Laser processing system and method with flexible control over focal spot shape and structure

Abstract

This application discloses a laser processing system and method with flexibly adjustable focal spot morphology. The system includes: a variable-magnification beam expander module configured to expand an emitted linearly polarized laser beam to a preset diameter; a power adjustment module configured to adjust the power of the expanded laser beam; a beam shaping module configured to shape the laser beam into a ring beam with a preset radius; an imaging module configured to scale the ring beam according to a preset ratio; a polarization control element configured to convert the scaled linearly polarized ring beam into a vector-polarized ring beam; and a focusing module configured to focus the vector-polarized ring beam to generate a focal spot with a diameter smaller than a preset diameter threshold, and to generate a flat-topped or ring-shaped spot by adjusting the system. This application provides a new solution for processing resolutions far below the diffraction limit, overcoming the technical problem of limited processing capabilities caused by the difficulty in controlling the focal spot morphology in conventional laser processing systems.

Description

Technical Field

[0001] This application relates to the field of laser processing, and more specifically, to a laser processing system and method with flexibly adjustable focal point morphology. Background Technology

[0002] Laser processing is widely used in fields such as biomedicine, aerospace, semiconductors, and 3C due to its many advantages, including high processing efficiency, non-selectivity to materials, small heat-affected zone, no contact, no mechanical stress, and no tool wear. It is gradually becoming one of the mainstream processing methods.

[0003] However, conventional laser processing equipment primarily uses galvanometers and field mirrors for processing, resulting in typically large focal spot sizes (>10μm). Therefore, high single-pulse laser energy is required to achieve the energy density and peak power at the focal spot that reach the material's damage threshold, enabling material removal. This leads to the actual focal spot size used in laser processing being much larger than the diffraction-limited focal size, significantly limiting the application of laser processing equipment in processing micron- or even nanoscale structures. Furthermore, laser processing typically only adjusts the minimum machinable aperture or linewidth by increasing or decreasing the single-pulse energy of the laser, without altering the spatial shape of the focal spot. This severely limits the application of laser processing in specific applications, such as processing through holes, blind holes, and highly rounded micro-holes, and also fails to meet special processing requirements such as minimal carbonization, minimal melting, and minimal edge chipping.

[0004] Existing technologies propose a method based on tightly focused radially polarized beams to obtain smaller focal spots, thereby overcoming the diffraction limit and achieving higher processing resolution. Furthermore, existing technologies also propose a method based on annular slit lenses to filter out low-order wave vector components in the focused laser beam, generating sub-diffraction-limited focal spots for even higher processing resolution.

[0005] Existing technologies propose a method based on beam shaping devices to transform a conventional Gaussian intensity distribution focal spot into a flat-top focal spot, in order to meet some special laser processing requirements, such as small taper cutting and fixed-depth blind hole processing.

[0006] However, among the aforementioned methods for controlling the focal spot morphology, the method based on tightly focused radially polarized beams has limited ability to compress the focal spot size, thus significantly limiting its application in sub-diffraction-limited micro-apertures. The method based on slit lenses suffers from significant energy loss and low utilization because most of the laser beam is blocked by the slit. Furthermore, the focal spots obtained by these two methods are solid circular focal spots with Gaussian intensity distributions in a plane perpendicular to the beam propagation direction, making it impossible to flexibly control their morphology and energy distribution. Methods based on beam shaping devices to adjust the focal spot energy distribution typically produce large flat-top focal spots, failing to meet the processing requirements for sub-micron level or even higher precision or higher processing resolution.

[0007] There is currently no effective solution to the above problems. Summary of the Invention

[0008] This application provides a laser processing system and method with flexibly adjustable focal spot morphology, offering a new solution for processing resolutions far below the diffraction limit and overcoming the technical problem of limited processing capabilities caused by the difficulty in controlling the focal spot morphology in conventional laser processing systems.

[0009] According to one aspect of the embodiments of this application, a laser processing system with flexibly adjustable focal spot shape structure is provided, comprising: arranged sequentially along the optical path:

[0010] A laser (1) is configured to generate a linearly polarized laser beam;

[0011] The variable magnification beam expander module (2) is configured to expand the laser beam to adjust the diameter of the laser beam;

[0012] The beam shaping module (5) includes multiple lenses configured to shape the laser beam to form a second annular beam;

[0013] Imaging module (6) is configured to scale the second annular beam to form a third annular beam;

[0014] The polarization control element (7) is configured to convert the linearly polarized third ring beam into a vector-polarized fourth ring beam in order to adjust the polarization state of the fourth ring beam.

[0015] The focusing module (8) is configured to focus the fourth annular beam to form a focal spot with a radius smaller than a preset radius threshold. The shape of the focal spot varies based on the distribution of the polarization state of the fourth annular beam.

[0016] The variable magnification beam expander module (2) is configured to be able to adjust the beam expansion factor and / or

[0017] The beam shaping module (5) is configured to adjust the size of the focal spot by adjusting the lens spacing between multiple lens groups.

[0018] According to another aspect of the embodiments of this application, a laser processing method with flexibly adjustable focal point morphology is also provided, including generating a laser beam, wherein the laser beam is linearly polarized;

[0019] Expand the laser beam to adjust its diameter;

[0020] The laser beam is shaped to form a second ring beam;

[0021] Scaling the second annular beam to form a third annular beam;

[0022] The linearly polarized third ring beam is converted into a vector-polarized fourth ring beam in order to adjust the polarization state of the fourth ring beam.

[0023] The fourth ring beam is focused to form a focal spot with a radius smaller than a preset radius threshold. The shape of the focal spot varies based on the distribution of the polarization state of the fourth ring beam.

[0024] This involves adjusting the magnification of the beam expander and / or adjusting the spacing between multiple lens groups to adjust the size of the focal spot.

[0025] In this embodiment of the invention, a variable magnification beam expander is used to expand the emitted linearly polarized laser beam. A beam shaping module shapes the laser beam into a ring beam with a preset radius. An imaging module scales the ring beam according to a preset ratio. A polarization control element converts the scaled ring beam into a vector-polarized ring beam. A focusing module focuses the vector-polarized ring beam to generate a focal spot with a diameter smaller than a preset diameter threshold. The size of the focal spot with a diameter smaller than the preset diameter threshold is then flexibly adjusted by changing the magnification of the variable magnification beam expander and the spacing between the mirror groups in the beam shaping module. Furthermore, the focal spot with a diameter smaller than the preset diameter threshold is converted into a flat-top spot or a ring spot by adjusting the fast axis direction of the polarization control element. This solves the technical problem of limited processing capacity caused by the single focal spot shape structure in conventional laser processing systems. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0027] Figure 1 This is a schematic diagram of a laser processing system with a flexibly adjustable focal spot shape according to an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the power regulation module according to an embodiment of this application;

[0029] Figure 3 This is a schematic diagram of the beam shaping module according to an embodiment of this application;

[0030] Figure 4 This is an embodiment of the present application. A schematic diagram of the polarization state distribution of the fourth ring beam when different values ​​are taken;

[0031] Figure 5 This is a schematic diagram of the focal spot obtained by the variable magnification beam expander module of an embodiment of this application when it takes different magnification factors;

[0032] Figure 6 for Figure 5 A distribution diagram of the beam intensity curve passing through the focal center in the embodiment;

[0033] Figure 7 This is a schematic diagram of the focal spot obtained when the distance between the first conical lens and the second conical lens takes different values ​​in the beam shaping module of an embodiment of this application;

[0034] Figure 8 for Figure 7 A distribution diagram of the beam intensity curve passing through the focal center in the embodiment;

[0035] Figure 9 This is a schematic diagram and intensity distribution diagram of a focal spot obtained by adjusting the fast axis direction of a polarization control element according to an embodiment of this application;

[0036] Figure 10 This is a schematic diagram of a laser processing system with a flexibly adjustable focal spot shape according to another embodiment of this application;

[0037] Figure 11 This is a flowchart illustrating a laser processing method with flexibly adjustable focal point morphology, as described in an embodiment of this application. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] Example 1

[0041] According to embodiments of this application, a laser processing system with flexibly adjustable focal spot morphology is provided. This system can generate focal spots with diameters smaller than a preset diameter threshold, significantly improving processing resolution. Furthermore, the focal spot can be controlled to form a flat-topped spot or a ring-shaped spot to facilitate special processing such as submicron-level micro-holes, ring structures, or straight blind holes. This application provides a new solution for processing resolutions far below the diffraction limit, overcoming the technical problem of limited processing capabilities caused by the difficulty in controlling the focal spot morphology in conventional laser processing systems.

[0042] Please see Figure 1 , Figure 1 This is a schematic diagram of a laser processing system with a flexibly adjustable focal spot structure according to an embodiment of this application, as shown below. Figure 1 As shown, the system includes a laser 1, a variable magnification beam expander module 2, a power adjustment module 3, a reflector 4, a beam shaping module 5, an imaging module 6, a polarization control element 7, a focusing module 8, and a control module 11 arranged sequentially along the optical path. Figure 1 The scenario in the embodiment also includes the product to be processed 9 and the processing platform 10.

[0043] The following sections will introduce each module in detail.

[0044] 1. Laser

[0045] Laser 1 is used to emit a laser beam with a Gaussian intensity distribution. In one embodiment, the laser wavelength is 200 nm to 1600 nm and the polarization state is linear polarization.

[0046] 2. Variable magnification beam expander module

[0047] The variable magnification beam expander module 2 is used to expand the emitted linearly polarized laser beam so that the diameter of the laser beam reaches a preset diameter threshold. The diameter of the expanded laser beam is D.

[0048] 3. Power regulation module

[0049] The power adjustment module 3 is used to precisely adjust the average power or single-pulse energy of the laser used for processing, so as to accurately control the amount of material removed by a single laser pulse. Specifically, the power adjustment module 3 includes: a half-wave plate 31, a polarizing beam splitter 32, and a beam termination device 33.

[0050] Please refer to the following: Figure 2 , Figure 2 This is a schematic diagram of the power adjustment module 3 according to an embodiment of this application. The linearly polarized laser output from the laser 1 changes its polarization direction after passing through the half-wave plate 31. After passing through the polarizing beam splitter 32, the component whose polarization direction is parallel to the horizontal plane (xoy plane), i.e., the p-polarized component, can be completely transmitted and used for laser processing, while the component whose polarization direction is perpendicular to the horizontal plane (xoy plane), i.e., the s-polarized component, is completely reflected.

[0051] Specifically, in the embodiment, by precisely adjusting the fast axis direction of the half-wave plate 31 through the control module, the polarization direction of the laser transmitted through the half-wave plate 31 can be flexibly adjusted, thereby flexibly adjusting the energy ratio of the laser transmitted through the polarization beam splitter (p-polarization) and the laser reflected by it (s-polarization), so as to achieve the purpose of flexibly controlling the average power and single pulse energy of the laser beam used for processing.

[0052] In some other embodiments, the laser light (p-polarized) passing through a polarizing beam splitter is used for laser processing. Meanwhile, to prevent unused s-polarized light from damaging the eyes and equipment, a beam termination device 33 is typically used to collect it.

[0053] 4. Reflector

[0054] Please refer to it again. Figure 1 The reflector 4 is positioned between the power adjustment module 3 and the beam shaping module 4 in the optical path to change the propagation direction of the laser beam. Those skilled in the art are familiar with the specific structure and working principle of the reflector, and can adapt the parameters such as the number, position, and angle of the reflector 4 according to actual needs, which will not be elaborated upon here.

[0055] 5. Beam Shaping Module

[0056] Please continue reading. Figure 1 The beam shaping module 5 is used to spatially shape the laser beam that passes through the power adjustment module 3 and is reflected by the reflector 4.

[0057] Specifically, the beam shaping module 5 includes a first conical lens 51 and a second conical lens 52. The first conical lens 51 and the second conical lens 52 are placed parallel to each other, and the central optical axes of the first conical lens 51 and the second conical lens 52 are respectively aligned with the optical axis of the laser beam.

[0058] Please refer to the following: Figure 3 , Figure 3 This is a schematic diagram of the beam shaping module in one embodiment of this application. Specifically, in this embodiment, a laser beam of diameter D is refracted after passing through the first conical lens 51. In any vertical plane passing through the center of the optical axis of the first conical lens 51, the angle γ at which the refracted laser beam deviates from the original incident beam direction can be obtained as follows:

[0059] γ=arcsin(n sinα)-α

[0060] Wherein, n and α are the refractive index and base angle of the first conical lens 51, respectively. Due to the circular symmetry of the first conical lens 51, a laser beam with diameter D is refracted by the first conical lens 51 and converted into a first annular beam, the radius of which increases linearly with the propagation distance. Then, the diverging first annular beam is collimated into parallel light using the second conical lens 52, generating a second annular beam with a wall thickness of ω2 = D / 2.

[0061] It should be noted that in some embodiments, the second conical lens 52 and the first conical lens 51 have the same base angle α.

[0062] In some other embodiments, by precisely adjusting the distance L between the first conical lens 51 and the second conical lens 52, the relationship between the radius R2 of the second annular beam and the incident beam diameter D and the distance L is as follows:

[0063] R2=L tanγ-D / 4

[0064] In some other embodiments, the beam diameter D after beam expansion is adjusted by adjusting the magnification of the variable magnification beam expansion module 2, and the radius R2 and wall thickness ω2 of the second annular beam can be flexibly adjusted by changing the distance L between the first conical lens 51 and the second conical lens 52 in the beam shaping module 5.

[0065] 6. Imaging module

[0066] Please refer to it again. Figure 1 The imaging module 6 is used to scale the second annular beam according to a preset ratio to generate a third annular beam whose radius and wall thickness are scaled proportionally.

[0067] Specifically, the imaging module 6 includes a first focusing lens 61 and a second focusing lens 62. The front focal plane of the first focusing lens 61 coincides with the rear surface of the second conical lens 52 in the beam shaping module 5. The rear focal plane of the first focusing lens 61 coincides with the front focal plane of the second focusing lens 62, and the rear focal plane of the second focusing lens 62 coincides with the plane where the polarization control element 7 is located. The central optical axis of the first focusing lens (61) coincides with the central optical axis of the second focusing lens (62).

[0068] Specifically, in this embodiment, the imaging module 6 scales the radius R2 and wall thickness ω2 of the second annular beam according to a certain ratio to generate a third annular beam with a radius R3 and a wall thickness ω3. The scaling ratio is equal to the ratio of the focal length f2 of the second focusing lens 62 to the focal length f1 of the first focusing lens 61. The expression for the third annular beam is as follows:

[0069]

[0070]

[0071] 7. Polarization control element

[0072] Polarization control element 7 is used to convert the linearly polarized third annular beam into a vector-polarized fourth annular beam. The radius R4 and wall thickness ω4 of the fourth vector-polarized annular beam are:

[0073] R4 = R3

[0074] ω4=ω3

[0075] After being focused by the focusing module 8, the fourth annular beam of vector polarization produces a focal spot with a diameter smaller than a preset diameter threshold at the focal plane of the focusing module 8.

[0076] In a specific embodiment, the polarization control element 7 is a first-order vortex waveplate, and the Jones matrix is:

[0077]

[0078] in, It is the azimuth angle in the horizontal plane (i.e., the xoy plane). Let be the angle between the fast axis direction of the first-order vortex waveplate and the polarization direction of the fourth annular beam. The Jones matrix of the fourth annular beam is:

[0079]

[0080] Where, E =

[10] T The Jones matrix is ​​for the linearly polarized third annular beam.

[0081] Please see Figure 4 , Figure 4 Showing The polarization state distribution of the vector-polarized fourth ring beam in the plane perpendicular to the beam propagation direction when different values ​​are taken:

[0082] (1) When At any given point, the polarization direction coincides with the radial direction, exhibiting a radial pattern from the inside out, i.e., radial polarization, such as... Figure 4 As shown in (a).

[0083] (2) When At any point, the polarization direction forms an acute angle with the radial direction, i.e., rotational polarization, such as... Figure 4 As shown in (b).

[0084] (3) When The polarization direction at any point is perpendicular to the radial direction, i.e., angular polarization, such as... Figure 4 As shown in (c).

[0085] (4) When At any point, the polarization direction forms an obtuse angle with the radial direction, i.e., rotational polarization, such as... Figure 4 As shown in (d).

[0086] Specifically, in this embodiment, the angle between the fast axis direction of the polarization control element 7 and the polarization direction of the third annular beam is adjusted. The polarization state distribution of the fourth ring beam can be changed by altering its vector polarization.

[0087] 8. Focusing Module

[0088] The focusing module 8 is used to focus the fourth annular beam of vector polarization to produce a focal spot with a diameter smaller than a preset diameter threshold.

[0089] It should be noted that the focusing module 8 can be a focusing objective lens or an aspherical lens.

[0090] Specifically, the beam diameter D after beam expansion is adjusted by adjusting the magnification of the variable magnification beam expansion module 2, and the radius R4 and wall thickness ω4 of the vector polarized fourth annular beam are flexibly adjusted by changing the distance L between the first conical lens 51 and the second conical lens 52 in the beam shaping module 5, thereby achieving the purpose of flexibly adjusting the size of the focused spot.

[0091] In other embodiments, the angle between the fast axis direction of the polarization control element 7 and the polarization direction of the third annular beam is adjusted. The polarization state distribution of the fourth annular beam with vector polarization is changed, and under the focusing conditions of the focusing module 8, the focal spot with a diameter smaller than the preset diameter threshold is transformed into a flat-top spot or an annular spot.

[0092] 11. Control Module

[0093] The control module 11 is independently located outside the optical path and is communicatively connected to each module for control. Specifically, the control module 11 can controllably drive the first conical lens 51 to move relative to the second conical lens 52 to adjust the distance between the first conical lens 51 and the second conical lens 52.

[0094] In some other embodiments, the control module 11 is also connected in communication with the processing platform 10 and is controlled to drive the processing platform (10) carrying the product to be processed 9 to move precisely in three dimensions relative to the focal spot along a predetermined path.

[0095] The following describes the operation process of a laser processing system with flexibly adjustable focal spot shape structure provided in this embodiment.

[0096] S1. The linearly polarized laser beam with a Gaussian intensity distribution emitted by laser 1 is expanded by the variable magnification beam expander module 2.

[0097] S2. The average power and single pulse energy of the expanded laser beam used for processing are adjusted with high precision using the power adjustment module 3. The adjusted laser beam is spatially shaped into a second ring beam after passing through the beam shaping module 5.

[0098] S3. The imaging module 6 is used to scale the second annular beam according to a preset ratio to generate a third annular beam whose radius and wall thickness are scaled proportionally.

[0099] S4. Use polarization control element 7 to convert the linearly polarized third annular beam into a vector-polarized fourth annular beam.

[0100] S5. The fourth ring beam with a diameter smaller than a preset diameter threshold is generated by focusing the vector polarization of the focusing module 8.

[0101] S6. By adjusting the magnification of the variable magnification beam expander module 2 and the distance between the mirror groups in the beam shaping module 5, the size of the focal spot with a diameter smaller than the preset diameter threshold can be flexibly adjusted.

[0102] S7. The focal spot with a diameter smaller than a preset diameter threshold is converted into a flat-top spot or an annular spot by means of the fast axis direction of the polarization control element 7.

[0103] Specifically, in the embodiment, the following parameters are used for simulation calculation: the center wavelength of the laser beam output by the laser is λ, the diameter is D0 = 3mm, the beam expander 2 expands the beam by 2x, 6x and 10x respectively, and the diameter of the expanded beam is D = 6mm, 18mm and 30mm; in the beam shaping module, the bottom angle of the first conical lens 51 and the second conical lens 52 is α = 20°, the refractive index is n = 1.46, and the distance L between the first conical lens 51 and the second conical lens 52 is adjustable from 100mm to 500mm; in the imaging module 6, the focal length of the first focusing lens 61 is f1 = 150mm, the focal length of the second focusing lens 62 is f2 = 30mm; the numerical aperture of the focusing module 8 is NA = 0.95.

[0104] Please see Figure 5 , Figure 5 This is a schematic diagram of the focal spot obtained when the variable magnification beam expander 2 takes different magnification factors in one embodiment of this application.

[0105] like Figure 5 As shown in (a), (b) and (c), as the beam expansion factor changes from 2x, 6x and 10x, the size of the expanded beam spot gradually increases, and the wall thickness of the vector-polarized fourth ring beam also gradually increases, causing more lower-order wave vectors to enter the focusing module 8, thus resulting in a gradual increase in the focal spot size.

[0106] Figure 5 (d) shows a schematic diagram of the reference focal spot obtained under the same focusing conditions by a vector beam that does not pass through the beam shaping module 5 and has the same radius and polarization distribution as the fourth annular beam.

[0107] Figure 6 for Figure 5 The beam intensity distribution curves passing through the focal center in the embodiment show that the full width at half maximum (FWHM) radii of the 2x, 6x, and 10x beam expansions, as well as the reference focal spot, are 0.21λ, 0.22λ, 0.27λ, and 0.61λ, respectively. As can be seen from the figure, the focal spot size obtained by the laser processing system with flexibly adjustable focal shape is much smaller than the reference focal spot size. This means that the laser processing system with flexibly adjustable focal shape provided by this invention can obtain a smaller focal spot, offering a new solution for processing resolutions far smaller than the diffraction limit, and the size of the focal spot can be flexibly adjusted by adjusting the beam expansion factor of the variable magnification beam expansion system 2.

[0108] Figure 7 This is a schematic diagram of the focal spot obtained when the distance L between the first conical lens 51 and the second conical lens 52 in the beam shaping module 5 takes different values. Figure 7 (a) is the focal spot with a focal length of L+30mm. Figure 7 (b) is the focal spot of L; Figure 7(c) is the focal spot with an L-30mm aperture. Figure 8 for Figure 7 The intensity curve distribution of the beam passing through the focal center in the embodiment.

[0109] Depend on Figure 7 (a) and Figure 7 (b) comparison, and in combination Figure 8 It can be seen that, after setting a reference distance L, if the distance L between the first conical lens 51 and the second conical lens 52 is increased, a fourth annular beam with a larger radius of vector polarization can be obtained. Under the same focusing conditions, as the radius of the incident beam increases, the degree of focusing of the beam also increases, thereby obtaining a smaller focal spot. Figure 7 As shown in (a).

[0110] Depend on Figure 7 (b) and Figure 7 (c) comparison, and in combination Figure 8 It can be seen that if the distance L between the first conical lens 51 and the second conical lens 52 is reduced, the size of the focal spot will increase accordingly, such as... Figure 7 As shown in (c).

[0111] This means that the laser processing system with flexibly adjustable focal spot structure provided by the present invention can flexibly adjust the size of the focal spot by adjusting the distance L between the first conical lens 51 and the second conical lens 52 in the beam shaping module 5, thereby providing a new approach for processing different scales with processing resolutions much smaller than the diffraction limit.

[0112] Please see Figure 9 , Figure 9 This is a schematic diagram and intensity distribution diagram of the focal spot obtained by adjusting the fast axis direction of the polarization control element 7 according to an embodiment of this application, wherein... Figure 9 (a) is the solid focal spot obtained when the included angle is 0°; Figure 9 (b) is the flat-top focal spot obtained when the included angle is 49°; Figure 9 (c) is the annular focal spot obtained when the included angle is 90°; Figure 9 (d) The point ring beam obtained by adding a vortex phase plate.

[0113] Specifically, by adjusting the angle between the fast axis direction of the polarization control element 7 and the polarization direction of the linearly polarized third annular beam, the polarization state distribution of the vector-polarized fourth annular beam can be flexibly adjusted, and under the focusing of the focusing module 8, focal spots with different spatial and energy distributions can be obtained at the focal plane. Figure 9As shown in (a), (b), and (c), the focal spot exhibits a Gaussian intensity distribution, and focal spots with a diameter smaller than a preset diameter threshold can be transformed into flat-topped or annular focal spots. Therefore, the laser processing system with flexibly adjustable focal spot morphology provided by this invention can flexibly adjust the focal spot morphology and energy distribution by adjusting the fast axis direction of the polarization control element 7. This greatly expands the processing capabilities and application range of the laser processing system.

[0114] In one embodiment, a vortex phase plate can be added between the polarization control element 7 and the second focusing lens 62 in the imaging module 6, and the angle between the fast axis direction of the polarization control element 7 and the polarization direction of the linearly polarized third annular beam can be adjusted to generate a point-ring beam, such as... Figure 9 As shown in (d), this provides a new approach for processing 3D irregular structures.

[0115] The laser processing system with flexibly adjustable focal spot structure proposed in this application has the following beneficial effects:

[0116] 1) By combining beam shaping and polarization control, a focal spot with a diameter much smaller than the preset diameter threshold was obtained, thereby greatly improving the processing resolution and providing a new solution for processing with a resolution much smaller than the diffraction limit.

[0117] 2) By adjusting the magnification factor of the variable magnification beam expander module 2 and the distance between the mirror groups in the beam shaping module 5, the size of the focal spot with a diameter smaller than the preset diameter threshold can be flexibly adjusted, which solves the problem that the focal spot size is not easy to control in the traditional laser processing system and greatly expands the processing capability and application range of the laser processing system.

[0118] 3) By adjusting the fast axis direction of the polarization control element 7, a focal spot with a diameter smaller than a preset diameter threshold can be transformed into a flat-top spot, an annular spot, or a dot-ring spot. This solves the problem of uncontrollable focal spatial morphology in traditional laser processing systems, making efficient processing of multi-scale irregular structures possible and further greatly expanding the processing capabilities and application range of laser processing systems. This results in a laser processing system with flexibly adjustable focal spot morphology, capable of generating focal spots with diameters much smaller than a preset diameter threshold, and with flexibly adjustable focal spot size, which can be transformed into a flat-top spot, an annular spot, or a dot-ring spot. This provides a new solution for processing resolutions far below the diffraction limit, possessing significant application value and broad market prospects.

[0119] Example 2

[0120] According to embodiments of this application, another laser processing system with flexibly adjustable focal spot morphology is provided. This optical system is mainly used to generate a focal spot with a diameter much smaller than a preset diameter threshold to significantly improve processing resolution, providing a new solution for processing resolutions far below the diffraction limit. Furthermore, the size of the focal spot can be flexibly adjusted and can be transformed into a flat-topped spot, a ring-shaped spot, or a dot-ring spot, greatly expanding the processing capabilities and application range of the laser processing system.

[0121] Please see Figure 10 , Figure 10 This is a schematic diagram of a laser processing system with a flexibly adjustable focal point structure according to another embodiment of this application. The system includes a laser 1, a beam expander 2, a power adjustment module 3, a reflector 4, a beam shaping module 5, an imaging module 6, a polarization control element 7, a focusing module 8, a product to be processed 9, a processing platform 10, and a control module 11, arranged sequentially along the optical path.

[0122] The power adjustment module 3 includes a half-wave plate 31, a polarizing beam splitter 32, and a beam termination device 33. The half-wave plate 31 is placed on a high-precision electrically controlled rotating stage. The beam shaping module 5 includes a first conical lens 51 and a second conical lens 52. The imaging module 6 includes a first focusing lens 61 and a first concave lens 63. The product to be processed 9 is placed on the processing platform 10.

[0123] Laser 1 is used to emit a laser beam with a Gaussian intensity distribution. In one embodiment, the wavelength of the laser beam is 200 nm to 1600 nm, and the polarization state is linear polarization.

[0124] By controlling the fast axis direction of the half-wave plate 31 in the power adjustment module 3, the polarization direction of the laser passing through the half-wave plate can be flexibly adjusted, thereby flexibly adjusting the energy splitting ratio of the transmitted and reflected light of the polarization beam splitter, and thus flexibly controlling the average power of the laser used for laser processing and the single pulse energy of the laser beam.

[0125] The beam shaping module 5 is used to spatially shape the laser beam that passes through the power adjustment module 3 and is reflected by the reflector 4. In some embodiments, the beam shaping module 5 may include a first conical lens 51 and a second conical lens 52. The first conical lens 51 and the second conical lens 52 are placed parallel to each other, and their central optical axis coincides with the optical axis of the laser beam. The first conical lens 51 is placed on a high-precision linear motor to precisely adjust the distance L between the first conical lens 51 and the second conical lens 52.

[0126] Imaging module 6 is used to scale the second annular beam according to a preset ratio to generate a third annular beam whose radius and wall thickness are scaled proportionally. In one embodiment, imaging module 6 includes a first focusing lens 61 and a concave lens 63. The front focal plane of the first focusing lens 61 coincides with the rear surface of the second conical lens 52; the rear focal plane of the concave lens 63 coincides with the rear focal plane of the first focusing lens 61, and the polarization control element 7 is placed on the rear focal plane of the concave lens 63. The central optical axis of the first focusing lens 61 coincides with the central optical axis of the concave lens 63.

[0127] In one embodiment, the imaging module 6 scales the wall thickness and radius of the second annular beam by a certain ratio to generate a third annular beam. The scaling ratio is equal to the ratio of the focal length f3 of the concave lens 63 to the focal length f1 of the first focusing lens 61.

[0128] The polarization control element 7 is used to convert the linearly polarized third ring beam into a vector-polarized fourth ring beam, and after being focused by the focusing module 8, a focal spot with a diameter smaller than a preset diameter threshold is generated at the focal plane of the focusing module 8.

[0129] The specific operation flow of the system in this embodiment is as follows:

[0130] The linearly polarized laser beam emitted by laser 1 is expanded by beam expander 2; the average power and single pulse energy of the expanded laser beam used for processing are precisely adjusted by power adjustment module 3; the laser beam with adjusted average power and single pulse energy is spatially shaped into a second ring beam after passing through beam shaping module 5; the second ring beam is scaled by imaging module 6 according to a preset ratio to generate a third ring beam whose radius and wall thickness are scaled proportionally; the linearly polarized third ring beam is converted into a vector-polarized fourth ring beam by polarization control element 7; and the vector-polarized fourth ring beam is focused by focusing module 8 to generate a focal spot with a diameter smaller than a preset diameter threshold.

[0131] In this embodiment, the size of the focal spot with a diameter smaller than a preset diameter threshold is flexibly adjusted by regulating the magnification of the variable magnification beam expander module 2 and the spacing between the mirror groups in the beam shaping module 5; the focal spot with a diameter smaller than the preset diameter threshold is transformed into a ring-shaped spot or a flat-topped spot by adjusting the fast axis direction of the polarization control element 7. This application overcomes the technical problem of limited processing capability caused by the single focal spot shape structure in conventional laser processing systems.

[0132] Example 3

[0133] According to an embodiment of this application, a laser micromachining method with controllable taper is provided, such as... Figure 11 As shown, the method includes:

[0134] Step S1101: The variable magnification beam expander expands the emitted Gaussian intensity distribution linearly polarized laser beam so that the diameter of the laser beam reaches a preset diameter threshold.

[0135] Step S1102: The power adjustment module adjusts the power of the laser beam used for processing and / or the energy of a single pulse.

[0136] Step S1103: The beam shaping module shapes the power-adjusted laser beam into a second annular beam with a preset radius;

[0137] In step S1104, the imaging module scales the second annular beam according to a preset ratio to generate a third annular beam whose radius and wall thickness are scaled proportionally.

[0138] Step S1105: The polarization control element converts the linearly polarized third annular beam into a vector-polarized fourth annular beam.

[0139] In step S1106, the focusing module focuses the vector polarized fourth annular beam to generate a focal spot with a diameter smaller than a preset diameter threshold.

[0140] In this embodiment, beam shaping and polarization control are combined to obtain a focal spot with a diameter much smaller than a preset diameter threshold, thereby greatly improving the processing resolution and providing a new solution for processing resolutions much smaller than the diffraction limit. The size of the focal spot with a diameter smaller than the preset diameter threshold is flexibly adjusted by regulating the magnification of the variable magnification beam expander module 2 and the mirror group spacing in the beam shaping module 5. The focal spot with a diameter smaller than the preset diameter threshold is transformed into a ring-shaped or flat-topped spot by adjusting the fast axis direction of the polarization control element 7. This solves the problem of uncontrollable focal spatial morphology in traditional laser processing systems, making efficient processing of multi-scale irregular structures possible and further greatly expanding the processing capabilities and application range of laser processing systems.

[0141] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0142] If the integrated units in the above embodiments are implemented as software functional units and sold or used as independent products, they can be stored in the aforementioned computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause one or more computer devices (which may be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0143] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0144] In the several embodiments provided in this application, it should be understood that the disclosed client can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection between units or modules, and may be electrical or other forms.

[0145] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0146] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0147] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A laser processing system capable of flexibly regulating a focal pattern structure, characterized by, The laser (1) is configured to generate a laser beam, the laser beam being linearly polarized. The variable expansion module (2) is configured to expand the laser beam to adjust the diameter of the laser beam. The beam shaping module (5) includes multiple groups of lenses and is configured to shape the laser beam to form a second annular beam. The imaging module (6) is configured to scale the second annular beam to form a third annular beam. The polarization control element (7) is configured to convert the linearly polarized third annular beam into a fourth annular beam with vector polarization to adjust the polarization state of the fourth annular beam. The focusing module (8) is configured to focus the fourth annular beam to form a focal spot with a radius less than a preset radius threshold, the shape of the focal spot varying based on the distribution of the polarization state of the fourth annular beam. The variable expansion module (2) is configured to adjust the expansion multiple of the expansion and / or The beam shaping module (5) is configured to adjust the size of the focal spot by adjusting the mirror group spacing between multiple groups of lenses. The beam shaping module (5) includes, arranged in sequence along the optical path:

2. The laser processing system according to claim 1, characterized by, The first conical lens (51) is configured to focus the laser beam to form a divergent first annular beam. The second conical lens (52) is configured to collimate the divergent first annular beam into parallel light to convert into the second annular beam with a preset radius and wall thickness. The preset radius of the second annular beam is determined based on the distance between the first conical lens and the second conical lens, and the wall thickness of the second annular beam is determined based on the diameter of the laser beam. The central optical axis of the second conical lens (52) coincides with the central optical axis of the first conical lens (51); and 3. The laser processing system of claim 2, wherein, The second conical lens (52) has the same base angle size as the first conical lens (51). The imaging module (6) includes, arranged in sequence along the optical path:

4. The laser processing system according to claim 2 or 3, characterized by The front focal plane of the first focusing lens (61) coincides with the rear surface of the second conical lens (52). The front focal plane of the second focusing lens (62) coincides with the rear focal plane of the first focusing lens (61), and the rear focal plane of the second focusing lens (62) coincides with the plane where the polarization control element (7) is located. The central optical axis of the first focusing lens (61) coincides with the central optical axis of the second focusing lens (62). The polarization control element (7) has a fast axis, and the polarization control element (7) is configured to adjust the direction of the fast axis to control the polarization state distribution of the fourth annular beam.

5. The laser processing system of claim 1, wherein, The optical axes of the beam shaping module (5), the imaging module (6), the polarization control element (7), and the focusing module (8) coincide.

6. The laser processing system of claim 1, wherein, ​ 7. The laser processing system of claim 1, wherein, The laser processing system further comprises a power adjustment module (3) disposed between the variable expansion module (2) and the beam shaping module (5) in the optical path, the power adjustment module (3) being configured to adjust the power of the expanded laser beam.

8. The laser processing system of claim 7, wherein, The power adjustment module (3) comprises, arranged in sequence along the optical path: a half-wave plate (31) configured to adjust the polarization direction of the laser beam; a polarization beam splitter prism (32) configured to transmit p-polarized laser in the laser beam and reflect s-polarized laser in the laser beam; a beam termination device (33) configured to block the s-polarized laser reflected by the polarization beam splitter prism (32).

9. The laser processing system according to claim 2 or 3, characterized by, Further comprising a control module (11) configured to drive the first conical lens (51) to move relative to the second conical lens (52) to adjust the distance between the first conical lens (51) and the second conical lens (52); drive the processing platform (10) carrying the product to be processed (9) to move accurately along a predetermined path in three-dimensional directions relative to the focal spot.

10. A method of processing by a laser processing system capable of flexibly adjusting a focal point configuration structure according to claim 1, characterized by, It comprises: generating a laser beam, the laser beam being linearly polarized; expanding the laser beam to adjust the diameter of the laser beam; shaping the laser beam to form a second annular beam; scaling the second annular beam to form a third annular beam; converting the linearly polarized third annular beam into a fourth annular beam with vector polarization to adjust the polarization state of the fourth annular beam; focusing the fourth annular beam to form a focal spot with a radius less than a preset radius threshold, the shape of the focal spot varying based on the distribution of the polarization state of the fourth annular beam; wherein the expansion multiple of the expansion is adjusted and / or the mirror group spacing between the groups of lenses is adjusted to adjust the size of the focal spot.

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