Laser cutting head, and a method for controlling the laser cutting of a workpiece.

Abstract

LASER CUTTING HEAD, AND METHOD FOR CONTROLLING THE LASER CUTTING OF A WORKPIECE. A laser cutting head (1) associable with a machine tool comprises a collimation group (2) for collimating a laser beam (L) from a laser emitting device, a focusing group (5) for focusing the collimated laser beam (L) onto a focal point (F), an optical element (8; 38) for receiving said focused laser beam (L) and reflecting a first focused portion (L1) thereof, and a wavefront sensor (9) for receiving said first focused portion (L1) of the laser beam (L), performing a phase measurement of a wavefront of said first focused portion (L1), obtaining a reconstructed wavefront based on the phase measurement and sending the reconstructed wavefront to an electronic processor (12);The electronic processor compares the reconstructed wavefront and a reference wavefront, determines one or more optical aberrations to which the laser beam (L) is subjected, reduces such optical aberrations and alters said focal point (F).

Description

/ 17 Laser cutting head, and a method for controlling the laser cutting of a workpiece.

[001] The present invention relates to laser cutting devices for cutting machine tools and, in particular, relates to a laser cutting head for use in a fiber optic laser cutting system in a cutting machine or combined cutting / punching machine for sheet metal.

[002] The use of laser systems for cutting, engraving and welding of workpieces is known and widespread in the machine tool industry for processing sheet metal and plate metal.

[003] As is known, a laser is a device capable of emitting monochromatic light, that is, with a single wavelength, coherent in space and concentrated in a beam of very high luminosity (brightness), through a stimulated emission process. The ability to concentrate a large amount of energy in a very small area allows laser devices to cut, engrave, and weld metals. Cutting metallic materials typically occurs by vaporization and, above all, by fusion. In the latter case, the laser beam melts a small area of ​​the workpiece and the molten metal (slag) is removed by a blast or jet of gas.

[004] Within laser emitting devices, different types of source can be used to generate a laser beam suitable for cutting metals. Gas lasers (carbon dioxide, carbon monoxide CO2) and solid-state lasers (coated glass laser diodes and fiber lasers) are commonly used.

[005] Due to the high energy required to cut metal sheets, even thick ones, the dimensions and weight of laser emitting devices are such that they cannot be positioned directly on machine tools. To overcome this disadvantage, a laser cutting head, or more simply a cutting or focusing head, can be positioned on Petition 870250102121, dated 07 / 11 / 2025, page 10 / 71 / 17 machine tool and connected to the laser emitting device by means of an optical chain (CO2 laser) or a transmission fiber (optical fiber, for example in YAG laser diodes) to emit the laser beam generated by the emitting device and focus it on the workpieces. Due to its small size and low weight, the cutting head can in fact be moved by the machine tool with precision and speed to perform the cutting of the product.

[006] In so-called fiber laser cutting systems, in which a fiber optic cable with a diffusing prism is used to bring the laser beam to the cutting head, the latter typically comprises a collimation group that transmits the light beam exiting the fiber optic to a focusing group capable of focusing the laser beam on the workpiece, that is, positioning its focal point or focus at a defined point on the surface of the workpiece or just below or just above such surface.

[007] The focused laser beam exits the cutting head through a nozzle that concentrates the blast or jet of gas used to remove the slag generated by the melting of the metal and reduce the likelihood of the slag reaching the focusing group. For this purpose, a transparent element or window or protective glass is also provided in the nozzle, which separates the interior of the cutting head from the external environment and allows the passage of the laser beam exiting the focusing group.

[008] The precise positioning of the focal point where all the power of the laser beam is concentrated is essential to perform the correct cutting of the material.

[009] Laser cutting heads, particularly high-power ones, are, however, subject to a phenomenon commonly known as “thermal focus shift,” which causes optical aberration of blurring or opacity, that is, a shift in focus relative to the desired and ideal point (on the surface of the workpiece or just below or just above), Petition 870250102121, dated 07 / 11 / 2025, page 11 / 71 / 17 as better explained below.

[0010] As is known, a small fraction of the energy of the laser beam passing through the lenses of collimating and focusing optical groups is absorbed and transformed into heat, mainly due to the non-absolute transparency of the optical elements (coating and substrate). Additional heat absorption can also be caused by contamination and / or damage to the surface layer usually provided on the lens surfaces.

[0011] Prolonged use of the machine tool, especially with extremely high laser powers, causes considerable heat absorption and a resulting increase in the temperature of the entire cutting head. This temperature increase affects all the optical elements that make up the cutting head, that is, the diffusing prism of the transmission fiber, the collimation group, the focusing group and the separation glass (in particular the last two, very close to the workpiece or the melting point area of ​​the same where very high temperatures are concentrated) and causes a variation in both the refractive index of the lenses and their shape.

[0012] The change in the refractive index and shape of the lens caused by the increase in temperature causes the focal point to shift.

[0013] To compensate for the phenomenon of “thermal focus shift”, the focal point position can be adjusted by appropriately moving a lens of the focusing group, which is mounted on a respective tray or lens transport slider that is linearly movable along an adjustment direction parallel to the direction of the laser beam so as to allow focusing of the laser beam. Alternatively, if it is appropriate or necessary that the lenses of the focusing group be kept fixed, the correct positioning of the focal point on the workpiece is obtained by appropriately moving a lens of the collimating group, which is mounted on a respective linearly movable tray or slide.

[0014] The movement of the focus group or collimation can be Petition 870250102121, dated 07 / 11 / 2025, page 12 / 71 / 17 manually controlled by an operator through visual inspection of the laser beam projected onto the workpiece, or by numerical control based on automatic measurement of the focal point displacement.

[0015] However, while visual inspection and manual control restrict the accuracy and repeatability of the cut to the operator's capabilities and hardly result in high-quality processing, on the other hand, focal point displacement measurements require a lot of time and expensive equipment and imply an increase in machine tool costs.

[0016] In addition, heat absorption also causes a number of other aberrations, such as spherical aberrations, coma and astigmatism, which also affect the wavefront of the laser beam, in particular the distribution of electromagnetic intensity within the laser beam, contributing to the decay of cutting characteristics or the inability to perform the cut.

[0017] An objective of the present invention is to improve known laser cutting heads for use in combined cutting / drilling machine tools for sheet metal, in particular fiber optic laser cutting heads.

[0018] Another objective is to obtain a laser cutting head capable of guaranteeing cutting precision and repeatability, particularly with extremely high laser powers and also in the case of intense and prolonged use of the machine tool on which the laser cutting head is mounted.

[0019] Another objective is to obtain a laser cutting head that allows a plurality of optical aberrations affecting the wavefront of the laser beam exiting the cutting head to be measured and reduced in a simple and effective manner.

[0020] Another objective is to obtain a laser cutting head with a compact form factor and particularly limited dimensions that is economical and easy to manufacture. Petition 870250102121, dated 07 / 11 / 2025, p. 13 / 71 / 17

[0021] These and other objectives are achieved by a laser cutting head according to the claims presented below.

[0022] The invention can be better understood and implemented with reference to the accompanying drawings which illustrate an exemplary and non-limiting embodiment thereof, in which: Figure 1 is a simplified cross-section of the laser cutting head of the invention according to a first embodiment; Figure 2 is a simplified cross-section of a variant of the laser cutting head shown in Figure 1; Figure 3 is a simplified section of the laser cutting head of the invention according to a different embodiment.

[0023] Figure 1 shows a first embodiment of the laser cutting head 1 according to the invention, which is associable with a cutting machine or a combination cutting and drilling machine for cutting and a mechanical part 100, for example a sheet metal part.

[0024] The laser cutting head 1 is fed by a laser emitting device, not shown in the figure, by means of optical transmission means 4, such as an optical chain or a transmission fiber. In particular, the emitting device is a solid-state fiber laser stimulated emission device, for example with high power, and the optical transmission means 4 comprise an optical fiber cable to carry a laser beam L generated by the emitting device to the laser cutting head 1, the latter being capable of emitting the laser beam L and focusing it on a focal point F placed on a surface 101 of the workpiece 100 facing the laser cutting head 1 or just below or just above said surface 101.

[0025] The laser cutting head 1 comprises a collimation group 2 which includes at least one collimation lens 3 for collimating the laser beam L coming from the laser emitting device and a group of Petition 870250102121, dated 07 / 11 / 2025, p. 14 / 71 / 17 focusing 5 which includes at least one focusing lens 6 to focus the laser beam L exiting collimated from collimation group 2 onto the focal point F.

[0026] The support and movement means 7 support and move along an adjustment direction X at least one between the collimation group 2 and the focusing group 5, for example, only the latter in the embodiment illustrated in figure 1, in order to change the focal point F of the laser beam L. The support and movement means 7 comprise linear guide means 71 for sliding support and guiding the focusing group 5 along the adjustment direction X, avoiding displacements and / or oscillations transverse to the adjustment direction X that would cause a displacement of the focal point direction F of the laser beam L and / or a modification of the size and / or shape of the same focal point F in the part 100.

[0027] The laser cutting head 1 additionally includes at least one optical element 8 for receiving the laser beam L that exits focused from the focusing group 5, reflecting at a given reflection angle, for example between about 10° and about 100°, a first focused portion L1 of the received laser beam L and transmitting to the focal point F a second focused portion L2 of the same received laser beam L. The optical element 8 is, for example, a beam splitter, in particular chosen from among a cubic beam splitter (CBS), an optical prism and a semi-transparent mirror.

[0028] The coating medium 15 of the laser cutting head 1 forms an internal space 20 adapted to contain at least the collimation group 2, the focus group 5, the support and movement means 7 and the optical element 8.

[0029] The internal space 20 is closed and hermetically sealed, that is, airtight, from an external environment where the laser cutting head 1 is located. In other words, the coating medium 15 prevents the entry into the internal space 20 of contaminants and foreign elements, in particular slag and solid and gaseous residues generated by laser cutting, which could Petition 870250102121, dated 07 / 11 / 2025, page 15 / 71 / 17 to soil the collimating lenses 3, the focusing lenses 5 and the optical element 8 or to compromise the functioning of the support and movement means 7.

[0030] For this purpose, the coating media 15, which may have a substantially cylindrical shape, parallelepiped shape or complex geometric shape, are provided with an inlet opening 51 coupled to the optical transmission medium 4, which allows the entry into the internal space 20 of the laser beam L generated by the emitting device, a lateral opening 53 hermetically sealed by a transparent optical element 11 for the transmission of the first focused portion L1 of the laser beam L towards the external environment and an outlet opening 52 positioned in a cutting nozzle 30 and hermetically sealed by a separating glass 32. The latter, in addition to being adapted to separate the internal space 20 of the laser cutting head 1 from the external environment, allows the transmission of the collimated and focused laser beam L, in particular the second focused portion L2, from the laser cutting head 1 towards the external environment.

[0031] The cutting nozzle 30 concentrates a blast or jet of gas intended to remove the slag generated by the melting of the workpiece 100 and at the same time helps to reduce the likelihood that said slag may reach the interior of the laser cutting head 1 with the consequences illustrated above.

[0032] Linear guidance means 71 and other anti-rotation means are also housed within the coating medium15, in particular they are fixed to an inner wall thereof. The anti-rotation means, of a known type and not shown in detail in the figures, are arranged to prevent the support and movement means 7 from rotating around a geometric axis parallel to the adjustment direction X during the movement of the collimation group 2 and the focusing group 5. The rotation of the lenses, in particular of the collimating lens 3, can in fact cause a displacement of the focal point F of the laser beam L and a variation in the size and / or shape of such focal point F Petition 870250102121, dated 07 / 11 / 2025, page 16 / 71 / 17 in document 100.

[0033] The laser cutting head 1 also comprises a wavefront sensor 9, of a known type and not described in detail, for example, a Shack-Hartmann wavefront sensor and an electronic processor 12 connected both to the wavefront sensor 9 and to the support and motion means 7, in particular to the linear guidance means 71.

[0034] The wavefront sensor 9, which in the illustrated embodiment is positioned outside the coating medium 15, is adapted to receive the first focused portion L1 of the laser beam L, which passes through the transparent optical element 11 closing the lateral aperture 53 of the coating medium 15, perform a phase measurement of a wavefront of the first focused portion L1, the latter being in particular collimated by a respective collimating optical system 19 positioned upstream of the wavefront sensor 9 with reference to a propagation direction P1 of the first focused portion L1, then obtain a reconstructed wavefront based on said phase measurement and send the reconstructed wavefront to the electronic processor 12.

[0035] The electronic processor 12 is then configured to perform a comparison between the reconstructed wavefront obtained by the wavefront sensor 9 and a reference wavefront and, consequently, determine based on this comparison one or more optical aberrations to which the first focused portion L1 of the laser beam L is subjected.

[0036] It should be noted that, with respect to the second focused portion L2 of the laser beam L that strikes and processes the part 100, the first focused portion L1 is subject to other optical aberrations due to the transparent optical element 11 that closes the side aperture 53 and through which said first focused portion L1 passes to reach the wavefront sensor 9. In order to improve the accuracy of the system, said additional optical aberrations are advantageously known by the electronic processor 12, for example, Petition 870250102121, dated 07 / 11 / 2025, page 17 / 71 / 17 for the initial or periodic calibration of the laser cutting head 1.

[0037] The reference wavefront with which the reconstructed wavefront is compared can be an ideal wavefront free of optical aberrations, for example, in the case where high precision processing of part 100 is required, or a predetermined wavefront affected by predefined optical aberrations, for example, in the case where the processing of part 100 must meet less stringent precision requirements.

[0038] The electronic processor 12 is then able to operate the support and motion means 7 to move the collimation group 2 and / or the focusing group 5 along the adjustment direction X, in particular only the focusing group in the mode illustrated in figure 1, in order to reduce the optical aberrations of the laser beam L, in particular of the second focused portion L2, taking into account the other aberrations to which only the first focused portion L1 is subject, and to vary the focal point F.

[0039] In more detail and with reference to what has already been highlighted, in the case of high-precision processing, i.e., with an ideal reference wavefront free of optical aberrations, the electronic processor 12 is configured to operate the support and movement means 7, so that the optical aberrations of the laser beam L are minimized and, in particular, zeroed, and the focal point F is changed accordingly, while in the case of processing with less stringent precision requirements, i.e., in the case of a predetermined reference wavefront affected by predefined optical aberrations, the electronic processor 12 is configured to operate the support and movement means 7 so that the optical aberrations of the laser beam L are less than or equal to such predefined optical aberrations, changing the focal point F accordingly.

[0040] Advantageously, the electronic processor 12 can control an alarm device, of a known type and not illustrated in the figures, Petition 870250102121, dated 07 / 11 / 2025, page 18 / 71 / 17, for example, a visual and / or acoustic alarm device. When the electronic processor 12 detects that the optical aberrations to which the laser beam L is subjected exceed a predetermined limit value, for example defined a priori by the user, it sends an activation signal to the alarm device which generates a visual and / or audible error signal. Thus, the user can interrupt the processing of part 100 before it is irreversibly damaged by the laser beam L, subject to aberrations that exceed the threshold and are therefore harmful to part 100, as it is not focused on the correct focal point F.

[0041] When coupled with a machine tool and put into use, the laser cutting head 1 is capable of performing a method according to the invention for controlling the laser cutting of a workpiece 100. This method comprises the steps of: perform laser cutting of part 100 using the laser cutting head 1 associated with the machine tool; feed the laser cutting head 1 with a laser beam L coming from a laser emitting device; collimate using collimation group 2 and focus the laser beam L at focal point F using focusing group 5; to reflect through the optical element 8 at least the first focused portion L1 of the laser beam L that exits the focusing group 5 in focus; perform using wavefront sensor 9 a phase measurement of a wavefront of said first focused portion L1; obtain, using the same wavefront sensor 9, a reconstructed wavefront based on the phase measurement; Using electronic processor 12, perform a comparison between the reconstructed wavefront and the reference wavefront; Petition 870250102121, dated 07 / 11 / 2025, page 19 / 71 / 17 to determine, using the same electronic processor 12 and based on said comparison, one or more optical aberrations to which the laser beam L is subjected; to reduce, in particular again by means of the electronic processor 12, the optical aberrations to which the laser beam L is subjected in order to change the focal point F.

[0042] According to what has been seen so far, if high-precision processing is required, that is, if the reference wavefront is an ideal wavefront free of optical aberrations, the reduction step comprises minimizing, in particular zeroing, one or more of the aforementioned optical aberrations. Alternatively, if processing with less stringent precision requirements is required and, therefore, the reference wavefront is a predetermined wavefront affected by predefined optical aberrations, the method according to the invention comprises the step of reducing the optical aberrations so that they are less than or equal to the predefined optical aberrations.

[0043] Advantageously, when optical aberrations exceed a predetermined limit value, defined a priori by the user, the method according to the invention comprises the step of emitting an error signal by means of an alarm device controlled by the electronic processor 12.

[0044] Advantageously, the method according to the invention may further comprise the step of calibrating the laser cutting head 1, once, for example, when the machine tool is switched on or periodically during the processing of the workpiece 100. It is thus possible to detect in particular the other optical aberrations introduced by the transparent optical element 11, to which the first focused portion L1 is subjected.

[0045] The laser cutting head 1 of the invention is therefore capable of guaranteeing cutting precision and repeatability, even with laser powers Petition 870250102121, dated 07 / 11 / 2025, p. 20 / 71 / 17 extremely high and in the context of intense and prolonged use of the machine tool on which the laser cutting head 1 is mounted.

[0046] Thanks to the wavefront sensor 9 connected to the electronic processor 12, it is indeed possible to measure a plurality of optical aberrations, including, for example, focus shift due to thermal focus shift, spherical aberration, coma and astigmatism, affecting the laser beam L that comes out of the cutting head, especially when the machine tool is used for a long time and with extremely high laser powers, causing an increase in the temperature of all optical elements and causing a change in both the refractive index of the lenses and their shape, with consequent shift of the focal point F.Based on the wavefront measurements, the electronic processor 12 is then able to modify the structure of the optical system, in particular by operating the support and movement means 7 of the 2 collimation and / or focusing optical groups 5, to easily and effectively reduce the optical aberrations to which the laser beam L is subjected and thus change the focal point F so that it is positioned and concentrated at the desired point on the surface 101 of the part 100 or just below or above such surface 101.

[0047] In a variant of the first embodiment of the laser cutting head 1 according to the invention, illustrated in figure 2, the exit opening 52 which is positioned in the cutting nozzle 30 is hermetically sealed by an optical element 38 capable of receiving the laser beam L exiting focused from the focusing group 5, reflecting with a reflection angle, for example between about 10° and about 100°, a first focused portion L1 of the received laser beam L and transmitting to the focal point F a second focused portion L2 of the same received laser beam L. The optical element 38 is, for example, a beam splitter, in particular chosen from among a cubic beam splitter (CBS), an optical prism and a semi-transparent mirror.

[0048] Optical element 38 is positioned as a glass of Petition 870250102121, dated 07 / 11 / 2025, page 21 / 71 / 17 separation adapted to separate the internal space 20 of the laser cutting head 1 from the external environment. Thus, the laser cutting head 1 requires fewer optical components and has a compact shape, particularly limited dimensions and reduced weight, thus being adapted to be associated in particular with a machine tool with strict dimensions and handling requirements. This variant is also economical and easy to manufacture.

[0049] Figure 3 shows a second embodiment of the laser cutting head 1 according to the invention, which is also associable with a cutting and / or punching machine tool, respectively for cutting and / or punching a mechanical part 100, for example, a metal sheet.

[0050] In this second embodiment, the laser cutting head 1 comprises components similar to those described above and indicated with the same reference numbers, namely, a collimation group 2 for collimating a laser beam L from a laser emitting device, a focusing group 5 for focusing the laser beam L exiting collimated from the collimation group 2 onto a focal point F, at least one optical element 8 for receiving the laser beam L exiting focused from the focusing group 5 and reflecting a first focused portion L1, and an electronic processor 12. The collimation group 2, the focusing group 5, and the optical element 8 are contained within the internal space 20 of the coating medium 15. In particular, the fixing means 70 support the collimation group 2 and the focusing group 5 and maintain them in a fixed position relative to the coating medium 15.

[0051] In a variant not shown, the optical element that receives the focused laser beam L, reflects the first focused portion L1 and transmits the second focused portion L2, also acts as a separating glass intended to separate the internal space 20 of the laser cutting head 1 from the external environment, with the aforementioned advantages of shape. Petition 870250102121, dated 07 / 11 / 2025, p. 22 / 71 / 17 compact, particularly limited dimensions, light weight and low costs of the laser cutting head 1.

[0052] The laser cutting head 1 in this second embodiment comprises at least one adaptive optical device 10 with adjustable shape.

[0053] As is known, the adaptive optical device 10 comprises an adaptive optical element 16 having a thickness such that it allows its deformability and a suitable support consisting of piezoelectric or electromagnetic or electromechanical actuators, not visible in the figure, connected to the adaptive optical element 16 and the electronic processor 12 to shape the form of at least one deformable surface 17 of the adaptive optical element 16. Thus, the electronic processor 12 is able to adjust the shape of the adaptive optical device 10 by controlling the piezoelectric or electromagnetic actuators that support the adaptive optical element 16.

[0054] The adaptive optical device 10 is positioned upstream of the focusing group 5 with reference to a propagation direction P of the laser beam L that goes from the collimation group 2 to the focusing group 5, preferably downstream of the collimation group 2. Specifically, with reference to figure 3, the laser beam L generated by the emitting device and transported by the optical transmission medium 4 to the laser cutting head, exits collimated from the collimation group 2, strikes the deformable surface 17 of the adaptive optical element 16 and is reflected by the latter towards the focusing group 5 following the propagation direction P.

[0055] The laser cutting head 1 according to this second embodiment also comprises at least one wavefront sensor 9 adapted to receive the first focused portion L1 of the laser beam L, perform a phase measurement of a wavefront of the first portion Petition 870250102121, dated 07 / 11 / 2025, p. 23 / 71 / 17 focused L1, obtain based on this measured phase a reconstructed wavefront and send the reconstructed wavefront to the electronic processor 12.

[0056] The electronic processor 12 is configured to perform a comparison between the reconstructed wavefront and a reference wavefront, determine, based on such comparison, one or more optical aberrations to which the laser beam L is subjected, exclude the additional optical aberrations to which only the first focused portion L1 is subjected, and control the piezoelectric or electromagnetic actuators to adjust the shape of the adaptive optical device 10, reduce the aforementioned optical aberrations, and change the focal point F.

[0057] Similar to what has already been seen, in the case of high-precision processing, the reference wavefront is an ideal wavefront free of optical aberrations and the electronic processor 12 is configured to adjust the shape of the adaptive optical device 10 so that the optical aberrations of the laser beam L are minimized and, in particular, zeroed, and thus changes the focal point F. In the case of processing with less stringent precision requirements, the reference wavefront is a predetermined wavefront affected by predefined optical aberrations and the electronic processor 12 is configured to adjust the shape of the adaptive optical device 10 so that the optical aberrations of the laser beam L are less than or equal to such predefined optical aberrations and changes the focal point F.

[0058] In a different embodiment not shown, the laser cutting head 1 according to the invention may comprise support and movement means 7, which support and move along an adjustment direction X at least one of the collimation group 2 and the focusing group 5, and an adaptive optical device 10, such components being contained in the internal space 20. In this case, the support and movement means 7 and the Petition 870250102121, dated 07 / 11 / 2025, page 24 / 71 / 17 actuators of the adaptive optical device 10 are connected to the electronic processor 12. The electronic processor, in order to reduce the optical aberrations of the laser beam L and change the focal point F, is capable of operating the support and movement means 7 of the optical groups and controlling the piezoelectric or electromagnetic actuators of the adaptive optical device 10, simultaneously or alternatively.

[0059] Alternatively to what is illustrated in the figures, the wavefront sensor 9 can be positioned and hermetically seal the side opening 53 of the coating medium 15 or be positioned inside the internal space 20 of the laser cutting head 1, in this second case the side opening 53 and the transparent optical element 11 that hermetically sealed said side opening are not necessary.

[0060] The laser cutting head 1 according to any of the other embodiments and variants described or according to a possible combination thereof, when associated with a machine tool and put into use, is also capable of implementing the steps of the invention method to control the laser cutting of a workpiece 100, as illustrated above.

[0061] Advantageously, the laser cutting head 1 of the invention may also include a cooling unit, which is externally fixed to a respective wall of the coating medium 15, and thermoconductive means, which connect the support and movement means 7 or the fixing means 70 to said wall of the coating medium 15, so as to extract, by thermal conduction, from the support and movement means 7 or fixing means 70 and from the collimating and focusing optical groups 2 and 5 the heat generated in the latter when traversed by the laser beam L. For this purpose, the support and movement means 7, the fixing means 70 and at least the respective wall of the coating medium 15 are made of material with high thermal conductivity. Petition 870250102121, dated 07 / 11 / 2025, page 25 / 71 / 17

[0062] In a version of the laser cutting head 1 of the invention not shown in the figures, the collimating lenses 3 and the focusing lenses 6 are cooled by a cooling system of a known type that includes the introduction of gas (typically nitrogen) at a controlled temperature inside the laser cutting head 1 in order to lap and thus cool the lenses. Petition 870250102121, dated 07 / 11 / 2025, p. 26 / 71

Claims

1 / 5 CLAIMS 1. Laser cutting head (1) associable with a machine tool, comprising: - a collimation group (2) for collimating a laser beam (L) from a laser emitting device; - a focusing group (5) for focusing the said laser beam (L) exiting collimated from the said collimation group (2) onto a focal point (F); - support and movement means (7) for supporting and moving along an adjustment direction (X) at least one of the said collimation group (2) and the focusing group (5); - at least one optical element (8; 38) for receiving the said laser beam (L) exiting focused from the said focusing group (5) and reflecting a first focused portion (L1) of the received laser beam (L); - an electronic processor (12) adapted to operate said support and movement means (7) to move at least one of said collimation group (2) and focusing group (5) along said adjustment direction (X);characterized in that it comprises at least one wavefront sensor (9) adapted to receive said first focused portion (L1) of the laser beam (L), perform a phase measurement of a wavefront of said first focused portion (L1), obtain a reconstructed wavefront based on said phase measurement and send said reconstructed wavefront to said electronic processor (12), the electronic processor being configured to perform a comparison between said reconstructed wavefront and a reference wavefront, determine based on said comparison one or more optical aberrations to which the laser beam (L) is subjected and operate said support and movement means (7) to reduce said one or more optical aberrations and change said focal point (F).

2. Laser cutting head (1) according to claim Petition 870250102121, dated 07 / 11 / 2025, page 27 / 71 2 / 5 1, characterized in that the reference wavefront is an ideal wavefront free of optical aberrations or a predetermined wavefront affected by predefined optical aberrations, the electronic processor (12) being configured to operate said support and movement means (7) in such a way that said one or more optical aberrations are, respectively, minimized and in particular zeroed or else less than or equal to the predefined optical aberrations.

3. Laser cutting head (1) associable with a machine tool, comprising: - a collimation group (2) for collimating a laser beam (L) from a laser emitting device; - a focusing group (5) for focusing the said laser beam (L) exiting collimated from the said collimation group (2) onto a focal point (F); - at least one adaptive optical device (10) with adjustable shape; - at least one optical element (8; 38) for receiving the said laser beam (L) exiting focused from the said focusing group (5) and reflecting a first focused portion (L1) of the received laser beam (L); - an electronic processor (12) adapted for adjusting the shape of the said adaptive optical device (10);characterized in that it comprises at least one wavefront sensor (9) adapted to receive said first focused portion (L1) of the laser beam (L), perform a phase measurement of a wavefront of said first focused portion (L1), obtain a reconstructed wavefront based on said phase measurement and send said reconstructed wavefront to said electronic processor (12), the latter being configured to perform a comparison between said reconstructed wavefront and a reference wavefront, determine based on said comparison one or more optical aberrations to which the laser beam (L) is Petition 870250102121, dated 07 / 11 / 2025, page 28 / 71 3 / 5 subjected and adjust the shape of said adaptive optical device (10) to reduce said one or more optical aberrations and change said focal point (F).; 4. Laser cutting head (1) according to claim 3, characterized in that the reference wavefront is an ideal wavefront free of optical aberrations or a predetermined wavefront affected by predefined optical aberrations, the electronic processor (12) being configured to adjust the shape of said adaptive optical device (10) so that said one or more optical aberrations are, respectively, minimized and in particular zeroed or else less than or equal to those predefined optical aberrations.

5. Laser cutting head (1) according to claim 3 or 4, characterized in that said adaptive optical device (10) is positioned upstream of said focusing group (5) with reference to a propagation direction (P) of said laser beam (L).

6. Laser cutting head (1) according to any one of claims 3 to 5, characterized in that said at least one wavefront sensor (9) is of the Shack-Hartmann type.

7. Laser cutting head (1) according to any one of claims 3 to 6, characterized in that said at least one optical element (8; 38) is a beam splitter, in particular chosen from a cubic beam splitter, an optical prism and a semi-transparent glass.

8. Laser cutting head (1) according to any one of claims 3 to 7, characterized in that it comprises a coating means (15) forming an internal space (20) adapted to contain at least said collimation group (2), focusing group (5), support and movement means (7) and at least one optical element (8).

9. Laser cutting head (1) according to claim 8, characterized in that said optical element (38) is adapted to separate the internal space (20) of the laser cutting head (1) from an external environment.

10. Laser cutting head (1) according to claim 8 or 9, characterized in that said coating medium (15) has a side opening (53) which is hermetically sealed by a transparent optical element (11) for the transmission of the first focused portion (L1) of the laser beam (L) towards the external environment, said wavefront sensor (9) being external to said coating medium (15).

11. Laser cutting head (1) according to any one of claims 3 to 10, characterized in that the laser emitting apparatus is a fiber laser, in particular a high-power fiber laser.

12. Method for controlling the laser cutting of a workpiece (100), which comprises the steps of: - performing laser cutting of said workpiece (100) by means of a laser cutting head (1) associated with a machine tool; - feeding said laser cutting head (1) with a laser beam (L); - collimating and focusing the laser beam (L) onto a focal point (F); - reflecting at least one first focused portion (L1) of said focused laser beam (L); and characterized in that it further comprises the steps of: - performing a phase measurement of a wavefront of said at least one first focused portion (L1); - obtaining a reconstructed wavefront based on the phase measurement; - performing a comparison between the reconstructed wavefront and a reference wavefront; Petition 870250102121, dated 07 / 11 / 2025, p.30 / 71 5 / 5 - determine based on comparison one or more optical aberrations to which said laser beam (L) is subjected; - reduce said one or more optical aberrations to which said laser beam (L) is subjected in order to change said focal point (F) of the laser beam (L).

13. A method according to claim 12, characterized in that the reference wavefront is an ideal wavefront free of optical aberrations and the reduction comprises minimizing, in particular zeroing, said one or more optical aberrations, or said reference wavefront is a target wavefront affected by predefined optical aberrations and said method comprises the step of reducing said optical aberrations so that they are less than or equal to those predefined optical aberrations.

14. Method according to claim 12 or claim 13, characterized in that the steps of performing a phase measurement and obtaining a reconstructed wavefront are implemented by a wavefront sensor (9).

15. Method according to any one of claims 12 to 14, characterized in that it further comprises the step of emitting an error signal when said optical aberrations exceed a predefined limit value. Petition 870250102121, dated 07 / 11 / 2025, pp. 31 / 71

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