Apparatus and method for laser-assisted processing of workpieces made of glass-based materials, and use of said apparatus and method

Abstract

The present invention relates to an apparatus (100) and method (100) for laser-assisted processing of a workpiece (2) made of a glass-based material, and more particularly to an apparatus (100) and method (100) for introducing a damaged area into the workpiece (2), wherein the apparatus (100) is configured to position the workpiece in a processing plane (W), and is provided with an ultrashort pulse laser (3), the focal region (1) of the ultrashort pulse laser (3) is at least partially located inside the workpiece, and the irradiation intensity is such that, under a predetermined operating state, X-rays in an energy range EM dependent on the composition of the workpiece are emitted from the focal region (1). The focal region (1) is surrounded in at least a portion of its area by at least one X-ray shielding element (300, 310), thereby providing a processing space (302). The shielding elements (300, 310) include a material having X-ray absorptivity adapted to the energy range EM, and in particular, the material of the shielding elements has particularly high X-ray absorptivity in the energy range EM.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for laser-assisted processing of a workpiece made of a glass-based material. The use of the apparatus and method is also covered by the present invention.

[0002] In the sense of this invention, a glass-based material is all material having a glassy network structure in at least a predetermined region, and / or all material made of glass material. A glass-based material is particularly glass itself, but it is also a glass ceramic obtained by at least partial crystallization of elements made of glass material.

[0003] Laser-assisted processing is based on introducing damage into glass-based materials using an ultrashort pulse laser that emits ultrashort laser pulses. A known application is laser cutting. In this case, a filamentous damage is usually introduced into the workpiece, and this damage generally extends perpendicularly through the thickness of the workpiece. If multiple damages are provided, a separation line is obtained that can separate the workpiece along it.

[0004] The mechanism often explained in this case is that microcracks originating from the damaged area weaken the material of the workpiece. When damaged areas occur adjacent to each other, the cracks connect, making separation along the connection line possible.

[0005] International Publication No. 2012 / 006736 describes a laser cutting method based on the nonlinear optical Kerr effect. This laser cutting method is based on two nonlinear effects: pulse self-focusing due to the optical Kerr effect and defocusing due to plasma generated in the material by the laser. In this case, the self-focusing is maintained over a focal length of approximately 500 to 1000 μm, and then, if the pulse energy is insufficient, the self-focusing is spatially dispersed so that self-focusing occurs again and a plasma channel is generated again.

[0006] European Patent Application Publication No. 3169635 describes the use of a Bessel beam with an axicon optical system to extend the laser focal line during laser cutting. The inventors of this document state that the difference from methods based on the Kerr effect, such as International Publication 2012 / 006736, is that the refocusing of the laser beam corresponding to International Publication 2012 / 006736 requires correction of the refractive index of the workpiece material, in this case glass. This inevitably produces a different damage pattern, which can be undesirable.

[0007] German Patent Application Publication No. 102018200033 describes a laser processing head incorporating an X-ray sensor, which detects X-rays according to process conditions, and a machine control unit adjusts process parameters based on the sensor signal. In particular, if the predetermined X-ray dose exceeds a certain level, processing is interrupted. Therefore, a rational manufacturing method in, for example, industrial mass production is impossible. A similar approach is pursued in German Patent Application Publication No. 102020127575.

[0008] German Patent No. 102018200030 describes the effects of X-ray emission in material processing using ultrashort laser pulses with appropriately arranged particle flow.

[0009] German Patent Application Publication No. 102018120022 describes the measurement technology monitoring of a workpiece processing process using an X-ray sensor to detect radiation with photon energies greater than 0.5 keV and to analyze, in particular, the energy distribution and dose output of this radiation. German Patent Application Publication No. 102018120019 describes a corresponding detector module, and German Patent Application Publication No. 102019000143 expands the sensor functionality to various types of radiation and evaluation variations.

[0010] German Patent Application Publication No. 102019000144 describes a test for the airtightness of a casing using an X-ray-sensitive sensor that is held at a predetermined distance from the casing wall via a spacer.

[0011] What is common to the above-mentioned documents is that rational processing of workpieces, which is necessary for the industrial mass production of workpieces made of, for example, glass-based materials, such as the cutting of sheet glass and / or glass strips, in particular the cutting of strips made of ultra-thin glass, becomes impossible.

[0012] The present inventors have recognized that X-rays having a characteristic spectrum can occur when processing glass-based workpieces using an ultrashort pulse laser, particularly when introducing filament-like damaged portions. As part of this recognition, it may also be mentioned that this occurs particularly when the incident laser energy is high and / or when bursts of laser pulses are used.

[0013] An object of the present invention is to provide an apparatus and a method that enable rational processing of workpieces made of glass-based materials. In this case, the present invention is based on the basic concept of attenuating the propagation of generated X-rays, thereby providing an efficient production environment and / or an efficient method for processing and / or producing elements made of glass-based workpieces, in particular elements made of glass and / or glass ceramic.

[0014] The above object is solved by the subject matter of each independent claim and the content of the present specification. Preferred embodiments are derived from the respective dependent claims.

[0015] The present invention includes an apparatus for laser-assisted processing of a workpiece made of a glass-based material, particularly an apparatus for introducing a damaged area into the workpiece, wherein the apparatus is configured to position the workpiece within a processing plane W. The apparatus further includes an ultrashort pulse laser that emits ultrashort laser pulses having wavelength λ, individual pulse energy Ep, and laser beam direction z, wherein the laser and / or laser pulses are configured such that the workpiece is at least substantially transparent to wavelength λ, and further includes a beam shaping optical system configured to form a focal region of the laser beam located at least partially inside the workpiece in a given operating state, wherein the irradiation intensity Ef is such that, in a given operating state, X-rays are emitted in at least one energy range EM depending on the composition of the workpiece, and the focal region is surrounded in at least a portion of the area by at least one X-ray shielding element, thereby providing a processing space, either alone or in combination with another shielding element. The shielding element is made of or includes a material having an X-ray absorbance adapted to the energy range EM.

[0016] Here, X-ray emission occurs particularly from the focal region.

[0017] Particularly advantageous is that the shielding element material has particularly high X-ray absorptivity in the energy range EM.

[0018] In the sense of the present invention, during processing, the workpiece made of a glass-based material is located in the focal region. In other words, the glass-based material is processed using ultrashort laser pulses. Therefore, within the scope of the present invention, this means that the workpiece may contain another material, for example, in its edge region. In the sense of the present invention, the region containing the glass-based material is processed using ultrashort laser radiation.

[0019] In the sense of the present invention, a damaged area generally refers to any form of material modification and / or material removal resulting from the interaction between an ultrashort laser pulse and the material of the workpiece. This may include areas of refractive index change, material discoloration, material structural weakening, and weakening in particular by cracks, localized melting, ablation, introduction of hollow channels and / or blind holes. The introduction of filamentous damaged areas is particularly advantageous.

[0020] A filament is understood to be a thread-like structure that extends for a sufficient length, with a diameter significantly smaller than the length of the filament. Particularly advantageous, the apparatus and / or method are configured to introduce a hollow channel-shaped filament into a workpiece. Such a hollow channel-shaped filament is characterized by a hollow space in the direction along the filament axis. Such a hollow channel goes beyond mere material damage and / or refractive index changes, allowing for reasonable further processing of the workpiece, such as separation or further expansion of the filament.

[0021] The device further includes an ultrashort pulse laser configured to emit ultrashort laser pulses. In the case of an ultrashort pulse laser, the pulse width of the laser pulse is extremely short, i.e., in the range of less than 1 ns, particularly in the range of a few picoseconds to femtoseconds, especially in the range of 40 fs to 20 ps. Particularly advantageous lower limits are 100 fs or 200 fs, and advantageous upper limits are 10 ps, ​​3 ps, or 1 ps. The upper and lower limits can be arbitrarily combined with each other. In this way, particularly advantageous ranges of 100 fs to 10 ps, ​​200 fs to 10 ps, ​​or 100 fs to 3 ps can be obtained.

[0022] With the pulse durations described above, it is possible to supply an average laser output in the range of 1W to 10kW or more.

[0023] The irradiation intensity Ef here represents the incident laser power per unit area, i.e., the beam cross-sectional area, measured at the point of interaction with the workpiece. When incident obliquely on the workpiece surface, the area occupied by the laser beam increases, and therefore the irradiation intensity decreases. The maximum achievable power density corresponds to the laser beam intensity at the focal point. The laser power is expressed as individual pulses, or with a repetition frequency f, which may be in the range of 10 kHz to 100 MHz in particular. rep It is emitted as a group of burst pulses having the following characteristics, and this group of burst pulses is also referred to as a burst packet in this specification. Preferred ranges are 25 kHz to 50 MHz, 50 kHz to 20 MHz, and / or repetition frequencies of 50 MHz, 20 MHz, 10 MHz, 8 MHz, 4 MHz, 2 MHz, or less than 1 MHz.

[0024] If the energy supplied by individual pulses is still insufficient, at least one burst packet of laser pulses can be injected. A burst packet consists of a group of ultrashort laser pulses or a sequence of ultrashort laser pulses, also referred to below as a burst individual pulse. Thus, one burst packet has at least two burst individual pulses. However, typically about 2 to 20 burst individual pulses are used, preferably 3 to 10, with an upper limit of approximately 100 burst individual pulses in total. A burst packet preferably has a pulse energy Ep of 100 μJ to 1 J. Similarly, favorable ranges are 100 μJ to 50 mJ or 100 μJ to 10 mJ. As already mentioned, Ep here represents the cumulative energy of the burst packet. The use of individual pulses is also possible.

[0025] The pulse duration of an individual pulse and / or a burst of individual pulses corresponds to the pulse duration of the laser, the duration of a burst packet, referred to as the burst duration Tb, which depends on the pulse duration of the burst individual pulse, the number of burst individual pulses in the corresponding burst packet, and the time interval between burst individual pulses, referred to as the intraburst delay Ti, measured at the point of maximum intensity of each burst individual pulse.

[0026] The individual burst pulses of a burst pulse group have, advantageously, time intervals in the range of several nanoseconds, for example, in the range of 15 ns, and therefore typically have an intrinsic burst pulse frequency in the megahertz range of 30 MHz to 60 MHz, preferably 50 MHz. In special cases, the burst pulse group itself may consist of further subpulses, i.e., so-called burst-in-burst modes or biburst modes having time intervals in the picosecond range and corresponding frequency bases in the gigahertz range.

[0027] In the sense of this specification, a laser emits laser radiation of wavelength λ. The laser radiation here is selected to be suitable for the processing of a desired material, particularly for the introduction of damage. This generally means that the laser wavelength λ is selected according to the desired mechanism of interaction with the material of the workpiece.

[0028] In the sense of this specification, UKP stands for ultrashort pulse. Generally, current UKP laser systems can supply laser wavelengths in the range of 350 nm to 2700 nm. Typical emission wavelengths are in the range of 350 nm to 1400 nm, preferably 400 nm to 1100 nm. Examples of ultrashort pulse laser systems include those with emission wavelengths of 800 nm, 1030 nm, or 1064 nm and corresponding frequency multiplier versions of 532 nm or 515 nm. Harmonic excitation wavelengths are also possible. Advantageously, the wavelength λ is selected such that the workpiece is transparent to the laser wavelength λ of the laser used, at least in the incident region of the laser beam. This should be understood as meaning that the transmittance of the workpiece at that location is greater than 50%, or greater than 85%, preferably greater than 90%, and particularly preferably greater than 95% at wavelength λ. In this way, filamentous damage, in particular hollow channels and / or blind holes, can be introduced into the workpiece.

[0029] Laser radiation is emitted in the direction z of the laser beam.

[0030] The apparatus further includes a beam shaping optical system configured to focus the laser beam in a focal region, where the irradiation intensity Ef is such that X-rays are emitted from the focal region under a given operating condition. This can be achieved, in particular, by the interaction between the high-energy laser radiation in the focal region and the material of the workpiece, and further, by the interaction with the surrounding medium, such as the atmosphere in the focal region, and therefore in the simplest case, with air.

[0031] Here, the irradiation intensity Ef, which is generally obtained as the quotient between the laser power and the beam diameter, is important. In the case of a pulse shape with a spatial and temporal normal distribution (Gaussian beam), the maximum irradiation intensity is

number

[0032] The workpiece is placed within the machining plane (W). Advantageously, the position of the machining plane and the position of the focal region are adjusted to match each other. This can be achieved by adjusting the machining plane, and / or individually or in combination, by adjusting the position of the laser, particularly its height, and / or the position of the beam shaping optical system.

[0033] Advantageously, the apparatus is configured such that the focal region is located at least partially within the workpiece. Particularly advantageous, the beam shaping optical system is configured such that the focal region is represented by an elongated focal line oriented at a predetermined angle α, preferably 90°, with respect to the workpiece, and such focal line is located within the workpiece in at least a portion of its area. In a typical case, the focal line penetrates the surface of the workpiece on at least one side, and especially on both sides.

[0034] As described above, the laser radiation generates X-rays within the apparatus described in the manner described below. The inventors have confirmed that the laser radiation is emitted in the energy range EM, which is typical for glass-based materials.

[0035] The emitted X-rays are shielded by at least one shielding element in the sense of the present invention. For this purpose, the shielding elements are arranged, either alone or in combination with other shielding elements, such that at least the focal region is surrounded by one or more shielding elements in at least a portion of the region, thereby providing a processing space. The shielding elements consist of or include a material having an X-ray absorptivity adapted to the energy range EM of the X-ray emission. In particular, the material of the shielding elements has a particularly high X-ray absorptivity in the energy range EM.

[0036] The basic principle of how shielding elements work is based on efficiently absorbing the generated X-rays. Therefore, the generated X-rays are, so to speak, retained within the processing space, and / or the radiation intensity outside the processing space is lower than the radiation intensity within the region.

[0037] The protective effect of a shielding element is crucial, and important is the corresponding dose equivalent H, which represents the biological effectiveness calculated from the energy dose by multiplying the energy dose E behind the shielding element by a weighting coefficient, taking into account that different types of radiation exert different effects on biological tissues. For X-rays, the weighting coefficient is 1. Here, [H]=1 and Sv=1J / kg apply.

[0038] Since X-rays have different effects on different biological tissues, a distinction is made between the directional dose equivalent H'(0.07,Ω) at a penetration depth of 0.07 mm for the skin, the directional dose equivalent H'(3,Ω) at a penetration depth of 3 mm for the eye, and the ambient dose equivalent H*(10) at a tissue depth of 10 mm for the torso. Each individual quantity is referred to as a dose equivalent in the sense of this specification. The dose equivalent output is the respective dose equivalent per unit time. In the sense of this specification, the dose equivalent output is measured at a distance of 10 cm from the outer wall of the shielding element.

[0039] In the meaning of the present invention, a shielding element is considered advantageous when all three dose equivalent outputs do not exceed a value of 10 μSv / h. Particularly advantageous are shielding elements in which all three dose equivalent outputs do not exceed a value of 1 μSv / h at a distance of 10 cm from its outer wall.

[0040] The protective effect of the shielding element is particularly enhanced when an irradiation intensity of more than 10 is formed at the focal point on the laser side of the wall by the laser process and its focusing optical system 13 W / cm 2 an irradiation intensity of more than 10 14 W / cm 2 an irradiation intensity of more than, preferably 10 15 W / cm 2 an irradiation intensity of more than, or particularly preferably 10 16 W / cm 2 an irradiation intensity of more than is formed at the focal point, and furthermore the dose equivalent output on the side of the shielding element opposite to the laser remains below 10 μSv / h or at 1 μSv / h, thus staying in the range of 0.1 to 10 μSv / h and / or in the range of 0.1 to 1 μSv / h.

[0041] The lower limit of 0.1 μSv / h is usually caused by ambient natural X-rays.

[0042] Or in other words, an advantageous embodiment is an apparatus in which the dose equivalent output outside the processing space under a predetermined operating state is less than 10 μSv / h, preferably less than 1 μSv / h, measured at a distance of 10 cm from the outer wall of the processing space.

[0043] As already explained, the dose equivalent refers to the directional dose equivalent at a (penetration) depth of 0.07 mm for the skin, the directional dose equivalent at a penetration depth of 3 mm for the eyes, and the ambient dose equivalent at a tissue depth of 10 mm for the torso.

[0044] In a likewise advantageous configuration, on the laser side of the wall, an irradiation intensity of more than 10 is generated by the laser process and its focusing optical system 13 W / cm 2 an irradiation intensity of more than 10 14 W / cm2 Ultra-high irradiation intensity, 10 15 W / cm 2 Ultra-high irradiation intensity or particularly advantageous is 10 16 W / cm 2 An irradiation intensity exceeding 7 keV is formed in the focal region, and the generated X-rays have photons with energies exceeding 7 keV, 10 keV, 12 keV, 15 keV, or 20 keV, and furthermore, on the side of the shielding element opposite the laser, the dose equivalent output remains below 10 μSv / h or below 1 μSv / h.

[0045] It should be readily apparent to the reader that a special arrangement of shielding elements is made so that X-rays emitted from the focal region can be absorbed.

[0046] The apparatus is particularly advantageous in that the X-rays have energies in the range of 2 keV to 40 keV, especially 3 keV to 30 keV or 4 keV to 40 keV.

[0047] In glass-based materials, the emitted X-rays have their maximum value particularly in the range of 6 keV to 10 keV.

[0048] In the sense of the present invention, the material of the shielding element is advantageously selected to have high X-ray absorptivity in the region where the maximum value of X-rays emitted from the workpiece is located, preferably made of a glass-based material.

[0049] Particularly advantageous is that the shielding element material has a maximum X-ray absorption in the energy range of 6 keV to 10 keV.

[0050] In this specification, the term "maximum value" can also be understood as a local maximum value.

[0051] An advantageous device is configured such that the shielding element consists of or includes materials selected from a group of predetermined materials, metals in particular from the group of iron, steel, special steel, tungsten, and glass, or plastic composites in particular from the group of plastic composites including tungsten or glass-filled plastic composites.

[0052] Generally, the goal for shielding elements is to achieve the highest possible shielding efficiency. Furthermore, the shielding element should be reasonably manufacturable and operable. Shielding characteristics fundamentally correlate with the number of charge atoms in the atomic nuclei of the material containing the shielding element. In this case, the overall ability of the shielding element to at least reduce and / or shield X-rays is obtained through the synergistic effect of the shielding element's thickness and / or shielding properties.

[0053] The aforementioned compromises are particularly favorable for metals. For example, lead is known as a good X-ray absorber. Nevertheless, it is not the most advantageous material for a given operation. In the sense of the present invention, iron-containing materials, especially steel and / or special steels, including non-alloy special steels and alloy special steels, in accordance with EN 10020:2000 [provided July 2000], are advantageous. Tungsten has also proven advantageous. Similarly, metal-filled plastic composites, especially tungsten-filled plastic composites, are also possible. Similarly possible and included in the present invention are beam shielding glass and / or glass-filled plastic composites, especially glass having high X-ray absorbency. Such glass is also used as dental glass and may contain barium, for example. Such glass has an aluminum equivalent thickness of over 100%, abbreviated as ALET, and can often have an aluminum equivalent thickness of over 200%.

[0054] In a favorable configuration, the apparatus is configured such that the X-ray shielding element surrounds the workpiece at least partially.

[0055] This means that it can be advantageous not only when the shielding element surrounds the focal region, but also when the workpiece is located within the processing space. As will be discussed later, this may be the entire workpiece, such as a sheet of glass, or a section of a continuous workpiece strip, for example, a section of a glass strip, in each individual processing step.

[0056] Advantageously, the device is configured to generate an X-ray-emitting plasma in the focal region of the laser beam.

[0057] Especially at high laser power, plasma can be generated and / or ignited, particularly in the focal region and / or within the workpiece. The inventors have recognized that the plasma in this case may emit X-rays. Simultaneously, the plasma in this case can be particularly advantageously used to machine a filamentous hollow channel-shaped damage into the workpiece. In this case, the action of the plasma results in a micro-explosion, which pushes the material into the workpiece perpendicular to the filament axis, thereby forming a hollow channel and / or blind hole as a hollow space.

[0058] In a more advantageous device, the laser is configured to emit at least one burst packet consisting of multiple laser pulses, wherein the burst packet has a repetition frequency f rep It consists of a sequence of ultrashort burst individual pulses having [a specific characteristic]. Particularly advantageous is that the first burst individual pulse of the burst packet generates an initial plasma, which is then sustained by energy supplied to it by subsequent burst individual pulses of the burst packet.

[0059] The burst individual pulses following the first burst individual pulse of the burst packet, so to speak, supply energy to the initial plasma afterward to maintain combustion. While particularly good material processing is possible in burst mode, it has also been confirmed that particularly large amounts of X-rays are generated. By using the present invention, it is possible to take advantage of the good processing ability and compensate for the disadvantage of higher X-rays.

[0060] The total pulse energy can be distributed evenly across the pulses of the burst packet, or it can be distributed with an energy content that decreases or increases throughout the burst packet. It has also been observed that particularly high dose outputs can result, especially in the latter case. Therefore, advantageously, the energy of individual burst pulses within the burst packet can be configured to be adjusted so that such energy is constant and / or advantageously reduced.

[0061] In another advantageous configuration of the apparatus, the laser is configured to emit a laser wavelength λ to which the workpiece is at least substantially transparent. Particularly advantageous is a laser wavelength λ of 500 nm to 1100 nm, and / or individual pulse duration of 200 fs to 11 ps, and / or burst duration of 1 ps to 500 ns, and / or cumulative energy of burst packets of 100 μJ to 10000 μJ, and / or repetition frequency f rep The frequency is 10kHz to 100MHz, and / or the workpiece is made of or contains glass and / or glass ceramics.

[0062] The above-mentioned transmittance is understood to mean that the transmittance of the workpiece at the laser incidence site is greater than 85% at wavelength λ, preferably greater than 90%, and particularly preferably greater than 95%.

[0063] Despite these conditions, in order to achieve interaction between the laser beam and the material of the workpiece, an ultrashort pulse laser is used in the sense of the present invention. In the case of such an ultrashort pulse laser, the pulse width is extremely short as described above, i.e., in the range of less than 1 ns, and in particular in the range of a few picoseconds to femtoseconds, especially in the range of 100 ps or 10 ps to 100 fs or 10 fs. Particularly advantageous is the range of 10 ps to 200 fs.

[0064] Particularly advantageous is that the workpiece includes glass and / or glass ceramic in at least the processing area and / or the focal area. Particularly advantageous is that it consists of these materials in at least that area.

[0065] In another advantageous embodiment, the focal region is configured to absorb X-rays that are at least partially emitted by the workpiece itself.

[0066] This is based on the understanding that glass-based materials themselves absorb X-rays, particularly in the spectral range in which X-rays generated by laser beams are emitted, at least partially. For example, if the laser's focal line is positioned to penetrate the surface of the workpiece on only one side, the generated X-rays will pass through the glass-based material and be absorbed on the other surface.

[0067] Generally, if one of the two workpiece surfaces is fractured by the focal line, it is possible to configure the system to generate X-rays and, consequently, dose output, depending on the energy distribution along the focal line. If pure internal modification occurs without penetrating the workpiece surface, the generated dose output is absorbed by the surrounding glassy material. When both surfaces are penetrated, two plasma torches emitting X-rays are generated as described above.

[0068] Thus, it is clear that the direction of emission can also be influenced by the arrangement of the focal line and the workpiece.

[0069] Another advantageous device has a workpiece holder on which the workpiece is placed during processing. The workpiece mounting portion is made of a material that absorbs X-rays, particularly glass and / or glass ceramic and / or X-ray shielding glass or a glass-filled plastic composite, in at least the region of the focal area in the z direction, or a free space, particularly a void, exists below the workpiece when viewed in the direction of the laser beam, and this free space is defined downwards in the z-direction extension by an element that absorbs X-rays in at least a portion of the region, particularly glass and / or glass ceramic and / or X-ray shielding glass and / or a glass-filled plastic composite.

[0070] In the sense of this invention, "downward" means, when viewed in the direction of the laser beam, a location below the workpiece and / or below the machining plane (W), on the side of the workpiece opposite the laser, that is, in other words, further away from the laser in the z direction.

[0071] These two embodiments allow the emitted X-rays to be absorbed below the workpiece. These two embodiments are particularly advantageous when the focal region is located at least partially below the workpiece, or in other words, when the workpiece is partially penetrated with a significant energy proportion below the workpiece plane.

[0072] Particularly advantageous is that the elements described above include a non-metallic material beneath the workpiece, or consist of a non-metallic material at least in the projection line of the focal region. Particularly advantageous is that the material is glass and / or glass ceramic or glass-filled plastic composite.

[0073] Based on this, the inventors recognize that the incidence of focused ultrashort laser pulses onto a metal surface also generates a significant amount of X-rays. Therefore, in the sense of the present invention, it is desirable to prevent such focused ultrashort laser pulses from incident on the metal surface of, for example, a conventionally known standard workpiece mounting section or standard workpiece holder. This becomes more important as the workpiece is substantially transparent to the incident laser radiation as described above, and therefore high-energy laser radiation can penetrate the workpiece. If the above-mentioned non-metallic material is present directly below the workpiece, particularly in contact with the workpiece, then no undesirable X-rays are generated at all or only at a (very) reduced level. A workpiece made of a glass-based material has a shielding effect that depends on the workpiece thickness, similar to the shielding effect on X-rays generated on the workpiece support. The thinner the workpiece to be processed, the greater the probability that X-rays generated on the workpiece surface will pass through the substrate to be processed and enter free space.

[0074] In the alternative solutions and / or embodiments described above, a free space exists below the workpiece. In this case, the laser's focal region is configured such that it is located within this free space when the laser penetrates the workpiece. This avoids incidence on the metal. The free space may be filled with a fluid, especially a gas, or in the simplest case, the ambient atmosphere and even air. In this case, the free space can be considered as an air gap. Particularly advantageous, the free space is defined downward in the direction of the laser beam, i.e., below the workpiece plane (W), by at least one element that absorbs X-rays, particularly an element made of glass and / or glass ceramic or a glass-filled plastic composite. A coating of the substrate with the above material can also be considered as the above element.

[0075] A particularly advantageous embodiment is configured in which the workpiece is supplied to the machining space on a supply plane (B) different from the machining plane (W), and in particular, the supply plane is located below or above the machining plane (W) when viewed in the z direction.

[0076] In other words, this means that the plane through which the workpiece is guided to the processing location and / or processing space is offset from the processing plane of the workpiece, particularly with respect to the laser beam direction z. Specifically, the feed plane is located above or below the laser processing plane, and consequently where the X-rays are generated. This, in particular, allows for the existence of a region of shielding elements in the region between the planes.

[0077] This basic method of planar offset is basically applicable to all types of workpieces in the sense of this specification. In the case of individual workpieces, for example, plates made of glass-based materials, the workpieces can be moved discretely from the supply plane (B) to the processing plane (W), for example, by a lift and / or carriage. This basic method is particularly advantageous in continuous processing and workpiece supply, for example, when the workpiece exists in the form of a strip made of glass-based material. In this case, the strip is moved from the supply plane (B) to the processing plane (W) while bending itself. Such glass strips can have a thickness of several millimeters, as is generally known, but may be thin or ultrathin glass having a thickness range as described herein.

[0078] An advantageous device is configured such that the shielding element has a supply opening that allows the workpiece to be introduced into the machining space.

[0079] This can be applied, for example, to the sequential processing of flat glass, but it can also be applied to the continuous processing of glass strips, especially those made of ultra-thin glass. In sequential processing, the supply opening may be the same as the removal opening.

[0080] In the sense of this specification, ultrathin glass is glass having a maximum thickness of 400 μm, and in particular a maximum thickness of 30 μm. The lower limit is about 5 μm at the time of the invention, and even smaller thicknesses are expected in further development. Lower limits of 2 μm or 3 μm are also possible, or even predictable. Therefore, the advantageous thickness range for ultrathin glass in the form of plates or strips and all other possible shapes is 5 μm to 400 μm, or 5 μm to 200 μm, or 5 μm to 100 μm, or 5 μm to 50 μm, or 5 μm to 30 μm, and in particular 7 μm to 40 μm.

[0081] Particularly preferably, the supply opening can be closed by at least one closing device, the closing device comprising a material that absorbs X-rays emitted in operation, the closing device being selected from the group consisting of a closing curtain, rollers and / or a water curtain or a combination thereof.

[0082] In particular, when supplying a workpiece into the processing space, the closing curtain and / or rollers may come into contact with the workpiece. When the device is incorporated into a manufacturing process in which a workpiece is formed using hot forming, it is especially advantageous if the workpiece is supplied at a position where it is sufficiently cooled and / or where the viscosity is such that the closing device forms only minimal indentations and / or scratches on the workpiece.

[0083] Particularly advantageous is that the selected closure device includes an X-ray absorbing material. For example, the corresponding roller may have a shaft made of metal, on which a cylindrical body made of absorbent plastic, in particular the filled plastic described above, is placed. In the simplest case, the feed opening is located on the processing plane (W) or on a feed plane (B) located near the processing plane (W).

[0084] Alternatively or additionally, the supply opening may be advantageously located in a plane (B) above or below the machining plane (W) when viewed perpendicular to the z-direction. In this case, particularly advantageously, the area of ​​the shielding element is located within the machining plane (W), especially between the supply plane (B) and the machining plane (W).

[0085] These arrangements are based on the basic method described above, which involves supplying the workpiece to the machine on an offset plane. X-ray emission occurs at least primarily from the laser's focal region, and therefore from the machining plane (W). If the supply aperture is located outside the plane (W), at least one region of the shielding element is located within the machining plane (W), particularly between the supply plane (B) and the machining plane (W). Thus, the X-rays emitted in operation are shielded and / or deflected by the other elements, so that the X-rays do not enter the supply aperture. These elements may be, for example, a workpiece mounting section and / or a workpiece holder, or in particular, the workpiece itself. Within the framework of the present invention, as described above, it has been confirmed that workpieces containing or made of glass-based materials absorb the X-rays generated during the laser processing described above. In an advantageous arrangement, a plate-like workpiece or workpiece element, such as a section of a glass strip, is located parallel to or on the machining plane (W). Therefore, the X-rays emitted along the plane interact with the workpiece over relatively long distances, at least greater than the thickness of the workpiece, and especially significantly greater distances. This provides a means to achieve good X-ray absorption in a given direction, i.e., in a direction parallel to the plane (W), based on a relatively large distance, even if the intrinsic X-ray absorption characteristics of the workpiece material are relatively low in some cases. Thus, the workpiece itself contributes to X-ray absorption in an advantageous apparatus.

[0086] Based on this configuration, it is readily apparent that the supply opening may be a single shielding element or the edge region of the shielding element itself, especially when the shielding element extends beyond the processing plane (W) in the direction of the supply plane (B), and the planes (W) and (B) are not located above or below each other.

[0087] In a particularly advantageous embodiment, the supply aperture is configured such that, as measured within the processing plane W, it is at a maximum distance of 200 cm from the focal region, particularly at a maximum distance of 150 cm, or a maximum distance of 100 cm, or a maximum distance of 50 cm, preferably in the range of 10 cm to 200 cm, or 10 cm to 150 cm, or 10 cm to 100 cm, or 10 cm to 50 cm. Particularly advantageous, a workpiece region and an air space exist between the focal region and the supply aperture. Both the workpiece, made of a glass-based material, and the air space absorb at least partially emitted X-rays.

[0088] This eliminates the need for the supply opening to be closable by a closing mechanism, and in the simplest case, it can be formed as a gap in the shielding element.

[0089] The embodiment is particularly suitable for workpieces in the form of continuous glass strips, but is not limited thereto. Therefore, a particularly advantageous configuration of the apparatus is adapted to supply workpieces in the form of strips made of glass-based material, particularly in the form of glass strips, especially in the form of ultrathin glass having thicknesses of 5 μm to 400 μm, 5 μm to 200 μm, 5 μm to 100 μm, 5 μm to 50 μm, or 5 μm to 30 μm, and especially in the form of 7 μm to 40 μm, and such workpieces are supplied particularly continuously into the processing space.

[0090] In the sense of this specification, "continuous" of course means that the workpiece is supplied not only over an infinite length of time, but also in such a way that it is supplied into the processing space for a length significantly longer than its width and generally for a period of time longer than a few seconds. A common element is a glass strip, which can generally be several meters or longer.

[0091] Particularly advantageous is that the device is configured to supply the glass strip to the processing space while bending the glass strip.

[0092] In this case, the flexibility of the strip material, which is made of a glass-based material, is utilized. If the supply plane (B) is located below or above the processing plane (W), the glass strip material can be supplied into the processing space within the processing plane (W) by deflecting it, for example, using a roller.

[0093] The thickness of a strip made of glass-based material generally determines the possible bending radius. As described, a particularly advantageous application of the present invention is the processing of ultra-thin glass strips. Since such processing involves extremely small bending radii, compact placement of the equipment and integration of the equipment into the manufacturing system are particularly well possible.

[0094] In another advantageous configuration of the apparatus, the shielding element has an extraction opening in addition to the supply opening, and the extraction opening is configured to have the measures and / or characteristics described in particular with respect to the supply opening, in particular the arrangement with respect to the processing plane W.

[0095] The extraction opening can be configured in sequential mode, and more advantageously, in continuous mode for processing strips made of glass-based materials.

[0096] Particularly advantageous, the apparatus includes a supply means configured to introduce a workpiece into the machining space, and particularly advantageously, a removal means configured to lead the workpiece out of the machining space and / or synonymously to remove the workpiece from the machining space.

[0097] In an advantageous development of the apparatus, the apparatus includes a sensor device configured to detect emitted X-rays and thereby provide sensor data, particularly a sensor device assigned to the processing space, where preferably the laser is configured to be controllable in consideration of the sensor data. In particular, the laser can be configured to switch off when the maximum X-ray emission value is reached, thus enabling safety technical functions.

[0098] The sensor device can be placed, for example, within the processing space and can detect the light reflection of the incident laser beam or, in particular, the emitted X-rays. Another quantifiable quantity can be considered in a similar manner, especially if that quantity correlates with the energy of the incident laser output and / or the intensity of the generated X-rays. Advantageously, the energy of the emitted laser output can be used as a control quantity for the laser and positioning device. For this purpose, the sensor device can be connected to the control device. For example, the amount of X-ray emission can be used as a measure of the incoming laser output, and such a quantifiable quantity can be used to drive and control the laser so that the desired processing parameters are maintained. In this way, the amount of generated X-rays can also be detected, and further safety measures in the production environment can be initiated. Of course, similarly, it is also possible to install a sensor device outside the processing space that detects residual X-rays that have penetrated the shielding element and uses the obtained value, in particular, for further safety measures.

[0099] A particularly advantageous apparatus is configured such that a filamentous damage area is formed in the workpiece by the laser and beam shaping optical system, and especially so that a filamentous hollow channel is formed.

[0100] Hollow channels have already been discussed. This concept, of course, includes blind holes. Filamentous hollow channels may penetrate the workpiece as through-openings, that is, they may connect one surface to another or terminate in the bulk portion of the workpiece, and thus can represent blind holes.

[0101] In a particularly advantageous configuration of the apparatus, the beam shaping optical system is configured to provide a laser intensity distribution in the focal region that is constant within a range of ±30% in the laser beam direction.

[0102] The basis for this is the understanding that if the intensity of the laser emission remains sufficiently constant over the length of the focal region, i.e., in the general z-direction, i.e., in the direction parallel to the optical axis and perpendicular to the processing plane (W), and / or remains within the aforementioned region, the emitted X-rays will be small. Alternative methods for focusing the laser as strongly as possible to a single point are not very advantageous because they result in increased X-ray emission, but they can be used to some extent. In this case, the shielding elements can be configured accordingly to absorb more X-rays.

[0103] As described above, the apparatus according to the present invention can be integrated into a manufacturing apparatus for workpieces made of glass-based materials. Particularly advantageous is an apparatus as a component of a glass manufacturing facility, in particular an apparatus for manufacturing ultrathin glass, in particular an apparatus arranged on a continuous glass strip having a lug, wherein the apparatus is configured to form the lug and / or transverse portions.

[0104] The crust is generally a region at the edge of a glass-based strip that extends longitudinally, i.e., in the direction of transport of the glass strip. The crust usually has a lower surface quality than the central region and may have a relatively large thickness and / or ripple, and is therefore advantageously removed from the glass strip. The corresponding method is called crust cutting or longitudinal cutting.

[0105] Alternatively or additionally, the described apparatus can be used to form a cross section. This cross section is formed perpendicular to the longitudinal direction of the glass strip or at a predetermined angle. For example, multiple of the described apparatuses, used for cutting the edges and for forming the cross section, can be placed on the glass strip.

[0106] In particular, the apparatus described makes it possible to structure or even characterize the workpiece, that is, for example, after the formation of a cross section, it is possible to assign a unique identification number or 1D / 2D barcode to each individual workpiece produced in order to obtain a feedbackable article. Such identifiers can be absolutely determined, for example, by modifying the workpiece surface by locally modifying the material within the substrate (preferably by using an ultrashort pulse laser, because the damaged areas of the material formed by this are spatially very limited). This includes the introduction of structures resulting from damaged areas that enable subsequent separation of workpieces, particularly those made of glass-based materials, as well as structured areas.

[0107] In addition to the apparatus described above, the present invention also includes a method for processing brittle workpieces using an ultrashort pulse laser. The description given with respect to the apparatus above is equally applicable to the method according to the present invention. All features and / or embodiments related to the apparatus also apply to the method described below.

[0108] The present invention provides a method for processing a brittle workpiece using an ultrashort pulse laser, particularly for introducing damage to the workpiece, wherein the workpiece is placed on a processing plane (W), the laser emits ultrashort laser pulses having wavelength λ and individual pulse energy Ep, the laser beam is focused to a focal region by a beam shaping optical system, where the individual pulse energy Ep is such that X-rays are emitted within the focal region, and at least one focal region is surrounded in at least a portion of its area by at least one X-ray shielding element, thereby providing a processing space, either alone or in combination with other shielding elements, thereby obtaining an X-ray intensity outside the processing space that is lower than the intensity inside the processing space.

[0109] Advantageously, when measured outside the processing space at a distance of 10 cm from the outer wall of the shielding element (300), it is possible to achieve an X-ray dose of less than 10 μSv / h, particularly advantageously less than 1 μSv / h, and especially an X-ray dose of 0.1 to 10 μSv / h or 0.1 to 1 μSv / h.

[0110] The material and composition of the shielding element, particularly its thickness, are selected such that the X-ray absorption described in particular occurs at the desired thickness, and especially outside the work space, only the aforementioned proportion of X-rays occurs relative to those occurring inside the work space.

[0111] In particular, the method can be configured such that the X-rays in the processing space have an energy greater than 1 keV, preferably 2 keV to 30 keV, and especially 3 keV to 20 keV.

[0112] Particularly advantageous is the use of a shielding element made of or containing a material selected from the group of metals, particularly iron, lead or lead foil, steel, special steel, tungsten, glass, or plastic composites, particularly tungsten or glass-filled plastic composites.

[0113] A method is advantageous in which a plasma is generated within the focal region of the laser beam, the plasma emits X-rays, and in particular, the laser emits burst packets of at least one laser pulse consisting of a series of ultrashort burst individual pulses.

[0114] Particularly advantageous is that the first burst pulse of the burst packet generates an initial plasma, and energy is supplied to this initial plasma by subsequent burst pulses of the burst packet, thereby maintaining the plasma.

[0115] The individual burst pulses following the first individual burst pulse in a burst packet essentially supply energy to the plasma afterward to maintain combustion. However, since the pulses following the first individual burst pulse in a burst packet have relatively small individual burst pulse energy, it is thought that the plasma explosion can be controlled. This can be particularly advantageous when using methods to separate brittle workpieces, also known as cutting.

[0116] A method is even more advantageous in which the laser wavelength λ is selected such that the workpiece (2) is at least substantially transparent to the laser wavelength λ. Particularly advantageous is a method in which the laser wavelength λ is 350 nm to 1100 nm, and / or the pulse duration of individual pulses is 200 fs to 11 ps, and / or the burst duration is 1 ps to 500 ns, and / or the cumulative energy of burst packets is 100 μJ to 1 J, and / or the repetition frequency f rep The frequency is 10 kHz to 100 MHz, and / or the workpiece consists of or includes glass and / or glass ceramic and / or silicon and / or ceramic. Equally favorable ranges for the stored energy of burst packets are 100 μJ to 50 mJ or 100 μJ to 10 mJ.

[0117] In an advantageous development of the method, the workpiece is placed on a workpiece mounting section, which is made of an X-ray absorbing material, particularly glass and / or glass-ceramic or glass-filled plastic composite, at least in the range of the focal region, or a free space exists below the workpiece (viewed in the direction of the laser beam), particularly a void, which is defined in at least a portion of the area downward by an element made of an X-ray absorbing element, particularly glass and / or glass-ceramic or glass-filled plastic composite, where the focal region of the laser is preferably located at least partially within the space.

[0118] As described above with respect to the apparatus, the method also advantageously utilizes the basic principle of offset between the supply plane (B) and the machining plane (W). In a particularly advantageous configuration of the method, the workpiece is supplied to the machining space in a supply plane (B) different from the machining plane (W), and in particular, the supply plane (B) is located below or above the machining plane (W) when viewed in the z direction. In this case, particularly advantageously, the area of ​​the shielding element is located within the machining plane (W), in particular between the supply plane (B) and the machining plane (W).

[0119] The basic method and / or configuration have already been described in detail in the above-mentioned device. The same applies to the method as to the device.

[0120] Advantageously, in this method, the shielding element has a supply opening through which the workpiece is introduced into the machining space.

[0121] Particularly advantageous, the supply opening is closed by at least one closing device containing a material that absorbs emitted X-rays, and in particular, the closing device is selected from the group consisting of a closing curtain, rollers and / or a water curtain or a combination thereof.

[0122] Particularly advantageous in this method is that the supply opening is located in a plane (B) above or below the processing plane (Z). In particular, the area of ​​the shielding element may be located in the processing plane (Z).

[0123] These configurations have already been described in detail in relation to the device.

[0124] Similarly, an advantageous method is one in which the workpiece exists in the form of a glass strip, particularly in the form of an ultrathin glass having a thickness of 5 μm to 100 μm, and is configured to be continuously supplied to the processing space.

[0125] Due to the ultra-thin glass, the aforementioned thickness range also applies here.

[0126] One method is advantageous in which the glass strip is supplied to the processing space while being bent.

[0127] In an equally advantageous manner, the generated X-rays are detected by a sensor device, particularly those generated within the processing space, thereby providing sensor data that is preferably taken into consideration when controlling the laser.

[0128] In particular, the method is configured to form filamentous damage, especially filamentous hollow channels or filamentous blind holes, within the workpiece.

[0129] A method in which the laser intensity distribution within the focal region in the direction of the laser beam remains constant within a range of ±30% is particularly advantageous. This has already been explained in detail.

[0130] A method for manufacturing a glass element, in particular an element made of ultrathin glass, comprising the method steps described above, wherein the supplied glass strip has an ear portion that is cut by the method or a transverse portion is formed by the method, is extremely advantageous.

[0131] Accordingly, the present invention also includes glass elements made of ultrathin glass, which are manufactured or can be manufactured by the embodiments described.

[0132] Therefore, the present invention also includes the use of the apparatus described above, and / or the use of the methods for manufacturing the glass elements described above, in particular ultrathin glass.

[0133] The present invention has the advantage of enabling the use of high-energy ultrashort laser pulses without damaging the manufacturing environment by generating X-rays. Furthermore, it can avoid the effects of X-rays on sensitive electronic circuits, particularly damage to them. High-energy ultrashort laser pulses enable rapid processing processes, especially those required in mass production. Therefore, overall, the present invention can realize rationally operating apparatus, methods, production facilities, and / or production environments.

[0134] The present invention will be further described below with reference to the examples and drawings. The embodiments shown in these drawings also represent the respective embodiments.

[0135] As described above, the present invention is suitable for separating workpieces made of glass-based materials. Such workpieces are generally brittle.

[0136] In a reasonably advantageous configuration, for this reason, plasma micro-explosion causes microcracks extending from hollow channel-shaped filaments into the bulk portion of the workpiece to form within the workpiece.

[0137] For this purpose, in one embodiment, a focused laser beam of a pulsed laser having a wavelength λ is designed for processing a workpiece made of a glass-based material, where the workpiece is transparent to the laser wavelength λ, and the filament is formed by the incidence of at least one burst packet of laser pulses, where at least one burst packet comprises a sequence of ultrashort burst individual pulses having a burst duration Tb, individual pulse energy Ep, and intraburst delay Ti, where the individual pulse energy of the burst individual pulse at the start of the burst duration Tb is greater than the individual pulse energy of the laser pulse at the end of the burst duration. Hollow channel-shaped filaments can be formed by using multiple burst packets. It is advantageous if each hollow channel-shaped filament is formed by a single burst packet.

[0138] When multiple burst packets are used to form a hollow channel-shaped filament, it is sufficient, in the sense of this specification, for a single burst packet, in particular the first burst packet, to have the characteristic that the first burst individual pulse of the burst packet has higher energy than the last burst individual pulse. Particularly advantageous, this applies to all of each burst packet. Particularly advantageous, within a single burst packet, it is sufficient that the individual pulse energy of each burst individual pulse is less than the individual pulse energy of the preceding burst individual pulse.

[0139] Workpieces made of glass-based materials as defined herein include materials that consist of or contain glass-based materials, at least in the filament region. Glass-based materials are typically brittle materials that can only undergo slight plastic deformation. Therefore, they are excellent in that they have low malleability. Brittle fracture often occurs near the yield limit when the ductility is low. In the sense of the present invention, glass-based workpieces and / or glass-based materials include, in particular, glass and / or glass ceramics, including green glass as a precursor product of glass ceramics.

[0140] To provide sufficient energy for filament formation using a reasonably and industrially available laser source, the filament is fabricated by the incidence of burst packets of at least one laser pulse, which advantageously form burst individual pulses. A burst packet consists of a sequence of ultrashort burst individual pulses. Thus, one burst packet has at least two burst individual pulses. However, typically about 2 to 20 burst individual pulses, advantageously 3 to 10, are used, with an upper limit of approximately 100 burst individual pulses in total.

[0141] The pulse duration of a burst individual pulse corresponds to the pulse duration of the laser, or the duration of the burst packet, called the burst duration Tb. This depends on the pulse duration of the burst individual pulse, the number of burst individual pulses in the corresponding burst packet, and the time interval between burst individual pulses, measured at the point of maximum intensity of each burst individual pulse, called the burst delay Ti. Therefore, the burst packet is f rep It has a repetition frequency known as [a specific frequency]. Each burst individual pulse has a burst individual pulse energy Ep that corresponds to the integral of the intensity characteristics of the burst individual pulse over the burst individual pulse period, and is correlated with the maximum intensity of the individual pulse in the burst packet over a certain burst individual pulse period.

[0142] It has been found that it is particularly suitable to adjust the burst individual pulse energy at the start of the burst duration Tb to be greater than the burst individual pulse energy at the end of the burst duration.

[0143] Until now, it has been assumed that as much energy as possible is accumulated in the workpiece by the burst pulses of the burst packet. The inventors have found that it is not necessary to use as much energy as possible, and that by controlling the time-controlled size of the energy input, it is possible to efficiently form hollow channel-shaped filaments on the one hand, and on the other hand to control the particularly mechanical interaction with the surrounding workpiece material.

[0144] In an advantageous configuration of this method, burst packets are configured to have a burst reduction of 40% to 90%, preferably 50% to 70%, and particularly advantageously 60% to 70%.

[0145] Burst cumulative BG is the burst individual pulse energy Ep of the last burst individual pulse of the burst packet at the end of the burst duration. xThen, the ratio of the burst individual pulse energy of the first burst individual pulse Ep0 of the burst packet at the start of the burst duration to the burst individual pulse energy is observed as a percentage. Therefore, the cumulative burst reduction BG is Ep x The quotient between and Ep0 is preferably expressed as a percentage. Accordingly, the following formula is used, namely, BG=(Ep x ) / (Ep0) The following holds true. For example, if Ep0 is 100 units, Ep x If the amount is 60 units, then BG = 0.6 = 60% is obtained.

[0146] The burst individual pulse energy is significantly reduced at the end of the burst duration for the first burst individual pulse. This makes it possible to extend relatively small and / or relatively short microcracks originating from the filament and extending from its periphery into the workpiece. This contributes to preventing undesirable weakening of the filament-formed workpiece.

[0147] In particular, it has been found that this method is advantageous if the burst individual pulse energy of one laser pulse is smaller than the burst individual pulse energy of the preceding burst individual pulse for the second and subsequent burst individual pulses of the burst packet.

[0148] This, of course, applies to the second burst individual pulse and beyond. Furthermore, the fact that the burst individual pulse energy of each laser pulse within a burst packet is greater than the burst individual pulse energy of the subsequent burst individual pulse can also be considered an equivalent representation.

[0149] In other words, this means that the burst pulse energy within a burst packet decreases over time. Thus, a significantly lower amount of energy is deposited by the burst packet, consisting of individual burst pulses within the workpiece and / or filament, yet it is still possible to efficiently form a hollow channel-shaped filament. This is particularly surprising because it is assumed that the maximum possible amount of energy must be available.

[0150] It has been found to be particularly advantageous when the burst individual pulse energy decreases linearly within the burst packet, or when the burst individual pulse energy decreases exponentially during the burst duration.

[0151] If the burst individual pulse energy is reduced exponentially, then the following equation holds: E(t) = E0(1-AF / 100) t It is particularly advantageous if it is reduced accordingly. In this case, E(t) symbolically represents the intensity of the burst individual pulse at time t of the burst packet, E0 represents the burst individual pulse energy of the first burst individual pulse of the burst packet, and AF represents the extraction coefficient of the entire burst packet, i.e., the decrease in the burst individual pulse energy of the last pulse of the burst packet relative to the first pulse. In the advantageous embodiment described above, where the last burst individual pulse has, for example, 60% of the burst individual pulse energy, the decrease rate is 40%.

[0152] It has been found to be particularly suitable in tests when a filamentous initial channel, especially an initial hollow channel that is expanded by subsequent burst individual pulses of the burst packet, is formed in the first burst individual pulse of the burst packet.

[0153] This will begin with the description of the filament formation mechanism described herein. In selected embodiments, a filamentous initial channel is already formed by the first burst individual pulse. This initial channel may already be a hollow channel. In this case, subsequent burst individual pulses of the laser in the burst packet further expand this initial channel, which means at least substantially an expansion of its diameter. As a result, a hollow channel-shaped filament is obtained in the workpiece.

[0154] While this refers to the diameter of a hollow channel, it should be noted that it is extremely rare in practice for a laser-treated filament within a workpiece to correspond to a uniform channel. The observations here are ideal and simplified explanations. Local variations in diameter are quite possible along the filament axis, i.e., along the longitudinal axis of the filament. It is also possible, and is included in the present invention, for a filament to have a different diameter at its beginning and / or end than in the middle.

[0155] However, when burst packets are used, a considerable amount of X-rays are generated, particularly as described above. Therefore, according to the present invention, the energy characteristics of the burst individual pulses within the burst packet are controlled. Alternatively, the present invention includes the formation of a filament by a single laser pulse, i.e., without the use of burst packets.

[0156] Another variation of this method involves the formation of a compressed region of the workpiece material, also called a compression zone or compression region, around a hollow channel-shaped filament, wherein the region has a particularly higher density compared to the starting material.

[0157] The compression of the surrounding material is thought to be a result of the initial channel being expanded by the laser pulse action. Simply put, a cylindrical region of compressed workpiece material exists around the hollow channel-shaped filament, where the filament axis and the cylindrical axis are located almost vertically overlapping. This compressed region of material has the advantage that the hollow channel-shaped filament, particularly the filament wall, can be mechanically stabilized by this region. As a result, the filament wall is, so to speak, hardened.

[0158] Surprisingly, the first burst individual pulse of a burst packet is sufficient to form an initial channel without first performing energy pooling, and the decrease in burst individual pulse energy within the burst packet leads to compression of the surrounding workpiece material.

[0159] It was observed that the burst pulses of the burst packet, when expanding the initial channel, can push the workpiece material into the workpiece, particularly perpendicular to the channel axis.

[0160] The compression described causes the workpiece material to be pushed, so to speak, into the filament wall and, consequently, into the workpiece, rather than being removed from the workpiece by interaction with the laser pulse. The advantage of the method described is that significantly less material is removed than would typically be pushed into a hollow channel-shaped filament by insertion. This is because the so-called ablated removed material is released into the production equipment as dust. This dust not only contaminates the sensitive beam shaping optics but also absorbs the incident laser radiation if it floats in the beam path and / or even within the initial channel. This is particularly true because the ablated material corresponds at least substantially to the material being processed by interaction with the laser radiation. This parasitic absorption negatively impacts the efficiency of the method.

[0161] In particular, the aforementioned reduction of burst pulse energy within a burst packet contributes to reducing a predetermined percentage of ablated material due to the compressed material.

[0162] The understanding that the above-mentioned compression occurs in the method described herein is based on a measurement test in which the workpiece on which filament formation is to be performed is first weighed. Subsequently, a filament is formed on the workpiece in the manner described herein, that is, a hollow channel-shaped filament is introduced into the workpiece as described above. The diameter and length of the hollow channel are measured, and the volume of the hollow channel is determined from there. The measured volume of the hollow channel is correlated with the specific gravity of the workpiece material, and it is confirmed that the weight is significantly less than expected for the volume of the inserted hollow channel, and thus material is removed from the workpiece by filament formation. In other words, the material here must still be present in the workpiece in a more reasonable form than the compressed material as described above.

[0163] In the method described, the relative weight loss per filament is less than 10%.

[0164] The relative weight loss per hollow channel-shaped filament is less than 10% (exemplarily, this is measured by manual scribing and breaking with a commercially available glass cutting machine for a 150 x 250 mm filament). 2(For a 2mm thick soda-lime glass of the specified size) the following procedure was followed: Particles, fingerprints, and other contaminants were removed manually or in an automated cleaning process (washing machine) by cleaning both sides with glass cleaning agent, ethanol, and compressed air. Subsequently, the prepared sample was weighed on a precision scale. Here, to improve measurement accuracy, the entire structure was enclosed in a transparent plastic box. Then, the sample was fixed on a photograph of the XY axis system. At this time, two stoppers were used on the sample to prevent slippage and to orient it. Laser processing was performed as described above, using an ultrashort pulse laser with a wavelength of 1064 nm and an energy of 400 μJ, with a pulse width of 10 ps, ​​in particular, in burst packets with 3 to 7 individual pulses. 90 × 160 mm 2 A two-dimensional pattern was formed from hollow channel-shaped filaments of a certain size. The sample was then weighed again. To eliminate measurement errors that may occur due to particle deposition during the laser process, the cleaning steps described above (glass cleaner, ethanol, compressed air) or an automated cleaning method were repeated, and the sample was weighed again. The following calculation protocol was used to calculate the relative weight loss per filament.

[0165] If the entire hollow channel material is removed from the sample, the theoretical weight loss per hollow channel-shaped filament is: m theo =(π / 4)d 2 hρ It is calculated by, here, d is the diameter of the hollow cylindrical filament determined from the SEM image of the fracture edge along the filament formation. h is the glass thickness, ρ is the density of the sample from the material datasheet.

[0166] Measured weight loss m mess Dividing this by the number of precursor damage parts N gives the actual weight loss m per precursor damage part. actual but m actual =mmess / N It is obtained as follows. Through the formation of the quotient, the relative mass loss, i.e. m rel =m actual / m theo You can obtain this.

[0167] Here, we will use a 2mm thick glass sample as an example. Specifically, we will use a sample thickness of h=2mm and ρ=2.5g / cm². 3 If the density and calculated filament diameter are d = 600 ± 60 nm, then per filament m theo A theoretical mass loss of 1413 ± 60 pg occurs.

[0168] The actual (average) weight loss is m mess =6±1mg and N=5.8·10 7 In this case, m per filament actual This results in 104 ± 17 pg. From this, the relative weight loss is calculated to be 7.4 ± 2.7%. All calculations are performed taking error propagation into account.

[0169] Relative weight loss m per hollow channel-shaped filament rel teeth, m rel =m actual / m theo The material compression ratio is measured by and may be less than 10%, and / or particularly advantageously, the workpiece has a material compression ratio of at least 1% relative to its intrinsic material density, measured at a radius of 3 μm around the longitudinal axis of each hollow channel-shaped filament.

[0170] The material compression ratio of at least 1% relative to the intrinsic material density was determined by the following measurement method, namely, Lena Bressel, Dominique de Ligny, Camille Sonneville, et al. Femtosecond laser induced density changes in GeO2 and SiO2 glasses: Fictive temperature effect [Invited], Optical Materials Express, Vol. 1, No. 4, 605 613 (1 August 2011) DOI:10.1364 / OME.1.000605, which allows for the measurement of Nd luminescence at approximately 890 nm with excitation at 488 nm. -1 The microscope had to have a spectral range and, in order to achieve a spatial resolution of less than 1 micrometer, it had to be equipped with appropriate motorized XYZ step motor axes and appropriate microscope objective lenses (NA > 0.7). The components according to the present invention were scanned using a step motor in the area to be measured. At each point, the Raman spectrum of the Nd peak was recorded. The position of the spectrum was recorded and converted to pressure and density using a standard spectrum. The standard spectrum was recorded by a glass or glass-ceramic body compressed with a belt press. Further inspection could be performed by Brillouin spectroscopy of spatial resolution. Here, a radius of 3 μm centered on the longitudinal axis or filament axis represents the measurement point of compression or compacting, and is hereinafter also referred to as the compression measurement line. The compression zone may extend further into the material of the workpiece centered on the filament.

[0171] In this specification, the diameter of a hollow channel-shaped filament refers to the section from one channel wall to the other, perpendicular to the filament axis. In the case of a cylindrical channel, the diameter is substantially equal at all points. However, a hollow channel-shaped filament may be tapered or widened in some location in the direction of any surface of the workpiece. In this case, it is referred to as a V-shaped filament. Similarly, a hollow channel-shaped filament may have localized constrictions so as to be so-called hourglass-shaped or X-shaped. The shape of the filament can be adjusted by the formation and location of the focal line.

[0172] A favorable method is to configure the hollow channel-shaped filaments to have a diameter of 100 nm to 3 μm. The ranges of 250 nm to 1.5 μm or 500 nm to 1 μm are particularly favorable. The pitch between individual filaments may be particularly 3 μm to 50 μm.

[0173] When the filament is formed in a V-shape or X-shape rather than as a hollow cylinder or a hollow cylinder with relatively strong local deviations, the diameter described above represents the diameter at the location of the maximum value, or in other words, the diameter at the widest location. In this specification, the diameter of the filament is measured particularly on the surface of the workpiece that is and / or was facing the laser. This location can also be uniquely detected on the workpiece to be processed.

[0174] As already explained, the present invention balances the need to rationally manufacture the largest possible filament, particularly the largest diameter filament, which may undesirably weaken the workpiece due to undesirable crack formation around the filament, with the need to control energy input and consequently crack formation. In this case, as described above, particularly advantageously, the workpiece material is compressed around the filament axis.

[0175] This is particularly advantageous because the focused laser beam generates a plasma within the workpiece that forms hollow channel-shaped filaments.

[0176] This starts with the idea that burst packets of ultrashort laser pulses ignite plasma, particularly within the elongated laser focal line within the workpiece. As described above, the plasma explosion can push the material into the workpiece perpendicular to the filament axis, and thus can form a hollow channel as a hollow space and / or a hollow channel-shaped filament having the geometric shape described above.

[0177] According to one embodiment of the method, the plasma causes microcracks to be formed within the workpiece, extending from hollow channel-shaped filaments into the bulk portion of the workpiece.

[0178] Such crack formation can be used as a basis, particularly when using methods to separate workpieces. Essentially, crack formation occurs perpendicular to the filament axis and runs from the filament into the bulk of the workpiece. The cracks are typically evenly distributed around the filament axis. This means that, viewed from above with respect to the filament and / or filament axis, there is a substantially uniform crack density in a 360° region around the filament. Methods according to the present invention have been found to result in fewer cracks, and consequently fewer cracks, and lower average crack lengths, compared to methods that do not reduce the individual pulse energy within the burst packet.

[0179] A particularly advantageous configuration of this method is that at least 90% of the microcracks terminate within the compression zone described above, and more preferably within a radius of 3 μm centered on the longitudinal axis of the hollow channel-shaped filament.

[0180] This is a statistical consideration. The number and length of microcracks are taken into account, and it is evaluated how many microcracks terminate within the compression region and how many extend beyond it. It is advantageous if at least 10% of the microcracks terminate within the compression region. As mentioned above, the degree of compression is measured within a radius of 3 μm centered on the longitudinal axis of the hollow channel-shaped filament. This means that, particularly advantageously, 90% of the microcracks terminate within a radius of 3 μm. Therefore, the compression region advantageously defines, so to speak, the majority of the microcracks.

[0181] In order to provide a particularly efficient separation method, another advantageous configuration of the method is such that the elongated focal line expands in a direction perpendicular to the filament axis, and the length and / or number of microcracks in the direction of focal line expansion is greater than the length and / or number of microcracks in the direction perpendicular to the expansion.

[0182] The direction of expansion of the focal line perpendicular to the filament axis will hereafter be referred to as the preferred direction. When the focal line expands in one direction, a plasma expanded in that direction is also generated. Plasma explosions are thought to be stronger in the expansion direction. In either case, the number of microcracks in the preferred direction is greater than the number in the direction perpendicular to the preferred direction, and / or the average length of microcracks in the preferred direction is longer than the average length in the direction perpendicular to the preferred direction. In other words, the stress distribution at the top of the narrow side of the ellipse is significantly greater than the stress distribution along the wider side, and therefore microcracks preferably propagate from that top.

[0183] In particular, the preferred direction can be selected to be in the direction of a separation line provided on the workpiece and / or at least substantially congruent to said separation line. This means that the magnification of the laser focal point relative to the workpiece is appropriately controlled. This can be achieved by a mobile optical device and / or a mobile workpiece holder controlled in particular by a microcontroller and / or data processing device. Therefore, the meaning of the present invention also includes the ability to individually adjust the preferred direction at any position on the workpiece, i.e., the preferred direction is variable depending on the position of the focal line on the workpiece and may be particularly adjustable.

[0184] The shape of the focal line magnification is arbitrarily selectable in the sense of the present invention. Particularly commonly, it is an elliptical laser focal point. In this case, the major axis of the ellipse coincides with the preferred direction. Linear and asymmetric magnification and any other suitable magnification shapes are also conceivable and included in the present invention.

[0185] The described method can be configured to emit X-rays that are attenuated and / or shielded by at least one shielding element.

[0186] The plasma explosion described above causes X-ray emission in the experimentally demonstrated embodiments. In particular, the plasma explosion can occur in the region of at least 2 keV to 20 keV and is therefore remarkably concentrated. The plasma explosion can be used, for example, as further as earlier to inspect materials and / or workpieces and / or workpieces to be processed, and in particular to simultaneously process materials and / or workpieces with a laser. Similarly, it has been shown that reducing the burst pulse energy within a burst packet can contribute to reducing the emitted X-rays.

[0187] With respect to the lowest possible X-rays on the other side of the shielding element (opposite the laser process), and therefore outside the processing space, the use of a laser beam with a preferred direction can be doubly advantageous.

[0188] Firstly, structuring the workpiece in the preferred direction allows for the use of a larger shot-to-shot distance (pitch). This means a reduction in the number of laser shots per cut length, and consequently, the X-ray dose. This reduces the X-ray dose rate generated, given a given throughput in the cutting process.

[0189] Secondly, the ablation cloud, i.e., the cloud above the workpiece consisting of material evaporated and / or desorbed by micro-explosion, interacts with the X-rays and, in addition to the aforementioned shielding elements and other technical devices, can significantly contribute to the attenuation of the X-rays. If the ablation cloud is also expanded in one direction by the use of a beam that expands in that direction, this can result in favorable attenuation of the X-rays in that direction. This is a particular advantage for such devices designed for cutting continuous strip material, because in this case, the X-rays are attenuated more strongly in the direction of the housing openings, i.e., the supply and / or removal openings, than in the direction perpendicular to them, when the cutting is performed parallel to the direction of the strip material transport, and this can ensure effective shielding by the housing closed in that direction.

[0190] Regardless of the lateral shape of the laser focal point, the ablation cloud can be influenced by other means, particularly by suction or compressed air. In this case, it is advantageous to adjust the flow profile so that, at a given point in the laser process, as few ablation products as possible are generated within the bulk through which the laser beam passes. This reduces the absorption of laser radiation, which in turn leads to a more efficient and stable structuring process of the workpiece, and in other words, reduces the generation of X-rays within the ablation cloud. Thus, it is based on the premise that already ablated and / or exfoliated material will not be excited again.

[0191] Furthermore, with an appropriate flow profile, the shielding effect of the ablation cloud can be advantageously utilized, as described in relation to structuring using a laser beam with a preferred direction.

[0192] As described above, it is advantageous to orient the laser beam towards the workpiece in the form of an elongated focal line. A favorable method to this end includes orienting the focused laser beam towards the workpiece in an elongated focal line. Particularly advantageous is the formation of the elongated focal line by a beam shaping optical system including optical elements selected from the group consisting of a spatial light modulator (SLM), axicon, frustum-of-cone axicon, double axicon, spherical aberration lenses, and / or chromatic aberration lenses.

[0193] To achieve spatial limiting of laser emission through a focal line, a so-called Bessel beam is ideally used. This beam consists of a central bright maximum portion surrounded by a relatively weak ring, and has the characteristic of maintaining a constant radius in the direction of propagation compared to a Gaussian beam emitted from a laser. This enables machining to greater depths and greater tolerance for workpiece orientation. Furthermore, this beam does not undergo diffraction.

[0194] The formation of a Bessel beam and a long, linear focal point is achieved, in particular, by the so-called axicon, which acts as a beam-shaping lens. The axicon as an optical element was described by McLeod in 1954 (John H. McLeod: The Axicon: A New Type oft Optical Element. J. Opt. Soc. Am. / Vol. 44, No. 8, August 1954). Thus, the axicon is an optical element that images light from a small point source into a linear, continuous focal line. McLeod describes various shapes of axicons, but the glass cone has proven to be the most important axicon.

[0195] A frustum-of-cone axicon has a chamfered face at the tip of the axicon cone along the laser beam axis. The central beam is not interrupted by the frustum-of-cone axis. This facilitates the positioning of the optical system, because it is usually extremely difficult to precisely orient the central beam of an axicon to the tip of the axicon. Similarly, the inclination in the manufacturing of the axicon and / or its precision, particularly the sharpness and symmetry of the cone tip, is not of great importance.

[0196] A double axicon has an incident surface configured such that the laser beam is shaped into a ring beam within the double axicon. The advantage of a double axicon is that the intensity of the laser beam inside the double axicon can be adjusted to be lower than the threshold intensity of the double axicon material by selecting the laser energy, the refractive index of the double axicon, and the axicon angle of the incident surface, so that the double axicon material is not destroyed in the beam path.

[0197] It may also be advantageous to form elongated laser focal points and / or linear focal points using a Gaussian optical system.

[0198] Next, a beam extension can be formed through the spherical aberration of the Gaussian lens. In particular, spherical lenses and / or cylindrical lenses, each having an aspherical portion, can be used here.

[0199] When utilizing spherical aberration, it is possible to configure the system so that the laser beam is not oriented toward the geometric center of the lens, and / or the lens is tilted. This can be done dynamically, i.e., the orientation of the lens relative to the laser beam can be controlled by actuators and a microcontroller and / or data processing device.

[0200] Furthermore, instead of a monochromatic laser, a pulsed multichromatic laser beam having a specific pulse duration and a specific laser beam wavelength can be used. This multichromatic laser beam can form a focal line along its beam direction using an optical device with chromatic aberration for wavelength-dependent focusing, and advantageously using at least one filter for wavelength-dependent filtering of the laser beam, allowing for selective and precise adjustment of the workpiece processing depth at the focal line. In particular, the length of the focal line can be adjusted through the formation of various focal points.

[0201] In many cases, the presence of an elongated laser focus is not important. In these cases, a conventional Gaussian optical system is usually sufficient. These cases are, of course, also included in the present invention.

[0202] As described above, the shape of the hollow channel or blind hole formed may be cylindrical, V-shaped, and / or X-shaped. This can be adjusted in particular through the focal position of the linear focus relative to the workpiece and the intensity profile of the focal line perpendicular to the beam direction.

[0203] In a favorable manner, the laser wavelength is 350 nm to 1100 nm, preferably 1020 nm to 1080 nm, and / or the pulse duration of individual pulses is 40 fs to 20 ps, ​​and / or the burst duration is 1 ps to 500 ns, and / or the individual pulse energy of the first individual pulse at the start of the burst duration is 100 μJ to 1 μJ, preferably 200 μJ to 500 μJ, and / or the workpiece consists of or includes glass and / or glass ceramic and / or silicon and / or ceramic.

[0204] As explained in the paragraph above, the density and / or length of microcracks around hollow channel-like elements can be controlled by reducing the individual pulse energy within the burst packet.

[0205] To enable efficient separation of the workpiece through filament formation, it has been proposed to appropriately adjust the distance between two adjacent filaments. When using burst packets, the distance between two adjacent filaments is advantageously 3 μm to 20 μm, particularly 3 μm to 10 μm or 4 μm to 8 μm. For glass with a thickness greater than 0.5 mm, an empirical formula for filament distance exists, namely, Distance [mm] = Workpiece thickness · Z This is particularly advantageous, and here the coefficient Z can take 3 to 7 values. The empirical formula for distance selection has been found to be particularly applicable to workpieces made of glass and / or glass ceramics having a thickness or material thickness in the range of 0.5 mm to 30 mm. For example, applying the formula to a workpiece with a thickness of 1 mm yields favorable filament distances of 3 μm to 7 μm.

[0206] Particularly advantageous are bursts with a cumulative burst rate of 90% to 70%, especially those involving burst packets containing 2 to 7 individual burst pulses, and especially 3 to 5 individual burst pulses.

[0207] The above parameters apply particularly to glasses containing silicon and boron.

[0208] The aforementioned combination of parameters enables a particularly rational method for processing the workpiece.

[0209] The present invention will be described in detail below with reference to the drawings. The drawings are schematic and are not necessarily drawn to scale. Similarly, each drawing represents an embodiment. The same reference numerals in different drawings have the same meaning. The drawings show the following: [Brief explanation of the drawing]

[0210] [Figure 1] This figure shows the spectral energy distribution of X-rays emitted during the burst processing of special steel. [Figure 2] This figure shows the spectral energy distribution during glass bursting, measured simultaneously at different distances from the focusing incident point. [Figure 3] This is a diagram showing the mass decay of iron. [Figure 4] This figure shows the transmittance of air, dependent on the energy of X-ray photons, measured at different distances from the radiation source. [Figure 5] This is a schematic diagram of the device. [Figure 6] This is a schematic diagram of another device. [Figure 7] This is a schematic diagram of another device. [Figure 8] This is a schematic diagram of another device. [Figure 9] This is a schematic diagram of another device. [Figure 10] This is a schematic diagram of another device. [Figure 11] This is a schematic diagram of another device. [Figure 12] This diagram schematically illustrates the self-absorption of the workpiece. [Figure 13] This is a schematic diagram of another device. [Figure 14] This is a schematic diagram of another device. [Figure 15] This diagram schematically shows an apparatus for producing glass strips, equipped with the above-described device. [Figure 16] This diagram shows burst packets of laser pulses. [Figure 17a] This figure shows an example of the energy characteristics of a laser pulse within a burst packet. [Figure 17b] This figure shows another example of the energy characteristics of a laser pulse within a burst packet. [Figure 17c] This figure shows another example of the energy characteristics of a laser pulse within a burst packet. [Figure 17d] This figure shows another example of the energy characteristics of a laser pulse within a burst packet. [Figure 18a] This figure shows an example of a processed workpiece. [Figure 18b] This figure shows another example of a processed workpiece. [Figure 18c] This figure shows another example of a processed workpiece. [Figure 19] This is a plan view showing the processed workpiece. [Figure 20] This figure shows a filament having microcracks within the workpiece. [Figure 21] This figure shows a filament with microcracks in the compression region. [Figure 22] This is a plan view showing a filament with shortened microcracks. [Figure 23] This is a plan view showing a filament with microcracks in the preferred direction. [Figure 24] This figure shows the dependency between microcrack length and preferred direction. [Figure 25] This is a plan view showing an example of a focal region with a preferred direction.

[0211] Figure 1 shows the spectral energy distribution of emitted X-rays when a burst packet of ultrashort laser pulses is irradiated onto a special steel. This graph shows the wavelength 1030 nm, repetition frequency 100 kHz, pulse duration 1 ps, average laser power 80 W, two separate burst pulses, and irradiation intensity at the focal point of approximately 1.2 × 10⁻¹⁶. 16 W / cm 2 The processing of special steel using a laser, based on this principle, is shown. The intensity of the emitted photons is plotted as the amount emitted in working units [AU (arbitrary units)] against the energy EPh [keV] of the emitted photons produced in laser processing of the laser beam.

[0212] As can be seen, extremely strong emission occurs at approximately 7 keV. From this, in the sense of the present invention, it can be derived that when processing glass-based materials in the corresponding equipment, the ultrashort laser beam is advantageously not incident on metal components, particularly components made of special steel.

[0213] Figure 2 shows the spectral energy distribution of emission when processing glassy materials, specifically glass, using ultrashort laser radiation, specifically burst packets. The intensity of the emitted photons is plotted in keV against the energy EPh of the emitted photons, as in Figure 1, as emission per working unit [AU]. The solid line S11 represents measurements using a mounted sensor at a distance of 38 cm from the processing location, i.e., in the area where the glass is processed by the ultrashort laser pulses. The dashed line S3 represents measurements using a sensor mounted at a distance of 106 cm from the processing location. The laser processing that forms the basis of this figure used the following parameters: an average laser power of 200 W at an emission wavelength of 1030 nm, a pulse repetition frequency of 50 kHz, two individual burst pulses, and a pulse duration of 1 ps for each individual burst pulse.

[0214] Thus, the inventors confirmed that X-rays are generated on a significant scale, specifically in the energy range of 4-10 keV, during the aforementioned laser processing of glass. The maximum value is in the range of approximately 6-9 keV. Similarly, it was confirmed that differences arise between measurements taken by multiple sensors mounted at different distances. These differences are derived from the inverse square law and the absorption characteristics of air. Higher energy radiation is absorbed less strongly by air than lower energy radiation, i.e., softer radiation.

[0215] Figure 3 shows the mass decay of iron. This means that the energy of photons incident on the iron element, Ephoton [MeV], indicates the iron's absorptive capacity ("absorptiveness" in Figure 3) (mass decay coefficient) per working unit. A logarithmic scale is chosen to display the photon energy. It can be seen that the absorptive capacity of iron in the range of 1 keV to 100 keV has its maximum value at approximately 6 to 12 keV. Surprisingly, this maximum absorptive value is in the region where X-rays are emitted when laser processing glassy materials, especially glass, using ultrashort laser pulses. In other words, when iron-containing materials are used against or within shielding elements, the material exhibits particularly good X-ray absorptiveness to the X-rays generated during the processing of glassy materials. By adjusting the materials of the glassy material to be processed and the shielding element here, such processing can be carried out particularly efficiently.

[0216] Figure 4 shows the energy-dependent transmittance of air at various distances from the source. It can be seen that the transmittance of air is remarkably energy-dependent. At a distance of 10 mm, air has approximately 75% transmittance for low-energy photons with an energy of 2.5 keV, while at a distance of 100 mm, the transmittance is less than 10%. In contrast, at a distance of 1 m, photons with an energy of up to 5 keV are almost completely absorbed, while 50% of the energy of photons with an energy of 10 keV is still recorded by the detector. Since the typical dimensions of a laser processing device (distance from the laser incident point to the inner wall) are in the range of approximately 1 m, it is predicted that X-rays with energies substantially above 5 keV, particularly above 7.5 keV or 10 keV, will be applied to the shielding element. Therefore, if the material of the shielding element has particularly good absorption capabilities in the 5 keV to 10 keV range, the shielding of the housing will be particularly effective.

[0217] As mentioned above, this is advantageous for shielding elements made of or containing iron-containing materials. Therefore, steel and / or special steels are particularly advantageous materials.

[0218] Figure 5 schematically shows the basic configuration of the apparatus corresponding to this specification. Apparatus (100) in particular is suitable for use in the method described. Apparatus (100) inserts a hollow channel-shaped filament (180) into a workpiece (2). The apparatus includes an ultrashort pulse laser (3) equipped with a beam shaping optical system (30). The apparatus focuses a laser beam (4) having wavelength λ onto the workpiece (2) as an elongated focal line in the focal region (1). At least a portion of this focal line is located within the workpiece, where a filament (180) is formed by interaction with ultrashort individual pulses or burst individual pulses of a burst packet.

[0219] The workpiece (2) is positioned on a workpiece holder (303). A positioning device (200) can position the incident point of the laser beam (4) of the ultrashort pulse laser (3) laterally and / or transversely on the surface of the workpiece (2). As described, the workpiece (2) is a workpiece containing glass-based materials, particularly glass and / or glass ceramics. The wavelength λ of the laser (3) is selected, as already described, such that the workpiece (2) is transparent to that wavelength.

[0220] As described above, the beam shaping optical system (30) can be formed so that the focal line expands perpendicular to the filament axis in order to provide a preferred direction (VR). Similarly, an aperture can be introduced into the beam path to form a correspondingly shaped focal point.

[0221] In the illustrated example, the positioning device (200) includes an xy table on which the workpiece (2) is placed on its underside. Alternatively or additionally, the laser (3) and / or beam shaping optical system (30) can be configured to move the laser beam (4), thereby making the incident point of the laser beam 4 movable even when the glass element (2) is fixed. Combinations of the two methods are also possible.

[0222] The ultrashort pulse laser (3), positioning unit (200), and / or beam shaping optical system (30) are connected to a control unit (210), such as a microcontroller and / or data processing unit.

[0223] As described above, particularly when burst packets are applied, plasma is generated by the interaction between the ultrashort laser pulse and the workpiece (2), resulting in the formation of filaments within the workpiece (2). At this time, X-rays are released. A shielding element (300) is used to protect the surroundings from these X-rays. The shielding element (300) is configured to form a processing space (302). Outside the processing space, the surroundings are protected from X-rays, particularly by the shielding element (300).

[0224] The shielding element (300) comprises the aforementioned material that at least partially absorbs X-rays, to an appropriate thickness. In the illustrated case, the shielding element (300) is manufactured from a special steel sheet surrounding at least the area of ​​the laser focal point. Optionally, a sensor device (400) is provided, capable of detecting, for example, the light reflection of the incident laser beam or, in particular, the emitted X-rays. Another quantifiable quantity can be assumed, especially if these correlate with the energy of the incident laser output. In this case, the energy of the emitted laser output can be used as a control quantity for the laser (3) and / or the positioning device (200). For this purpose, the laser (3) and / or the positioning device (200) are connected to a control device (210). In this way, high process stability can be achieved, for example, by using the amount of X-ray emission as a measure of the incoming laser output and driving and controlling the laser (3) so that the desired processing parameters are maintained using the quantifiable quantity.

[0225] In this embodiment, the workpiece (2) is mounted on a workpiece holder (310). Its surface defines a machining plane W extending in the xy direction within the framework of this specification. Machining of the workpiece (2) is performed within and / or in the immediate vicinity of this plane. The shielding element extends beyond the machining plane W in the z direction in the direction of the laser beam (4) to a plane B from which the workpiece (2) can be fed and / or removed.

[0226] The edges of the shielding element (300) and / or the region in the z-direction below the edges of the shielding element (300) constitute the so-called supply opening and / or removal opening. In other words, the supply opening is located in a plane (B) perpendicular to the z-direction below the machining plane (W). In particular, the region of the shielding element (300) is located within the machining plane (W). Here, the supply plane or removal plane (B) is in shadow of the generated X-rays based on the geometric arrangement of the workpiece mounting section (303) and the workpiece (2) itself.

[0227] The workpiece (2) is generally introduced into the machining space (302) by a lift device (201) that can move up and down in the z direction.

[0228] In this embodiment, the workpiece (2) can be sequentially supplied into the processing space (302), and therefore this is particularly suitable for plate-shaped workpieces, especially plate glass.

[0229] The workpiece mounting section (303) is made of a material that absorbs X-rays in the z-direction, at least in the region of the laser beam (4) and / or its extension. This material includes, as described above, glass and / or glass ceramic or glass-filled plastic composites. This takes into account the recognition that, as described above, a large amount of X-rays are generated when laser radiation is incident on a metal, particularly an iron-containing metal. In the illustrated embodiment, this problem is avoided by making the workpiece mounting section (303) from a different material.

[0230] In the example of the embodiment corresponding to Figure 5, it should be noted that the shielding element (300) of course has an aperture for the laser beam (4) to be processed. In this case, the resulting X-rays can reach the surroundings through the aperture. This can be reduced by the optical element (30) absorbing the X-rays emitted in the z direction, because the optical element is generally made of glass. Another effect is that during plasma laser processing, a cloud of particles from the material of the workpiece may be generated, particularly rising from the workpiece in the z direction. This cloud itself also absorbs the resulting X-rays.

[0231] Those skilled in the art will readily understand that the basic method of the present invention is applicable to variations and modifications of the illustrated apparatus. In particular, a closed apparatus, in particular a closed working space (302), can be provided. The working space (302) is opened, in particular for supplying and / or removing the workpiece, and closed during processing. Such a working space is mainly suitable for sequential processing of workpieces.

[0232] Figure 6 shows a device (100) that processes the workpiece (2) into a strip, thereby enabling a continuous process. For example, the strip is made of glass. In this example, it is ultrathin glass obtained from a draw tank (250) using the down-draw method (see Figure 15). The present invention can be applied to alternative methods for manufacturing ultrathin glass, as well as to the overflow fusion method. In this case, the ultrathin glass has a maximum material thickness of approximately 100 μm, and in this example, the material thickness is 20 μm to 50 μm.

[0233] The apparatus (and other apparatuses described herein) utilize the above-described basic principle in which the machining plane (W) is different from the supply plane (B). In particular, the supply plane (B) can be positioned offset downward from the machining plane (W) when viewed in the z-direction. As shown in the following figure, it is also possible to position the supply plane (B) above the machining plane (W).

[0234] At least one deflection device (203) deflects the strip material toward a laser processing apparatus equipped with a laser (3) and moves it toward the processing plane (W). This configuration takes advantage of the bendability of the workpiece (2) made of a glass-based material, which exists particularly as thin glass and / or glass ceramic, and especially as ultrathin glass.

[0235] Based on the distance to the draw tank, laser processing is performed in the cold region of the equipment. However, it is also possible for laser processing to be performed in the hot region (220) closer to the direction of the draw tank (250). The strip material can be accommodated and / or stored on a drum formed, for example, as a roller, in this case a glass roller (221). For this purpose, the drum rotates according to the drawing speed of the glass strip material (see Figure 15).

[0236] Similarly, a shielding element (300) is provided that at least partially surrounds the laser processing (1) area and forms a processing space (302), and further shields the surroundings from the emitted X-rays as described above. As explained with reference to Figure 5 above, in this example, the supply plane and / or extraction plane (B) is located below the processing plane (W) in the z direction. The region between these planes is where the shielding element (300) is located.

[0237] A gap (305) exists below the processing plane (W) (viewed in the z direction). Therefore, when irradiation is performed using a focused laser beam, the laser beam (4), i.e., its focal region (1) and / or the laser beam region with high energy density, passes through the workpiece (2) but does not incident on any other material capable of generating X-rays.

[0238] In this case, an arbitrary shielding element (310) can also be provided below the workpiece. This may be made of the above-mentioned material, particularly glass and / or the above-mentioned plastic composite material. However, as stated above, in this apparatus, the focused laser beam does not reach the shielding element (310) at least at high energy densities, so metallic materials are also possible.

[0239] As can be easily understood, the region between the additional shielding element (310) and the region of the shielding element (300) facing the supply plane and / or the extraction plane B forms the supply opening and / or extraction opening (320).

[0240] It should be reiterated here that the drawings are purely schematic in nature. In particular, the illustrations of the radius of curvature and / or deflection radius are not drawn to scale. It is known to those skilled in the art that these can be adapted to the specific workpiece.

[0241] Figure 7 shows an embodiment similar to the basic method shown in Figure 6, except that the supply plane and / or take-off plane (B) is located above the processing plane (W) in the z-direction. This can be achieved particularly by the arrangement of the deflection device (203). In this case as well, a gap (305) is provided below the workpiece (2), and an optional shielding element (310) is provided. It should be noted that the deflection device (203) may also be made of or contain an X-ray absorbing material. For example, in the roller configuration, it may be made of metal and / or plastic, particularly the filled plastic as described above. This, of course, applies to all embodiments in which the deflection device (203) is present.

[0242] The embodiment shown in Figure 7 illustrates a shielding element (300) with particularly compact dimensions. Here, the deflection of the supply plane (B) to the processing plane (W) occurs outside the processing space (302). As with the embodiment in Figure 6 (and all other corresponding embodiments), the workpiece (2) itself absorbs the X-rays generated in the direction of the plane (W). The laser (3) is positioned at the aperture of the shielding element (300), and therefore, in this embodiment, the laser (3) itself contributes to the shielding of the X-rays it generates. This is a basic scheme for any arrangement applicable to all embodiments. The same is of course true for the alternative arrangements described above.

[0243] Figure 8 shows another variation similar to the embodiments in Figures 6 and 7, in which a shielding element (300) can also be provided below the machining plane W. In particular, a box is formed here as a so-called closed machining space (302). A supply opening and / or removal opening (320) can be formed as a slit, in particular, within the shielding element (300). The deflection of the workpiece strip (2) from the supply plane (B) to the machining plane (W) is performed here within the machining space (302). Of course, the deflection here can also be performed outside the machining space, as in Figure 7.

[0244] Figure 9 shows another variation and / or embodiment, in which the workpiece (2), in particular a strip made of a glass-based material, in particular glass, in particular an ultrathin sheet glass strip, is deflected multiple times. The supply plane (B) intersects multiple times on the sides of the supply opening and / or the removal opening (320), respectively. A corresponding number of deflection devices (203) are provided. Since the glass-based material described itself absorbs the X-rays generated during its processing, in this embodiment, even if X-rays leak from the supply opening or the removal opening (320), they must pass through the glass-based material multiple times. Due to self-absorption, the X-rays can be blocked and / or the amount of leaked X-rays is reduced at least significantly.

[0245] Similarly, an optional aperture (312) made of the same material as a shielding element (300) which may be attached to the region of the supply opening and / or take-out opening (320) and which shields X-rays from the region is also illustrated. The aperture (312) may be formed as part of the shielding element (300). In particular, the aperture (312) and / or additional shielding element may be configured below the working plane (W) according to the extending state of the workpiece, in particular the strip-shaped workpiece (2). In this embodiment, the extending state is represented by a bent shielding element (310) below the supply plane (B).

[0246] Another embodiment is shown in Figure 10, in which the deflection device is improved to simultaneously form a workpiece holder (208). The deflection device here is formed, for example, as a roller, particularly as a rotatable roller, and can be realized by supplying a workpiece (2), particularly a strip-shaped one, to the processing space (302) via the roller. The deflection device and workpiece holder (208) here, as in the prior embodiments, cause the workpiece (2) to be introduced from the supply plane and / or removal plane (B) to the processing plane (W). The deflection device and workpiece holder (208) here are mounted, at least partially, within the processing space (302). The deflection device and workpiece holder (208) may consist of a material that absorbs X-rays in particular, or may contain a material that absorbs X-rays at least on its surface. Particularly suitable are glass-based materials or plastics, particularly glass-filled plastics.

[0247] Figure 11 shows another embodiment in which the supply aperture (320) and / or extraction aperture (320) are located at a distance A from the location of the laser processing (1) and / or the location of the laser focal point (1). A is measured from the laser focal point (1), more precisely from the center line of the laser focal point, to the inner wall of the shielding element (300) at the location where the supply aperture and / or extraction aperture (320) are located. Distance A is selected so that the generated X-rays must pass through a sufficiently long air section, in which the air is absorbed as described above before the X-rays can leak from the supply aperture and / or extraction aperture (320) at undesirable high dose power. As described, since the X-rays generated during the above-described processing of glass-based materials are in the energy range of approximately 8 keV and / or higher, A is advantageously selected in the range of 10 mm to 1000 mm. In this embodiment, since the processing plane (W) is located within the plane of the supply opening and / or the removal opening (320), this embodiment is also suitable for workpieces (2) that do not have sufficient flexibility for deflection, or for surroundings where sufficient structural space can be used and this embodiment is preferred as it is the easiest to realize.

[0248] In designing distance A, it should also be considered that the material of the workpiece 2 absorbs the generated X-rays more efficiently than air. Typically, X-rays are observed primarily in the z-direction, i.e., in the bulk and / or depth of the workpiece (2). Due to self-absorption of the glassy material, the main proportion of the generated X-rays, XEm, particularly the proportion of the maximum dose output, leaks from the processing location at an angle α measured from the surface of the workpiece (2). If distance A is appropriate, these X-rays (more precisely, the main proportion) will not pass through the supply opening and / or the extraction opening (320), because α > 1° or 1° < α ≤ 90° holds true.

[0249] It should be noted here that, in this embodiment as well, other shielding elements (310, 300) are provided individually or in any combination.

[0250] The basic method for the directional dependence of X-ray XEm emission during processing of glass-based materials using ultrashort laser pulses is explained in detail with reference to Figure 12. The processing area (1) of the laser beam in the workpiece (2) is shown. This is where interaction occurs, that is, plasma is generated particularly in the laser focal region as described above. Stronger absorption occurs inside the workpiece (2), which is made of a glass-based material. Absorption occurs outside the workpiece due to air, but this is weaker than absorption by the workpiece material itself. Since the main proportion of the emitted X-rays is generated in the bulk portion of the workpiece (2) and thus below the workpiece surface in the z-direction, the main proportion XEm of the X-rays enters at an angle α from the workpiece surface. Here, α is measured from the plane of the workpiece surface, and thus in the xy-direction. α is greater than 0°, in particular greater than 1°. In particular, α is in the range of 1° to 90°, where the main proportion XEm represents the arithmetic mean value of the angle-dependent emission intensity averaged over all emission angles. It is therefore clear that the geometrical design of the processing space (302), in particular with regard to the distance A to the processing plane W in the z-direction and / or with regard to the arrangement relative to the processing plane W, and / or the suitable geometrical arrangement of the supply opening and / or the removal opening (320) can be used for reducing leaking X-rays.

[0251] FIG. 13 shows a further embodiment in which the supply opening and / or the removal opening (320) are, as it were, closed off by at least one deflection device and / or supply means and / or removal means (203). The at least one deflection device and / or supply means and / or removal means (203) advantageously consists of or comprises a material that absorbs X-rays, in particular the material described with reference to the shielding element (300) and / or the plastics and / or filled plastics mentioned above. These supply means and / or removal means (203) can in particular be configured as rollers. By means of a suitable combination and / or arrangement of these supply means and / or removal means (203), the supply opening and / or removal opening (320) for X-rays can be closed, as shown for example in FIG. 13.

[0252] An alternative means for closing the supply opening and / or the removal opening (320) is shown in Figure 14. Here, the supply opening and / or the removal opening (320) is closed by a curtain (326) made of a medium that absorbs X-rays, in particular a fluid. The fluid here can be applied to the region of the supply opening and / or the removal opening (320), for example by a fluid nozzle (325). Such fluids are generally, for example, gas curtains and / or water curtains.

[0253] Here, it should be emphasized once again that all elements illustrated and / or described with respect to one embodiment can be combined with other embodiments. With the teachings provided in the present specification, those skilled in the art can produce an apparatus that meets individual requirements and can provide more efficient X-ray protection.

[0254] Figure 15 shows an embodiment in which the apparatus (100) described in the present specification is used as a strip in the production environment of a glass-based workpiece (2). In this example, the workpiece (2) is in particular ultra-thin glass obtained from a draw tank (250) by the down-draw method. A corresponding application of the method according to the present invention is likewise possible in alternative ultra-thin glass production methods such as the overflow fusion method. Here, the ultra-thin glass has a material thickness within the ranges mentioned above, advantageously a material thickness of at most 400 μm or 100 μm, and in particular the material thickness in this example is 20 μm to 50 μm. By means of a deflection device (203), the strip is deflected in the direction of the apparatus (100) which comprises a laser (3) and shielding elements (300, 310). Based on the distance to the draw tank, the laser processing is here carried out in the cold region of the installation. However, it is likewise possible to carry out the laser processing in the high-temperature region, closer in the direction of the draw tank (250). The strip can be received and / or stored on a drum, for example in the form of a roller, here a glass roller (221). For this purpose, the drum rotates in accordance with the drawing speed of the glass strip. The apparatus (100) described in the present specification can be used in particular for cutting the edges and / or forming the transverse portions of the glass strip (2).

[0255] Figure 16 shows three burst packets of laser pulses as plots of laser pulse intensity I over time t. Since the energy of each individual laser pulse corresponds to the integral of the laser output over a given time, the energy E of the laser pulse correlates to the intensity of the laser pulse at the observed standard plane. Accordingly, the figures shown here correspond to schematic plots of laser pulse energy over a given time. Three burst packets are shown, each consisting of four laser pulses, here consisting of individual burst pulses, where Tb is the burst duration. Tb is determined as the time from the point of maximum intensity of the first laser pulse (41) of each burst packet to the point of maximum intensity of the last pulse of each burst packet.

[0256] In the illustrated example, the number of individual burst pulses in one burst packet is 4. For example, 2 to 20 individual burst pulses and / or 2 to 10 individual burst pulses are advantageous in one burst packet. The width of the individual pulses is advantageously 300 fs to 11 ps. Tb is advantageously in the range of 1 ps to 500 ns, and Ti is advantageously in the range of 400 fs to 400 ns. To fabricate a hollow channel-shaped filament in a glass-based workpiece, it may be advantageous that a single burst packet is incident on the workpiece. The use of 2 to 10 burst packets, especially 2 to 5 burst packets, is equally possible and advantageous. The time interval between individual burst packets is called the inter-burst delay Td. 1 / Td may advantageously be 1 to 1000 kHz.

[0257] The parameters mentioned above are selected depending, in particular, on the specific composition of the glass-based material of the workpiece, the desired geometric shape of the filaments, and the distance between the filaments.

[0258] The energy Ep0 of the first individual pulse (41) of a burst packet is favorably equal to the energy Ep0 of the last individual pulse (42) of the same burst packet. xIt can be adjusted to be greater than [a certain value]. The inventors have confirmed that this can reduce the emitted X-rays.

[0259] Figures 17a to 17d show favorable characteristics of the energy of individual burst pulses over time t in individual burst packets. For simplicity, these characteristics are shown as curves and not as discrete value points. The number of individual pulses in a burst packet is arbitrary and favorably within the range described above. The simplest energy characteristic is the linear characteristic corresponding to Figure 17a. In this case, the energy of the individual pulses in the burst packet decreases at least at a nearly uniform rate. Similarly, it is possible that one or more first individual pulses in a burst packet have at least substantially uniform energy, and subsequent pulses have smaller, and in particular, similarly constant, energy. This corresponds to a two-stage energy characteristic as shown in Figure 17b.

[0260] Similarly, nonlinear characteristics, such as the exponential reduction of individual pulse energies within a burst packet corresponding to Figure 17c, are also possible. Here, the individual pulse energies within the burst packet can be configured to initially rise and then fall, with the first individual pulse favorably having higher energy than the last individual pulse. In this case, one or more laser pulses following the first individual pulse have higher energy, and then their energy decreases towards the last individual pulse. Such characteristics are shown in Figure 17d.

[0261] Figures 18a to 18c show cross-sections of a filament-formed workpiece (2) made of a glass-based material that can be manufactured using the apparatus and method described herein, to schematically illustrate possible shapes of a hollow channel-shaped filament. Figure 18a shows the simplest case in which a cylindrical hollow channel is fabricated as a filament (180) within the workpiece (2). The filament is substantially located in the region of the laser focal point (1). The filament axis A passes through the center point of the filament. The filament wall is axially symmetric. In the illustrated example, the filament (180) connects the top surface (O) and the bottom surface (U) of the workpiece (2). Thus, the hollow channel-shaped filament (180) is a through channel or through opening. As described above, it is also possible for the filament to terminate within the workpiece. In this case, which is not shown, the filament becomes a blind hole. The workpiece has a workpiece thickness (s). The workpiece thickness (s) includes ultrathin or thin glass with a thickness of a few micrometers, and standard glass with a thickness of a few centimeters. In particular, the range of 10 μm to 200 μm, and therefore the range of thin glass including ultrathin glass, and the range of 0.5 mm to 3 mm, and therefore the range of base glass or plate glass are applicable.

[0262] Figure 18a also shows the compression region (22) surrounding the filament. The compression region (also called the compression zone) and its occurrence have been explained earlier. This region extends into the workpiece material almost perpendicular to the filament axis.

[0263] As shown in Figure 18b, a frustoconical filament (180), also synonymously referred to as a V-shaped filament, can be constructed. Here, the frustoconical filament can also be referred to as a hollow channel. The frustoconical filament is further axially symmetric with respect to the filament axis (A). In this illustration, the filament opens downwards toward the workpiece. This means that the diameter (dU) of the filament (180) at the bottom surface of the workpiece (2) is greater than the diameter (dO) at the top surface. This configuration as a blind hole, not shown, is also possible. The expansion of the filament in one direction toward the workpiece can be achieved by adjusting the focal position of the beam shaping optical system, particularly by adjusting the convergence of the laser beam and the distance to the workpiece. The other channel angle β is approximately 0.05 to 0.1°. This other channel angle is measured between the perpendicular line passing through the workpiece and the inner wall of the filament, and therefore corresponds to half the opening angle.

[0264] Figure 18c illustrates an hourglass-shaped or synonymous X-shaped filament (180) formed as a similarly continuous hollow channel. In this embodiment, it can be formed, in particular, by setting the narrowest focusing region of the laser within the workpiece. The channel angle and / or opening angle β are preferably the same region as that for the V-shaped filament. The X-shaped filament (180) is characterized by a constriction in the filament diameter in a region along the filament axis (A). In the illustrated example, the constriction is located in the center of the workpiece (2), i.e., equidistant from the surface of the workpiece (2). Embodiments also exist in which the constriction is located closer to the surface of the workpiece than when it is located opposite.

[0265] The compression region (22) is not shown in Figures 18b and 18c for clarity. However, of course, the compression region (22) may be provided in V-shaped and / or X-shaped filaments (180). In this case, the compression region (22) is particularly continuous with each channel wall.

[0266] Figure 19 shows a plan view of the workpiece (2) on which the filaments have been formed. The hollow channel-shaped filaments (180) are arranged in a set pattern within the workpiece (2). This is also referred to as a structured workpiece (2). The filaments (180) are surrounded by a compression region (22), in which the workpiece material is compressed by the action of irradiation with ultrashort laser pulses, as described above. Similarly, as described above, at least 1% compression exists as a so-called compression measurement line (23) at a radius of 3 μm centered on the filament axis. This means that the degree of compression, which is synonymous with compression, can be measured at this compression measurement line (23).

[0267] Figure 20 schematically illustrates a general mechanism for separating glass-based workpieces using laser filament formation. This represents a plan view of the workpiece. The filament (180) is surrounded by microcracks (50) of length RL. Microcracks are generally described as being generated by shock waves, which cause a plasma explosion in the material of the workpiece (2) at the focal region of the ultrashort laser pulse, potentially generating X-rays. When microcracks (50) connect to microcracks (51) connected to adjacent filaments, these microcracks (51) can form a consistent crack line, along which the workpiece can be separated.

[0268] Figure 21 schematically shows a plan view of another workpiece (2) in which filament formation was performed by reducing the individual pulse energy within the burst packet. In this case, because the energy of the last individual pulse of the burst packet is less than the energy of the first individual pulse of the burst packet used to form the filament (180), the crack length RL is shorter than in the conventional technique, and the generation and / or emission of X-rays is also reduced. Reducing the laser pulse energy within the burst packet is thought to at least reduce the uncontrollable energy input into the material of the workpiece (2). The energy input to the plasma is, so to speak, better controlled. In this case, the generation of X-rays is also reduced. This is surprising, as it is usually assumed that it is more advantageous to accumulate as much laser energy as possible into the material of the workpiece during filament formation.

[0269] Microcracks (50), when viewed in a plan view, typically extend in a beam-like manner from a central filament (180) into the material of the workpiece. In this case as well, microcracks of adjacent filaments connect to one or more connected microcracks (51), thereby forming a separation line.

[0270] Therefore, the shortened crack length RL has the disadvantage that the filaments (1) must be placed in close proximity to each other in order to form the connected filaments (51) and thus the separation line. However, this is offset by the advantage that shorter and / or fewer microcracks can be propagated into the material of the workpiece (2) away from the separation line. Otherwise, these cracks weaken the edges of the workpiece after separation, as is evident in the reduction of edge strength. Furthermore, the high edge strength is advantageous because it allows for rational further processing and / or application of the filament-formed workpiece, and in particular, it results in very few defective products. Similarly, the potential disadvantage here is also compensated for by the reduction of X-rays.

[0271] Figure 22 illustrates an advantageous embodiment with drawings similar to those in Figures 20 and 21. According to this embodiment, the microcrack (50) extends within the compression region (22). Therefore, the crack length RL is smaller than the width of the compression ring around the filament (180). In order to form a consistent separation line with connected microcracks (51), the compression regions (22) must be at least in contact with each other and / or overlap. This is especially true with respect to the compression measurement line. If the filaments (180) are too far apart from each other, the microcrack (52) will not form, and therefore an interrupted separation line will be formed at that location. This is particularly advantageous by adjusting the breaking force required for the actual separation of the workpiece portion along the separation line. That is, it is advantageous because in many cases, the filament-formed workpiece is not separated or individualized on its own, but rather an additional mechanical force, i.e., separation force, is required for this purpose. This facilitates further processing, especially transport, of the filament-formed workpiece.

[0272] In this example in Figure 22, the reduction of individual pulse energy in the burst packet is similarly applied, thereby achieving a state in which the microcracks (50) in the compressed region (22) are, so to speak, killed. In the compressed material, crack propagation appears to be blocked, but the individual pulse energy reduced in the burst packet as described above can simultaneously minimize the generated X-rays, allowing for particularly good adjustment so that the microcracks (50) terminate within the compressed region (22), especially within the compression measurement line. The compression measurement line is not shown here for clarity.

[0273] A particularly advantageous embodiment is illustrated in Figure 23. In the illustrated form, similar to Figures 20 to 22, the control of the energy of individual pulses within a burst packet is optional and not essential. When viewed in a plan view, the laser focus is expanded in the direction of the separation line, particularly in the direction of the intended separation line. As a result, a preferred direction is formed as described above. As a result, the crack length RL of the microcracks (50) in the preferred direction (VR) is longer than the crack length of the microcracks (50) that do not extend in the preferred direction. This allows the filaments (180) to be arranged further apart from one another in the preferred direction, forming connected microcracks (51) from the microcracks in the preferred direction, which in turn form the separation line, while fewer and / or shorter microcracks propagate into the material of the workpiece (2), whereby less edge embrittlement can be achieved. The above-described reduction of the individual pulse energy in the burst packet particularly advantageously makes it possible to limit microcracks outside the preferred direction in the compression region (22), in particular inside the compression measurement line, while the microcracks (50) in the direction of the preferred direction propagate outside the compression region.

[0274] As described above, the ablation cloud, that is, the cloud above the workpiece (2) consisting of material evaporated and / or blown away by micro-explosions, is interacting with the generated X-rays, and in addition to technical devices such as the shielding elements described above, it contributes significantly to the attenuation of X-rays. If the ablation cloud is likewise expanded in the preferred direction VR by the use of the laser beam (4) expanded in the preferred direction VR, this can lead to advantageous attenuation of X-rays in the direction of the preferred direction (VR). Since this may and / or normally faces in particular the direction of the supply opening (320) and / or the extraction opening (320), the incoming X-rays can likewise be advantageously reduced at this location in this direction.

[0275] Accordingly, a particularly good compromise with respect to processing efficiency, edge stability and X-ray protection is achieved.

[0276] Figure 24 schematically shows the relationship between the crack length RL of an individual microcrack and the characteristic angle Ω of that crack with respect to the preferred direction. The expressions that can be read from Figure 24 are qualitative. Here, the average crack length RL is shown in relation to the angle Ω. The angle Ω represents the angle between the direction of the microcrack's movement and the axis of the preferred direction, i.e., the major axis of the ellipse in this example of elliptical focal expansion, as described above.

[0277] A highly nonlinear relationship exists between RL and Ω. The shortest crack length and the minimum value of RL occur perpendicular to the preferred direction where Ω is 90°. In contrast, the crack length is maximum in the direction of the preferred direction where Ω is 0°. This indicates that the efficient orientation of the preferred direction in the direction of the separation line yields an overproportionate advantage in terms of the efficiency and edge strength of this method.

[0278] The shape of the focal point magnified in the preferred direction is not limited to the elliptical shape described earlier in the plan view. In essence, all applicable shapes are included in the present invention. Figure 25 illustrates several possible plan views of the focal point magnified in the preferred direction. VR represents the preferred direction as a vector, which lies on the planned separator line (53). The first example is an elliptical magnification with its major axis on the separator line (53). Furthermore, teardrop-shaped magnifications, heart-shaped magnifications, triangular magnifications, and / or magnifications consisting of two or more parts are also possible, using the axis of symmetry on the separator line (53).

[0279] As illustrated, the present invention, as a whole, has the advantage of providing an apparatus and method that enables efficient processing of glass-based materials while protecting the surroundings from emitted X-rays. The means and measures used for this purpose are usable in a manufacturing environment. [Explanation of symbols]

[0280] 1 Focal area 2 Workpiece 3 Lasers 4 Laser beams 22 Compression Area 23 Compression measurement line 30 Beam shaping optics 41. The first pulse of the burst packet 42 Last pulse of burst packet 50 microcracks 51 Connected Microcracks 52 No microcracks 53 Separation line 100 devices 180 filaments 200 Positioning device 201 Lifting device 203 Deflection device, supply means and / or extraction means 208 Deflection device and workpiece mounting section 210 Control device 221 Laura 250 Draw Tank 300 Shielding element 302 Processing space 303 Workpiece placement section 305 Free space 312 aperture 320 supply opening, removal opening 400 Sensor Devices W Machining plane B Supply plane, extraction plane Tb burst duration Ti Burst Delay Td (Burst Delay) Ep01 Pulse energy of the first pulse of one burst packet Ep x Pulse energy of the last pulse of a burst packet A Filament axis O Top surface U bottom surface dO Filament diameter on the upper side dU Filament diameter on the bottom side s Workpiece thickness α XEm angle β channel angle RL Crack Length VR preferred direction Ω Angle relative to the preferred direction XEm emitted X-rays

Claims

1. An apparatus (100) for laser-assisted processing of a workpiece (2) made of a glass-based material, and in particular an apparatus (100) for introducing a damaged portion into the workpiece (2), The apparatus (100) is configured to position the workpiece within the processing plane (W), An ultrashort pulse laser (3) is provided that emits an ultrashort laser pulse having a wavelength λ, an individual pulse energy Ep, and a laser beam direction having at least one component in the direction z perpendicular to the processing plane (W). The laser and / or laser pulse are configured such that the workpiece is at least substantially transparent to the wavelength λ. Furthermore, a beam shaping optical system (30) is provided, configured to form a focal region (1) of the laser beam located at least partially inside the workpiece in a predetermined operating state, wherein the irradiation intensity Ef is such that, in a predetermined operating state, X-rays are emitted in at least one energy range EM. At least the focal region (1) is surrounded in at least a portion of the area by at least one X-ray shielding element (300), thereby providing a processing space (302), either alone or in combination with another shielding element (310). The shielding elements (300, 310) are made of or include a material having an X-ray absorptivity adapted to the energy range EM, preferably the material of the shielding elements (300, 310) has a particularly high X-ray absorptivity in the energy range EM. device (100),

2. The apparatus (100) according to claim 1, wherein the X-rays are in an energy range of at least 4 keV to 20 keV, and preferably have a maximum value in the range of 6 keV to 10 keV.

3. The apparatus (100) according to at least one of claims 1 to 2, wherein the material of the shielding element (300, 310) has a maximum X-ray absorptivity in the energy range of 5 keV to 8 keV.

4. The apparatus (100) according to at least one of claims 1 to 3, wherein, in the predetermined operating state, the dose equivalent output outside the processing space (302) is less than 10 μSv / h, preferably less than 1 μSv / h, and particularly 0.1 to 10 μSv / h or 0.1 to 1 μSv / h, when measured at a distance of 10 cm from the outer wall of the processing space (302).

5. The shielding element (300, 310) is made of a material selected from the group of metals, particularly iron, lead or lead foil, steel, special steel, tungsten, or glass, or a material selected from the group of plastic composites, particularly tungsten or a plastic composite filled with glass, or comprises the said material, in the apparatus (100) according to at least one of claims 1 to 4.

6. The apparatus (100) according to at least one of claims 1 to 5, wherein the X-ray shielding elements (300, 310) at least partially surround the workpiece (2).

7. The apparatus (100) according to at least one of claims 1 to 6, wherein the apparatus (100) is configured to generate a plasma that emits X-rays in the focal region of the laser beam (1).

8. The laser (3) has a repetition frequency f ｒｅｐ It emits a burst packet of at least one laser pulse consisting of a sequence of ultrashort burst individual pulses (41) having the following characteristics: Preferably, the apparatus (100) according to at least one of claims 1 to 7, wherein the first burst individual pulse of the burst packet generates an initial plasma, and energy is supplied to the initial plasma by subsequent individual pulses of the burst packet, thereby maintaining and / or amplifying the initial plasma.

9. The apparatus (100) has a laser wavelength λ of 350 nm to 1100 nm, and / or the pulse duration of individual pulses, particularly burst individual pulses, is 40 fs to 20 ps, ​​and / or the burst duration Tb is 1 ps to 500 ns, and / or the cumulative energy of burst packets is 100 μJ to 1 J, and / or the repetition frequency f ｒｅｐ The apparatus (100) according to at least one of claims 1 to 8, wherein the frequency is 10 kHz to 100 MHz and / or the workpiece is made of or contains glass and / or glass ceramic.

10. The apparatus (100) according to at least one of claims 1 to 9, wherein the focal region (1) is configured to absorb X-rays emitted at least partially by the workpiece (2) itself.

11. A workpiece placement section (303) is provided for placing the workpiece (2) during processing, where, The workpiece mounting portion (303) is made of an X-ray absorbing material, particularly glass and / or glass ceramic or glass-filled plastic composite, in at least the area of ​​the focal region (1) and / or its extension, or A free space (305), particularly a void, exists in the z-direction below the workpiece (2), and the free space (305) is defined in at least a portion of the region downward in the z-direction by an X-ray absorbing element (310), particularly by an element (310) made of glass and / or glass ceramic or glass-filled plastic composite material. The apparatus (100) according to at least one of claims 1 to 10.

12. The apparatus (100) according to at least one of claims 1 to 11, wherein the workpiece (2) is supplied to a processing space on a supply plane (B) different from the processing plane (W), and in particular the supply plane is located below or above the processing plane (W) when viewed in the z direction.

13. The apparatus (100) according to at least one of claims 1 to 12, wherein the shielding element (300) has a supply opening (320) into which the workpiece can be introduced into the processing space (302).

14. The apparatus (100) according to claim 13, wherein the workpiece (2) itself absorbs X-rays in the direction of the supply opening (320).

15. The supply opening (320) can be closed by at least one closing device (203, 326) comprising a material that absorbs X-rays emitted under a predetermined operating state, wherein the closing device is selected from the group consisting of a closing curtain, rollers and / or a water curtain or a combination thereof, and is particularly preferably the device (100) according to at least one of claims 13 to 14, wherein the closing device comprises a material corresponding to claims 1 to 4.

16. The apparatus (100) according to at least one of claims 13 to 15, wherein the supply opening (320) is located within a supply plane (B), preferably where the supply plane (B) is different from the processing plane (W), and particularly preferably the area of ​​the shielding element is located within the processing plane (W), particularly between the supply plane (B) and the processing plane (W).

17. The supply opening (320) is measured at a maximum distance A of 200 cm from the focal region (1) on the processing plane (W), particularly at a maximum distance A of 150 cm, or a maximum distance A of 100 cm, or a maximum distance A of 50 cm, and is preferably within the range of 10 cm to 200 cm, or within the range of 10 cm to 150 cm, or within the range of 10 cm to 100 cm, or within the range of 10 cm to 50 cm. Particularly preferable, between the focal region and the supply aperture, there exists a region of the workpiece and an air space that absorbs at least partially emitted X-rays. The apparatus (100) according to at least one of claims 13 to 16.

18. The apparatus (100) is configured to supply the workpiece (2) in the form of a strip made of a glass-based material, particularly in the form of a thin glass or ultrathin glass having a thickness of 5 μm to 400 μm, or 5 μm to 200 μm, or 5 μm to 100 μm, or 5 μm to 50 μm, or 5 μm to 30 μm, and particularly in the form of a thin glass or ultrathin glass having a thickness of 7 μm to 40 μm, and the workpiece is supplied particularly continuously to the processing space (302). The apparatus (100) according to at least one of claims 1 to 17.

19. The apparatus (100) according to claim 18, wherein the apparatus (100) is configured to supply a strip made of a glass-based material (2) to the processing space (302) while bending it.

20. The apparatus (100) according to at least one of claims 13 to 19, wherein the shielding element (300) has, in addition to the supply opening (320), an extraction opening (320) having measures and / or characteristics described in particular in relation to the supply opening.

21. The apparatus (100) according to at least one of claims 1 to 20, comprising a supply means (203) configured to introduce the workpiece (2) into the processing space (302), and preferably a removal means (203) configured to lead the workpiece out of the processing space (302).

22. The apparatus includes a sensor device (400), in particular a sensor device (400) assigned to the processing space (302), The sensor device (400) is configured to detect emitted X-rays and thereby provide sensor data, and preferably the laser (3) is configured to be controllable in consideration of the sensor data. The apparatus (100) according to at least one of claims 1 to 21.

23. The apparatus (100) according to at least one of claims 1 to 22, wherein the laser (3) and the beam shaping optical system (30) are configured to form a filamentous damaged portion (180), in particular a filamentous hollow channel or a filamentous blind hole, within the workpiece (2).

24. The apparatus (100) according to at least one of claims 1 to 23, wherein the beam shaping optical system (30) is configured to provide a laser intensity distribution in the focal region that is constant within a range of ±30% in the laser beam direction z.

25. The apparatus (100) is arranged as an element of a glass manufacturing apparatus, and more particularly as an element of an ultra-thin glass manufacturing apparatus, and more specifically in a continuous glass strip having a lug portion. The device is configured to form the ear portion and / or cross portion. The apparatus (100) according to at least one of claims 1 to 24.

26. A method for processing a glass-based workpiece (2) using an ultrashort pulse laser (3), particularly a method for introducing a damaged area into the workpiece (2), The workpiece is positioned on a processing plane (W), and the laser (3) emits ultrashort laser pulses having wavelength λ and individual pulse energy Ep in the laser beam direction z, where the laser wavelength λ is selected such that the workpiece (2) is at least substantially transparent to the laser wavelength λ. The laser beam is focused to a focal region (1) by a beam shaping optical system (30), and the individual pulse energy Ep within the focal region is large enough to emit X-rays. At least the focal region (1) is surrounded in at least a portion of its area by at least one X-ray shielding element (300), thereby providing a processing space (302) either alone or in combination with another shielding element (310), in particular, that outside the processing space, when measured at a distance of 10 cm from the outer wall of the shielding element (300), an X-ray dose of less than 10 μSv / h, preferably less than 1 μSv / h, and especially an X-ray dose of 0.1 μSv / h to 10 μSv / h or an X-ray dose of 0.1 to 1 μSv / h. method.

27. The workpiece (2) includes a glass-based material in at least the focal region (1), The X-rays in the processing space (302) are generated within an energy range EM of at least 4 keV to 20 keV, and have a maximum value particularly in the range of 6 keV to 10 keV. Preferably, the material of the shielding element has a maximum X-ray absorption value in the energy range of 6 keV to 10 keV. The method according to claim 26.

28. The shielding elements (300, 310) are made of a material selected from the group of metals, particularly iron, steel, special steel, tungsten, and glass, or a material selected from the group of plastic composites, particularly plastic composites filled with tungsten or glass, or include the said material. The method according to at least one of claims 26 to 27.

29. The method according to at least one of claims 26 to 28, wherein an X-ray emitting plasma is generated in the focal region of the laser beam (1), preferably the laser (3) emits a burst packet of at least one laser pulse consisting of a sequence of ultrashort individual pulses, particularly preferably the first individual pulse of the burst packet generates an initial plasma, and energy is supplied to the initial plasma by subsequent individual pulses of the burst packet, thereby maintaining and / or amplifying the initial plasma.

30. The laser wavelength λ is 350 nm to 1100 nm, and / or the pulse duration of the individual pulses, particularly burst individual pulses, is 40 fs to 20 ps, ​​and / or the burst duration Tb is 1 ps to 500 ns, and / or the cumulative energy of the burst packet is 100 μJ to 1 J, and / or the repetition frequency f ｒｅｐ The frequency is 10 kHz to 100 MHz, and / or the workpiece is made of or contains glass and / or glass ceramics. The method according to at least one of claims 26 to 29.

31. The workpiece (2) is placed on the workpiece placement section (303), and here, The workpiece mounting portion (303) is made of a material that absorbs X-rays in the z-direction, particularly glass and / or glass ceramic or glass-filled plastic composite, in at least the area of ​​the focal region (1) and / or its extension, or Below the workpiece, there is a free space (305), particularly a void, in the z-direction, and the free space (305) is defined in at least a portion of the region in the z-direction by elements (300, 310) that absorb X-rays, particularly elements made of glass and / or glass-ceramic or glass-filled plastic composite material. The focal region (1) of the laser is preferably at least partially located within the free space (305). The method according to at least one of claims 26 to 30.

32. The workpiece (2) is supplied to a processing space (302) on a supply plane (B) different from the processing plane (W), In particular, the supply plane (B) is located below or above the processing plane (W) when viewed in the z direction, preferably the area of ​​the shielding element (300) is located within the processing plane (W), particularly between the supply plane (B) and the processing plane (W). The method according to at least one of claims 26 to 31.

33. The method according to at least one of claims 26 to 31, wherein the shielding element (300) has a supply opening (320) for introducing the workpiece into the processing space (305).

34. The supply opening (320) is closed by at least one closing device (203, 326) which includes a material that absorbs emitted X-rays. In particular, the closing device (203, 326) is selected from the group consisting of closing curtains, rollers and / or water curtains or combinations thereof, and preferably the closing device includes the corresponding material according to claims 26 to 27. The method according to claim 33.

35. The method according to at least one of claims 33 to 34, wherein the supply opening (320) is located in a supply plane (B) that is above or below the processing plane (W) when viewed in the z direction.

36. The workpiece (2) is in the form of a strip made of a glass-based material, and is particularly a thin or ultrathin glass strip having a thickness of 5 μm to 400 μm, or 5 μm to 200 μm, or 5 μm to 100 μm, or 5 μm to 50 μm, or 5 μm to 30 μm, and is particularly 7 μm to 40 μm, and the workpiece (2) is particularly continuously supplied to the processing space (302). The method according to at least one of claims 26 to 35.

37. The method according to claim 35, wherein the glass strip is supplied to the processing space (302) while being bent.

38. The method according to at least one of claims 26 to 37, wherein the shielding element (300) has, in addition to the supply opening (320), an extraction opening (320) having measures and / or characteristics described in particular in relation to the supply opening.

39. The method according to at least one of claims 26 to 38, wherein the workpiece (2) is transported into the processing space (302) using supply means (201, 203) and / or transported out of the processing space (302) using removal means (201, 203).

40. The method according to at least one of claims 26 to 39, wherein the generated X-rays are detected by a sensor device (400), and in particular X-rays generated within the processing space (302) are detected, thereby providing sensor data which is preferably taken into consideration when controlling the laser (3).

41. The method according to at least one of claims 26 to 40, wherein a filamentous damaged portion (180), particularly a filamentous hollow channel or a filamentous blind hole, is formed in the workpiece (2).

42. The method according to at least one of claims 26 to 41, wherein the laser intensity distribution within the focal region (1) is constant within a range of ±30% in the laser beam direction z.

43. A method for manufacturing glass elements, particularly elements made of ultra-thin glass, The method includes steps according to at least one of claims 26 to 42, The supplied glass strip (2) has an ear portion which is separated by the method described in any one of claims 26 to 42, and / or a transverse portion which is formed by the method described in any one of claims 26 to 42. method.

44. Glass elements manufactured by the method described in any one of claims 26 to 43, more particularly glass elements made of ultrathin glass.

45. Use of an apparatus (100) according to at least one of claims 1 to 25 or a method according to at least one of claims 26 to 43 for processing and / or manufacturing glass elements (2), particularly ultrathin glass.

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