CN112440005A

CN112440005A - Bessel beam with axicon for cutting transparent materials

Info

Publication number: CN112440005A
Application number: CN202010616737.1A
Authority: CN
Inventors: 张龙; A.奥勒; J-W.彼得斯
Original assignee: Lumentum Operations LLC
Current assignee: Lumentum Operations LLC
Priority date: 2019-08-28
Filing date: 2020-06-30
Publication date: 2021-03-05
Also published as: WO2021036155A1; WO2021036155A8; WO2021035565A1

Abstract

A bessel beam laser cutting system may include an ultrafast laser light source, an axicon, a first lens, and a second lens. The ultrafast light source may be configured to emit a light beam into the axicon. The axicon may be configured to diffract the light beam into a first/main bessel beam in an axicon near field and a ring beam in an axicon far field. The first lens may be configured to focus the annular light beam. The second lens may be configured to converge the focused ring beam into a second/secondary bessel beam to modify the transparent material, wherein a modified depth of modification produced by the second/secondary bessel beam is in a range of tens of micrometers to several millimeters inside the transparent material.

Description

Bessel beam with axicon for cutting transparent materials

Cross Reference to Related Applications

Priority of Patent Cooperation Treaty (PCT) application PCT/CN2019/102977 entitled "bessel beam with axicon for glass cutting" filed 2019, 8, 28, 35u.s.c. § 119, entitled "bessel beam for glass cutting", the entire content of which is incorporated herein by reference.

Technical Field

The present disclosure relates to a system for laser cutting transparent materials, and more particularly, to a system for cutting transparent materials such as glass using a bessel beam generated by an axicon. Transparent in this sense means transparent to the laser wavelength used. Which may be opaque to the human eye.

Background

A bessel beam is a non-diffractive laser beam with an extended depth of field (also known as the rayleigh range) and self-reconstructing properties. The extended depth of field enables the production of an elongated focal region with a uniform energy distribution.

Disclosure of Invention

According to some embodiments, a bessel beam laser cutting system may include: an ultrafast laser light source configured to emit a light beam into the axicon; the axicon is configured to diffract the light beam into a first bessel beam in an axicon near field and a ring beam in an axicon far field; a first lens configured to focus the annular light beam; and a second lens configured to converge the focused annular beam into a second bessel beam to modify the transparent material, wherein a depth of modification produced by the second bessel beam is in a range of tens of micrometers to several millimeters inside the transparent material.

According to some embodiments, a cutting system for transparent materials may comprise: an ultrafast laser light source configured to emit ultrashort laser pulses (e.g., laser pulses with pulse durations from several femtoseconds to several hundred picoseconds) into an axicon; the axicon is configured to diffract the ultrashort laser pulse into a first bessel beam in an axicon near-field and a ring beam in an axicon far-field, wherein a depth of field length of the first bessel beam is in a range of 10 millimeters in air to 1 meter in air; a first lens configured to focus the annular light beam; and a second lens configured to converge the focused annular beam into a second bessel beam to modify the transparent material, wherein a depth of field length of the second bessel beam is in a range of 30 millimeters in air to 15 millimeters in air; and wherein the depth of cut of the second bessel beam is in the range of 20 microns to 10 millimeters in the transparent material.

According to some embodiments, a bessel beam cutting system may include: a light source configured to emit a light beam into the axicon; wherein the diameter of the beam is related to the net aperture of the axicon (e.g., for an 85% net aperture of a 1 inch axicon, the diameter would be less than or equal to 22.8 millimeters); the axicon is configured to diffract the input light beam into a first bessel beam in an axicon near field and a ring beam in an axicon far field; wherein the apex angle of the axicon is configured to be in the range of 100 to 180 degrees; and a first lens and a second lens configured to reduce the annular light beam into a second bessel light beam to modify the transparent material, wherein an axial magnification of the annular light beam by the first lens and the second lens is in a range of 1/2500 to 1, and wherein a modification depth of the second bessel light beam is in a range of 30 micrometers to 10 millimeters at the transparent material.

Drawings

Fig. 1 is a diagram of an example embodiment described herein.

Detailed Description

The following detailed description of example embodiments refers to the accompanying drawings.

In some cases, a laser-based cutting system may be used to cut a particular geometry in a transparent material, such as glass. For example, existing laser-based cutting systems include high aberration laser-based cutting systems, polarization-induced focus-shifted laser-based cutting systems, holographic refractive or reflective laser-based cutting systems, and/or for cutting holes in transparent materials, and the like. However, in many cases, existing laser-based cutting systems generate debris along the cutting street/track (e.g., composed of jetted particles of transparent material) when cutting a particular geometry in a transparent material, thereby affecting the quality of the edges and sidewalls of the cut geometry and contaminating the surfaces of the cut portion around the cutting street (e.g., in terms of dimensional accuracy, sidewall smoothness, etc.). Furthermore, in many cases, existing laser cutting systems can form heat affected zones that extend beyond the geometry being cut, which can damage the area along the cutting streets/tracks of the geometry.

Some embodiments described herein provide a cutting system that uses an ultrafast laser light source that generates a pulse train of ultrafast laser pulses to generate a bessel beam to cut or modify a transparent material such as glass. In some embodiments, the laser cutting system may be configured to generate the bessel beam by using an axicon, a first lens, and a second lens. In some embodiments, the laser light source may be configured to provide one or more ultrashort laser pulses to produce one or more corresponding bessel beams to cut the transparent material. In some embodiments, the bessel beam may be configured to cut holes in the transparent material by vaporizing the transparent material within the bessel beam's depth of field, which may prevent debris from accumulating in the holes and affecting the quality of the holes. In some embodiments, the bessel beam may be configured to produce a heat affected zone having a smaller area than that produced by existing laser-based cutting systems, which may result in less damage to the surrounding area of the geometry cut by the cutting system.

Fig. 1 is a diagram of an example bessel beam cutting system 100 described herein. As shown in fig. 1, the bessel beam cutting system may include a light source 102, an axicon 104, a first lens 106, and/or a second lens 108.

The light source 102 may be configured to emit an input light beam into the axicon 104. The input light beam may be a laser beam, such as a laser beam having a wavelength range in the visible and near infrared spectrum. For example, the light source 102 may be a gaussian laser light source configured to emit a gaussian laser beam (e.g., a laser beam having a gaussian intensity distribution) into the axicon 104. As another example, the light source 102 may be a top hat laser light source configured to emit a top hat laser beam (e.g., a laser beam having a top hat intensity profile) into the axicon 104. Light source 102 may be configured to emit an input light beam into axicon 104 at an angle to the input surface of axicon 104. For example, the light source 102 may be configured to emit an input light beam into the axicon 104 at a 90 degree angle (e.g., within a suitable tolerance, such as within two degrees) from the input surface of the axicon 104.

The axicon 104 may be configured to have an output surface that includes the apex of the axicon 104. The output surface of the axicon 104 may be defined by the apex angle of the apex. For example, the apex angle of the axicon 104 may be configured to be in the range of 100 to 180 degrees (e.g., the apex angle may be configured to be greater than or equal to 100 degrees and less than 180 degrees). Additionally or alternatively, the axicon 104 may not include a vertex angle, but rather one or more diffractive optical elements.

An input light beam (e.g., emitted by light source 102) may enter axicon 104 via an input surface of axicon 104 and propagate through axicon 104 (e.g., via refraction and/or diffraction and due to the apex angle of axicon 104) to an output surface of axicon 104. As a result, the axicon 104 may be configured to emit an output beam from an output surface of the axicon 104 that includes the bessel beam in the near field 110 of the axicon 104 and the annular beam in the far field 112 of the axicon 104. The bessel beam may have a depth of field 114. The annular beam may have an annular width 116. The divergence angle of the output beam from the output surface of axicon 104 depends on the apex angle of axicon 104. For example, a larger apex angle of axicon 104 results in a larger convergence in near field 110 and a larger divergence in far field 112, resulting in a larger divergence angle of the output beam from the output surface of axicon 104. Conversely, a smaller apex angle of axicon 104 results in a smaller divergence angle of the output beam from the output surface of axicon 104.

The axicon 104 may be configured to transmit a bessel beam and/or an annular beam into an input surface of a first lens 106 (e.g., a convex lens or a positive lens). The first lens 106 may be configured to focus the bessel beam and/or the annular beam and emit the focused bessel beam and/or the annular beam having an annular width 118 from an output surface of the first lens 106.

The first lens 106 may be disposed a distance 120 from the axicon 104. The focal length of the first lens 106 may depend on the apex angle of the axicon 104. For example, the first lens 106 should be configured to have a short focal length to enable the Bessel beam and/or the annular beam emitted from the axicon 104 to converge for a larger apex angle axicon 104. Additionally, the distance 120 may be configured to correspond to a net aperture of the first lens 106. The distance 120 may be configured to be within a suitable range so as not to cut the output beam from the axicon 104.

The first lens 106 may be configured to transmit the focused bessel beam and/or the annular beam into an input surface of the second lens 108 (e.g., a convex lens or a positive lens). The second lens 108 may be disposed a distance 122 from the first lens 106. Distance 122 may be configured to correspond to a focal length of first lens 106 (FL1) and/or a focal length of second lens 108 (FL 2). For example, the distance may be the focal length of the first lens 106 plus 1.5 times the focal length of the second lens 108 (e.g., distance 122 ═ FL1+ (1.5 × FL 2)).

The second lens 108 may be configured to converge the focused bessel beam and/or the annular beam into a sub-bessel beam (e.g., in the near field of the second lens 108). The secondary bessel beam may be configured to have a depth of field 124.

In this manner, the first lens 106 and the second lens 108 may be configured to be used in combination to magnify (or demagnify) the bessel beam and/or the annular beam into a secondary bessel beam. In some embodiments, the first lens 106 and the second lens may be configured to provide an axial magnification in the range of 1/2500-1 (e.g., the axial magnification may be configured to be greater than or equal to 1/2500 and less than or equal to 1). In some embodiments, the axial magnification of the first and

second lenses

106, 108 may be configured to correspond to a ratio between the length of the depth of field 114 of the bessel beam and the length of the depth of field 124 of the secondary bessel beam. For example, the axial magnification may be configured as a ratio of the length of the depth of field 114 of the bessel beam divided by the length of the depth of field 124 of the secondary bessel beam. In some embodiments, the focal length of first lens 106, the focal length of second lens 108, distance 120, distance 122, and so forth may be adjusted to provide an axial magnification corresponding to the ratio.

In some embodiments, one or more parameters related to the light source 102, the axicon 104, the first lens 106, and/or the second lens 108 may be configured to control characteristics of the input light beam, the bessel beam, the annular light beam, the focused bessel beam, and/or the annular light beam and/or the sub-bessel beam. For example, one or more parameters may be configured such that the diameter of the input beam is within the net aperture of the axicon 104 (e.g., for an 85% net aperture of a 1 inch axicon, the diameter of the input beam may be configured to be less than or equal to 22.8 millimeters); the length of the depth of field 114 of the bessel beam may be configured to be in the range of 10 millimeters to 1 meter in air (e.g., the length of the depth of field 114 may be configured to be greater than or equal to 10mm in air and less than or equal to 1 meter in air); the depth of field 124 of the sub-bessel beam may be configured to have a length in the range of 30 micrometers (μm) and 15mm in air (e.g., the length of the depth of field 124 may be configured to be greater than or equal to 30 μm and less than or equal to 15mm in air), and so on.

In a first configuration example, the light source 102 may be configured to emit an input light beam having a diameter of 3mm, the axicon 104 may be configured to have an apex angle of 178 degrees, and the first lens 106 and the second lens 108 may be configured to provide an axial magnification of 1/280. This may create a bessel beam with a depth of field 114 having a length of 190mm in air, an annular beam with an annular width 116 of 1.5mm, and a sub-bessel beam with a depth of field 124 having a length of 400 μm in air. In a second configuration example, which is a variation of the first configuration example, the light source 102 may be configured to emit an input light beam with a diameter of 15mm, which increases the length of the depth of field 114 of the bessel beam to 950mm in air, and increases the length of the depth of field 124 of the sub bessel beam to 2mm in air. In a third example of a configuration, the light source 102 may be configured to emit an input light beam having a diameter of 20mm, the axicon 104 may be configured to have an apex angle of 170 degrees, and the first lens 106 and the second lens 108 may be configured to provide an axial magnification of 1/25, thereby increasing the length of the depth of field 124 of the sub-bessel beam to 10mm in air. Other configuration examples may be envisaged.

In some embodiments, one or more parameters related to the light source 102, the axicon 104, the first lens 106, and/or the second lens 108 may be configured to control the form factor length of the bessel beam cutting system 100 (e.g., the distance from the light source 102 to the second lens 108). For example, the axicon 104 may be configured to have a small apex angle, such as 170 degrees, which may result in a shorter length of the depth of field 124 of the bessel beam (e.g., shorter than a 190 millimeter (e.g., in air) length of the depth of field 124 of the bessel beam when the apex angle of the axicon 104 is 178 degrees as described in the first configuration example herein). This may allow the first lens 106 to move closer to the axicon 104, which may shorten the distance 120 between the axicon 104 and the first lens 106. Further, the first lens 106 and the second lens 108 may be configured to have a small focal length, such as 30mm for the first lens 106 and 8mm for the second lens 108, which may shorten the distance 122 between the first lens 106 and the second lens 108 (e.g., the distance 122 ═ 30mm + (1.5 × 8mm) ═ 42mm according to the above formula). Thus, in some embodiments, the form factor length of the bessel beam cutting system 100 (e.g., the distance from the light source 102 to the second lens 108) may be configured to be less than or equal to 100 mm.

In some embodiments, the bessel beam cutting system 100 may be configured to cut transparent materials such as glass, sapphire, silicon, and/or other transparent materials (e.g., green transparent materials, red transparent materials, non-Ultraviolet (UV) blue transparent materials, etc.). For example, the bessel beam cutting system 100 may be configured to direct a secondary bessel beam toward a transparent workpiece to cut a particular geometry in the workpiece. In some embodiments, the workpiece may be placed at a certain distance from the second lens 108 to allow the transparent workpiece to be coextensive with the depth of field 124 of the secondary bessel beam. This may allow the elongated focused region of the depth of field 124 of the secondary bessel beam to cut the workpiece by causing a uniform distribution of the energy supplied by the laser within the workpiece.

In some embodiments, the secondary bessel beams may be configured to have a cutting depth and/or a modified depth in the range of tens of microns to a few millimeters in the transparent material (e.g., 20 microns to 10 millimeters in the transparent material). For example, the depth of cut and/or the modified depth may be 0.3mm to 1mm in a transparent material (e.g., glass, silicon, sapphire, etc., which may be transparent to the wavelength associated with the input beam) (e.g., the depth of cut may be configured to be greater than or equal to 0.3mm and less than or equal to 1 mm). For example, when the depth of field 124 of the additional bessel beam is 400 μm in air, the secondary bessel beam may be configured to have a cut depth and/or modified depth of 0.3mm in float glass (such as described in the first configuration example herein). As another example, when the depth of field 124 of the additional bessel beam is 2mm in air, the secondary bessel beam may be configured to have a 1mm cut depth and/or modified depth in float glass (e.g., as described in the second configuration example herein).

In some embodiments, the light source 102 may be configured as an ultrafast laser light source (e.g., configured to have a burst mode, such as a flat burst mode (e.g., a burst pulse in which all individual pulses within a burst have the same pulse energy), a falling burst mode, a sawtooth-like burst mode, etc.) to provide one or more corresponding ultrashort laser pulses (e.g., laser pulses lasting from attosecond to nanosecond) as the one or more input beams. A burst ultrafast laser pulse may be a series of pulses in which the time interval between pulses is less than the pulse period of the burst repetition rate (e.g., when the frequency of the burst is 100kHz (i.e., the pulse/burst period is 10 mus), the temporal inter-pulse distance within the burst may be less than 10 mus, such as 12 ns).

One or more input beams may propagate through the bessel beam cutting system 100 as described herein and into a workpiece (e.g., a transparent workpiece) to produce an optical filament in the workpiece (e.g., due to the high power density of the depth of field 124 of the additional bessel beam being focused into the workpiece). The ultrashort laser pulses may be configured to have a burst energy in a range of 50 microjoules (μ J) to 2 mJ; a power in a range of 8 watts (W) to 200W; and a repetition frequency in a range of 50 kilohertz (kHz) to 500 kHz. For example, the ultrashort laser pulses may be configured to have a burst energy in the range of 100 μ J to 250 μ J; a power in the range of 8W to 20W; a repetition frequency in the range of 70kHz to 80 kHz.

For example, the light source 102 may be configured to generate a burst of ultrashort laser pulses (e.g., energy equal to the temporal pulse spacing within a burst such as, for example, 12ns in flat burst mode), where the burst of ultrashort laser pulses have a combined burst energy of 100 μ J, a power of 8W, and/or a frequency of 80kHz, which may enable the sub-bessel beam to cut a workpiece to a depth of 0.3mm (e.g., when the light source 102, the axicon 104, the first lens 106, and/or the second lens 108 are configured as described herein with respect to the first configuration example). As another example, the light source 102 can be configured to generate bursts of ultrashort laser pulses of equal energy (e.g., in a flat-burst mode), where the bursts of ultrashort laser pulses have a combined burst pulse energy of 250 μ J, a power of 20W, and/or a frequency of 80kHz, which can enable an additional bessel beam to cut a workpiece to a depth of 1mm (e.g., when the light source 102, the axicon 104, the first lens 106, and/or the second lens 108 are configured as described herein with respect to the second configuration example).

In some embodiments, the bessel beam cutting system 100 and/or the workpiece may be configured to move relative to each other (e.g., the bessel beam cutting system may move the bessel beam cutting system 100 laterally or may move the workpiece laterally). By creating optical filaments in the workpiece, the bessel beam cutting system 100 can create "line" defects (e.g., perpendicular to the surface of the material) through a large amount of transparent material. By moving the workpiece laterally relative to the bessel beam cutting system 100, multiple defect "lines" can be created adjacent to one another, connecting the created defects. As a result, the bessel beam cutting system 100 creates an energy curtain inside a large number of workpieces. The energy curtain may cause the workpiece to crack, which may prepare the workpiece for mechanical or thermal separation.

As noted above, fig. 1 is merely provided as one or more examples. Other examples may be different than that described with respect to fig. 1.

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

Even if specific combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. 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 be directly dependent on only one claim, the disclosure of various embodiments includes each dependent claim in combination with every other claim in the set of claims.

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. In addition, 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". Further, as used herein, the article "the" is intended to include the item or items referred to by the conjoined article "the" and may be used interchangeably with "the item or items. Further, as used herein, the term "set" is intended to include one or more items (e.g., related items, unrelated items, combinations of related 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. In addition, as used herein, the term "having," variants thereof, and 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. In addition, as used herein, the term "or" when used in series is intended to be inclusive and may be used interchangeably with "and/or" unless specifically stated otherwise (e.g., if used in conjunction with "or" only one of ").

Claims

1. A bessel beam laser cutting system comprising:

an ultrafast laser light source configured to emit a light beam into the axicon;

the axicon configured to diffract the light beam into a first Bessel light beam in an axicon near field and a ring light beam in an axicon far field;

a first lens configured to focus the annular light beam; and

a second lens configured to converge the focused annular beam into a second Bessel beam to modify the transparent material,

wherein the depth of the modification produced by the second bessel beam is in the range of tens of micrometers to several millimeters inside the transparent material.

2. The bessel beam laser cutting system of claim 1, wherein:

the diameter of the light beam is 3 mm;

the vertex angle of the shaft cone is 178 degrees;

the depth of field length of the first Bessel beam is 190mm in air;

the annular width of the annular light beam is 1.5 mm;

the axial magnification of the annular light beam by the first lens and the second lens is 1/280;

the depth of field length of the second bessel beam is 400 microns in air; and

the modified depth produced by the second bessel beam is 0.3mm in the transparent material.

3. The bessel beam laser cutting system of claim 1, wherein:

the diameter of the light beam is 15 mm;

the vertex angle of the shaft cone is 178 degrees;

the depth of field length of the first bessel beam is 950mm in air;

the depth of field length of the second Bessel beam is 2mm in air; and

the modified depth produced by the second bessel beam is 1mm in the transparent material.

4. The bessel beam laser cutting system of claim 1, wherein:

the diameter of the light beam is 3 mm;

the vertex angle of the shaft cone is 178 degrees;

the depth of field length of the first Bessel beam is 190mm in air;

the annular width of the annular light beam is 1.5 mm;

the axial magnification of the annular light beam by the first lens and the second lens is 1/100;

the depth of field length of the second Bessel beam is 2mm in air; and

5. The bessel beam laser cutting system of claim 1, wherein the ultrafast laser light source is configured to emit a train of ultrashort laser pulses as a beam, and wherein:

a burst energy associated with the burst of ultrashort laser pulses is in a range of 100 microjoules to 250 microjoules;

the power associated with the burst of ultrashort laser pulses is in the range of 8 watts to 20 watts; and

the repetition rate associated with the burst of ultrashort laser pulses is in the range of 70khz to 80 khz.

6. The bessel beam laser cutting system of claim 1, wherein the beam has a gaussian intensity profile or a top hat intensity profile.

7. The bessel beam laser cutting system of claim 1, wherein the first lens is configured as a convex lens and the second lens is configured as a concave lens.

8. The bessel beam laser cutting system of claim 1, wherein the bessel beam laser cutting system has a form factor length of less than or equal to 100 millimeters.

9. A cutting system for transparent materials, comprising:

an ultrafast laser light source configured to emit ultrashort laser pulses into an axicon;

the axicon is configured to diffract the ultrashort laser pulse into a first bessel beam in an axicon near-field and a ring beam in an axicon far-field,

wherein the first Bessel beam has a depth of field length in the range of 10 millimeters in air to 1 meter in air;

a first lens configured to focus the annular light beam; and

wherein the depth of field length of the second Bessel beam is in the range of 30 microns in air to 15 millimeters in air; and is

Wherein a cutting depth of the second bessel beam is in a range of 20 micrometers to 10 millimeters in the transparent material.

10. The cutting system for transparent materials of claim 9, wherein the ultrafast light source is configured to emit ultrashort laser pulses in a burst mode.

11. The cutting system for transparent materials of claim 9, wherein the apex angle of the axicon is configured to be in the range of 170 to 180 degrees.

12. The cutting system for transparent materials of claim 9, wherein:

the energy of the ultrashort laser pulse is in the range of 100 micro joules to 250 micro joules; and is

The power of the ultrashort laser pulse is in the range of 8 watts to 20 watts.

13. The cutting system for transparent materials of claim 9, wherein:

the vertex angle of the shaft cone is 170 degrees;

the focal length of the first lens is configured to be 30 mm;

the focal length of the second lens is configured to be 8 mm; and is

The cutting depth of the second bessel beam is 1mm in the transparent material.

14. The cutting system for transparent materials of claim 9, wherein the first lens is configured at a distance from an axicon, and

wherein the distance corresponds to a numerical aperture of the first lens.

15. The cutting system for transparent materials of claim 9, wherein the second lens is configured at a distance from the first lens, and

wherein the distance corresponds to a focal length of the first lens and a focal length of the second lens.

16. A bessel beam cutting system comprising:

a light source configured to emit a light beam into the axicon;

wherein the diameter of the beam is related to the net aperture of the axicon;

the axicon is configured to diffract the input light beam into a first Bessel light beam in an axicon near field and an annular light beam in an axicon far field;

wherein the apex angle of the axicon is configured to be in the range of 100 to 180 degrees; and

a first lens and a second lens configured to reduce the annular beam into a second Bessel beam to modify the transparent material,

wherein the first and second lenses have axial magnifications in the range of 1/2500-1 for the annular light beam, and

wherein the modified depth of the second bessel beam is in a range of 30 micrometers to 10 millimeters in the transparent material.

17. The bessel beam cutting system of claim 16, wherein the axial magnification of the annular beam by the first and second lenses corresponds to a ratio between a depth of field length of the first bessel beam and a depth of field length of the second bessel beam.

18. The bessel beam cutting system of claim 16, wherein the focal length of the first lens is configured to be 30mm, the focal length of the second lens is configured to be 8mm, and the distance between the first and second lenses is configured to be 42 mm.

19. The bessel beam cutting system of claim 16, wherein the second bessel beam has a depth of field length in the range of 400 microns in air to 2 millimeters in air.

20. The bessel beam cutting system of claim 16, wherein the second bessel beam is used to create a curtain of energy within the glass to prepare the glass for mechanical or thermal separation.