces where ion-exchange diffusion may occur.

[0332] However, when polishing is performed, ion-exchange material that has been diffused may be removed at various locations within the sheet. Polishing may be performed through bmsh polishing techniques, which may perform edge removal to remove a very small amount of material (e.g., about 10 micrometers of material) at surfaces. However, bmsh polishing may also be used to remove more material from surfaces. Bmsh polishing may deliver a fine polish without removing compressive regions entirely at edge surfaces, allowing resulting sections that are formed to have high edge strengths due to the removal or reduction in the size of any edge flaws. Additionally, where bmsh polishing is performed, the roughness of surfaces that have been subjected to bmsh polishing may be lower than other surfaces that have not been subjected to bmsh polishing. For example, surfaces that have been bmsh polished may have an average surface roughness of about 100 nanometers or less.

[0333] FIG. 49B illustrates a section 4900B, with this section 4900B showing the section 4900A after polishing. The line 4906 illustrates the example edge profile after polishing. As illustrated, compressive regions 4904B, 4904D at the comers are removed after polishingSP24-277-3alongside some of the compressive regions 4904A, 4904C, 4904D at the other surfaces. Thus, after polishing, the compressive region is not present at all surfaces of the section and the compressive region is present in inconsistent levels around the surfaces.

[0334] To avoid having locations where no compressive region is present, brush polishing may be performed in a different manner so that a different edge profile is obtained, with less material being removed at the comers. This may provide the sections with higher edge strengths due to the presence of the compressive region at the edges. However, by removing less material at the comers, the final edge profiles that are available are more limited — the contact angle that may be accomplished at edge surfaces becomes more limited, and the apex distance for the edge also becomes more limited.

[0335] However, where edges of sections have been pre-chamfered, compressive regions may remain at more consistent levels at all surfaces of the sections. FIG. 49C illustrates an example section that has been pre-chamfered and then exposed to ion-exchange material. The section 4900C has a first surface 4912A, a second surface 4912E opposite the first surface 4912A, and an edge surface extending between the first surface 4912A and the second surface 4912E. The edge surface comprises a first portion 4912B, a second portion 4912D, and an apex portion 4912C. While the apex portion 4912C is relatively flat, the first portion 4912B and the second portion 4912D are rounded and connect the edge surface to the first surface 4912A and the second surface 4912E.

[0336] A compressive region comprising ion-exchange material is positioned at each of the surfaces. For example, a compressive region 4914A is positioned at the first surface 4912A, a compressive region 4914B is positioned at the first portion 4912B of the edge surface, a compressive region 4914C is positioned at the apex portion 4912C of the edge surface, a compressive region 4914D is positioned at the second portion 4912D of the edge surface, and a compressive region 4914E is positioned at the second surface 4912E. The compressive region generally possesses a DOL T6 at all surfaces of the section 4900C, with this DOL T6 being about the same at the surfaces 4912A-4912E.

[0337] FIG. 49D is a schematic view illustrating a section 4900D, with the section 4900D showing the section 4900C of FIG. 49C after brush polishing. Even after polishing is performed, a compressive region remains at all surfaces. The line 4918 is indicative of the amount of material removed at the edge surface of the section 4900D. As illustrated, some portion of the compressive regions 4914B, 4914C, 4914D are removed at the edge surface, resulting in a smaller DOL for compressive regions 4914B, 4914C, 4914D at the edge surface relative to the compressive regions 4914A, 4914E at other surfaces. However, the DOL at theSP24-277-3edge surface may still remain greater than about 3 micrometers at all locations of the edge surface. Retaining DOL ensures that a compressive region is retained at the edge surface, which improves the strength of the edge. In some embodiments, the DOL of compressive regions 4914A, 4914E at surfaces 4912A, 4912E may be at least about 5 micrometers more than the DOL of compressive regions 4914B, 4914C, 4914E at the edge surface. Polishing may also result in a reduced surface concentration of ion-exchange material (e.g., potassium) at the edge surface relative to the surface concentration of ion-exchange material at the surfaces 4912A, 4912E.

[0338] By chamfering edges before ion-exchange processing, the final apex distance of the edge surfaces may be greater than or equal to the DOL of the compressive regions at surfaces 4912A, 4912E. This may allow the sheets to be maintained with a high strength due to the presence of compressive regions at all surfaces, and hence the compressive stress at all surfaces, while also allowing edge surfaces to have greater contact angles so that the comers of the chamfered part are less likely to fail through cracking or chipping.

[0339] FIG. 50 is a block diagram illustrating various components within an example laser system 5000. The laser system 5000 includes a laser 5002. The laser 5002 may possess various forms, and the laser may be configured to generate laser beams in bursts of pulses in some embodiments. In some embodiments, the laser may be an ultrafast last that is configured to generate laser beams in pulses having pulse widths that are at the femtosecond or picosecond level. The laser 5002 may have similar properties to those used for other lasers described herein, but these properties may be modified in other embodiments.

[0340] The laser system 5000 also includes a motion platform 5008, a rotatable optical element holder 5010, and one or more actuators 5014. The motion platform 5008 may act as a mechanical stage where a sheet may be positioned during laser processing. The motion platform 5008 may be configured to retain a sheet in a fixed position relative to the motion platform 5008, and the motion platform 5008 may be configured to move as needed so that perforations or modifications may be formed at the appropriate locations within the sheet. The actuator(s) 5014 may help cause movement of the movement platform 5008, but actuator(s) may be included in the movement platform 5008 in other embodiments to generate movement of the movement platform 5008. The rotatable optical element holder 5010 may be configured to hold a rotatable optical element where one is used. The rotatable optical element holder 5010 may be configured to retain a rotatable optical element in a fixed position relative to the rotatable optical element holder 5010, and the rotatable optical element holder 5010 may be configured to move and / or rotate as needed so that the rotation optical element is positioned inSP24-277-3the correct location and / or is oriented in the correct orientation. The actuator(s) 5014 may help cause movement of the rotatable optical element holder 5010, but actuator(s) may be included in the rotatable optical element holder 5010 in other embodiments to generate movement of the rotatable optical element holder 5010. The actuator(s) 5014 may be provided in various forms. Actuator(s) 5014 may be provided in the form of a linear actuator, a rotary actuator, a mechanical actuator such as a rack and pinion type or cam type actuator, or another type of actuator.

[0341] The laser system 5000 also includes a spatial light modulator 5012. The spatial light modulator 5012 is a device that may impart a phase between 0 and 2n (in 256 steps) at each independent pixel to an incoming laser beam which is reflected off the spatial light modulator 5012. The spatial light modulator 5012 may have a particular resolution (e.g., 1152 pixels by 1920 pixels) with a pitch between adjacent pixels (e.g., about 8 micrometers). However, the spatial light modulator 5012 may have different resolutions, pitches, and other properties. In some embodiments, the spatial light modulator 5012 may be a liquid crystal spatial light modulator configured to use liquid crystals to modulate light. In other embodiments, the spatial light modulator 5012 may be a digital micromirror device (DMD) configured to use an array of small mirrors to reflect and modulate light. However, other types of modulators may be used. Also, passive beam shaping devices such as a diffractive optical element may also be used.

[0342] The laser system 5000 also includes one or more processors 5004. The processor(s) 5004 may be configured to perform a variety of functions, and the processor(s) 5004 may execute operations or instructions stored at the memory device(s) 5006 or at another location. The processor(s) 5004 may be any means configured to execute various programmed operations or instructions stored in a memory device (e.g., memory device(s) 5006) such as a device or circuitry operating in accordance with software or otherwise embodied in hardware or a combination of hardware and software (e.g. a processor operating under software control or the processor embodied as an application specific integrated circuit (ASIC) or field programmable gate array (FPGA) specifically configured to perform the operations described herein, or a combination thereof) thereby configuring the device or circuitry to perform the corresponding functions of the processor(s) 5004 as described herein.

[0343] The laser system 5000 also includes memory device(s) 5006. In an example embodiment, the memory device(s) 5006 may include one or more non-transitory storage or memory devices such as, for example, volatile and / or non-volatile memory that may be either fixed or removable. The memory device(s) 5006 may be configured to store instructions,SP24-277-3computer program code, and additional data in a non-transitory computer readable medium for use, such as by the processor(s) 5004 for enabling the components of the laser system 5000 to carry out various functions in accordance with example embodiments of the present invention. For example, the memory device(s) 5006 may be configured to buffer input data for processing by the processor(s) 5004. Additionally or alternatively, the memory device(s) 5006 may be configured to store instructions for execution by the processor(s) 5004. The memory device(s) 5006 may include computer program code that is configured to, when executed, cause processor(s) 5004 to perform various methods described herein. The memory device(s) 5006 may serve as non-transitory computer readable mediums having stored thereon software instructions that, when executed by one or more processors, cause methods described herein to be performed.

[0344] The laser system 5000 may also include one or more communication interface(s) 5016. The communications interface(s) 5016 may be configured to enable communication to other components outside of the laser system 5000. However, the communications interface(s) 5016 may also be configured to enable communication between elements within the laser system 5000. The communications interface(s) 5016 may also include one or more communications modules configured to communicate with one another in any of a number of different manners including, for example, via a network. In this regard, the communications interfaces 5016 may include any of a number of different communication backbones or frameworks including, for example, Ethernet, global positioning system (GPS), cellular, WiFi, or other suitable networks. The network may also support other data sources, including GPS. In this regard, numerous other peripheral devices may be included in the laser system 5000. In some embodiments, some or all of the communications interfaces 5016, may be configured to communicate using short-range wireless technologies such as Bluetooth (e.g., Bluetooth Version 4.1 or another version), Wi-Fi, NearLink, near-field communication (NFC), low power wide area networks (LPWAN), ultra-wideband (UWB), wireless local area network (WLAN) in accordance with IEEE 802.11(b), IEEE 802.11(g), and / or IEEE 802.11(n) standards, and / or low-rate wireless personal access networks (LR-WPAN) pursuant to the IEEE 802.15.4 standard.

[0345] The components of the laser system 5000 may be connected in various ways, and the connections between the components may be wired or wireless connections in some embodiments. For example, the laser system 5000 may connect to other devices using a Bluetooth connection, a Wi-fi connection, or another similar short range wireless technology. However, other connection approaches may be used for the laser system 5000.SP24-277-3

[0346] FIG. 51 is a flow chart illustrating an example method 5100 for modifying a sheet to form an internal feature in the sheet. At operation 5102, a laser beam is generated. This laser beam may be an Airy beam, a caustic beam, a Bessel beam, a multi-segment Bessel beam, or a multi-spot or multi-focus Gaussian beam in some embodiments, but other laser beams may be generated in other embodiments.

[0347] At operation 5104, the laser beam is directed to a rotatable optical element. The rotatable optical element may be similar to one of the rotatable optical elements of FIGS. 18A or 18B in some embodiments. The rotatable optical element may be provided in the form of a Dove prism and may include a first surface and a second surface. The laser beam may be directed to the rotatable optical element so that the laser beam is received at the first surface with a first beam profile, so that the laser beam exits the rotatable optical element at the second surface with a second beam profile, and so that the laser beam is directed to the sheet after exiting the first optical element to generate the internal feature in the sheet. However, the rotatable optical element may include a k-mirror assembly.

[0348] At operation 5106, the rotatable optical element is rotated. The rotatable optical element may be rotated by a first angle, and the rotatable optical element may be rotated while the laser beam is actively being directed to the rotatable optical element. By doing so, an internal feature may be formed in the sheet. The second beam profile is rotated relative to the first beam profile by a second angle when the first optical element is rotated by the first angle. The second angle may be at least about 1.25 times more than the first angle, at least about 1.5 times more than the first angle, at least about 1.75 times more than the first angle, at least about 2 times more than the first angle, at least about 2.25 times more than the first angle, or at least about 2.5 times more than the first angle.

[0349] At operation 5108, a determination is made regarding whether further internal features are needed. If further internal features are not needed, then the method 5100 may be completed. If further internal features are needed, then the method 5100 may proceed to operation 5110. At operation 5110, a position of the sheet may be adjusted relative to the rotatable optical element, and the method 5100 may then proceed again through the discussed operations. By adjusting the position of the sheet, any new internal features formed at the sheet may be formed at a different location. While method 5100 is used to form internal features in a sheet, the method 5100 may be used to make other modifications to a sheet.

[0350] FIG. 52 is a flow chart illustrating an example method 5200 for singulating sections of a sheet to form individual substrates. In the method 5200, the sheet and the sections thereinSP24-277-3may comprise glass, and the sheet may be subjected to ion-exchange to increase the strength of the sheet and the sections therein.

[0351] At operation 5202, laser perforations are formed in a sheet. Section contour(s) within a glass sheet are defined by a laser perforation process. The laser perforations may be performed in patterns to form the section contour(s), with the section(s) having one or more internal edges. The laser perforations may be formed using laser beams such as a multiplesegment Bessel-like laser beam, a continuously curving Airy-like laser beam, or a multi-spot Gaussian beam.

[0352] Any sections within the sheet may be similar to the sections described in reference to FIG. 32 in some embodiments. Sections may include a first surface extending in a first plane and a second surface opposite the first surface, with the second surface extending in a second plane parallel to the first plane. An edge surface may extend between the first surface and the second surface, and the edge surface may have a non-linear profile having an apex. A first comer may join the edge surface and the first surface, and a second comer may join the edge surface and the second surface. The edge surface may extend further at the apex than it does at the first comer and the second comer. Sheets and any sections formed therein may comprise glass or other materials. Any laser perforations that are formed may extend fully through a depth of the sheets.

[0353] At operation 5204, ion-exchange processing is performed with the sheet. Ionexchange processing may be performed before any sections have been singulated from the sheet. The perforations formed in operation 5202 may serve as conduits for ion-exchange, and the internal edges of sections within the sheets may be fully ion-exchanged even though the section(s) are held within a larger sheet through the ion-exchange process. By using a laser process that may create non-linear shaped laser perforations (e.g., curved perforations, multisegment perforations, etc.), edge chamfers may retain the sections more effectively within the larger sheet. This addresses the problem of “pop-out” for the sections during later handling. Material that is diffused during the ion-exchange may be positioned along the first surface, the second surface, and the edge surface of sections that are formed within sheets.

[0354] The laser perforations themselves comprise modified regions that extend through the depth of the sheet. The laser modified regions form internal part edges that are chamfered — for example, the laser perforations and the edges formed by the laser perforations may be curved and / or may comprise multiple angles extending through the depth of the sheet. Thus, the laser perforations may have more complex shapes than other laser perforations, which are typically straight.SP24-277-3

[0355] Laser perforations may generate perforations within sheets, and these perforations may have any of the shapes described herein. The perforations may, for example, possess any of the shapes illustrated in FIGS. 26A or 26B. Perforations may cause the sections to have contact angles between a line normal to their flat side surfaces and the edge surface as described herein, and these contact angles may be at least about 10 degrees, at least about 12.5 degrees, at least about 15 degrees, at least about 17.5 degrees, or at least about 20 degrees. These contact angles may be measured at the comers where edge surfaces meet the flat side surfaces. Laser perforations may be formed using a multi-segment angled Bessel beam profde, a caustic beam profde, a modified Airy beam profile, or a curving Bessel beam profile, but other laser beam profiles may be used in other embodiments.

[0356] At operation 5206, the sheet or section(s) within the sheet may be coated with coating material. The coating material may be an ink, a dielectric coating such as an anti-reflective layer, a metal, or a polymer. However, other coating materials may be used. The coating material may be selected to impart different properties on the sheet and the sections therein. For example, the coating material may be used to change the cosmetic appearance of the sheet, to make the material less reflective, or to impart other properties. In some embodiments, operation 5206 may optionally be omitted.

[0357] At operation 5208, section(s) may be released from other portions of the sheet. The frame of the glass sheet is cut off, and this may result in parts being releasing the parts whose contour(s) were defined in the laser perforation step.

[0358] At operation 5210, edge surface(s) of the section(s) may be polished. Polishing may optionally be performed to further raise the edge strength of the section(s). Polishing may be done through fine polishing processes such as brush polishing, but other approaches may be used. Even where polishing is performed at operation 5210, polishing may remove less material than the DOL of ion-exchange material diffused during operation 5204. In other words, even after operation 5210, a compressive region comprising ion-exchange material may remain positioned around the edge surface and other surfaces of the section(s). However, polishing at the edge surfaces may tend to reduce the DOL of compressive regions at edge surfaces relative to other surfaces of sections. In some embodiments, the DOL of compressive regions at the edge surface may be at least about 5 micrometers less than a DOL of the compressive regions at each of the first surface and the second surface.

[0359] FIG. 53 is a flow chart illustrating an example method 5300 for forming a chamfered edge in a sheet. The sheet may comprise glass in some embodiments.SP24-277-3

[0360] At operation 5302, a laser beam is generated. The laser beam may be a caustic laser beam or a curving Bessel beam. In some embodiments, the laser beam may have an intensity profile, and the intensity profile may have a rectangular or an oval shape. However, other shapes may be used for the intensity profile in other embodiments. In some embodiments, the laser beam may be generated in bursts, with each of the bursts comprising a plurality of pulses. Each of the bursts may include at least five pulses, and a time delay may be provided between each of the pulses. The time delay may at least about 12 nanoseconds in some embodiments, but a different time delay value may be used in other embodiments. At operation 5304, the laser beam is directed to a sheet so that the laser beam may form the chamfered edge.

[0361] At operation 5306, a first phase is applied to the laser beam. The first phase may be a prism phase. The first phase may reduce angles of light rays within the laser beam relative to the optical axis relative to when the first phase is not applied. Additionally or alternatively, the first phase may reduce resolution requirements of a phase mask relative to when the first phase is not applied. In some embodiments, operation 5306 may only be performed when the laser beam generated at operation 5304 is a caustic beam.

[0362] At operation 5308, a second phase is applied to the laser beam. The second phase may flatten an intensity profile of the laser beam in its lengthwise direction (e.g., in the z-coordinates) relative to when the second phase is not applied. Additionally or alternatively, the second phase may increase a usable length of the laser beam during cutting relative to when the second phase is not applied. In some embodiments, operation 5308 may only be performed when the laser beam generated at operation 5304 is a caustic beam.

[0363] At operation 5310, a first half of the laser beam is formed downstream proximate to the conjugate plane of the 4f system and the other half may be formed upstream proximate to the conjugate plane of the 4f system using a binary phase mask. In doing so, the binary phase mask may form a first half of the laser beam that is symmetric to a second half of the laser beam. In some embodiments, operation 5310 may only be performed when the laser beam is a curving Bessel beam.

[0364] At operation 5312, an optical delay element (e.g., a glass piece) is positioned relative to the laser beam. The optical delay element may be positioned so that about one half of the laser beam travels through the optical delay element while a remaining portion of the curving Bessel beam does not travel through the optical delay element. By doing so, the optical delay element may spatially offset half of the laser beam relative to the remaining portion of the laser beam along a length of the laser beam. In some embodiments, operation 5312 may only be performed when the laser beam is a curving Bessel beam.SP24-277-3

[0365] At operation 5314, a first polarization mask is positioned relative to the laser beam. The first polarization mask may be a split quarter wave plate in some embodiments. The splitquarter wave plate may be formed by obtaining a quarter wave plate having four comer sections and by flipping two opposing comer sections relative to each other. This may create a multisection waveplate where each waveplate section has a fast axis that is orthogonal to the fast axis of the waveplate sections adjacent to it. In some embodiments, operation 5314 may only be performed when the laser beam is a curving Bessel beam.

[0366] At operation 5316, a second polarization mask is positioned relative to the laser beam. The second polarization mask may be a quarter wave plate in some embodiments. By positioning the second polarization mask, a circular input polarization may be obtained. In some embodiments, operation 5316 may only be performed when the laser beam is a curving Bessel beam.

[0367] Using the method 5300, one or more chamfered edges having the desired properties may be formed, with the chamfered edge(s) having a corresponding edge surface. The edge surface may extend between a first surface of the sheet and a second surface of the sheet opposite the first surface. A contact angle is defined between a line normal to the first surface and a portion of the edge surface immediately adjacent to the first surface, and the contact angle may be at least about 12.5 degrees or more, at least about 15 degrees or more, at least about 17.5 degrees or more, at least about 20 degrees or more, at least about 22.5 degrees or more, at least about 25 degrees or more, at least about 27.5 degrees or more, or at least about 30 degrees or more.

[0368] The methods described herein are merely exemplary, and the methods may be modified in various ways within departing from the scope of the present inventions. For example, the various methods herein may be modified to add further operations or to omit certain operations. In some embodiments, the methods described herein may be fully or partially combined together. In some embodiments, the order of operations in the methods may be adjusted, and some of the operations may be performed simultaneously in some embodiments (e.g., operations 5306 and 5308 may be performed simultaneously in some embodiments).CONCLUSION

[0369] Many modifications and other embodiments set forth herein will come to mind to one skilled in the art to which these embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to beSP24-277-3understood that the embodiments are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the invention. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the invention. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated within the scope of the invention. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

SP24-277-3WHAT IS CLAIMED IS:

1. A sheet comprising:a first surface extending in a first plane;a second surface opposite the first surface extending in a second plane parallel to the first plane, wherein a first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction; andperforations extending between the first surface and the second surface, the perforations defining a section of the sheet retained within a frame of the sheet, wherein the perforations form an edge in the sheet, the edge is an internal edge in the sheet, the edge has a non-linear profile having an apex, a first comer joins the edge and the first surface, a second comer joins the edge and the second surface, the edge extends further in the second direction at the apex than at the first comer and the second comer, the sheet comprises a compressive region positioned along the first surface, the second surface, and the edge, the compressive region being a region within the sheet where material is under compressive stress, and the sheet comprises glass.

2. The sheet of claim 1, wherein the compressive region is formed through ion-exchange with ion-exchange material diffusing into the sheet to create the compressive region.

3. The sheet of any of claims 1-2, wherein the compressive region extends entirely from the first surface to the second surface at one or more locations on the sheet.

4. The sheet of any of claims 1-3, further comprising:one or more coatings present on the sheet,wherein the one or more coatings comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer.

5. The sheet of any of claims 1-4, wherein a depth of layer of the compressive region at the edge is about 5 micrometers or more.

6. A substrate comprising:a first surface extending in a first plane;SP24-277-3a second surface opposite the first surface extending in a second plane parallel to the first plane, wherein a first direction extends normal to the first plane and the second plane, and a second direction extends perpendicularly to the first direction; andan edge extending between the first surface and the second surface, the edge being formed from laser perforations extending from the first surface and the second surface, wherein the edge has a non-linear profile having an apex, a first comer joins the edge and the first surface, a second comer joins the edge and the second surface, the edge extends further in the second direction at the apex than at the first comer and the second comer, the substrate comprises a compressive region positioned along the first surface, the second surface, and the edge, the compressive region being a region within the substrate where material is under compressive stress, and the substrate comprises glass.

7. The substrate of claim 6, wherein the compressive region is formed through ionexchange with ion-exchange material diffusing into the substrate to form the compressive region.

8. The substrate of claim 7, wherein the ion-exchange material in the compressive region comprises potassium or sodium.

9. The substrate of any of claims 7-8, wherein a surface concentration of the ionexchange material at the edge is less than a surface concentration of the ion-exchange material at the first surface.

10. The substrate of any of claims 6-9, wherein the edge comprises a curved shape or a plurality of flat surfaces.

11. The substrate of any of claims 6-10, wherein the edge defines an apex distance that is equal to or greater than a depth of layer of the compressive region at the first surface, with the apex distance being a maximum distance that the apex extends out in the second direction relative to the first comer.

12. The substrate of any of claims 6-11, wherein a depth of layer of the compressive region at the edge is about 5 micrometers or more.SP24-277-313. The substrate of claim 12, wherein the depth of layer of the compressive region at the edge is less than a depth of layer of the compressive region at the first surface.

14. The substrate of claim 13, wherein the depth of layer for the compressive region at the edge is at least about 5 micrometers less than the depth of layer for the compressive region at the first surface.

15. The substrate of any of claims 6-14, wherein a roughness average at the first surface, the second surface, or the edge is less than or equal to 100 nanometers.

16. The substrate of any of claims 6-15, further comprising:one or more coatings present on the substrate,wherein the one or more coatings comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer.

17. The substrate of any of claims 6-16, wherein a first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the edge immediately adjacent to the first surface, a second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the edge immediately adjacent to the second surface, and the first contact angle and the second contact angle are both at least about 10 degrees or more such that a change in direction for the edge from the first surface to the second surface is at least about 20 degrees.

18. The substrate of claim 17, wherein the first contact angle and the second contact angle are both at least about 12.5 degrees or more such that the change in direction for the edge from the first surface to the second surface is at least about 25 degrees.

19. The substrate of claim 18, wherein the first contact angle and the second contact angle are both at least about 20 degrees or more such that the change in direction for the edge from the first surface to the second surface is at least about 40 degrees.

20. A method for making a substrate, the method comprising:forming laser perforations in a sheet, wherein the laser perforations define the substrate having an edge within the sheet, the edge is an internal edge within the sheet, theSP24-277-3substrate defines a first surface extending in a first plane, a second surface opposite the first surface extending in a second plane parallel to the first plane, and the edge extending between the first surface and the second surface, a first direction extends normal to the first plane and the second plane, a second direction extends perpendicularly to the first direction, the edge has a non-linear profile having an apex, a first comer joins the edge and the first surface, a second comer joins the edge and the second surface, and the edge extends further in the second direction at the apex than at the first comer and the second comer;creating a compressive region in the sheet, with the compressive region positioned along the first surface, the second surface, and the edge; andreleasing the substrate from other portions of the sheet,wherein the substrate comprises glass.

21. The method of claim 20, wherein the compressive region is created by performing ion-exchange with the sheet, wherein, during ion-exchange, ion-exchange material is diffused into the sheet to form the compressive region.

22. The method of any of claims 20-21, wherein the laser perforations extend fully through a depth of the sheet.

23. The method of any of claims 20-22, further comprising:coating the sheet or the substrate with one or more coatings,wherein the one or more coatings comprise at least one of an ink, a dielectric coating, an anti-reflective layer, a metal, or a polymer.

24. The method of any of claims 20-23, further comprising:polishing the edge of the substrate,wherein the edge is polished either before the substrate is released from the other portions of the sheet or after the substrate is released from the other portions of the sheet.

25. The method of any of claims 20-24, wherein, after polishing of the edge, the compressive region remains positioned around the edge.SP24-277-326. The method of claim 25, wherein a depth of layer of the compressive region at the edge is at least about 5 micrometers less than a depth of layer of the compressive region at the first surface.

27. The method of any of claims 20-26, wherein a first contact angle is defined between a first line normal to the first surface and a second line tangent to a portion of the edge immediately adjacent to the first surface, a second contact angle is defined between a third line normal to the second surface and a fourth line tangent to a portion of the edge immediately adjacent to the second surface, and the first contact angle and the second contact angle are both at least about 12.5 degrees or more such that a change in direction for the edge from the first surface to the second surface is at least about 25 degrees.

28. The method of any of claims 20-27, wherein the laser perforations are formed using at least one of a multi-segment angled Bessel beam profile, a caustic beam profile, an Airy beam profile, a curving Bessel beam profile, or a multi-spot Gaussian beam.

29. A substrate formed by the process of:forming laser perforations in a sheet, wherein the laser perforations define the substrate having an edge within the sheet, the edge is an internal edge within the sheet, the substrate defines a first surface extending in a first plane, a second surface opposite the first surface extending in a second plane parallel to the first plane, and the edge extending between the first surface and the second surface, a first direction extends normal to the first plane and the second plane, a second direction extends perpendicularly to the first direction, the edge has a non-linear profile having an apex, a first comer joins the edge and the first surface, a second comer joins the edge and the second surface, and the edge extends further in the second direction at the apex than at the first comer and the second comer;creating a compressive region in the sheet, with the compressive region positioned along the first surface, the second surface, and the edge; andreleasing the substrate from other portions of the sheet,wherein the substrate comprises glass.

30. The substrate of claim 29, wherein the compressive region is created by performing ion-exchange with the sheet, wherein, during ion-exchange, ion-exchange material is diffused into the sheet to form the compressive region.

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