Optical system for outputting transverse multi-focus light spots through double mirrors

Abstract

The invention discloses an optical system for outputting transverse multi-focus light spots through double mirrors, and belongs to the technical field of laser processing. The device comprises a focusing unit and a positioning unit which are sequentially arranged along a light path, the focusing unit is used for focusing the incident light and projecting the focused incident light to the positioning unit; the positioning unit is an aspheric reflector and is used for reflecting and splitting incident light spots into transverse multi-focus light spots; and partitioning the reflector based on the energy ratio of different light spots, determining a lateral offset phase based on the lateral offset distance of different light spot focuses, and superposing the lateral offset phases of the corresponding light spots in different partitions of the reflector to obtain the aspheric reflector. According to the invention, with fewer optical elements and a simplified light path structure, the output of transverse multi-focus distribution light spots is realized, and the requirements of different scenes in actual processing are met.

Description

Technical Field

[0001] This application belongs to the technical field of laser processing, and more specifically, relates to an optical system with a double-mirror output of a horizontally multi-focus spot. Background Art

[0002] The Gaussian distribution focused spot commonly used in laser welding has an extremely high energy density. When acting on the material surface, it will cause the surface material to undergo a phase change in an extremely short time, resulting in serious spatter and the resulting weld depression, severely degrading the quality of the welded joint; moreover, the sudden temperature rise process of the material will cause the keyhole to close frequently, increasing the probability of the appearance of bubbles and seriously affecting the welding depth.

[0003] The laser spot with a horizontally multi-focus distribution introduces two or more spots on the welding path, and the previous spot is in a defocused state, forming a preheating with a larger area; the latter spot is a normal Gaussian distribution focused spot, which welds the preheated material, reducing the probability of defects such as bubbles, spatter, and depression, and improving the welding depth. Currently, the solution for the horizontally multi-focus distribution spot applicable to high-power processing scenarios is mainly the superposition of two independent laser beams. The two laser beams are coupled and output as front-and-back distributed lasers through a special laser head, but this method requires a high precision of the welding head. The relative positions of the foci of the two laser beams are not easy to calibrate, it is difficult to achieve defocus for a single laser beam, the overall structure is relatively complex, and when the number of foci is greater than 2, it is difficult to achieve the output of front-and-back multi-focus distribution by using the coupling means, the structure of the welding head is too complex, and it is very difficult to calibrate. Summary of the Invention

[0004] In view of the above defects or improvement requirements of the prior art, this application provides an optical system with a double-mirror output of a horizontally multi-focus spot, aiming to solve the technical problem that the structure and operation of the existing optical system with a horizontally multi-focus distribution spot are too complex.

[0005] To achieve the above object, this application provides an optical system with a horizontally multi-focus distribution spot, aiming to solve the existing one. The system includes a focusing unit and a positioning unit arranged in sequence along the optical path;

[0006] The focusing unit is used to focus the incident light and project the focused incident light onto the positioning unit;

[0007] The positioning unit is an aspherical mirror that reflects and splits the incident spot into a horizontally multi-focus spot; based on the energy ratio of different spots, the aspherical mirror is partitioned, and based on the horizontal offset distance of the foci of different spots, the horizontal offset phase is determined. The horizontal offset phases of the corresponding spots are superimposed in each partition to obtain the aspherical mirror.

[0008] Preferably, the aspherical mirror is partitioned based on the energy proportion of different light spots, specifically: the aspherical mirror is radially partitioned based on the energy proportion of different light spots to obtain multiple regions, and the light source divergence angle corresponding to the annular dividing line between adjacent partitions is:

[0009]

[0010] where θ0 is the emission angle of the real light source, and θ i is the emission angle of the light source corresponding to the i-th annular dividing line, i = 1, 2, 3, …, N; dot_part i is the energy proportion of the corresponding light spot. After calculating the emission angles of the light sources corresponding to N - 1 ellipsoidal surfaces, the emission angle of the N-th ellipsoidal surface is set as θ0.

[0011] Preferably, the homogenization treatment is performed on the mirror after radial partitioning, specifically:

[0012] M radiation lines R are drawn outward from the center point of the mirror at a preset angular difference. 1,2,…,M Let R i , i = 1, 2, … M intersect with the annular dividing line L at point D i , then the height difference at D i is:

[0013] Δ(R i ) = H0(D i ) - H1(D i )

[0014] where H1() is the regional function of partition S1, H0() is the regional function of partition S0, and S0 and S1 are the partitions on both sides of the annular dividing line L respectively; the height of the smaller partition S0 remains unchanged; the height of the points at the annular dividing line L in partition S1 is subtracted by Δ(R i ), and this process is the homogenization operation at R i in partition S1; the homogenization operation is performed at M radiation lines in partition S1 to achieve the homogenization operation of partition S1, and the homogenization operation is performed on all partitions except partition S0 to achieve the overall homogenization treatment of the mirror.

[0015] Preferably, the aspherical mirror is partitioned based on the energy proportion of different light spots, specifically: the mirror is angularly partitioned based on the energy proportion of different light spots to obtain multiple fan-shaped regions, and the angle occupied by the i-th fan-shaped region is: 2 × π × dot_part i ; where, dot_part i is the energy proportion of the corresponding light spot, i = 1, 2, 3, …, N;

[0016] Preferably, each sector region is further divided into 2 small sector regions with an angle of π×dot_part i The same small sector regions are symmetrically distributed in the mirror.

[0017] Preferably, homogenization processing is performed on the mirror after angular partitioning, specifically:

[0018] Starting from the center point of the mirror, M circular lines L are made along the radial direction at a preset distance 1,2,…,M ; the height of the sector region S1 remains unchanged, and the height of the points at the circular line L i , i = 1, 2, … M in other sector regions is subtracted by H0 - H1, where H0 is the average height of all points at the circular line L i in other sector curved surface regions, and H1 is the average height of all points at the circular line L i in the S1 region; this process is the homogenization operation at the circular line L i , and the homogenization operation is performed on all circular lines R 1,2,…,M in the mirror to achieve the overall homogenization processing of the mirror.

[0019] Preferably, the transverse offset phase is determined based on the transverse offset distance of different light spot foci, specifically:

[0020]

[0021] where f(x) represents the transverse offset phase; x is the distance between a point on the mirror and the center point; F0 is the focusing distance; RR is the transverse offset distance; B is an integral constant, and substituting f(x) = 0, B can be obtained.

[0022] Preferably, the focusing unit is an ellipsoidal surface mirror, a focusing lens, or a combination of a plane mirror and a focusing lens placed along the optical path.

[0023] Preferably, the curved surface of the ellipsoidal surface mirror is the projection surface on the ellipsoidal surface, and the equation of the ellipsoidal surface is specifically expressed as:

[0024]

[0025] where x, y, z are the three-dimensional coordinates of the points on the ellipsoidal surface; b 2 is the parameter of the equation of the ellipsoidal surface; a perpendicular line is drawn from the center point of the curved surface of the mirror to the connection line between the light source and the focusing point, h is the length of the perpendicular line, and l1 and l2 are the distances from the light source and the focusing point to the perpendicular line respectively; the included angle between the connection line between the light source and the focusing point and the tangent plane at the center point of the curved surface is β.

[0026] Preferably, in the equation of the ellipsoidal surface:

[0027]

[0028]

[0029]

[0030]

[0031] Among them, F1 and F2 are respectively the preset collimation distance and the preset focusing distance of the ellipsoidal surface mirror.

[0032] Preferably, the system includes a light source for generating a Gaussian beam incident on the focusing unit.

[0033] Generally speaking, compared with the prior art, the above technical solutions conceived by this application have the following beneficial effects:

[0034] (1) This application discloses an optical system with double-mirror output and transverse multi-foci. Through the focusing unit and the positioning unit, a transverse multi-foci distribution light spot can be obtained from a laser light source without other optical elements. It can achieve the output of a transverse multi-foci distribution light spot with fewer optical elements and a streamlined optical path structure. The energy of each light spot is arbitrarily adjustable, and the spacing between different light spots is adjustable, meeting the requirements of different scenarios in actual processing;

[0035] (2) Based on the energy and spacing of the output target light spot, this application proposes an aspherical mirror phase design method by combining the optical path principle and the energy conservation principle, which can realize the design and control of the transmission characteristics and light field distribution of the shaped beam, facilitating the satisfaction of different application requirements; There are many selectable modes for the light spot shaping in this application, not limited to the quantity limit of two. By dividing more shaping regions on the mirror surface, a transverse point distribution of three or more can be achieved; By changing the distribution of the mirror dividing line, the energy adjustment of each focus can be independently realized;

[0036] (3) In this application, after the aspherical mirror adopts the homogenization operation, the continuity problem of the entire mirror surface during the combination of multiple curved surfaces is solved, and the processing difficulty of complex surface shapes is reduced. Description of the Drawings

[0037] Figure 1 is a schematic structural diagram of an optical system with double-mirror output and transverse double-foci light spots provided in Embodiment 1 of this application;

[0038] Figure 2 is a schematic diagram of radially partitioning the positioning unit mirror according to the light spot energy ratio provided in Embodiment 1 of this application;

[0039] Figure 3 is a schematic diagram of angularly partitioning the positioning unit mirror according to the light spot energy ratio provided in Embodiment 1 of this application;

[0040] Figure 4 is the design schematic diagram of the focusing unit mirror provided in Embodiment 1 of the present application;

[0041] Figure 5 is the design schematic diagram of the offset phase of the positioning unit mirror provided in Embodiment 1 of the present application;

[0042] Figure 6 is the schematic diagram of homogenizing the radial partition mirror provided in Embodiment 1 of the present application;

[0043] Figure 7 is the schematic diagram of homogenizing the angular partition mirror provided in Embodiment 1 of the present application;

[0044] Figure 8 is the schematic diagram of the target spot energy distribution provided in Embodiment 1 of the present application;

[0045] Figure 9 is the schematic diagram of the optical system structure for outputting a double-mirror transverse triple-focus spot provided in Embodiment 2 of the present application;

[0046] Figure 10 is the schematic diagram of the target spot energy distribution provided in Embodiment 2 of the present application;

[0047] Figure 11 is the schematic diagram of the optical system structure for outputting a double-mirror transverse point-ring / ring spot provided in Embodiment 3 of the present application;

[0048] Figure 12 is the schematic diagram of the target spot energy distribution provided in Embodiment 3 of the present application;

[0049] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1. Laser; 2. Focusing unit; 3. Positioning unit; 4. Working surface; 5. Gaussian beam; 6. Intermediate beam; 7. Output beam; 8. First spot area in the radiation area; 9. First spot dividing line in the radiation area; 10. Second spot area in the radiation area; 11. Second spot dividing line in the radiation area; 12. Third spot area in the radiation area; 14. Light source protection device; 21. First spot on the working surface; 22. Second spot on the working surface; 23. Third spot on the working surface. Detailed implementation manners

[0050] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] The embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0052] Embodiment 1:

[0053] As Figure 1 shown, an optical system for outputting a transverse multi-focus spot with a double mirror includes: a light source 1, a focusing unit 2, and a positioning unit 3 sequentially arranged along the optical path;

[0054] The light source 1 is used to generate a Gaussian beam 5;

[0055] The focusing unit 2 uses an ellipsoidal reflector to focus the Gaussian beam emitted by the light source at the collimation distance to the focusing distance and emit it onto the positioning unit 3;

[0056] The phase of the reflecting surface of the focusing unit 2 is determined by the following method: Based on the preset collimation distance and preset focusing distance of the focusing unit, an ellipsoidal phase is superimposed on the plane mirror to construct the surface equation of the focusing unit.

[0057] The phase of the reflecting surface of the positioning unit 3 is determined by the following method: According to the energy distribution of the incident Gaussian beam and the energy distribution of the target transverse multi-focus spot, the transverse offset phase of different foci is determined, and then the mirror division area is determined according to the energy distribution, and the corresponding transverse offset phase is superimposed on different mirror division areas on the plane mirror;

[0058] The center of the positioning unit 3 is located on the central axis of the light beam emitted by the focusing unit 2, and is used to focus the Gaussian spot shaped by the focusing unit 2 at a preset position on the working surface 4 to form a target transverse multi-focus distribution spot, spot 21 and spot 22.

[0059] The focusing unit 2 is a rotating ellipsoidal reflector, a focusing lens, or a combination of a plane reflector and a focusing lens arranged along the optical path.

[0060] In this embodiment, the focusing unit 2 uses a rotating ellipsoidal reflector, and the rotating ellipsoidal reflector has the function of collimating and focusing the light beam emitted by the light source, and its reflecting surface shape is given according to the preset focal length; the positioning unit 3 uses a homogenizing aspherical reflector, and the homogenizing aspherical reflector has the function of shaping the input Gaussian beam, and its homogenizing aspherical mirror surface shape is solved according to the given parameters;

[0061] The optical system provided in this embodiment has the ability to output a transverse multi-focus spot with adjustable output energy and spacing. At the same time, the functions of collimation, focusing, and positioning are realized through two reflectors, reducing the number of optical elements; the discontinuous part of the surface of the homogenizing aspherical reflector is homogenized, making the mirror surface smooth without grooves, reducing the processing difficulty, and at the same time can withstand the action of high-power lasers; the intensity of the target spot can be adjusted to realize the adjustable distribution of the energy of the transverse multi-focus spot.

[0062] When the shape of the reflecting surface is completely determined, the optical system has a determined incident direction and an exit direction; the ellipsoidal reflector of the focusing unit includes a focus in the incident direction and a focus in the exit direction, which are respectively denoted as the front focus and the rear focus; the focal plane corresponding to the front focus is denoted as the front focal plane; the focal plane corresponding to the rear focus is denoted as the rear focal plane; the distance from the front focus to the center point of the focusing unit is the front focal length, and the sum of the distances from the rear focus to the center point of the positioning unit through the center point of the focusing unit is the rear focal length. Since the focusing unit focuses the Gaussian beam to a preset position and then the positioning unit splits the Gaussian spot into multiple laterally distributed spots, the phase of the homogenizing aspherical mirror of the positioning unit presents a non-uniform gradient. When the reflecting surface shape of the homogenizing aspherical mirror is different (i.e., the phase setting is different), the distribution pattern of the laterally multi-focus spots obtained by the optical system is also different. Adjusting the reflecting surface phase of the positioning unit 3 can change the distribution of the laterally multi-focus spots obtained after shaping. The laterally multi-focus spots include: two laterally focused spots, multiple laterally focused spots, and laterally dot-ring-dot distributed spots. According to the surface equation of the positioning unit, it can be determined by solving with the energy distribution of the target spot on the preset focal plane as a condition, and its shape is a free surface that is not rotationally symmetric.

[0063] Figure 1 In it, the focusing unit 2 focuses the input beam 5 emitted by the light source 1 into an intermediate beam 6, and the positioning unit 3 splits the intermediate beam 6 through the reflecting surface and emits an exit beam 7. The exit beam 7 is focused on the rear focal plane 4, and a determined number and spacing of target laterally multi-focus spots 21, 22 are obtained on the rear focal plane 4. Among them, the focusing unit 2 adopts an ellipsoidal reflector and has both collimating and focusing functions.

[0064] The light rays forming the input beam enter the homogenizing aspherical mirror after passing through the front focus or approximately passing through the front focus, and the incident direction of the input beam is perpendicular to the front focal plane; the input beam is a Gaussian beam emitted by the light source 1 located at the front focus, and the light source 14 is a laser.

[0065] The reflecting surface shape of the positioning unit 3 is determined in the following way: according to the energy distribution of the incident Gaussian beam and the energy distribution of the target laterally multi-focus spots, determine the lateral offset phases of different foci, and then determine the mirror division regions according to the energy distribution. Superimpose the corresponding lateral offset phases on different mirror division regions on the plane mirror to construct the surface equation of the reflecting surface shape corresponding to the target laterally multi-focus spots; among them, the spot distribution pattern of the target light field corresponds to the desired laterally multi-focus spots.

[0066] According to the energy proportion of different points on the target surface, the radiation area on the mirror surface of the positioning unit 3 is divided by the light source, and the dividing line is Figure 1The 9 in it divides the entire radiation area into two parts, namely area 8 and area 10, thus realizing beam shaping with a preset energy distribution.

[0067] By dividing the incident light field into multiple parts according to the energy ratio requirements of the target intensity-adjustable circular symmetric light spot, and mapping the energy of each part to the corresponding position on the rear focal plane respectively, the mapping relationship between the incident light field and the target light field energy distribution is determined. For example, Figure 1 In it, area 8 on the reflecting surface of the positioning unit 3 corresponds to the light spot 21 on the working surface 4, and area 9 corresponds to the light spot 22 on the working surface 4.

[0068] The energy mapping relationship between the incident light field and the target light field is determined according to conditions such as the collimation focal length, focusing focal length, and energy ratio. Its meaning is as follows: The light sources corresponding to different light spots on the target surface are the same, all being Figure 1 The light source in it, that is, the front focus, and the collimation focal lengths are also the same. The difference lies in the focal positions of different light spots, that is, the rear foci. According to the geometric optical relationship of the two foci of the ellipsoid, we only need to apply the same ellipsoidal phase on the first mirror surface and different lateral offset phases on different regions of the second mirror surface to ensure the separation of the light spots on the target surface. The division of different regions on the mirror surface is determined by the preset energy ratio of different light spots. Through the above design, it is possible to achieve laterally multi-focal light spots with preset energy and spacing on the target surface.

[0069] The shape of the reflecting surface of the rotating ellipsoidal mirror of the focusing unit 2 is determined by the following method:

[0070] Based on the preset collimation distance and preset focusing distance of the focusing unit, an ellipsoidal phase is superimposed on the plane mirror to construct the surface equation of the rotating ellipsoid that meets the preset conditions, so that the target light spot is located at the preset position.

[0071] It should be noted that the specific adjustment effects caused by customizing the reflecting surface shape and replacing the homogenizing aspherical mirror with different mirror surface shapes include: adjustable collimation focal length and focusing focal length; adjustable energy ratio of each point; each point can be shaped into a ring light spot with a preset radius; adjustable point spacing.

[0072] The specific radial sub-region method of the reflecting surface mirror of the positioning unit 3 is: by dividing the point light source with a divergence angle of θ3, the energy ratio of different parts is determined. For example, Figure 2 As shown, the cone with a divergence angle of θ3 emitted from the point light source will form the outermost gray area S3 on the reflecting mirror surface. The cone with a divergence angle of θ1 emitted from the point light source will form the gray area S1 and its boundary L1 on the reflecting mirror surface. The cone with a divergence angle of θ2 emitted from the point light source will form the gray area S2 and its boundary L2 on the reflecting mirror surface. Superimposing more shaping phases on the mirror surface will correspondingly obtain more energy ratios and corresponding circular ring areas.

[0073] As Figure 2 shown, the gray part S1 in the figure is the light source irradiation area with an energy proportion of dot_part1, the gray part S2 is the light source irradiation area with an energy proportion of dot_part2, and the gray part S3 is the light source irradiation area with an energy proportion of dot_part3. All the gray parts together constitute the total irradiation area of the point light source, and dot_part1 + dot_part2 + dot_part3 = 1. The radius of the light source divergence angle on the reflecting surface is F1 * tanθ3, which is the size of the light gray area S3; the radius of the boundary divergence angle on the reflecting surface is F1 * tanθ1, which is the size of the gray area S1, and the radius of the boundary divergence angle on the reflecting surface is F1 * tanθ2, which is the size of the gray area S2.

[0074] Given the total divergence angle θ3, and the energy proportion dot_part1 of the gray area S1 and the energy proportion dot_part2 of the gray area S2, according to the formula:

[0075]

[0076] Thus, the light source divergence angle θ1 corresponding to the boundary L1 to be obtained is:

[0077]

[0078] Similarly, the light source divergence angle θ2 corresponding to the boundary L2 is

[0079]

[0080] where F1 is the collimation distance of the focusing unit mirror, θ3 is the light source divergence angle, dot_part1 is the energy occupied by the focus 1, and dot_part2 is the energy occupied by the focus 2.

[0081] The specific angular sub-region method of the reflecting surface of the positioning unit 3 is: divide the mirror surface into fan-shaped regions, as Figure 3 shown, where the shaded part S1 of the mirror surface is focused into the focus 1, S2 is focused into the focus 2, and S3 is focused into the focus 3. Assume that the energy proportion of the focus 1 in the total energy of the light source is dot_part1, the energy proportion of the focus 2 in the total energy of the light source is dot_part2, and the energy proportion of the focus 3 in the total energy of the light source is dot_part3, and dot_part1 + dot_part2 + dot_part3 = 1.

[0082] Then, the angles of the two sector-shaped shaded parts in the S1 region with respect to the complete circle are 2*π*dot_part1, and the angle of each part is π*dot_part1; similarly, for the S2 region, the angles of the two sector-shaped shaded parts with respect to the complete circle are 2*π*dot_par2, and the angle of each part is π*dot_part2; for the S3 region, the angles of the two sector-shaped shaded parts with respect to the complete circle are 2*π*dot_part3, and the angle of each part is π*dot_part3.

[0083] For the mirror surface design of the reflecting surface of the focusing unit 2, as Figure 4 shown in the schematic diagram of the mirror surface, according to the distance F1 from the light source to the center point of the focusing unit and the distance F2 from the target transverse multi-focus to the center point of the focusing unit, the curve equation of the rotating ellipsoid mirror surface can be uniquely determined.

[0084] According to the following formula:

[0085]

[0086]

[0087]

[0088]

[0089] Among them, F1 is the collimation distance of the focusing unit, F2 is the focusing distance, h1 is the distance from the center point of the focusing unit to the light source-target connection line, l1 is the horizontal distance from the light source to the center point of the focusing unit, l2 is the horizontal distance from the target to the center point of the focusing unit, b 2 is the parameter of the ellipsoid equation, and β is the angle between the tangent line at the center point of the focusing unit and the light source-target connection line.

[0090] The final ellipsoid equation can be obtained as:

[0091]

[0092] As Figure 5 shown in the schematic diagram of the mirror surface, according to the lateral offset distance RR, the corresponding lateral offset phase can be determined.

[0093] According to the following formula:

[0094]

[0095] And Δθ = θ1 - θ2, from the reflection relationship, it can be known that The lateral offset phase can be obtained as:

[0096]

[0097] Among them, f(x) represents the lateral offset phase; x is the distance between a point on the mirror and the center point; F0 is the focal length; RR is the lateral offset distance; B is the integration constant. Substituting f(x) = 0, B can be obtained.

[0098] For the mirror surface design of the reflecting surface of the positioning unit 3, for different energy regions, its ellipsoidal phase offset is calculated according to the surface equation, and the phases in the same energy region are the same.

[0099] The mirror surface of the reflecting surface of the positioning unit 3 is divided into rings for mirror surface homogenization. Specifically: homogenization is performed on the boundaries of different regions of the reflecting surface of the positioning unit 3 to make the mirror surface smooth without grooves. In Figure 6 In the shown mirror surface schematic diagram, when different phases are superimposed in the gray regions S1 and S2, it will cause a height difference in the boundary L between different regions, and this height difference changes unevenly with the angle, which will cause scratches in the middle of the finally processed mirror surface. In the case of more partitions in the mirror surface area, this defect will be aggravated, seriously affecting the shaping effect of the mirror and reducing the power threshold of the mirror. An optimization method for the boundary height difference of the mirror surface is proposed, as Figure 6 shown, 1000 radial lines are made from the center of the mirror along the radius, Figure 6 One of them, R1, is shown in. The intersection of R1 and the boundary L is D2. Take a point D1 on R1 in the S1 region and a point D3 on R1 in the S2 region; the equation of the S1 region is H1, and the equation of the S2 region is H2. The height of the boundary between the two regions on the R1 radial line is:

[0100] Δ(R1) = H2(D2) - H1(D2)

[0101] Thus, the height of the points in the S1 region remains unchanged, still H1(D1), and the height of the points in the S2 region subtracts the boundary height difference, that is, H2(D3) - Δ(R1). Thus, the mirror surface homogenization on H1 is achieved. This operation is performed on all 1000 radial lines, and finally the homogenization of the entire mirror surface can be achieved. In the case where there are more than two partitions on the mirror surface, homogenization can still be performed according to this operation, and the optical performance of the mirror surface can be not affected.

[0102] The mirror surface of the reflecting surface of the positioning unit 3 is divided into sectors for mirror surface homogenization. Specifically: as Figure 7 shown, elliptical dotted lines are made from the inside to the outside on the mirror surface. The heights of the boundaries of the R1 region at the dotted line are H 11 and H 12 , and the average height is The heights of the boundaries of the S2 region at the dotted line are H 21 and H 22 , and the average height is The heights of the boundaries of the S3 region at the dotted line are H31 and H 32 , with an average height of Therefore, the height difference between the S2 area and the S1 area is The height difference between the S3 area and the S1 area is

[0103] Taking the S1 area as a reference, the height within the S2 area on this imaginary line is subtracted by To achieve homogenization, the height within the S3 area on this imaginary line is subtracted by To achieve homogenization.

[0104] An optical system for outputting a laterally multi-focal spot with double-mirror output provided in Embodiment 1, in which the focusing unit uses a rotating ellipsoidal mirror, the positioning unit uses a homogenized aspherical mirror, and the curved surface equation of the focusing unit is determined based on a preset front focal length and a preset rear focal length; and in combination with the principle of equal optical path and the principle of energy conservation, the curved surface equation of the positioning unit is determined, and the reflecting surface shapes of the rotating ellipsoidal mirror and the aspherical mirror corresponding to the target laterally multi-focal spot are constructed. The Gaussian beam emitted by the light source is collimated, focused and split to generate a target laterally multi-focal spot on the working surface; and the phase of the reflecting surface of the aspherical mirror of the positioning unit is adjusted to correspondingly adjust the number, energy and spacing of the generated target laterally multi-focal spots. It solves the technical problem of how to simplify the optical path as much as possible, meet the diversification of shaping modes while reducing the processing complexity, and improve the stability and applicability. With fewer optical elements and a streamlined optical path structure, it realizes an adjustable output quantity, adjustable intensity, adjustable spacing, and target laterally multi-focal spot, which is applicable to the requirements of different scenarios in actual processing.

[0105] In Embodiment 1, the included angle between the incident light ray 5 and the middle light ray 6 is 90 degrees, and the included angle between the middle light ray 6 and the outgoing light ray 7 is 90 degrees, forming the focal point 22 on the target surface. The focal point 21 is 1 mm in front of the focal point 22, as Figure 1 shown. In Embodiment 1, the front focal length of the rotating ellipsoidal mirror is taken as 125 mm, the rear focal lengths of both focal points are 300 mm, the energy proportion of the focal point 21 is 50%, the energy proportion of the focal point 22 is 50%, the distance between the two focal points is 1 mm, and the energy distribution of the spot on the rear focal plane is as Figure 8 shown.

[0106] In Embodiment 1, the front and rear two focal points can be applied to scenarios that require repeated welding. Some materials cannot reach the required processing strength during a single welding process, while the two laser action areas on the weld seam during a single processing can achieve the purpose of repeated welding and greatly improve the efficiency;

[0107] Embodiment 2:

[0108] A double-mirror laterally multi-focal spot optical system for outputting a laterally triple-focal combined spot is provided, and the optical system is asFigure 9 As shown, in this embodiment, the incident light ray 5 forms a 90-degree angle with the intermediate light ray 6, and the intermediate light ray 6 forms a 90-degree angle with the outgoing light ray 7, forming a focal point 22 on the target surface. The focal point 21 is 1 mm in front of the focal point 22, and the focal point 23 is 1 mm behind the focal point 12. As Figure 9 shown, in this embodiment, the front focal length of the rotating ellipsoidal mirror is taken as 125 mm, and the rear focal lengths are all 300 mm. The energy proportion of the focal point 21 is 50%, the energy proportion of the focal point 22 is 25%, and the energy proportion of the focal point 23 is 25%. The distance between the three focal points is 1 mm, and the energy distribution of the light spot on the rear focal plane is as Figure 10 shown.

[0109] In Implementation Example 2, a welding effect is added on the basis of Embodiment 1, which can be applied to repetitive welding scenarios and further improve the welding efficiency;

[0110] Embodiment 3:

[0111] A dual-mirror transverse multi-focal spot optical system for outputting a transverse dot-ring - dot combined light spot is provided. The optical system is as Figure 11 shown. In this embodiment, the incident light ray 5 forms a 90-degree angle with the intermediate light ray 6, and the intermediate light ray 6 forms a 90-degree angle with the outgoing light ray 7, forming a focal point 22 on the target surface. The focal point 21 is 1 mm in front of the focal point 22, and the radius of the ring 23 is 0.3 mm. As Figure 1 shown, in this embodiment, the front focal length of the rotating ellipsoidal mirror is taken as 125 mm, and the rear focal lengths are all 300 mm. The energy proportion of the focal point 21 is 60%, the energy proportion of the focal point 22 is 10%, and the energy proportion of the ring 23 is 30%. The energy distribution of the light spot on the rear focal plane is as Figure 12 shown.

[0112] In Implementation Example 3, the ring light spot on the path can increase the preheating range and reduce the uneven distribution caused by the preheating of the ordinary Gaussian distribution light spot, improving the stability effect on the molten pool during the welding process.

[0113] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or a combination thereof, but cannot be interpreted as excluding the existence or the possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or a combination thereof.

[0114] In the description of the embodiments of the present application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected and the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected and can rotate relative to each other after connection. "Sliding connection" means that the two are connected and can slide relative to each other after connection. The orientation terms mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., are only references to the directions in the drawings. Therefore, the orientation terms are used to better and more clearly illustrate and understand the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the embodiments of the present application.

[0115] In addition, in the embodiments of the present application, mathematical concepts such as symmetry, equality, parallelism, and perpendicularity are mentioned. These limitations are all in view of the current technological level, rather than absolute strict definitions in the mathematical sense. A small amount of deviation is allowed, and approximate symmetry, approximate equality, approximate parallelism, approximate perpendicularity, etc. are all acceptable. For example, when it is said that A is parallel to B, it means that A is parallel to B or approximately parallel to B, and the included angle between A and B can be between 0 degrees and 10 degrees. When it is said that A is perpendicular to B, it means that A is perpendicular to B or approximately perpendicular to B, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0116] In the embodiments of the present application, terms such as "first" and "second" are used to distinguish different objects, rather than to describe the specific order of the objects. For example, the first focus and the second focus are used to distinguish different foci, rather than to describe the specific order of the foci.

[0117] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0118] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality of" refers to two or more. For example, a plurality of light spots refers to two or more light spots, etc.; a plurality of foci refers to two or more foci, etc.

[0119] In the embodiments of the present application, the various numerical numbers involved are only for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0120] As described above, it is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

1. An optical system with double-mirror output and a horizontally multi-focal spot, characterized in that, The system includes a focusing unit and a positioning unit arranged in sequence along the optical path; The focusing unit is used to focus the incident light and project the focused incident light onto the positioning unit; The positioning unit is an aspherical mirror that reflects and splits the incident light spot into a transverse multi-focus light spot; the aspherical mirror is partitioned based on the energy ratio of different light spots, the transverse offset phase is determined based on the transverse offset distance of the foci of different light spots, and the transverse offset phases of the corresponding light spots are superimposed in each partition to obtain the aspherical mirror.

2. The system according to claim 1, wherein Partitioning the aspherical mirror based on the energy ratio of different light spots specifically means: radially partitioning the aspherical mirror based on the energy ratio of different light spots to obtain a plurality of regions, and the divergence angle of the light source corresponding to the annular demarcation line between adjacent partitions is: where θ0 is the emission angle of the real light source, and θ i is the emission angle of the light source corresponding to the i-th annular dividing line, i = 1, 2, 3, …, N; dot_part i is the energy proportion of the corresponding light spot, After calculating the emission angles of the light sources corresponding to the N - 1 ellipsoidal surfaces, the emission angle of the N-th ellipsoidal surface is defined as θ0.

3. The system according to claim 2, wherein Performing homogenization processing on the mirror after radial partitioning, specifically: From the center point of the mirror, draw M radiation lines R outward at a preset angular difference 1,2,…,M , let R i , i = 1, 2, … M and the annular dividing line L intersect at D i points, then the height difference at D i is: Δ(R i ) = H0(D i ) - H1(D i ) Among them, H1() is the area function of partition S1, H0() is the area function of partition S0, and S0 and S1 are the partitions on both sides of the annular dividing line L respectively; the height of the smaller partition S0 remains unchanged; subtract the height of the points at the annular dividing line L in partition S1 by Δ(R i ), and this process is the homogenization operation at R i in partition S1; perform the homogenization operation at M radiation lines in partition S1 to achieve the homogenization operation of partition S1, and perform the homogenization operation on all partitions except partition S0 to achieve the overall homogenization treatment of the mirror.

4. The system according to claim 1, characterized in that, Partition the aspherical mirror based on the energy proportion of different light spots, specifically: partition the mirror angularly based on the energy proportion of different light spots to obtain multiple fan-shaped regions, where the angle occupied by the \(i\)-th fan-shaped region is: \(2\times\pi\times dot\_part\) i ; where, \(dot\_part\) i is the energy proportion of the corresponding light spot, \(i = 1, 2, 3, \cdots, N\); 5. The system according to claim 4, wherein Each sector region is further divided into two small sector regions with an angle of π×dot_part i and the same small sector regions are symmetrically distributed in the mirror.

6. The system according to claim 4 or 5, characterized in that, Performing homogenization processing on the mirror after angular partitioning, specifically: Starting from the center point of the mirror, M loop lines L are made along the radial direction at a preset distance 1,2,…,M ; the height of the fan-shaped area S1 remains unchanged, and the height of the points on the loop line L i , at i = 1, 2, … M is subtracted by H0 - H1, where H0 is the average height of all points on the loop line L i in other fan-shaped curved surface areas, and H1 is the average height of all points on the loop line L i in the area S1; this process is the homogenization operation at the loop line L i , and the homogenization operation is performed on all loop lines R 1,2,…,M in the mirror to achieve the overall homogenization treatment of the mirror.

7. The system according to claim 1, wherein Determining the transverse offset phase based on the transverse offset distance of the foci of different light spots, specifically: Where f(x) represents the transverse offset phase; x is the distance between a point on the mirror and the center point; F0 is the focusing distance; RR is the transverse offset distance; B is an integration constant. Substituting f(x) = 0, B can be obtained.

8. The system according to claim 1, characterized in that The focusing unit is an ellipsoidal surface mirror, a focusing lens, or a combination of a plane mirror and a focusing lens placed along the optical path.

9. The system according to claim 8, characterized in that, The surface of the ellipsoidal surface mirror is the projection surface on the ellipsoidal surface, and the equation of the ellipsoidal surface is specifically expressed as: where x, y, and z are the three-dimensional coordinates of the points on the ellipsoidal surface; b 2 is the parameter of the ellipsoidal surface equation; draw a perpendicular line from the center point of the curved surface of the mirror to the line connecting the light source and the focal point, h is the length of the perpendicular line, and l1 and l2 are the distances from the light source and the focal point to the perpendicular line respectively; the angle between the line connecting the light source and the focal point and the tangent plane at the center point of the curved surface is β.

10. The system according to claim 9, wherein In the equation of the ellipsoidal surface: Where F1 and F2 are the preset collimation distance and the preset focusing distance of the ellipsoidal surface mirror, respectively.

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