Modular pluggable laser gang hole whirl cut scanning head and scanning processing method

Abstract

The application provides a modular pluggable laser group hole rotary cutting scanning head and a scanning processing method, which comprises, in sequence along an optical path, a dove prism, a half-wave plate, a beam shaper, a first focusing mirror, a second focusing mirror, a scanning galvanometer and a field lens. The dove prism is used for rotating the light beam; the half-wave plate is used for adjusting the polarization direction of the light beam; the beam shaper is a diffractive optical element or a spatial light modulator, and is used for splitting a single incident light beam into an array light beam; the first focusing mirror and the second focusing mirror constitute a 4f imaging system; the scanning galvanometer is used for realizing high-speed scanning in the field of the field lens; and the field lens is used for focusing the light beam emitted by the scanning galvanometer on the surface of a sample. The modular pluggable laser group hole rotary cutting scanning head and the scanning processing method have high processing efficiency, can obtain a true circular micro hole, effectively inhibit heat accumulation, and improve the hole wall roundness and quality.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a modular, pluggable laser multi-hole rotary cutting scanning head and scanning processing method. Background Technology

[0002] With the rapid growth in demand for micro-hole arrays (such as earpiece arrays for mobile phone cover plates, micro-holes for fuel injectors, vias for flexible circuit boards, and micro-hole arrays for drug sustained release) in fields such as consumer electronics, semiconductors, aerospace, and medical devices, increasingly higher requirements are being placed on processing efficiency, micro-hole roundness, and consistency.

[0003] Currently, there are various high-performance commercial rotary cutting scanning machining heads on the market, such as Fraunhofer ILT's HDO-7, Zhongke Micro Precision's four-light wedge-based rotary cutting machining head, SCANLAB's precSYS, Aerotech's AGV5D, Novata Photonics' PRECESSION ELEPHANT III, and Canon's MA-1010 five-axis galvanometers. These products can flexibly adjust the machining micro-hole diameter by adjusting the output beam angle and adjust the machining taper by adjusting the beam's lateral displacement, achieving high-quality single-hole machining of through holes, and have significant advantages in the field of precision single-hole machining.

[0004] However, the aforementioned commercial products are all single-focus rotary cutting solutions, which can only process one micro-hole at a time. When processing a large number of micro-hole arrays (such as 100×100 arrays or 1000×1000 arrays), single-hole rotary cutting requires processing tens of thousands or even millions of times per hole, which is extremely inefficient and cannot meet the needs of mass production.

[0005] Traditional DOE (Diffractive Optical Elements) beam splitting + galvanometer scanning processing methods, which use the array focal points generated by DOE beam splitting and galvanometer scanning for processing, can only employ a "punching" processing method because the sub-beams lack high-speed rotation capabilities. ("Punching" processing refers to a processing method where the array focal points act simultaneously on the sample surface, and the aperture and depth are adjusted by controlling the number of pulses and the duration of the pulses.) This processing method has the following prominent problems: 1. Poor micro-aperture roundness: Due to the ellipticity of the laser output spot itself, the beam expansion system and optical path will also introduce aberrations, which will cause the spot of each focal point to be elliptical rather than ideally circular, directly degrading the roundness of the micro-aperture. 2. Poor consistency: It is difficult to maintain a consistent energy distribution and roundness at each focal point in the array; 3. Severe thermal ablation: The "punching" processing method applies the array focus to the sample surface simultaneously, resulting in severe local heat accumulation and obvious thermal ablation effect, causing the product to melt and carbonize.

[0006] Furthermore, both single-focus rotary cutting and traditional DOE beam splitting + galvanometer scanning punching methods often face the problem of roundness degradation when adjusting the hole diameter. For example, to obtain microholes larger than the spot diameter, single-focus rotary cutting requires increasing the scanning radius, which easily leads to elliptical hole shapes; while in punching, when increasing the number of pulses to enlarge the hole, heat accumulation can severely damage the roundness and quality of the hole wall. Summary of the Invention

[0007] This invention provides a modular, pluggable laser multi-hole rotary cutting scanning head and scanning method that can realize one-time rotary cutting and scanning processing of massive micro-hole arrays, improve processing efficiency, eliminate the influence of laser output spot ellipticity and optical path aberration on the roundness of micro-holes, obtain true round micro-holes, and effectively suppress heat accumulation, thereby improving the roundness and quality of hole walls.

[0008] The technical solution adopted in this invention is: a modular and pluggable laser multi-aperture rotary cutting scanning head, which includes a Dowell prism, a half-wave plate, a beam shaper, a first focusing mirror, a second focusing mirror, a scanning galvanometer, and a field mirror arranged sequentially along the optical path; The Daowei prism is designed with a 45° angle, and its rotation center (i.e., optical axis) coincides with the optical axis of the incident beam, which is used to make the beam rotate and realize rotary scanning; and the Daowei prism is coaxially mounted on a high-speed rotary motor. When the high-speed rotary motor drives the Daowei prism to rotate on its optical axis, the rotation angle of the emitted image is twice the rotation angle of the Daowei prism. The half-wave plate is used to adjust the polarization direction of the beam so that the beam matches the polarization direction of the beam shaper. The beam shaper is a diffractive optical element or a spatial light modulator used to split a single incident light beam into an array beam. The beam shaper is located on the front focal plane of the first focusing mirror, and its optical axis center coincides with the optical axes of the first focusing mirror and the second focusing mirror. The first focusing lens and the second focusing lens constitute a 4f imaging system, and the rear focal plane of the first focusing lens coincides with the front focal plane of the second focusing lens; The scanning galvanometer is used to achieve high-speed scanning within the field lens area; the field lens is used to focus the light beam emitted from the scanning galvanometer onto the sample surface, and the front focal point of the field lens coincides with the rear focal point of the second focusing lens.

[0009] Furthermore, the focal lengths of the first focusing lens and the second focusing lens are F1 and F2, respectively, and the scaling ratio of the 4f imaging system is F2 / F1.

[0010] Furthermore, it also includes a first reflecting mirror and a second reflecting mirror arranged along the optical path between the Dove prism and the half-wave plate. The first reflecting mirror and the second reflecting mirror are used to adjust the beam transmission direction so that the beam is incident on the diffractive optical element or the spatial light modulator in a polarized direction.

[0011] Furthermore, it also includes a third and a fourth reflecting mirror arranged along the optical path between the second focusing mirror and the scanning galvanometer, the third and fourth reflecting mirrors being used to adjust the beam transmission direction so that the beam is emitted to the scanning galvanometer.

[0012] Furthermore, it also includes a sealed housing, in which the Dove prism, the first reflector, the second reflector, the half-wave plate, the first focusing lens, the second focusing lens, the third reflector, and the fourth reflector are all disposed; the sealed housing is provided with a slot, the inner wall of the slot is configured to allow the laser beam to pass through, and the diffractive optical element or the spatial light modulator is pluggably disposed in the slot.

[0013] Furthermore, the sealed housing is provided with an inlet and an outlet. The inlet is used to receive the laser beam and is equipped with a window lens, which is made of anti-reflection quartz glass. The outlet is used to output a modulated beam that propagates along the center of the optical axis. The scanning galvanometer and the field lens are both located at the outlet.

[0014] Furthermore, the diffractive optical element or the spatial light modulator is mounted on a mounting bracket, which is adjustable in multiple directions and can be plugged into the slot and locked by a locking mechanism.

[0015] Furthermore, the sealed housing is provided with an air passage interface, a water passage interface, and an electrical control interface; the air passage interface is a standard quick-connect connector for connecting positive pressure clean and dry gas; the water passage interface is a standard inlet and outlet water connector for connecting circulating cooling water to quickly remove the heat generated by the high-speed rotating motor during operation; the electrical control interface is a standard industrial connector that integrates motor drive lines, galvanometer control lines, and encoder feedback lines.

[0016] The present invention further provides the following technical solutions: A scanning and processing method using a laser multi-hole rotary cutting scanning head, characterized by employing the laser multi-hole rotary cutting scanning head as described above, comprising the following steps: S1: A high-speed rotating motor drives the Daowei prism to rotate at a preset angular velocity ω around the optical axis. The light beam is incident along the optical axis of the Daowei prism, and the light field pattern of the outgoing beam rotates at a preset angular velocity 2ω around the optical axis. According to the image rotation characteristics of the Daowei prism, when the Daowei prism rotates by an angle θ with its optical axis as the axis, the outgoing image rotates by an angle 2θ around the optical axis. The incident beam's light field distribution is as follows: The output beam's light field distribution is as follows: In the formula, t represents time; S2: The polarization direction of the rotating beam is adjusted by a half-wave plate so that the rotating beam illuminates the target surface of the diffractive optical element or the target surface of the spatial light modulator at a preset angle. When the beam of light shines on the target surface of the diffractive optical element, the single incident beam is split into an M×N array beam by the complex amplitude transmittance function of the diffractive optical element. When the beam of light shines on the target surface of the spatial light modulator, the phase hologram preloaded on the target surface of the spatial light modulator modulates the single incident beam into an M×N array beam. Where M≥1, N≥1, and M and N are both integers; S3: The array beam emitted from the diffractive optical element or the spatial light modulator enters the 4f imaging system. First, the first focusing lens with a focal length of F1 performs a Fourier transform on the array beam, and then the second focusing lens with a focal length of F2 performs an inverse Fourier transform on the array beam, scaling the array beam according to the F2 / F1 ratio, while accurately imaging the phase information of the target surface of the diffractive optical element or the target surface of the spatial light modulator. S4: The scaled array beam is incident on the scanning galvanometer along the center of the entrance port of the scanning galvanometer, which enables the array beam to be quickly positioned. Then it enters the field lens and is focused on the sample surface by the field lens to form a micron-scale focal spot array. Among them, the diameter of the focused spot The relationship with the field lens focal length F is as follows: , In the formula, Let λ be the beam quality factor of the incident laser, and λ be the wavelength of the incident laser. The diameter is the incident beam diameter.

[0017] Furthermore, the actual focal distance d on the focal plane f Separation angle θ from diffractive optical elements s The relationship is: , In the formula, F is the focal length of the field lens.

[0018] Compared to existing technologies, the modular, pluggable laser multi-hole rotary drilling scanning head and scanning processing method of this invention, by setting diffractive optical elements or spatial light modulators, splits a single beam of light into an array beam in one go, and then, in conjunction with the rotation of the Dowell prism, achieves high-throughput processing of multi-hole rotary drilling, effectively improving processing efficiency. At the same time, by setting a high-speed rotating motor to drive the Dowell prism to rotate at high speed, the elliptical spot of each focal point is transformed into a circularly symmetrical spot under the time averaging effect, eliminating the ellipticity of the laser output spot and the beam expansion image astigmatism, and processing true circular micro-holes. Moreover, rotary drilling makes the energy uniformly distributed in the circumferential direction, avoiding heat accumulation, thereby avoiding the product's thermal melting and carbonization problems caused by thermal ablation effect, and improving the roundness and quality of the hole wall. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but should not be construed as limiting the invention. In the drawings, Figure 1 : A perspective view of the modular, pluggable laser multi-aperture rotary cutting scanning head of the present invention; Figure 2 : A schematic diagram of the structure of the modular pluggable laser multi-aperture rotary cutting scanning head of the present invention, embodiment one; Figure 3 : A schematic diagram illustrating the principle of the array beams rotating around their respective optical axes in this invention; Figure 4 : Figure 3 Enlarged view at point A (showing the change in beam cross-section shape before and after the rotation of the Dowell prism, demonstrating that the elliptical spot is equivalent to a circular focal spot after high-speed rotation). Figure 5 A schematic diagram comparing the roundness of the modular, pluggable laser multi-aperture rotary cutting scanning head of this invention with that of traditional DOE beam splitting processing; Figure 6 : A schematic diagram of the structure of the modular pluggable laser multi-aperture rotary cutting scanning head of the present invention, embodiment two; Figure 7 : Flowchart of the laser multi-hole rotary cutting scanning head scanning processing method of the present invention.

[0020] Names and numbers of each component 1. Daowei Prism; 2. High-speed Rotary Motor; 3. First Reflector; 4. Second Reflector; 5. Half-wave Plate; 6. Diffractive Optical Element; 7. First Focusing Mirror; 8. Second Focusing Mirror; 9. Third Reflector; 10. Fourth Reflector; 11. Scanning Galvanometer; 12. Field Mirror; 13. Spatial Light Modulator; 30. Sealed Housing; 31. Light Inlet; 32. Window Lens; 33. Light Outlet; 34. Gas Interface; 35. Water Interface; 36. Electrical Control Interface. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] Example 1 like Figure 1 and Figure 2 As shown, the modular pluggable laser multi-aperture rotary cutting scanning head of the present invention includes a sealed housing 30, an optical module, and a lens module.

[0023] The sealed housing 30 is provided with an inlet 31 and an outlet 33. The inlet 31 is used to receive a collimated, linearly polarized laser beam with an adaptable diameter, and a window lens 32 is installed in the inlet 31. The window lens 32 is made of anti-reflection quartz glass to ensure high transmittance, while also sealing the optical interface of the sealed housing 30 to isolate external dust. The outlet 33 is used to output a modulated beam that propagates along the center of the optical axis.

[0024] The optical module includes a Dowell prism 1, a first reflecting mirror 3, a second reflecting mirror 4, a half-wave plate 5, a beam shaper, a first focusing mirror 7, a second focusing mirror 8, a third reflecting mirror 9, and a fourth reflecting mirror 10 arranged sequentially along the optical path. All of these components are housed within a sealed housing 30. The sealed housing 30 has slots, the inner walls of which are designed to allow the laser beam to pass through. The beam shaper is removably mounted within these slots.

[0025] Specifically, the Daowei prism 1 adopts a 45° angle design, with its rotation center (i.e., optical axis) coinciding with the optical axis of the incident beam. This ensures that when the laser beam enters from the optical axis (i.e., the rotation center), the outgoing beam also exits along the optical axis without lateral displacement. The Daowei prism 1 is coaxially mounted on a high-speed rotary motor 2, which is used to rotate the beam to achieve rotary scanning. The high-speed rotary motor 2 drives the Daowei prism 1 to rotate at high speed around the optical axis at an angular velocity ω, and the outgoing beam rotates at high speed around the optical axis at an angular velocity 2ω. In this embodiment, the rotary scanning frequency of the Daowei prism 1 can cover 0-1000Hz (corresponding to a rotational speed range of 0-60000rpm).

[0026] The following is a verification of the image rotation characteristics of the Dowell Prism 1: Since the Daowei prism 1 is a truncated right-angle prism with an isosceles trapezoidal cross-section, when the Daowei prism 1 rotates by an angle θ with its optical axis as the axis, the emitted image rotates by an angle 2θ around the optical axis.

[0027] Suppose the incident beam is a collimated Gaussian beam propagating along the optical axis, and its optical field distribution in cylindrical coordinates (r, θ) is as follows. It can be represented as: Where E represents the electric field amplitude of the scanning galvanometer, and w represents the waist radius of the beam.

[0028] When the Dove prism 1 rotates around the optical axis at an angular velocity ω, the light field distribution of the emitted beam... for: Where t is time; That is, the light field pattern of the emitted beam rotates around the optical axis at an angular velocity of 2ω.

[0029] In this embodiment, the beam shaper is a diffractive optical element (DOE) 6, used to split a single incident beam into an M×N array beam (M≥1 and N≥1, where M and N are both integers), and each sub-beam inherits the rotational characteristics of the incident beam. The diffractive optical element 6 is mounted on a mounting bracket (not shown), and this mounting bracket has multi-degree-of-freedom adjustment (including translation and tilt adjustment in the X, Y, and Z directions); the mounting bracket can be plugged into a slot and locked by a locking mechanism. Therefore, the user can select a diffractive optical element 6 of appropriate specifications according to processing needs and replace the diffractive optical element 6 by quick plugging and unplugging; and for target light fields with special focal distributions or special spacing, the customer can customize the diffractive optical element 6.

[0030] Furthermore, after the mounting bracket is inserted into the slot, the diffractive optical element 6 is located on the front focal plane of the first focusing mirror 7, and its optical axis center coincides with the optical axis of the first focusing mirror 7 and the second focusing mirror 8.

[0031] When it is necessary to replace the diffractive optical element 6, loosen the locking mechanism of the mounting bracket, take out the current diffractive optical element 6, and insert the target diffractive optical element 6; adjust the degrees of freedom of the mounting bracket (X and Y translation to align with the optical path, tilt adjustment to be perpendicular to the optical axis), and fine-tune to the optimal state by observing the focal plane array light spot; finally, lock and fix it.

[0032] In addition, the diffractive optical element 6 is made of fused silica material using a sixteen-level etching process and is designed in a standard size. It is equipped with multiple standard diffractive optical elements 6 with different focal array distributions (such as 5×5, 10×10, 20×20) and different focal spacings.

[0033] The first reflecting mirror 3 and the second reflecting mirror 4 are used to adjust the direction of beam transmission so that the beam enters the diffractive optical element 6 at a preset angle.

[0034] The half-wave plate 5 is used to adjust the polarization direction of the light beam, rotating it to match the optimal response polarization direction of the diffractive optical element 6. This satisfies the polarization state requirements of the diffractive optical element 6 for the incident light, ensuring maximum diffraction efficiency. For lasers of different wavelengths, the angle of the half-wave plate 5 can be changed or adjusted as needed.

[0035] The focal lengths of the first focusing lens 7 and the second focusing lens 8 are F1 and F2, respectively, forming a 4f imaging system. The rear focal plane of the first focusing lens 7 coincides with the front focal plane of the second focusing lens 8.

[0036] The third reflecting mirror 9 and the fourth reflecting mirror 10 are used to adjust the direction of beam transmission so that the beam is emitted from the light outlet 33 to the scanning galvanometer 11.

[0037] The lens module includes a scanning galvanometer 11 and a field lens 12. Both the scanning galvanometer 11 and the field lens 12 are located on the outside of the sealed housing 30 and at the light outlet 33. The scanning galvanometer 11 is used to realize high-speed, high-precision two-dimensional scanning within the area of ​​the field lens 12.

[0038] The field lens 12 has a focal length of F and is used to focus the light beam emitted from the scanning galvanometer 11 onto the sample surface. The diameter of the focused spot can be adjusted by replacing the field lens 12 with different focal lengths as needed. Furthermore, the front focal point of the field lens 12 coincides with the rear focal point of the second focusing lens 8, and their optical path lengths are F+F2.

[0039] In a preferred example, field lens 12 may be a telecentric field lens, and different focal lengths may be changed as needed, preferably from 20mm to 1000mm.

[0040] In addition, the sealed housing 30 is also equipped with an air inlet 34, a water inlet 35, and an electrical control interface 36. The air inlet 34 is a standard quick-connect connector for connecting positive pressure clean and dry gases (such as nitrogen, air, etc.) to prevent external dust from entering and extend service life. The water inlet 35 is a standard inlet / outlet water connector for connecting circulating cooling water to quickly remove the heat generated by the high-speed rotating motor 2 during operation, preventing temperature exceedances and optical drift. The electrical control interface 36 is a standard industrial connector that integrates motor drive lines, galvanometer control lines, and encoder feedback lines.

[0041] like Figures 2 to 4 ( Figure 4 The change in the beam cross-sectional shape before and after rotation of the Dowell prism 1 is shown in the figure, illustrating that the elliptical beam spot is equivalent to a circular focal spot after high-speed rotation. The working principle of this example is as follows: The collimated laser beam enters the sealed housing 30 through the window lens 32 of the light inlet 31 and is incident on the Daowei prism 1. The high-speed rotating motor 2 drives the Daowei prism 1 to rotate at an angular velocity ω, and the outgoing beam rotates at 2ω. The rotating beam is incident on the diffractive optical element 6 after being adjusted by the first reflecting mirror 3 and the second reflecting mirror 4 and polarized by the half-wave plate 5. The beam is split into an M×N array by the diffractive optical element 6. Each sub-beam inherits the rotation characteristics and rotates at high speed around its own optical axis, realizing a multi-aperture parallel spin-cut array beam. After being scaled by the 4f imaging system, the array beam is adjusted by the third mirror 9 and the fourth mirror 10 and then emitted from the light outlet 33. Finally, it is deflected by the scanning galvanometer 11 and focused by the field mirror 12 before being output.

[0042] 1. Verification of the principle of rotating M×N array beam generated by the rotating Dove prism 1 and the static diffractive optical element 6 in this embodiment: (1) Mathematical description of the incident light field The beam E output from Dove Prism 1 rotates around the optical axis at an angular velocity of 2ω. out1 When (r, θ, t) is incident on diffractive optical element 6, in cylindrical coordinates (r, θ, t), it is a field E that rotates with time t. in2 (r, θ, t): Where E0(r, θ) is the static light field distribution at t=0, this formula shows that the entire intensity pattern It rotates at an angular velocity of 2ω.

[0043] (2) Outgoing light field and far-field diffraction (a) The transmittance function of diffractive optical element 6 is as follows: Diffractive optical element 6 is a thin phase element whose angular transmittance function T(θ) is a periodic function. For a diffractive optical element 6 that generates N equally angularly distributed beams, its transmittance can be expanded into a Fourier series: Where m is the diffraction order, with values ​​ranging from 0, ±1, ±2, ..., c m It is the Fourier coefficient of the m-th order, which determines the relative amplitude and phase of the beam at that order. This function is static and does not change with time.

[0044] (b) A rotating incident light field illuminates a static diffractive optical element 6, and the outgoing light field E is located close to the rear surface of the diffractive optical element 6. out2 (r, θ, t) is the product of the two:

[0045] To analyze the characteristics of each diffraction order m on the focal plane of field lens 12, E out2 Analyzing the portion of (r, θ, t) corresponding to that order, the contribution of the m-th order beam is proportional to... The product of the term and the incident field; importantly, the incident field E in2(r, θ, t) can be expanded into a superposition of angular harmonics: Among them, A k (r) is the amplitude of each angular harmonic of the static light spot E0(r, θ).

[0046] Substituting the expansion into E out2 (r, θ, t), and extract the m-th order diffracted beam, the far-field complex amplitude E corresponding to this order. m It is the superposition of all angular harmonic components that satisfy L=k+mN. To see its time dependence, we substitute the variable k=L-mN, then: in, These are polar coordinates on the far-field plane centered on the optical axis of that order, with the time factor recombined: The global phase factor in the above formula This value is eliminated during intensity calculation and has no effect on the intensity distribution. Therefore, the far-field intensity distribution of the m-th order beam is: This expression has explicit The function form means that: (c) Final conclusions and physical picture The above mathematical derivation rigorously proves that the transverse intensity distribution of the m-th order diffracted beam rotates precisely around its own optical axis (ρ=0) with an angular velocity of 2ω.

[0047] Therefore, please refer to Figure 3 and Figure 4 ( Figure 4 This demonstrates the change in beam cross-sectional shape before and after rotation of the Dowell prism 1, showing that an elliptical beam spot is equivalent to a circular focal spot after high-speed rotation. The Dowell prism 1 imparts a rotation factor (θ) to the original beam. When the sub-beam (2ωt) passes through the static angular grating of the diffractive optical element 6, it is completely and indiscriminately replicated on every diffraction order. The rotation center of each sub-beam is its own geometric center (in the far-field plane). The arrangement of the entire array is determined by the fixed grating period of the diffractive optical element 6. The macroscopic configuration of the array does not rotate, and each sub-beam rotates independently at its own position. Moreover, the rotation of all sub-beams is completely synchronous, with the same angular frequency 2ω, and their initial azimuth relationship remains fixed at any given moment.

[0048] In summary, by using "rotating Dove prism 1 + static diffractive optical element 6", a parallel beam array in which all sub-beams or sub-foci rotate at high speed and synchronously around their own optical axes can be generated.

[0049] 2. The focal distance in this embodiment is calculated as follows: Based on the design principle of the diffractive optical element 6, let the effective focal length of the focusing system be EFL (in this embodiment, the equivalent focal length of the 4f imaging system + field lens 12), and the separation angle of the diffractive optical element 6 be θ. s Then the distance d between adjacent foci on the focal plane satisfies:

[0050] In the optical path of this embodiment, the magnification of the 4f imaging system is F2 / F1, and the focal length of the field lens 12 is F. Therefore, the actual focal distance d... f for:

[0051] When the Dove prism 1 rotates at an angular velocity ω, the rotational angular velocity of each focal point in the array is 2ω; the laser repetition frequency is... The number of pulses required for a single focal point to rotate one revolution is: The machining aperture and depth can be precisely controlled by adjusting the number of laser pulses.

[0052] Example 2 like Figure 6 As shown, the structure in this embodiment is the same as that in Embodiment 1, and will not be described again here. The difference is that the beam shaper in this embodiment is a spatial light modulator (SLM) 13, which realizes dynamically programmable group aperture spin cutting.

[0053] Specifically, the first reflector 3 and the second reflector 4 adjust the beam direction so that the rotating beam illuminates the target surface of the spatial light modulator 13 at a preset angle (i.e., polarization direction).

[0054] The half-wave plate 5 adjusts the polarization direction of the beam to be parallel to the liquid crystal orientation of the spatial light modulator 13 (i.e., to match the polarization direction of the spatial light modulator 13) in order to meet the polarization state requirements of the spatial light modulator 13.

[0055] The spatial light modulator 13 is used to modulate a single incident light beam into an M×N array beam, where each sub-beam inherits the rotational characteristics of the incident light beam. Specifically, the target surface of the spatial light modulator 13 is preloaded with a phase hologram based on an iterative Fourier transform algorithm. This phase hologram is designed to modulate the incident light beam into an M×N array beam (M≥1, and N≥1, where M and N are both integers), thereby modulating a single incident light beam into an M×N array beam.

[0056] Therefore, by connecting the spatial light modulator 13 to a control system and loading the phase hologram through the host computer software, the user can switch the array light field with different array sizes, different focal spacings, and different energy distributions, thereby realizing high-speed processing of irregularly shaped complex distribution group holes.

[0057] 1. The beam diameter of the present invention is calculated as follows: Field lens 12 focusing spot diameter The calculation formula is as follows:

[0058] Among them, M 2 The beam quality factor of the incident laser is represented by λ, and the wavelength of the incident laser is represented by λ. The diameter of the incident beam is represented by F, and the focal length of field lens 12 is represented by F.

[0059] 2. The principle of wide-range true circular aperture control based on rotation effect in this invention is as follows: This invention not only solves the roundness problem of the array focal point, but also realizes the processing of true circular holes over a wide range, from sub-spot diameter to far exceeding the spot diameter. The principle behind this invention is: ① Sub-spot diameter micropores By precisely controlling the ratio of single-pulse energy to the material damage threshold and utilizing the edge energy distribution of the rotating focal point, micropores smaller than the physical diameter of the focal spot can be fabricated. The rotational effect ensures that energy deposition remains isotropic even at the sub-spot scale, and the roundness of the pores is superior to that of traditional punching processes.

[0060] ② Micropores far exceeding the diameter of the light spot By increasing the number of pulses applied to the material or extending the laser's action time, the rotating focus accumulates material removal in the circumferential direction. Because the energy is always uniformly distributed, the hole wall expands isotropically, effectively suppressing localized protrusions or elliptical deformations caused by heat accumulation in traditional punching processes.

[0061] ③ Synergistic control of process parameters: By adjusting the laser power, single pulse energy, repetition frequency, rotation speed of the Daowei prism and the number of pulses in a coordinated manner, a continuous, smooth and perfectly round transition of the aperture from submicron to hundreds of micron can be achieved, meeting the needs of all scenarios from ultra-precision drilling to efficient large hole forming.

[0062] 4. The principle of improving the roundness of micropores in this invention is as follows: When the Dowell prism 1 rotates at a high speed with an angular velocity ω, the elliptical light spots at each focal point rotate at a high speed with an angular velocity 2ω. Under the time averaging effect, the elliptical light spots are transformed into circularly symmetrical light spots, and their equivalent roundness approaches 1, fundamentally eliminating the influence of the ellipticity of the laser output spot and the beam spread image astigmatism on the roundness of the micro-hole. Since the rotation of the Dowell prism 1 causes an overall rotational effect of the light spot pattern, the focal spots distributed in the M×N array obtained from the diffraction optical element 6 or the spatial light modulator 13 and the focusing of the field lens 12 all rotate at a high speed with an angular velocity 2ω around their respective optical axes. Therefore, when the array focal points act on the sample surface simultaneously, each micro-hole is subjected to rotary drilling.

[0063] like Figure 1 , Figure 2 and Figure 7 As shown, the present invention also provides a scanning processing method for a laser multi-hole rotary cutting scanning head, comprising the following steps: S1: The high-speed rotating motor 2 drives the Daowei prism 1 to rotate at a preset angular velocity ω around the optical axis at high speed; the linearly polarized laser beam provided by the external collimated laser source enters the sealed housing 30 through the light inlet 31 and the window lens 32, and is incident along the optical axis direction (i.e., the rotation center) of the Daowei prism 1. Since the beam is incident from the rotation center, the outgoing beam propagates along the optical axis direction and does not undergo lateral displacement. Based on the image rotation characteristics of the Daowei prism 1, when the Daowei prism 1 rotates by an angle θ with its optical axis as the axis, the emitted image rotates by an angle 2θ around the optical axis; therefore, when the high-speed rotating motor 2 drives the Daowei prism 1 to rotate at an angular velocity ω, the light field pattern of the emitted beam rotates at a high speed around the optical axis at an angular velocity 2ω, realizing rotary scanning and roundness improvement.

[0064] In this step, when the incident beam's light field distribution is The output beam's light field distribution is as follows: , In the formula, t represents time.

[0065] S2: The rotating beam passes sequentially through the first reflecting mirror 3 and the second reflecting mirror 4 to adjust its angle, and then passes through the half-wave plate 5 to adjust its polarization direction, so that the rotating beam illuminates the target surface of the diffractive optical element 6 or the target surface of the spatial light modulator 13 at a preset angle (please refer to...). Figure 2 , Figure 6 ); When the beam of light is irradiated onto the target surface of the diffractive optical element 6, the single incident beam is split into an M×N array beam (M≥1 and N≥1, where M and N are both integers) by the complex amplitude transmittance function T(x,y) of the diffractive optical element 6. Each sub-beam inherits the rotation characteristics and rotates at high speed around its own optical axis. When the beam of light shines on the target surface of the spatial light modulator 13, the phase hologram preloaded on the target surface of the spatial light modulator 13 modulates the single incident light into an M×N array beam (M≥1 and N≥1, where M and N are both integers). Each sub-beam inherits the rotation characteristics and rotates at high speed around its own optical axis, thus realizing parallel processing of multiple holes.

[0066] In this step, when the beam-splitting angles of the diffractive optical element 6 are different (e.g., θ respectively), xm θ yn When ), the propagation directions of each sub-beam are different.

[0067] By finely adjusting the angles of the first reflector 3 and the second reflector 4, it can be ensured that the light beam is incident perpendicularly or at a designed angle (i.e., an angle that matches the polarization direction of the diffractive optical element 6 or the spatial light modulator 13).

[0068] Since the incident beam itself is already rotating at high speed, after passing through the diffractive optical element 6 or the spatial light modulator 13, the wavefront of each sub-beam carries a rotational phase factor related to time t. Therefore, each sub-beam inherits the rotational characteristics of the incident beam, and the focal point on its focal plane rotates at a high speed with an angular velocity of 2ω around its own optical axis center, realizing the core function of parallel rotary cutting of multiple apertures.

[0069] S3: The array beam emitted from the diffractive optical element 6 or the spatial light modulator 13 enters the 4f imaging system. First, the array beam is subjected to Fourier transform by the first focusing lens 7 with a focal length of F1, and then the array beam is subjected to inverse Fourier transform by the second focusing lens 8 with a focal length of F2. The array beam is scaled according to the F2 / F1 ratio, and the phase information of the target surface of the diffractive optical element 6 or the target surface of the spatial light modulator 13 is accurately imaged.

[0070] In this step, the actual focal distance d on the focal plane f Separation angle θ from diffractive optical element 6 s The relationship is: d f =F2 / F1·F·tan(θ s ) In the formula, F is the focal length of field lens 12.

[0071] This step involves adjusting the overall spacing of the array beams to match processing requirements.

[0072] S4: The scaled array beam is guided by the third reflecting mirror 9 and the fourth reflecting mirror 10, and exits from the light outlet 33. It enters the scanning galvanometer 11 along the center direction of the light inlet of the scanning galvanometer 11, and then the array beam exiting from the scanning galvanometer 11 enters the field mirror 12. Finally, the field mirror 12 focuses the parallel beam exiting from the scanning galvanometer 11 onto the sample surface to form an array of M×N micrometer-scale focal spots. Among them, the diameter of the focused spot The relationship with the field lens focal length F is as follows: , In the formula, Let λ be the beam quality factor of the incident laser, and λ be the wavelength of the incident laser. Where is the diameter of the incident beam, and F is the focal length of field lens 12.

[0073] In this step, the array beam is incident on the scanning galvanometer 11 along the center direction of the light inlet of the scanning galvanometer 11 to achieve rapid positioning of the array beam, supporting large-format processing.

[0074] Furthermore, users can replace the field lens 12 with different focal lengths as needed to flexibly adjust the focused spot diameter. In addition, the output M×N array focal points simultaneously act on the sample surface. Since each focal point rotates at high speed around its own optical axis at an angular velocity of 2ω, each micropore undergoes rotary shearing and scanning processing. The rotational characteristics of each focal point in the array bring the following effects: a. Improved roundness: The ellipticity and optical path astigmatism of the original laser spot are eliminated under the time averaging effect, the focal spot is circularly symmetrical, and the processed micro-holes are close to true circular holes (please refer to...). Figure 5 (a) Schematic diagram of the roundness of the micro-hole array processed by the laser multi-hole rotary cutting scanning head of the present invention; (b) Schematic diagram of the roundness of the micro-hole array processed by conventional DOE beam splitting. b. Suppression of heat accumulation: Rotary cutting scanning makes the energy evenly distributed in the circumferential direction, avoiding heat accumulation caused by continuous pulse irradiation at the same position in punching processing; c. Parallel processing: The processing of M×N micro-holes can be completed in one go, which is M×N times more efficient than single-hole rotary cutting.

[0075] S6: When the processing range exceeds the scanning area of ​​the field lens 12, the sample is moved step by step in conjunction with the external motion platform to move the next processing area into the field lens 12 area, and the scanning galvanometer 11 continues to process, realizing the processing of a large number of holes in an ultra-large area.

[0076] In addition, the present invention can adjust the diameter of the focused spot by changing the field lens 12 with different focal lengths; or adjust the laser power, single pulse energy, repetition frequency; or adjust the rotation speed of the Dowell prism 1; or adjust the number of pulses or the duration of action on the material to adjust the aperture of the processed micro-hole, thereby realizing one-time rotary cutting of array micro-holes from sub-spot diameter to far larger than the spot diameter.

[0077] In summary, the modular, pluggable laser multi-hole rotary cutting scanning head and scanning processing method of the present invention have the following advantages: 1. Parallel processing capability: By setting diffractive optical element 6 or spatial light modulator 13, a single beam of light is split into an M×N array beam at one time, and then combined with the rotation of Daowei prism 1, high-throughput machining of multi-hole rotary drilling is achieved; compared with the traditional multi-axis linkage single-hole rotary cutting system, the laser multi-hole rotary cutting scanning head of the present invention has a simple structure and does not require complex five-axis linkage control, which greatly reduces equipment cost and debugging difficulty.

[0078] 2. Elimination of elliptic aberration: By setting a high-speed rotating motor 2 to drive the Dowell prism 1 to rotate at high speed, the elliptical spots of each focal point are transformed into circularly symmetrical spots under the time averaging effect, eliminating the ellipticity of the laser output spot and beam expansion image astigmatism, and processing micro-holes that are close to true circular holes; at the same time, by utilizing the independent high-speed rotation of each focal point, it is possible to achieve the processing of micro-holes with a diameter close to the spot diameter (roundness > 0.95); by coordinating the adjustment of laser power, pulse number and rotation speed, the processing aperture range can be greatly widened (from sub-spot diameter to far exceeding the spot diameter) while always maintaining the roundness of the micro-holes, and each focal point inherits the same rotation characteristics, so that the roundness and aperture height of all micro-holes in the array are consistent.

[0079] 3. Suppressing heat accumulation: Rotary drilling distributes energy evenly in the circumferential direction, avoiding heat accumulation and thus effectively preventing product melting and carbonization caused by thermal ablation, improving the roundness and quality of the hole wall.

[0080] 4. By setting the diffractive optical element 6 or the spatial light modulator 13 as a pluggable module, the user can flexibly select the appropriate specifications of the diffractive optical element 6 or the spatial light modulator 13 according to the processing needs, and flexibly adjust the target light field distribution by quickly plugging and unplugging the diffractive optical element 6 or the spatial light modulator 13.

[0081] 5. The modular design of the laser borehole rotary cutting scanning head of this invention, coupled with a standardized interface, allows users to obtain borehole rotary cutting capabilities simply by providing a collimated laser beam. Furthermore, users do not need to understand the internal optical principles; they can use it simply by connecting according to the interface specifications. The internal optical path of the module is pre-calibrated at the factory. When changing processing tasks, only the diffraction optical element 6 or the phase diagram of the spatial light modulator 13 needs to be replaced, without the need for complete module disassembly. As an independent product, the laser borehole rotary cutting scanning head of this invention can be used with femtosecond / picosecond lasers to achieve efficient and high-quality rotary cutting scanning processing of massive boreholes.

[0082] Any combination of various embodiments of the present invention, provided it does not violate the inventive concept of the present invention, shall be regarded as the content disclosed by the present invention; within the scope of the technical concept of the present invention, any simple modifications to the technical solution and any combination of different embodiments that do not violate the inventive concept of the present invention shall be within the protection scope of the present invention.

Claims

1. A scanning processing method for a laser multi-aperture rotary cutting scanning head, comprising a modular, pluggable laser multi-aperture rotary cutting scanning head, wherein the laser multi-aperture rotary cutting scanning head includes a Dowell prism, a half-wave plate, a beam shaper, a first focusing mirror, a second focusing mirror, a scanning galvanometer, and a field mirror arranged sequentially along the optical path; the Dowell prism is designed with a 45° angle, and its rotation center coincides with the optical axis of the incident beam, which is used to rotate the beam to achieve rotary cutting scanning; and the Dowell prism is coaxially mounted on a high-speed rotary motor, wherein when the high-speed rotary motor drives the Dowell prism to rotate on its optical axis, the rotation angle of the output image is twice the rotation angle of the Dowell prism; The half-wave plate is used to adjust the polarization direction of the beam so that the beam matches the polarization direction of the beam shaper. The beam shaper is a diffractive optical element or a spatial light modulator used to split a single incident light beam into an array beam. The beam shaper is located on the front focal plane of the first focusing mirror, and its optical axis center coincides with the optical axes of the first focusing mirror and the second focusing mirror. The first focusing lens and the second focusing lens constitute a 4f imaging system, and the rear focal plane of the first focusing lens coincides with the front focal plane of the second focusing lens; The scanning galvanometer is used to achieve high-speed scanning within the field lens area; the field lens is used to focus the light beam emitted from the scanning galvanometer onto the sample surface, and the front focal point of the field lens coincides with the rear focal point of the second focusing lens; Its features are, Includes the following steps: S1: high-speed rotating motor drives the Dove prism to rotate at a preset angular velocity ω around the optical axis, and the light beam is incident along the optical axis direction of the Dove prism. The light field pattern of the outgoing light beam rotates at an angular velocity of 2ω around the optical axis; according to the image rotation characteristics of the Dove prism, when the Dove prism rotates by an angle θ with the optical axis as the axis, the outgoing image rotates by an angle of 2θ around the optical axis; when the incident light beam has a light field distribution of E in (r, θ), the outgoing light beam has a light field distribution of: In the formula, t represents time; S2: The polarization direction of the rotating beam is adjusted by a half-wave plate so that the rotating beam illuminates the target surface of the diffractive optical element or the target surface of the spatial light modulator at a preset angle. When the beam of light shines on the target surface of the diffractive optical element, the single incident beam is split into an M×N array beam by the complex amplitude transmittance function of the diffractive optical element, and each sub-beam inherits the rotation characteristics and rotates at high speed around its own optical axis. When the beam of light shines on the target surface of the spatial light modulator, the phase hologram preloaded on the target surface of the spatial light modulator modulates the single incident beam into an M×N array beam, and each sub-beam inherits the rotation characteristics and rotates at high speed around its own optical axis. Where M≥1, N≥1, and M and N are both integers; S3: The array beam emitted from the diffractive optical element or the spatial light modulator enters the 4f imaging system. First, the first focusing lens with a focal length of F1 performs a Fourier transform on the array beam, and then the second focusing lens with a focal length of F2 performs an inverse Fourier transform on the array beam, scaling the array beam according to the F2 / F1 ratio, while accurately imaging the phase information of the target surface of the diffractive optical element or the target surface of the spatial light modulator. S4: The scaled array beam is incident on the scanning galvanometer along the center of the entrance port of the scanning galvanometer, which enables the array beam to be quickly positioned. Then it enters the field lens and is focused on the sample surface by the field lens to form a micron-scale focal spot array. Among them, the diameter of the focused spot The relationship with the focal length F of the field lens is as follows: where M 2 is the beam quality factor of the incident laser light, λ is the wavelength of the incident laser light, D beam is the diameter of the incident beam.

2. The scanning and processing method of the laser multi-hole rotary cutting scanning head as described in claim 1, characterized in that: The actual focal point spacing d on the focal plane f The relationship between the separation angle Θ of the diffractive optical elements and the focal point spacing d on the focal plane is: s The relationship between the separation angle Θ of the diffractive optical elements and the focal point spacing d on the focal plane is: In the formula, F is the focal length of the field lens.

3. The scanning and processing method of the laser multi-hole rotary cutting scanning head as described in claim 1, characterized in that: The laser multi-aperture rotary cutting scanning head also includes a first mirror and a second mirror arranged along the optical path between the Dove prism and the half-wave plate. The first mirror and the second mirror are used to adjust the beam transmission direction so that the beam is incident on the diffractive optical element or the spatial light modulator in a polarized direction.

4. The scanning processing method of the laser multi-hole rotary cutting scanning head as described in claim 3, characterized in that: The laser multi-aperture rotary cutting scanning head also includes a third and a fourth reflecting mirror arranged along the optical path between the second focusing mirror and the scanning galvanometer. The third and fourth reflecting mirrors are used to adjust the beam transmission direction so that the beam is emitted to the scanning galvanometer.

5. The scanning and processing method of the laser multi-hole rotary cutting scanning head as described in claim 4, characterized in that: The laser multi-aperture rotary scanning head also includes a sealed housing, in which the Dowell prism, the first reflector, the second reflector, the half-wave plate, the first focusing lens, the second focusing lens, the third reflector, and the fourth reflector are all disposed. The sealed housing is provided with a slot, the inner wall of which is configured to allow the laser beam to pass through. The diffractive optical element or the spatial light modulator is pluggably disposed in the slot.

6. The scanning processing method of the laser multi-hole rotary cutting scanning head as described in claim 5, characterized in that: The diffractive optical element or the spatial light modulator is mounted on a mounting bracket that is adjustable in multiple directions and can be plugged into the slot and locked by a locking mechanism.

7. The scanning processing method of the laser multi-hole rotary cutting scanning head as described in claim 5, characterized in that: The sealed housing is provided with a light inlet and a light outlet. The light inlet is used to receive the laser beam and is equipped with a window lens. The window lens is made of anti-reflection quartz glass. The light outlet is used to output a modulated beam that propagates along the center of the optical axis. The scanning galvanometer and the field lens are both located at the light outlet.

8. The scanning processing method of the laser multi-hole rotary cutting scanning head as described in claim 5, characterized in that: The sealed housing is equipped with an air passage interface, a water passage interface, and an electrical control interface; the air passage interface is a standard quick-connect connector for connecting positive pressure clean and dry gas; the water passage interface is a standard inlet and outlet water connector for connecting circulating cooling water to quickly remove the heat generated by the high-speed rotating motor during operation; the electrical control interface is a standard industrial connector that integrates motor drive lines, galvanometer control lines, and encoder feedback lines.

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