Reflective light field modulation system for laser cutting, laser head and laser

Abstract

The present application relates to a kind of for laser cutting reflective light field regulation system, laser head and laser, comprising: laser light source, for emitting Gaussian beam;First off-axis parabolic mirror, first off-axis parabolic mirror is arranged on the emission path of Gaussian beam, and first off-axis parabolic mirror is used to reflect and collimate Gaussian beam;Second off-axis parabolic mirror, second off-axis parabolic mirror is arranged on the reflection path of Gaussian beam, and mirror surface of second off-axis parabolic mirror is provided with light field regulation phase unit, second off-axis parabolic mirror is used to reflect and focus reflected Gaussian beam, while re-distributing spot energy, to realize laser cutting, so as to realize guarantee cutting speed and quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser equipment, in particular to a reflective light field regulation system for laser cutting, a laser head and a laser. BACKGROUND

[0002] Laser processing is a non-contact thermal processing method, which is widely used in the automobile, ship, aviation, electronics and home building material industries due to its unique non-contact, cutting speed and cutting quality advantages.

[0003] In addition, the fiber laser combined with the laser cutting head has the advantages of fast cutting speed and accurate cutting in plate cutting. In addition, the laser head is the core device of laser cutting, and its traditional optical path mainly collimates the laser emitted by the laser through a collimating mirror, and then focuses through a focusing mirror, so as to realize the shaping of the light beam. Therefore, the cutting head optical path has a crucial influence on the final cutting effect.

[0004] With the development of industry demand, high-power lasers have gradually entered the market. The above-mentioned traditional optical path system is applied to high-power lasers. The high-power laser beam passes through the collimating and focusing lens in turn. In the continuous working state, the lens will absorb the energy of the laser beam and heat up. The thermal deformation of the lens will cause the spot to deform, affecting the cutting effect, and in severe cases, the laser head will be scrapped.

[0005] In addition, although the aspheric lens has good aberration correction effect, with the increase of power, the processing and coating cost of the lens will also increase, and the processing difficulty will also make the lens consistency poor, making it difficult to achieve mass production. The metal curved reflective optical path gradually applies to the high-power cutting field due to its good water cooling effect, good thermal conductivity and good aberration correction effect. The conventional metal curved mirror mainly includes a spherical mirror and an off-axis parabolic mirror. The spherical mirror will have aberration problems and cannot be applied to laser cutting. The light beam parallel to the parabolic optical axis will be well focused by the off-axis parabolic mirror and obtain good aberration correction effect, but the out-of-focus spot will have certain energy deviation or spot deformation. In addition, high-power lasers are often used for thick plate cutting, which requires focusing the light beam to adapt to different thicknesses of the plate. Direct use of the off-axis parabolic mirror will cause energy distribution deviation after focusing, which will cause some positions to be not cut through or the cutting section to be not smooth, resulting in poor cutting quality.

[0006] Therefore, there is at least the technical problem of poor cutting speed and quality in the prior art. SUMMARY

[0007] (1) Technical problem to be solved

[0008] In view of the above-mentioned defects and deficiencies of the prior art, the present application provides a reflective light field regulation system for laser cutting, a laser head and a laser, which solves the technical problem of poor cutting speed and quality in the prior art.

[0009] (II) Technical solutions

[0010] In order to achieve the above-mentioned purpose, the main technical solutions adopted by the present application include:

[0011] In a first aspect, the present application provides a reflective light field regulation system for laser cutting, comprising: a laser light source for emitting a Gaussian beam; a first off-axis parabolic mirror, which is arranged on the emission path of the Gaussian beam, and is used for reflecting and collimating the Gaussian beam; and a second off-axis parabolic mirror, which is arranged on the reflection path of the Gaussian beam, and has a mirror surface provided with a light field regulation phase unit, and is used for reflecting and focusing the reflected Gaussian beam, and re-distributes the energy of the light spot, so as to realize laser cutting.

[0012] In one possible embodiment, the distance between the laser light source and the first off-axis parabolic mirror is the focal length of the first off-axis parabolic mirror.

[0013] In one possible embodiment, the light field regulation unit comprises at least one annular protrusion.

[0014] In one possible embodiment, the determination process of the light field regulation phase unit comprises: determining a light field regulation surface of the second off-axis parabolic mirror; wherein the light field regulation surface is used to represent the area on the second off-axis parabolic mirror where the light field regulation phase unit needs to be etched; determining the height size information of the light field regulation phase unit; and etching the light field regulation phase unit on the second off-axis parabolic mirror based on the light field regulation surface and the height size information.

[0015] In one possible embodiment, the determination of the light field regulation surface of the second off-axis parabolic mirror comprises: determining a first energy proportion of an irradiation area of the reflected Gaussian beam on the original mirror surface of the second off-axis parabolic mirror; determining a second energy proportion of the Gaussian beam reflected by the second off-axis parabolic mirror reaching a target position; wherein the target position is the focusing position of the second off-axis parabolic mirror; determining a position coordinate mapping relationship between the irradiation area and the target position based on the energy mapping relationship of the first energy proportion and the second energy proportion; and determining the light field regulation surface of the second off-axis parabolic mirror based on the position coordinate mapping relationship.

[0016] In a possible embodiment, determining the height size information of the light field regulation phase unit comprises: performing phase distribution design through a GS algorithm to determine the height size information of the light field regulation phase unit.

[0017] In a second aspect, the embodiments of the present application provide a laser head, comprising a laser head body, and the laser head further comprises the reflective light field regulation system for laser cutting according to any one of the first aspect.

[0018] In a third aspect, the embodiments of the present application provide a laser, comprising the laser head according to the second aspect.

[0019] (III) Advantages

[0020] The present application has the following advantages:

[0021] The embodiments of the present application provide a reflective light field regulation system for laser cutting, a laser head and a laser, comprising a laser light source, a first off-axis parabolic mirror and a second off-axis parabolic mirror with a light field regulation phase unit on the mirror surface, the laser light source emits a Gaussian beam, the first off-axis parabolic mirror reflects and collimates the Gaussian beam, and the second off-axis parabolic mirror reflects and focuses the reflected Gaussian beam, and at the same time, redistributes the energy of the light spot, so that the reflective light field regulation system can regulate the light field of the laser beam, obtain a three-dimensional circularly symmetric light spot with symmetrical energy distribution, and keep the defocused light spot within a controllable range, so that the cutting effect can be consistent when dealing with thick plates, and the cutting speed and quality can be guaranteed.

[0022] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 Fig. 1 shows a schematic diagram of a reflective light field regulation system for laser cutting provided by the embodiments of the present application;

[0025] Figure 2 Fig. 2 shows a schematic diagram of a second off-axis parabolic mirror etched with a light field regulation unit provided by the embodiments of the present application;

[0026] Figure 3 A schematic diagram of the energy distribution of the light spot at the position of the nozzle after focusing is shown, using a reflective light field regulation system provided by an embodiment of the present application;

[0027] Figure 4A A schematic diagram of the energy distribution of the light spot at the position of the nozzle after focusing is shown, using a reflective light field regulation system provided by an embodiment of the present application;

[0028] Figure 4B A schematic diagram of the energy distribution of the light spot at the position of 4 mm below the nozzle after focusing is shown, using a reflective light field regulation system provided by an embodiment of the present application;

[0029] Figure 4C A schematic diagram of the energy distribution of the light spot at the position of 8 mm below the nozzle after focusing is shown, using a reflective light field regulation system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to better explain the present application, so as to be understood, the present application is described in detail below by specific embodiments, combined with the accompanying drawings.

[0031] In order to solve the problem of poor cutting speed and quality in the prior art, a reflective light field regulation system for laser cutting, a laser head and a laser are provided by an embodiment of the present application, which comprises a laser light source, a first off-axis parabolic mirror and a second off-axis parabolic mirror provided with a light field regulation phase unit on the mirror surface. The laser light source emits a Gaussian beam, the first off-axis parabolic mirror reflects and collimates the Gaussian beam, and the second off-axis parabolic mirror reflects and focuses the reflected Gaussian beam, while redistributing the energy of the light spot. Therefore, the reflective light field regulation system can regulate the light field of the laser beam, obtain a three-dimensional circularly symmetric light spot with symmetrical energy distribution, and keep the defocused light spot within a controllable range, so as to maintain consistent cutting effect when dealing with thick plates and ensure cutting speed and quality. In addition, the pair of off-axis parabolic mirrors can adjust the length of the free space branch, facilitate the insertion of other optical elements, and will not affect the alignment of the light beam, greatly reducing the size and volume of the laser head.

[0032] In order to better understand the above technical solutions, exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a clearer, more thorough understanding of the present application and to convey the complete scope of the present application to those skilled in the art.

[0033] First embodiment

[0034] Please refer to Figure 1 , Figure 1 A schematic diagram of a reflective light field modulation system for laser cutting is shown. As Figure 1 shown, the reflective light field modulation system comprises:

[0035] A laser light source 110 for emitting an incident light beam, and the incident light beam energy distribution is Gaussian, that is, the laser light source 110 can be a fiber laser;

[0036] A first off-axis parabolic mirror 120, which is arranged on the emission path of the Gaussian light beam, and the first off-axis parabolic mirror 120 is used for reflecting and collimating the Gaussian light beam located at the focal point;

[0037] A second off-axis parabolic mirror 130 with light field modulation function, which is arranged on the reflection path of the Gaussian light beam, and the mirror surface of the second off-axis parabolic mirror 130 is provided with a light field modulation phase unit, and the second off-axis parabolic mirror 130 is used for reflecting and focusing the reflected Gaussian light beam, and redistributing the spot energy, so as to realize laser cutting.

[0038] In order to facilitate the understanding of the reflective light field modulation system, the following will be described through specific embodiments.

[0039] Specifically, as Figure 1 shown, in the case where the focal length of the first off-axis parabolic mirror 120 is f1 and the focal length of the second off-axis parabolic mirror 130 is f2, the position at a distance f1 to the left side of the first off-axis parabolic mirror 120 is the front focal point, and the position at a distance f2 to the right side of the second off-axis parabolic mirror 130 is the rear focal point. In addition, the laser light source 110 is located at the front focal point position, and the incident light beam emitted by the laser light source 110 is incident on the cross section of the first off-axis parabolic mirror 120, which will exit parallel light beams in the direction perpendicular to the incident direction, and the mirror surface is not rotationally symmetric, and the focal point position will also rotate when rotating around the optical axis, so the first off-axis parabolic mirror 120 needs to be fixed. Then, the parallel light beams are incident on the second off-axis parabolic mirror 130, and selecting a suitable cross section can make the incident parallel light converge at the rear focal point 140 in the 90° direction.

[0040] Therefore, the purpose of the reflective light field modulation system is to use two off-axis metal curved mirrors (i.e. off-axis parabolic mirrors) to realize high-power laser cutting, and at the same time adjust the longitudinal position of the focal point, and control the light intensity energy distribution.

[0041] It should be noted that the mirror surface or cross section of the first off-axis parabolic mirror 120 can be the existing mirror surface or cross section, but for the second off-axis parabolic mirror 130, since it needs to have the light field regulation function, the mirror surface or cross section of the second off-axis parabolic mirror 130 needs to be designed accordingly.

[0042] In order to facilitate understanding of the design process of the light field regulation unit of the second off-axis parabolic mirror 130, the following will be described through specific embodiments.

[0043] Specifically, the light field regulation surface of the second off-axis parabolic mirror is determined, wherein the light field regulation surface is used to represent the area of the second off-axis parabolic mirror that needs to be etched with the light field regulation phase unit, the height size information of the light field regulation phase unit is determined, and the light field regulation phase unit is etched on the second off-axis parabolic mirror based on the light field regulation surface and the height size information.

[0044] The process of determining the light field regulation surface of the second off-axis parabolic mirror includes: determining a first energy proportion of the irradiation area of the reflected Gaussian beam on the original mirror surface of the second off-axis parabolic mirror; determining a second energy proportion of the Gaussian beam reflected by the second off-axis parabolic mirror reaching the target position; wherein the target position is the focusing position of the second off-axis parabolic mirror; determining the position coordinate mapping relationship between the irradiation area and the target position based on the energy mapping relationship between the first energy proportion and the second energy proportion; determining the light field regulation surface of the second off-axis parabolic mirror based on the irradiation area and the position coordinate mapping relationship on the original mirror surface.

[0045] For example, as shown in FIG. 6, the light field regulation surface of the second off-axis parabolic mirror 130 is determined based on the irradiation area and the position coordinate mapping relationship on the original mirror surface of the second off-axis parabolic mirror 130. Figure 1As shown, according to the law of conservation of energy, the input beam energy on the reflecting surface mirror (i.e., the second off-axis parabolic mirror 130) is equal to the output beam energy on the target image surface (i.e., the mirror surface at the back focal point 140), based on the calculation formula of the input Gaussian beam intensity distribution, the first energy ratio of the input beam irradiating the annular region S1 on the cross section of the second off-axis parabolic mirror 130 is determined, that is, the percentage of the beam energy received in the annular region S1 on the second off-axis parabolic mirror 130 to the total beam energy, and it will correspond to the spot energy at the nozzle focal point position, that is, the light rays in the S1 region of the incident beam will reach the corresponding S'1 region of the target image surface after transmission through the second off-axis parabolic mirror 130, and the second energy ratio at this time is determined, and according to the energy mapping relationship between the first energy ratio and the second energy ratio, the position coordinate mapping relationship between the input beam and the output beam can be obtained, that is, the position coordinate mapping relationship between the S1 region and the S'1 region. Subsequently, the sampling points in the second off-axis parabolic mirror 130 can be determined according to the S1 region, the S'1 region and the position coordinate mapping relationship. For example, the application can select part of the region of the middle annular region (i.e., the region between the outer ring far from the center and the inner ring close to the center) of the S1 region as the candidate region of the sampling point, then based on the position coordinate mapping relationship, find the mapping region corresponding to the candidate region of the sampling point in the S'1 region, then calculate the light energy of the mapping region, if the calculated light energy meets the preset energy requirement, the point in the candidate region is taken as the sampling point. And the above steps can be repeatedly executed until all regions of the middle annular region are subjected to the above steps, and the confirmation of the sampling point is completed. The specific energy value of the preset energy requirement can be calculated according to actual needs, and the embodiments of the application are not limited thereto. In addition, based on the above method, the application can determine all sampling points on the cross section of the second off-axis parabolic mirror 130, and fit all sampling points into a light field regulation curve, so that at least one concentric elliptical region as shown can be set on the second off-axis parabolic mirror 130 by this method. Figure 2

[0046] It should be understood that the specific method of fitting all sampling points into a light field regulation curve can be set according to actual needs, and the embodiments of the application are not limited thereto.

[0047] For example, all sampling points can be fitted into a light field regulation curve by polynomial fitting.

[0048] In addition, the height size information of the light field regulation phase unit is determined, including: performing phase distribution design through the GS algorithm to determine the height size information of the light field regulation phase unit.

[0049] ​For example, while keeping the distance between the laser source 110 and the first off-axis parabolic mirror 120 constant, according to the principle of equal optical path, a light field modulation phase unit (scale: micrometer to millimeter) is introduced on the second off-axis parabolic mirror 130. The height distribution of the light field modulation phase unit on the second off-axis parabolic mirror 130 can be designed to achieve longitudinal phase control, enabling changes in the axial position of the light spot (i.e., the optical axis direction). The size distribution on the second off-axis parabolic mirror 130 can also be designed to control the transverse phase, allowing adjustment of the energy distribution of the light spot on the image plane. Furthermore, the gradient phase can be specifically obtained based on Huygens-Fresnel diffraction optics theory and Fourier transform. Huygens-Fresnel diffraction optics... (Paraxial condition), where, Let λ be the amplitude of the light wave, i be a complex number used to describe the vibration of the light wave, λ be the wavelength, and r0 be the distance from the diffraction center to the observation screen. Let be the amplitude at a point on the wavefront, k be the wave number, r be the length from point Q on the wavefront to point P on the observation screen, and ∑ be the area of ​​the diffraction unit; the Fourier transform is... x0 is the phase plane, x1 is the imaging plane, Z is the propagation distance, λ is the wavelength, i represents a complex number used to describe the vibration of the light wave, F0 is the light field on the phase plane x0, F1 is the light field on the imaging plane x1, and C0 is a constant. Subsequently, the phase distribution is designed using the GS algorithm, that is, the height and size distribution of the tiny protrusions on the mirror are calculated. Specifically:

[0050] Energy intensity assignment step: Assign a phase to the energy intensity of the target image plane. Steps to construct the light field function: Take the phase Combined with the light intensity on the output surface, they form the light field function; the inverse Fourier transform steps: the light field function undergoes one inverse Fourier transform to obtain the light field distribution on the phase surface, including the phase. And light intensity information; the obtained phase information phase Substituting these steps into the energy intensity assignment step, the light field function construction step, and the inverse Fourier transform step, a Fourier transform is performed again, combining the light source intensity distribution. This process is repeated, iterating again by combining the phase information of the imaging plane with the intensity of the light field on the target image plane, until the mean square error and SSE are less than the specified error. Finally, annular regions with different phase change rates are generated. For details, please refer to [link to documentation]. Figure 2 .

[0051] And, based on the light field regulation curved surface and height size information, etching the light field regulation phase unit on the second off-axis parabolic mirror 130, including: based on the concave surface of the second off-axis parabolic mirror 130, determining the area (i.e. the light field regulation curved surface) of the parabolic mirror that needs to be etched according to the light spot energy distribution range on the target image surface, then etching the gradient offset phase calculated in the above step on the concave surface, in order to improve the uniformity of the light spot, the junction of the annular partition of the mirror needs to be homogenized, and the homogenization of the discontinuous partition not only can control the axial image surface light spot energy uniformity, but also can make the mirror smooth and reduce the processing difficulty, and finally obtain the off-axis mirror with light field regulation function as shown in Figure 2 The light field regulation unit includes at least one annular convex as shown in Figure 2

[0052] And, after the light beam is incident on the second off-axis parabolic mirror 130 after processing, the light rays will produce different phase delays after passing through the small convex on the parabolic concave mirror, and the range is 0-2π, and the angle of the small convex unit (i.e. the light field regulation unit) is different, which will reflect the parallel incident light (90±0.1°) into the image surface S'1 area, and maintain the energy correspondence. The light spot energy uniformity can be defined as S is the average value of the energy in the S area, and E max is the maximum value of the energy in the S area, and the calculation shows that the uniformity of the light spot energy before regulation is 45.55%, as shown in Figure 3 After regulation, the uniformity is 60.74%, 70.82% and 82.21%, respectively, as shown in Figures 4A to 4C The light spot energy distribution on different image surfaces displayed by the light field regulation phase.

[0053] In summary, by means of the above technical scheme, the laser light source emits a Gaussian light beam, and the first off-axis parabolic mirror reflects and collimates the Gaussian light beam, and the second off-axis parabolic mirror reflects and focuses the reflected Gaussian light beam, and redistributes the light spot energy, so that the reflective light field regulation system can regulate the light field of the laser light beam, obtain a three-dimensional circularly symmetric light spot with symmetrical energy distribution, and keep the defocused light spot within a controllable range, so that the cutting effect can be kept consistent when dealing with thick plates, and the cutting speed and quality can be guaranteed. Moreover, the pair of off-axis parabolic mirrors can adjust the length of the free space branch, facilitate the insertion of other optical elements, and will not affect the light beam alignment, greatly reducing the size and volume of the laser head.

[0054] It should be understood that the above reflective light field regulation system for laser cutting is only exemplary, and those skilled in the art can make various modifications according to the above method, and the modified scheme also belongs to the protection scope of the present application.​

[0055] Second embodiment

[0056] The embodiment of the present application provides a laser head, comprising a laser head body, and the laser head further comprises the reflective light field regulation system for laser cutting as described in the first embodiment on or in the laser head body.

[0057] Since the reflective light field regulation system described in the embodiment is used to implement the reflective light field regulation system described in the first embodiment of the present application, details are not described again, and the related description of the first embodiment can be referred to.

[0058] Therefore, the laser head using the reflective light field regulation system for laser cutting has the following advantages: good water cooling effect, which can greatly improve the damage threshold of the lens, and better adapt to the high-power laser continuous working scene; good laser beam aberration elimination effect; in the defocus state, the spot can also keep the circular spot unchanged and the energy distribution coaxial with the circular spot.

[0059] Third embodiment

[0060] The embodiment of the present application provides a laser, comprising the laser head as described in the second embodiment.

[0061] Since the laser head described in the embodiment is used to implement the laser head described in the second embodiment of the present application, details are not described again, and the related description of the second embodiment can be referred to.

[0062] In the description of the present application, it should be understood that the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0063] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0064] In the present application, unless otherwise explicitly specified and limited, a first feature is "on" or "under" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature is "over", "above" and "on top of" a second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. A first feature is "under", "below" and "underneath" a second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0065] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0066] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A reflective light field modulation system for laser cutting, characterized in that, The laser head comprises: a laser light source for emitting a Gaussian beam; a first off-axis parabolic mirror, which is arranged on the emission path of the Gaussian beam, and is used for reflecting and collimating the Gaussian beam; a second off-axis parabolic mirror, which is arranged on the reflection path of the Gaussian beam, and the mirror surface of the second off-axis parabolic mirror is provided with a light field control phase unit, and the second off-axis parabolic mirror is used for reflecting and focusing the reflected Gaussian beam, and re-distributes the energy of the light spot to realize laser cutting; The determination process of the light field control phase unit comprises: determining a light field control surface of the second off-axis parabolic mirror; wherein the light field control surface is used to represent the area on the second off-axis parabolic mirror that needs to be etched with the light field control phase unit; determining the height size information of the light field control phase unit; based on the light field control surface and the height size information, etching the light field control phase unit on the second off-axis parabolic mirror; The determination of the light field control surface of the second off-axis parabolic mirror comprises: determining a first energy proportion of an irradiation area of the reflected Gaussian beam on the original mirror surface of the second off-axis parabolic mirror; determining a second energy proportion of the Gaussian beam reflected by the second off-axis parabolic mirror reaching a target position; wherein the target position is the focusing position of the second off-axis parabolic mirror; based on the energy mapping relationship between the first energy proportion and the second energy proportion, determining the position coordinate mapping relationship between the irradiation area and the target position; based on the position coordinate mapping relationship, determining the light field control surface of the second off-axis parabolic mirror.

2. The reflective light field modulation system of claim 1, wherein, The distance between the laser light source and the first off-axis parabolic mirror is the focal length of the first off-axis parabolic mirror.

3. The reflective light field modulation system of claim 1 or 2, wherein, The light field control phase unit comprises at least one circular ring type protrusion.

4. The reflective light field modulation system of claim 1, wherein, The determination of the height size information of the light field control phase unit comprises: determining the height size information of the light field control phase unit through GS algorithm for phase distribution design.

5. A laser head comprising a laser head body, characterized in that The laser head further comprises the reflective light field control system for laser cutting as claimed in any one of claims 1-4, which is arranged on or in the laser head body.

6. A laser characterized by, The laser head comprises the laser head as claimed in claim 5.

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