WO2021035565A1

WO2021035565A1 - Bessel beam with axicon for glass cutting

Info

Publication number: WO2021035565A1
Application number: PCT/CN2019/102977
Authority: WO
Inventors: Long Zhang; Andreas Oehler; Jan-Willem Pieterse
Original assignee: Lumentum Operations Llc
Priority date: 2019-08-28
Filing date: 2019-08-28
Publication date: 2021-03-04
Also published as: WO2021036155A1; CN112440005A; WO2021036155A8

Abstract

A method for cutting glass comprises: generating an incident Gaussian beam with a ultrafast laser; converting the incident Gaussian beam into a Bessel beam with an axicon; transmitting the Bessel beam through a lens with the large focal length and a tight-focus lens successively; and focusing the beam on glass for cutting the glass.

Description

BESSEL BEAM WITH AXICON FOR GLASS CUTTING

A Bessel beam is a non-diffraction beam with an extended Rayleigh range and a characteristic of self-reconstruction. An extended Rayleigh range enables generation of an elongated focal area and results in a uniform distribution of pulse energy in a transparent material. Some aspects described herein enable less than 1.1 millimeter (mm) glass cutting. For example, some aspects enable cutting of 0.33 mm glass with a low-power, low-pulse-energy ultrafast laser source.

Figure 1 shows an example of an optical setup for glass cutting. In some aspects, a Bessel beam may be generated by a 178° axicon. An intersectional range (X1) of approximately 190 mm may be generated in a near field after the axicon when an input Gaussian beam is approximately 3 mm. In a far field, an annular beam with an annular width (B1) of approximately 1.5 mm may be provided. A beam expander with an axial magnification of 1/280 may be used to get a subsidiary “Rayleigh range” (X2) . In this case, X2 may be sensitive to a distance Y2 between the two lenses L1 and L2. In some aspects, Y2 may be optimized to obtain a uniform distribution of pulse energy in X2. The distance Y2 may be optimized by using a tick glass (e.g., approximately 5 mm) measured filament length from a side.

As an example, X2 may be approximately 400 micrometers (μm) in the air and may be usable to cut an approximately 0.3 mm gloat glass. In some aspects, to achieve a longer X2, an input beam may be enlarged or a magnification may be increased. For example, X2 may be increased to approximately 2 mm in the air if the input beam is increased to approximately 15 mm or an axial magnification is increased to 1/100.

Additionally, or alternatively, an ultrafast laser with a burst mode may be used for glass cutting. For example, when an ultrashort burst pulse is tightly focused into glass, an optical filament may be generated as a result of a self-focusing effect in a high-power-density area. With respect to an elongated focal area at X2, glass with a certain thickness may be modified in a long filament area. For example, an approximately 0.3 mm glass sample may be processed using a 3-pulse, flat burst mode. Since the sample is associated with a threshold thinness, cutting may be achieved with a burst energy of ～100 micro-Joules (μJ) and an approximately 8 Watt (W) output power at 78 kilohertz (kHz) . As another example, with an approximately 1 mm glass sample, a limited X2 may not enable cutting of such a thick glass (e.g., without a threshold thinness) . As a result, an incident beam may be enlarged to approximately 15 mm. In this case, the burst energy may be increased to approximately 250 μJ and approximately 20 W output power at 78 kHz, which results in a successful processing result. Other values for an incident beam, a burst energy, an output power and/or the like may be used for, for example, thicker glass and other transparent materials.

Some aspects described herein may be deployed with a relatively compact configuration. For example, to minimize the layout, an axicon with a small apex angle may be used. This may result in a large divergence and short X1, and may result in a shortening of the propagation distance (Y1) . Y1 may be defined by an NA of L1. Y2 may be determined based on adding focal length of L1 + approximately 1.5 times an FL of L2. Then, a relatively short focal length may be used for L1 so that a large divergence generated by an axicon is compensated. Further, in view of X2, a clear aperture, and a working distance, an axial magnification may be optimized accordingly. For example, a 170° axicon may be selected and lenses may be optimized with a focal length of 30 mm and 8 mm, respectively. In this way, a layout may be approximately 100 mm or less.

A length of X1 may be determined (e.g., X1 depends on an axicon angle and an input beam diameter) . For example, if an approximately 2 mm X2 cuts an approximately 1mm glass, axial magnification may be determined by X1/X2. For example, for a 170° axicon, a large divergence angle may be achieved when a laser passes through. In this case, divergent light generated by the axicon does not converge using a lens (L1) with a large focal length (e.g., 100 mm) . As a result, a tight-focus lens may be selected (e.g., 30mm) . Further, the focal length of L2 may be determined as approximately X1/X2. For example, the focal length of approximately 8 mm may be determined. In some aspects, a larger L2 may improve cutting of thick glass. In some aspects, a limited size L2 may ensure a threshold power density to ensure generation of a filament inside glass. In some aspects, a shorter L2 may have a small aperture, which may block some power. In some aspects, a distance between L2 and X2 is decreased for a shorter L2. In some aspects, a 175° or 178° axicon may be selected to ensure availability of different values for L1 and L2.

In this way, a glass cutting system may use a Bessel beam and an ultrafast burst laser for glass cutting. In some aspects, such a glass cutting system may improve glass cutting relative to other methods for glass cutting, such as high aberration, polarization induced focal shifts, holographic refraction or reflection, and/or the like. In some aspects, such a glass cutting system may be applicable to any other transparent material beside glass, such as silicon at 1.5 μm is, green transparent materials, red transparent materials, non-ultraviolet (UV) blue transparent materials, and/or the like. In some aspects, a laser requirement could be further reduced for thin (e.g., less than approximately 0.7 mm) glass cutting, resulting in a reduced heat affected zone and lower cost. In some aspects, such a glass cutting system may enable debris free cutting of transparent materials. In some aspects, such a glass cutting system may include a burst mode laser, a Bessel beam, an axicon, an ultrafast laser, and/or the like to enable ultrafast glass cutting.

Some aspects provide glass cutting with a Bessel beam using an optical axicon. Some aspects elongate a focal range (e.g., a Raleigh range) by 10 to 20 times. Some aspects provide added sideways motion to create an energy curtain inside transparent material. Some aspects use an elongated high energy beam with fluence to alter (crack) a material as a preparation for mechanical/thermal separation.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementations.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software.

It will be apparent that systems and/or methods, described herein, may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the implementations. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set.

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related items, and unrelated items, etc. ) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method, device, optical device, optical system, glass cutting system, axicon, laser, computer program product, and non-transitory computer-readable medium as substantially described herein with reference to and as illustrated by the accompanying drawings.