A diffractive-refractive light field modulation system and modulation method for laser cutting

Abstract

The application discloses a kind of diffractive-refractive optical field regulation systems and regulation methods for laser cutting, including sequentially arranged: light source, light source is used to generate high-power Gaussian beam;Upper protective mirror, for protecting main light path;Collimating mirror, collimating mirror is used to collimate high-power Gaussian beam into parallel Gaussian beam, diffractive-refractive regulation mirror, diffractive-refractive regulation mirror is used to converge parallel Gaussian beam;Lower protective mirror, for protecting main light path.The diffractive-refractive optical field regulation system of scheme setting sets up one gathering regulation mirror, one side is refractive surface, avoid using single diffractive regulation, only focal plane is flat top distribution, focal point before and after beam is high gauss problem, make long focal depth range before and after focal point form flat top beam;The other side is diffractive surface, avoid single refractive regulation, focal plane is flat top distribution problem, make focal plane form flat top spot distribution, to improve the cutting effect when high-brightness laser cutting thick plate.

Description

Technical Field

[0001] This application belongs to the field of laser cutting technology, specifically relating to a refractive diffraction optical field control system and control method for laser cutting. Background Technology

[0002] Laser cutting, as a non-contact thermal processing method, is widely used in industries such as automotive, shipbuilding, aerospace, electronics, and building materials due to its unique advantages in non-contact operation, cutting speed, and cutting quality. Fiber lasers paired with laser cutting heads offer advantages such as high cutting speed and precision in sheet metal cutting. As the core component of laser cutting, the laser head's traditional optical path primarily involves a collimating lens first collimating the laser beam emitted from the laser, and then a focusing lens refocusing it to shape the beam. Therefore, the optical path of the cutting head has a crucial impact on the final cutting effect.

[0003] With the development of industry demands, the need for faster thin-plate cutting has increased. Using high-brightness lasers in conjunction with traditional optical path cutting heads can improve the cutting speed of thin plates, thus becoming an industry trend. However, because high-brightness lasers have a very fine spot size, their advantages are not obvious for cutting thick plates, resulting in poor cutting effects.

[0004] In the existing technology, high-brightness laser cutters cannot simultaneously meet the speed and quality requirements for both thin and thick plate cutting. Summary of the Invention

[0005] This application provides a refractive diffraction-type optical field control system and method for laser cutting, which solves the problem that existing high-brightness laser cutters cannot simultaneously achieve good thin plate cutting and thick plate cutting effects, which easily leads to poor cutting quality of thick plates.

[0006] The technical solution adopted in this application is as follows:

[0007] A refractive diffraction-based optical field manipulation system for laser cutting includes, in sequence:

[0008] A light source, used to generate a high-power Gaussian beam;

[0009] A protective lens is used to protect the main optical path;

[0010] A collimating lens is used to collimate the high-power Gaussian beam into a parallel Gaussian beam.

[0011] A refractive diffraction control mirror, used to converge the parallel Gaussian beam;

[0012] The lower protective lens is used to protect the main optical path.

[0013] In a preferred embodiment, the two sides of the refractive and diffraction control mirror are respectively provided with a refractive control surface and a diffraction control surface, with the refractive control surface facing the collimating mirror and the diffraction control surface facing the lower protective mirror.

[0014] This solution also includes a refractive diffraction-based optical field manipulation method, applied to the optical field manipulation system described above, the method comprising:

[0015] (1) Set the focal length of the collimating lens to be The focal length of the refractive diffraction control mirror is The distance from the left side of the collimating lens The location is the front focal point, and the distance from the right side of the diffraction control mirror is... The position is the back focus, and the numerical aperture of the incident Gaussian beam is set to NA1, and the numerical aperture of the outgoing beam is set to NA2.

[0016] (2) Designing the curvature of the refractive control surface of the aforementioned refractive diffraction control mirror, specifically including the following steps:

[0017] Step 1: Determine the optical power of the refractive control surface;

[0018] Step 2: Determine the fitting center curvature of the refractive control surface;

[0019] Step 3: Determine the curvature distribution equation of the refractive control surface;

[0020] (3) Design the phase of the diffraction control surface of the diffraction control mirror.

[0021] In a preferred embodiment, step one further includes: based on the The NA1 and NA2 determine the optical power of the refractive control surface:

[0022] According to the formula for the transverse magnification of an ideal optical system: ,

[0023] According to the formula for angular magnification of an ideal ray system: ,

[0024] Combining the formulas for the transverse magnification of the ideal optical system and the angular magnification of the ideal ray system, we can solve for f2.

[0025] According to the lens power formula: This yields the refractive power of the curved surface.

[0026] In a preferred embodiment, step two further includes:

[0027] According to the lens manufacturer's formula: The radius of curvature R1 of the fitting center of the refractive control surface is obtained, and the curvature K = ,

[0028] Wherein, R2 tends to infinity.

[0029] In a preferred embodiment, step three further includes: selecting five sampling image planes: the focal plane, 15mm in front of the focal plane, 40mm in front of the focal plane, 15mm behind the focal plane, and 40mm behind the focal plane; and selecting multiple proportionally proportioned sampling image points on each sampling image plane, and jointly fitting a set of equations.

[0030] In a preferred embodiment, step three further includes: based on the input Gaussian beam intensity distribution: This yields the intensity distribution of the flat-top beam output at each sampled image plane and the position coordinate mapping relationship between the input and output beams at each sampled image point. Simultaneously, Snell's law is applied: The normal direction of each sampled image point is obtained.

[0031] As a preferred embodiment, the design of the diffraction control surface phase includes:

[0032] S01: Select the plane at the midpoint of the part to be cut as the target image plane, and assign a phase to the energy intensity of the target image plane;

[0033] S02: The phase is combined with the light intensity on the output surface to form the light field function;

[0034] S03: The optical field function is subjected to an inverse Fourier transform to obtain the optical field distribution on the phase surface;

[0035] S04: The light field distribution information is incorporated into S01 to S03 and combined with the light source intensity distribution to perform a Fourier transform.

[0036] Repeat steps S01 through S04 until the mean square error and SSE are less than the specified values. .

[0037] In a preferred embodiment, the upper protective mirror, the collimating mirror, the refractive diffraction control mirror, and the lower protective mirror are coaxially arranged.

[0038] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows:

[0039] (1) This scheme first outputs a high-power incident beam from the light source. The energy distribution of the incident beam is Gaussian. After passing through the upper protective mirror, the energy distribution and divergence angle of the incident beam remain unchanged. After passing through the collimating mirror, the incident beam is collimated into parallel light, that is, the divergence angle is 0 and the energy distribution is still Gaussian. After passing through the refraction control surface of the refraction and diffraction control mirror, the beam is modulated into a long focal depth rough flat-top beam. After passing through the diffraction control surface of the refraction and diffraction control mirror, the beam is modulated into a long focal depth precision flat-top beam. After passing through the lower protective mirror, the beam converges below the cutting nozzle. When cutting thick plates, the long focal depth precision flat-top beam, combined with a high-brightness laser, can increase the kerf and improve the air passage, effectively increasing the cutting speed. At the same time, it prevents the burst hole caused by excessive concentration of energy in the center and improves the cutting quality.

[0040] (2) The light source is located at the front focal point. After the incident beam passes through the collimating lens, it will exit as a parallel Gaussian beam in the same direction as the incident direction. Then, the parallel Gaussian beam is incident on the refraction and diffraction control mirror. The refraction control surface and the diffraction control surface are designed by the control method in this scheme, so that when laser cutting is performed, the incident parallel Gaussian beam is focused to the middle of the plate below the nozzle, and at the same time, a flat-top beam with a long focal depth and a more precise focal plane is formed inside the plate.

[0041] By using collimating mirrors and diffraction control mirrors, a more precise flat-top beam is generated. Combined with a high-brightness laser for laser cutting, this solves the problem of cutting quality and speed of thick plates, which is difficult for high-brightness lasers to address. It can achieve both rapid cutting of thin plates and rapid and stable cutting of thick plates, realizing the full-scenario advantages of high-brightness lasers. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0043] Figure 1 This is a schematic diagram of the structure of a light field modulation system in one embodiment of the present invention;

[0044] Figure 2 This is a light spot energy distribution diagram at the focal point in one embodiment of the present invention;

[0045] Figure 3 This is a light spot energy distribution diagram at the focal point in another embodiment of the present invention;

[0046] Figure 4 This is a diagram showing the energy distribution of the light spot at the focal point in one embodiment of the present invention.

[0047] Explanation of reference numerals in the attached figures:

[0048] 1-Light source, 2-Upper protective mirror, 3-Collimating mirror, 4-Folding diffraction control mirror, 5-Lower protective mirror, 6-Thick plate. Detailed Implementation

[0049] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0050] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0051] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0052] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0053] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0054] like Figures 1 to 4As shown, this application provides a refractive diffraction-based optical field manipulation system for laser cutting, such as... Figure 1 As shown, it includes the following settings in sequence:

[0055] Light source 1 is used to generate a high-power Gaussian beam;

[0056] Upper protective lens 2 is used to protect the main optical path;

[0057] Collimating lens 3 is used to collimate a high-power Gaussian beam into a parallel Gaussian beam.

[0058] The diffraction control mirror 4 is used to focus the parallel Gaussian beam.

[0059] Lower protective mirror 5 is used to protect the main optical path.

[0060] The upper protective mirror 2, collimating mirror 3, refractive diffraction control mirror 4, and lower protective mirror 5 are set coaxially.

[0061] Furthermore, the two sides of the refractive and diffraction control mirror 4 are respectively provided with a refractive control surface and a diffraction control surface, with the refractive control surface facing the collimating mirror 3 and the diffraction control surface facing the lower protective mirror 5.

[0062] In this scheme, light source 1 is used to generate a high-power Gaussian beam, upper protective mirror 2 is used to protect the main optical path system and prevent dust from entering from the fiber optic interface, collimating mirror 3 is used to collimate the high-power Gaussian beam into a parallel Gaussian beam, refractive diffraction-type optical field control focusing mirror 7 is used to converge the parallel Gaussian beam and control the beam spot distribution at its focal plane and the beam energy distribution within the long focal depth range, upper protective mirror 5 is used to protect the main optical path system and prevent dust from entering from the cutting nozzle, and the beam distribution inside the thick metal plate is a flat-top beam, which makes the beam spot larger, the kerf wider, the airflow stable, and the energy distribution uniform, preventing local heat accumulation from forming a burst hole.

[0063] First, a high-power incident beam is output from light source 1. The energy distribution of the incident beam is Gaussian. After passing through the upper protective mirror 2, the energy distribution and divergence angle of the incident beam remain unchanged. After passing through the collimating mirror 3, the incident beam is collimated into parallel light, that is, the divergence angle is 0, and the energy distribution is still Gaussian. After passing through the refraction control surface of the refraction and diffraction control mirror 4, the beam is modulated into a long focal depth coarse flat-top beam. Then, after passing through the diffraction control surface of the refraction and diffraction control mirror 4, the beam is modulated into a long focal depth precision flat-top beam. After passing through the lower protective mirror 5, the beam converges below the cutting nozzle. When cutting the thick plate 6, inside the thick metal plate, this long focal depth precision flat-top beam, combined with a high-brightness laser, can increase the kerf, unblock the air path, effectively improve the cutting speed, and at the same time prevent the burst hole caused by excessive energy concentration in the center, thus improving the cutting quality.

[0064] The collimating lens 3 is a projection-type collimating lens, primarily used to collimate the incident beam emitted by the fiber laser. Simultaneously, a refractive diffraction control mirror 4 is provided, mainly for focusing and controlling the light field of the directly incident beam. Based on the beam focusing and beam shaping near the focal point achieved by the refractive diffraction control mirror 4, a more perfect flat-top distribution of the beam at the focal point can be achieved. Meanwhile, within 20mm before and after the focal point, the beam spot exhibits a relatively rough flat-top distribution, thus improving the cutting effect when the high-brightness laser cuts the thick plate 6. The flat-top light distribution near the focal point, compared to a Gaussian distribution, increases the beam spot diameter. When paired with a high-brightness laser, this results in a wider kerf and more stable airflow; it also prevents overheating of the kerf, improving energy utilization.

[0065] If a single refractive light field control system is used, that is, only refractive control is set, a relatively rough approximate flat-top light effect can be achieved in a longer focal depth range. However, when cutting a thick negative-focus plate 6, the flat-top shape is not obvious, resulting in an insignificant effect of using this approximate flat-top beam for cutting because the focal point is located inside the plate.

[0066] If a single diffraction-based light field control system is used, that is, only a diffraction control mirror is set, a relatively ideal flat-top beam effect can be achieved at the focal point. However, this flat-top beam effect is difficult to maintain before and after the focal point. Beyond 2mm before and after the focal point, the beam spot will basically convert back to a Gaussian beam, resulting in an insignificant cutting effect when using this approximate flat-top beam to cut thick plates.

[0067] The proposed scheme employs a refractive diffraction-based optical field control system with a focusing control mirror. One side is a refractive surface, which avoids the problem of a flat-top beam distribution only at the focal plane and a Gaussian bias before and after the focal point, as seen in a single diffraction-based optical field control system. This results in a flat-top beam over a longer focal depth range before and after the focal point, thus improving the cutting effect of the high-brightness laser when cutting the thick plate 6. The other side is a diffraction surface, which avoids the Gaussian bias of the beam distribution at the focal plane, as seen in a single refractive optical field control system. This results in a more perfect flat-top beam distribution at the focal plane, further improving the cutting effect of the high-brightness laser when cutting the thick plate 6.

[0068] This application also provides a diffraction-based optical field manipulation method, applied to the optical field manipulation system described above, the method comprising:

[0069] (1) Set the focal length of collimating lens 3 to be The focal length of the diffraction control mirror 4 is 3 meters to the left of the collimating lens The position is the front focal point, 4 meters to the right of the diffraction control mirror. The position is the back focus, and the numerical aperture of the incident Gaussian beam is set to NA1, and the numerical aperture of the outgoing beam is set to NA2.

[0070] (2) Design the curvature of the refractive control surface of the refractive diffraction control mirror 4, specifically including the following steps:

[0071] Step 1: Determine the optical power of the refractive control surface;

[0072] Step 2: Determine the fitting center curvature of the refractive control surface;

[0073] Step 3: Determine the curvature distribution equation of the refractive control surface;

[0074] (3) Design the phase of the diffraction control surface of the diffraction control mirror 4.

[0075] Preferably, the light source 1 is located at the front focal point. After the incident beam passes through the collimating lens 3, it will exit as a parallel Gaussian beam in the same direction as the incident direction. Then, the parallel Gaussian beam is incident on the refraction and diffraction control mirror 4. The refraction control surface and the diffraction control surface are designed using the control method in this scheme, so that during laser cutting, the incident parallel Gaussian beam is focused to the middle of the plate below the nozzle, and at the same time, a flat-top beam with a long focal depth and a relatively precise focal plane is formed inside the plate.

[0076] By using collimating mirror 3 and diffraction control mirror 4, a more precise flat-top beam is generated. Combined with a high-brightness laser for laser cutting, the problem of cutting quality and speed of thick plates 6, which is difficult to solve with high-brightness lasers, is solved. It can achieve both fast cutting of thin plates and fast and stable cutting of thick plates 6, realizing the full-scene advantages of high-brightness lasers.

[0077] Specifically, to achieve good cutting results, the diffraction control mirror can be set in the following way:

[0078] In a preferred embodiment, step one further includes: based on NA1 and NA2 determine the optical power of the refractive control surface:

[0079] According to the formula for the transverse magnification of an ideal optical system: ,

[0080] According to the formula for angular magnification of an ideal ray system: ,

[0081] By combining the formulas for the transverse magnification of an ideal optical system and the angular magnification of an ideal ray system, we can obtain the following solution. ,

[0082] According to the lens power formula: This yields the refractive power of the curved surface.

[0083] It is understandable that the focal length of collimating lens 3 is determined by its lens properties, i.e., it is a known quantity. Meanwhile, NA1 and NA2 are also known quantities. Therefore, by combining the formula for the transverse magnification of an ideal optical system with the formula for the angular magnification of an ideal ray system, we can obtain... ,Will Substitute and solve. .

[0084] Furthermore, step two also includes:

[0085] According to the lens manufacturer's formula: The radius of curvature R1 of the fitted center of the refractive control surface is obtained, and the curvature K = ,

[0086] Among them, R2 tends to infinity.

[0087] Where n is the refractive index of the lens, which is an inherent parameter of the material depending on the lens material, and L is the center thickness of the lens. Since the two sides of the refractive and diffraction control mirror 4 are the refractive control surface and the diffraction control surface respectively, i.e., the two sides are respectively set with a refractive mirror surface and a diffraction mirror surface, the other side of the refractive mirror surface can be regarded as a plane here, and R2 tends to infinity. The value obtained in step one is... Substituting the value, we can obtain the radius of curvature R1. The curvature and the radius of curvature are reciprocals of each other, and thus we can obtain the curvature K.

[0088] In a preferred embodiment, step three further includes: selecting five sampling image planes: the focal plane of the refraction control surface, 15mm in front of the focal plane, 40mm in front of the focal plane, 15mm behind the focal plane, and 40mm behind the focal plane; and selecting multiple proportional sampling image points on each sampling image plane, and jointly fitting a set of equations.

[0089] It should be noted that the number of sampling planes is not limited. In this embodiment, five planes are selected as sampling planes. If too few sampling planes are selected, the data support strength may be insufficient. If too many sampling planes are selected, the computational load will be too large and the time consumption will be long. The specific number of sampling planes selected can be determined according to actual needs.

[0090] Furthermore, the sampling image point is actually a part of the sampling image surface. The proportional sampling image point mentioned in this scheme means that the selected sampling image points occupy an equal proportion of the sampling image surface.

[0091] Furthermore, step three also includes: based on the input Gaussian beam intensity distribution: This yields the intensity distribution of the flat-top beam output at each sampled image plane and the position coordinate mapping relationship between the input and output beams at each sampled image point. Simultaneously, Snell's law is applied: This yields the normal direction of each sampled image point.

[0092] Specifically, in this step, the intensity distribution of the input Gaussian beam is as follows: (like Figure 2 As shown), the intensity of the flat-top beam output from the five sampling image planes. Distribution as (e.g.) Figure 3 (as shown)

[0093] (r) <r1),

[0094] (r) <r2),

[0095] (r) <r3),

[0096] (r) <r4),

[0097] (r) <r5);

[0098] Based on this energy mapping relationship, the approximate position coordinate mapping relationship between the input beam and the output beam can be obtained. Furthermore, according to Snell's law: , among which, among which The refractive index of the incident medium is... The refractive index of the exit medium, The direction of the incident beam (the angle between the incident beam and the normal to the refracting surface). The direction of the emitted beam (the angle between the emitted beam and the normal to the refracting surface).

[0099] For each sampling image point, according to the law of conservation of energy, the energy of the input beam on the refraction control surface is equal to the energy of the output beam on the target image surface.

[0100] Σn=C1;Σn=C2;Σn=C3;Σn=C4;Σn=C5, where n is the normalized number of rays and C is a constant.

[0101] Based on this beam direction mapping relationship, combined with the position coordinate mapping relationship between the input and output beams that conforms to the law of energy conservation, the normal direction of each sampling image point of the optimal refraction control surface is obtained, and the curvature distribution equation of the refraction control surface is obtained. The curvature of the refraction control surface is designed based on this data.

[0102] In one embodiment, designing the phase of the diffraction control surface includes: based on the principle of equal optical path length, it can be expressed as follows: By introducing optical field modulation phase units (scale: micrometer to millimeter) into the diffraction control mirror 4, and designing the height distribution on the diffraction control surface, modulation of the outgoing wavefront can be achieved, thus controlling the wavefront phase distribution of the outgoing light and adjusting the energy distribution of the light spot on the image plane. The specific gradient phase can be determined according to Huygens-Fresnel diffraction optics theory. (Parax condition) and Fourier transform , For phase plane, Z represents the imaging surface, and Z represents the propagation distance. The phase distribution is designed using the GS algorithm, which calculates the height distribution of the tiny protrusions on the diffraction control surface.

[0103] The precise flat-top beam intensity distribution output from the focal plane is as follows: (r) <r3),

[0104] The specific steps are as follows:

[0105] S01: Select the plane at the midpoint of the part to be cut as the target image plane, and assign a phase to the energy intensity of the target image plane;

[0106] S02: The phase is combined with the light intensity on the output surface to form the light field function;

[0107] S03: The optical field function is transformed by an inverse Fourier transform to obtain the optical field distribution on the phase plane;

[0108] S04: Input the light field distribution information into S01 to S03 and combine it with the intensity distribution of light source 1 to perform Fourier transform.

[0109] Repeat steps S01-S04 until the mean square error and SSE are less than the specified values. .

[0110] Based on the above principles and steps, regions with different phases (corresponding heights) are ultimately generated on the diffraction control surface. In S01, the energy distribution of the light spot on the target image plane is as follows: Figure 4 As shown, light rays passing through the uneven, minute protrusions on the diffraction control surface will produce different phases (range 0-2π). Simultaneously, the different angles of the minute protrusion units diffract parallel incident light rays into the image plane while maintaining energy correspondence. The energy uniformity of the light spot can be defined as... , The average energy density in region S. This represents the maximum energy density within region S.

[0111] In one embodiment, based on the light field control system and light field control method of this scheme, the uniformity of the light spot energy at the focal point before refraction control is calculated to be 46.2%, the uniformity of the light spot energy at the focal point after refraction control is 81.6%, and the uniformity of the light spot energy at the focal point after refraction and diffraction control is 96.5%.

[0112] When the refractive control surface and the diffraction control surface are close together, the light output will be interfered with by the scattering of the latter surface, making it difficult to directly use as the input of the latter surface. If a double lens is set to increase the distance, the stray light will be dispersed due to the greater distance of the light path, and will not cause any impact. Based on the principle of the shortest optical path and Snell's law, the scattered light path is calculated, and the two surface scattering light paths are designed to control the stray light scattered back by the diffraction control surface and then scattered again by the refractive control surface outside the spot area, so as to achieve stray light-free light transmission between the two control surfaces on a single control lens.

[0113] Furthermore, due to the energy conservation setting, the output spot of this optical path ensures full utilization of energy, preventing excessive energy in the center of the spot from burning the machine tool blade, while avoiding overheating and hole explosion, thus avoiding energy waste. This ensures both cutting speed and cutting effect, thereby improving the cutting efficiency of high-brightness laser cutters when cutting thick plates, enabling a single high-brightness laser cutter to meet the cutting needs of different scenarios.

[0114] When calculating the cutting speed using the light spot output from this optical path, the following formula can be used: Speed ​​≈ (High-brightness laser power / (plate thickness * light spot diameter)) * plate absorption characteristic coefficient.

[0115] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0116] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0117] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for controlling a refractive and diffractive optical field, characterized in that, A refractive diffraction-based optical field manipulation system for laser cutting, the system comprising, in sequence: A light source, used to generate a high-power Gaussian beam; A protective lens is used to protect the main optical path; A collimating lens is used to collimate the high-power Gaussian beam into a parallel Gaussian beam. A refractive diffraction control mirror, used to converge the parallel Gaussian beam; Lower protective lens, used to protect the main optical path; The refractive and diffraction control mirror has a refractive control surface and a diffraction control surface on its two sides, with the refractive control surface facing the collimating mirror and the diffraction control surface facing the lower protective mirror. The method includes: (1) Set the focal length of the collimating lens to be The focal length of the refractive diffraction control mirror is The distance from the left side of the collimating lens The location is the front focal point, and the distance from the right side of the diffraction control mirror is... The position at which the beam is located is the back focus, and the numerical aperture of the incident Gaussian beam is set. The numerical aperture of the emitted beam is ; (2) Designing the curvature of the refractive control surface of the aforementioned refractive diffraction control mirror, specifically including the following steps: Step 1: Determine the optical power of the refractive control surface; Step 2: Determine the fitting center curvature of the refractive control surface; Step 3: Determine the curvature distribution equation of the refractive control surface; (3) Design the phase of the diffraction control surface of the aforementioned diffraction control mirror; Step one also includes: based on the The above and stated Determine the optical power of the refractive control surface: According to the formula for the transverse magnification of an ideal optical system: , According to the formula for angular magnification of an ideal optical system: , Combining the formulas for the transverse magnification and angular magnification of the ideal optical system, we can obtain the solution. , According to the lens power formula: Thus, the refractive control surface optical power is obtained; Step two also includes: According to the lens manufacturer's formula: The radius of curvature of the fitting center of the refractive control surface is obtained. curvature K= , Among them, the It tends toward infinity; Step three further includes: selecting five sampling image planes: the focal plane, 15mm in front of the focal plane, 40mm in front of the focal plane, 15mm behind the focal plane, and 40mm behind the focal plane of the refraction control surface; and selecting multiple proportional sampling image points on each of the sampling image planes, and jointly fitting a set of equations. The design of the diffraction control surface phase includes: S01: Select the plane at the midpoint of the part to be cut as the target image plane, and assign a phase to the energy intensity of the target image plane; S02: Combine the phase with the light intensity on the output surface to form a light field function; S03: The optical field function is subjected to an inverse Fourier transform to obtain the optical field distribution on the phase surface; S04: Input the light field distribution information into S01 to S03 and perform Fourier transform in combination with the light source intensity distribution.

2. The method for controlling the refractive and diffractive optical field according to claim 1, characterized in that, Step three also includes: based on the input Gaussian beam intensity distribution: The intensity distribution of the flat-top beam output at each of the sampling image planes and the position coordinate mapping relationship between the input beam and the output beam at each of the sampling image points are obtained. Snell's law is then applied: The normal direction of each sampled image point is obtained.

3. The method for controlling the refractive and diffractive light field according to claim 1, characterized in that, Repeat steps S01 through S04 until the mean square error and SSE are less than the specified values. .

4. The method for controlling the refractive and diffractive optical field according to claim 1, characterized in that, The upper protective mirror, the collimating mirror, the refractive diffraction control mirror, and the lower protective mirror are arranged coaxially.

Images