CN116626905A - Laser scanning processing system and method - Google Patents
Laser scanning processing system and method Download PDFInfo
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- CN116626905A CN116626905A CN202211004785.0A CN202211004785A CN116626905A CN 116626905 A CN116626905 A CN 116626905A CN 202211004785 A CN202211004785 A CN 202211004785A CN 116626905 A CN116626905 A CN 116626905A
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0927—Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
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- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/0944—Diffractive optical elements, e.g. gratings, holograms
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
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Abstract
The application discloses a processing system based on laser scanning, which comprises: the laser, the beam expander, the shaper, the spatial filter system and the scanning processing system are sequentially arranged along the light path; wherein, the laser emits a Gaussian beam of a fundamental mode; the beam expander expands the Gaussian beam to a preset diameter and then enters the shaper; the shaper carries out phase modulation on the Gaussian beam after beam expansion for a diffraction device so as to shape and obtain a flat-top beam with uniformly distributed energy; the spatial filtering system achieves diffraction limit optical performance, and images, low-pass filters and collimates the light beam after phase modulation so as to remove secondary diffraction peaks of energy distribution of the flat-top light beam; and the scanning processing system scans and focuses the light beams emitted by the space filtering system to obtain light spots without side lobes. The laser scanning system can solve the problems that the existing laser scanning system uses shaping light spots for processing, secondary diffraction peaks appear around the light spots when the light spot size is close to the diffraction limit, side lobes appear in processing, and the processing effect is affected.
Description
Technical Field
The application relates to the technical field of laser precise scanning processing, in particular to a laser scanning processing system and a laser scanning processing method.
Background
Currently, in laser processing technology, a fundamental mode gaussian beam is typically used, and a focusing and scanning system is used to focus the laser beam into a circular gaussian spot. The light spot is characterized in that the light spot is round, the energy distribution center is strong, and the edges are weak. For some occasions with the requirement of precision machining, the laser spot size is required to be small, the spot energy is uniformly distributed, and a common Gaussian spot cannot meet the requirement of machining, so that a shaping device is generally adopted to shape a laser beam into a homogenized beam.
However, in order to ensure good uniformity, it is generally considered that the resulting shaped spot size is not less than 1.5 times the diffraction limit. When the size of the target light spot is close to 1.5 times of the diffraction limit, the diffraction efficiency of the system is limited, secondary diffraction peaks are inevitably generated around the light spot, side lobes are generated around the main light spot during actual processing, and the method is acceptable when the laser processing precision requirement is low, but can have a certain influence on the processing effect when the laser processing precision requirement is high.
Disclosure of Invention
In order to overcome the defects in the prior art, the embodiment of the application provides a laser scanning processing system and a laser scanning processing method, which can solve the problems that secondary diffraction peaks appear around a light spot when the size of a shaping light spot of the existing laser scanning system is close to a diffraction limit, side lobes appear in processing, and the processing effect is affected.
Specifically, the application provides a laser scanning processing system, which comprises: the laser, the beam expander, the shaper, the spatial filter system and the scanning focusing system are sequentially arranged along the light path; wherein, the laser emits a Gaussian beam of a fundamental mode; the beam expander expands the Gaussian beam to a preset diameter and then enters the shaper; the shaper is used as a diffraction device to carry out phase modulation on the Gaussian beam after beam expansion so as to shape and obtain a flat-top beam with uniformly distributed energy; the space filtering system images, low-pass filters and collimates the light beam after phase modulation so as to remove a secondary diffraction peak of energy distribution of the flat-top light spot; the scanning focusing system scans and focuses the light beams emitted by the spatial filtering system to obtain processing light spots without side lobes; wherein, the spatial filter system includes setting gradually: the first Fourier lens performs Fourier transform on the light beam after phase modulation to obtain a flat-top light spot with a side lobe on a focal plane; the precise pinhole performs low-pass filtering on the flat-top beam with the side lobe; a second Fourier lens for performing inverse Fourier transform on the low-pass filtered light beam to obtain a collimated light beam; the back focal plane of the first Fourier lens is coincident with the front focal plane of the second Fourier lens, the precise pinhole is positioned at the coincident focal plane, and the center of the precise pinhole is coincident with the center of the light beam; the first fourier lens uses a beam diameter such that the starry ratio of cohesive spots is > 90%; the wave front distortion of the light beam after being collimated by the second Fourier lens is less than 0.25 lambda.
In one embodiment of the application, the ratio of the focal length of the second fourier lens to the first fourier lens is f2/f1=m, where m >0.
In one embodiment of the application, the first fourier lens and the second fourier lens have the same optical structural parameters, both of which are disposed against the precision pinhole mirror.
In one embodiment of the application, the precision pinhole size range is (1±10%) L, l=2.54 λf 1 Wherein λ is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam after beam expansion, and is the focal length of the first Fourier lens.
In one embodiment of the application, the shape of the precision pinhole is the same as the flat top spot shape.
In one embodiment of the application, the focal length f of the first Fourier lens 1 In the range of 50-500mm.
In addition, an embodiment of the present application provides a laser scanning processing method, including: expanding the fundamental mode Gaussian beam emitted by the laser; the Gaussian beam after beam expansion is incident into a diffraction device shaper for phase modulation so as to shape and obtain a flat-top beam with uniformly distributed energy; imaging, low-pass filtering and collimation are carried out on the light beam after phase modulation through a spatial filtering system so as to remove a secondary diffraction peak of a flat-top light spot; scanning and focusing the light beams emitted by the spatial filtering system to obtain processing light spots without side lobes; wherein the imaging, low-pass filtering and collimating the phase modulated beam to remove the secondary diffraction peak of the energy distribution of the flat-top beam comprises: carrying out Fourier transform on the light beam after phase modulation by a first Fourier lens, and obtaining a flat-top light spot with a side lobe on a focal plane of the light beam; performing low-pass filtering on the flat-top beam with the side lobe by a precision pinhole; and performing inverse Fourier transform on the low-pass filtered light beam by a second Fourier lens to obtain a collimated light beam; the back focal plane of the first Fourier lens is coincident with the front focal plane of the second Fourier lens, the precise pinhole is positioned at the coincident focal plane, and the center of the precise pinhole is coincident with the center of the flat-top light spot; the first fourier lens uses a beam diameter such that the stark ratio of the focused beam is > 90%; the wave front distortion of the light beam after being collimated by the second Fourier lens is less than 0.25 lambda.
In one embodiment of the present application, the low-pass filtering the flat-top beam with side lobes by the precision pinhole includes: the precise pinhole size range is set to be (1+/-10%) L, l=2.54 λf 1 and/D for low-pass filtering the Gaussian beam, wherein λ is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam after beam expansion, and is the focal length of the first Fourier lens.
In one embodiment of the application, the ratio of the focal length of the second Fourier lens to the first Fourier lens is f 2 /f 1 =m, where m>0。
In one embodiment of the application, the shape of the precision pinhole is the same as the flat top spot shape.
From the foregoing, it will be appreciated that the above-described embodiments of the application may have one or more of the following advantages:
(1) The method comprises the steps of carrying out phase modulation on a Gaussian beam through a shaper to obtain a flat-top beam with uniformly distributed energy, setting a spatial filtering system meeting diffraction limit performance of the Gaussian beam, and carrying out low-pass filtering on the shaped beam to remove secondary diffraction peaks of the energy distribution of the flat-top beam, so that a light spot without side lobes can be obtained, and the precision machining quality of materials is improved;
(2) The spatial filtering system performs Fourier transform on the incident light beam through the first Fourier lens, an image with a secondary diffraction peak is obtained at the focal plane, the image at the focal plane of the precise pinhole is subjected to low-pass filtering, the high-frequency component corresponding to the secondary diffraction peak is filtered, only the central uniform light beam passes through, and the second Fourier lens performs inverse Fourier transform on the uniform light beam from the image plane to output a collimated light beam;
(3) The precision pinhole size range is according to the formula l=2.54 λf 1 a/D determination, wherein λ is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam for the focal length of the first Fourier lens, and when the size range of the Gaussian beam meets (1+/-10%) L, high-frequency side lobes can be removed, and the energy distribution of the shaping light spot of the low-frequency part is not influenced.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
fig. 1 is a schematic structural diagram of a laser scanning processing system according to an embodiment of the present application;
FIG. 2 is a schematic diagram of an energy distribution of a fundamental Gaussian beam according to an embodiment of the application;
fig. 3 is a schematic diagram of energy distribution of a shaped light spot according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of a spatial filtering system according to an embodiment of the present application;
FIG. 5 is a schematic diagram of the filtered spot energy distribution according to an embodiment of the present application;
fig. 6 is a flowchart of a laser scanning processing method according to an embodiment of the present application.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described below with reference to the accompanying drawings in combination with embodiments.
In order to enable those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments of the embodiments are all within the protection scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and claims of the present application and in the above figures are applicable to distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, it is possible to provide a device for the treatment of a disease. The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be further noted that the division of the embodiments in the present application is only for convenience of description, and should not be construed as a specific limitation, and features in the various embodiments may be combined and mutually referenced without contradiction.
The embodiment of the application provides a laser scanning processing system and a laser scanning processing method, which aim to solve the problems that secondary diffraction peaks appear around a light spot when the size of a shaping light spot of the existing laser scanning system is close to a diffraction limit, side lobes appear in processing, and the processing effect is affected.
As shown in fig. 1, a first embodiment of the present application proposes a laser scanning processing system, for example, including: the laser, the beam expander, the shaper, the spatial filter system and the scanning focusing system are sequentially arranged along the light path.
The energy distribution of the fundamental mode Gaussian beam emitted by the laser is shown in fig. 2. And expanding the Gaussian beam to a preset diameter by a beam expander and incidence the Gaussian beam to the shaper. The beam-expanded Gaussian beam is subjected to phase modulation by using a shaper as a diffraction device so as to shape the Gaussian beam to obtain a flat-top beam with uniformly distributed energy, wherein the energy distribution is shown in figure 3. And carrying out low-pass filtering on the shaped flat-top beam by a spatial filtering system meeting diffraction limit optical performance so as to remove secondary diffraction peaks of energy distribution of the flat-top beam. The scanning focusing system comprises a galvanometer and a field lens and is used for scanning and focusing the light beams emitted by the spatial filtering system to obtain processing light spots without side lobes.
Further, as shown in fig. 4, the spatial filtering system is located between the shaper as the diffraction device and the scanning focusing system composed of the galvanometer and the field lens, and includes, for example: a first fourier lens, a precision pinhole, and a second fourier lens. The focal planes of the first Fourier lens and the second Fourier lens are coincident, a precise pinhole is placed at the focal plane, the center of the pinhole is coincident with the center of the light beam, and the shape and the direction of the pinhole are identical with those of the Gaussian light beam.
And, the optical properties of the first and second fourier lenses satisfy the diffraction limited optical properties to ensure that an undistorted image is obtained at the focal plane. The diffraction limited optical properties were satisfied: the first fourier lens uses a beam diameter such that the stark ratio of the focused beam is > 90%; the wave front distortion of the light beam collimated by the second Fourier lens is less than 0.25 lambda. It may use a plano-convex lens, a biconvex lens, an aspherical lens, a lens group, or the like. As a non-limiting example, in the present application, an aspherical surface or a combination of positive and negative lenses is employed. Preferably, the first and second fourier lenses, for example, employ an aspherical lens or lens group, which more readily achieves diffraction limited optical performance for aberration-free imaging and collimation.
Further, the ratio of the focal length of the second Fourier lens to the first Fourier lens is f 2 /f 1 =m, where m>0. As a preferred embodimentThe first fourier lens and the second fourier lens have, for example, the same optical structural parameters, both being placed against a precision pinhole mirror, wherein the back focal plane of the first fourier lens coincides with the front focal plane of the second fourier lens.
Specifically, the working principle of the spatial filtering system is as follows:
the incident light beam modulated by the diffraction device is fourier-transformed by the first fourier lens, and an image with a secondary diffraction peak as shown in fig. 3 is obtained at the focal plane.
The image at the focusing plane of the precise pinhole is subjected to low-pass filtering, and the high-frequency component corresponding to the secondary diffraction peak is filtered, so that only the central uniform light beam passes through.
The second fourier lens performs inverse fourier transform on the homogenized beam from the image plane, outputs a collimated beam, and enters a scanning focusing system to obtain an energy distribution without secondary diffraction peaks as shown in fig. 5 for processing.
In addition, preferably, a scanning focusing system is formed by a galvanometer and a field lens, and a processing light spot with uniform size and uniform energy distribution can be obtained in a specific range by matching the optical system.
In one embodiment, the focal length range between the first fourier lens and the precision pinhole is, for example, 50-500mm, and more preferably, 100-300mm, and the total length of the spatial filtering system is the sum of the focal lengths of the two fourier lenses, so that the system structure is prevented from being increased due to overlarge focal length, the focal length is prevented from being too small, the imaging quality is ensured, and the processing precision of the precision pinhole is matched.
In one embodiment, the shape of the precision pinhole is the same as the shape of the shaped spot. It should be noted that the shape of the shaping light spot and the corresponding precise pinhole may be circular, square, etc., and the present application is not limited thereto.
In one embodiment, the precision pinhole size range is determined, for example, according to the formula l=2.54 λf/D, where λ is the wavelength of the gaussian beam, f is the focal length of the first fourier lens, and D is the diameter of the gaussian beam. Specifically, the size range of the precise pinhole is (1+/-10%) L, so that high-frequency side lobes can be removed, and the energy distribution of the shaping light spots of the low-frequency part is not influenced, thereby ensuring a good filtering effect.
In a specific embodiment, for example, a gaussian beam with a wavelength of 355nm and a beam diameter of 4mm is shaped by a DOE device, and a square light spot with a square shape of 45 μm and no side lobes is obtained on a 160×160 format by using a biaxial scanning galvanometer and a field lens with a focal length of 255 mm. The diffraction limit of the system is 27.6 μm, the target spot size is 1.63 times of the diffraction limit of the system, and it is expected that the side lobe of the spot will affect the processing effect as shown in fig. 3 by the directly obtained energy distribution of the shaped spot.
In the above, for example, a set of spatial filter systems is used, the focal length of the first fourier lens is 100mm, and the focal length of the second fourier lens is 100mm; the image of the first fourier lens on the focal plane, the width of the main peak being 17.6 μm, the shape of the pinhole being square, the side length being 20±1 μm, the secondary diffraction peaks on both sides of the main peak being filtered out, so that a 45 μm sidelobe-free spot as shown in fig. 4 is obtained on the focal plane of the field lens.
In summary, in the laser scanning processing system provided by the embodiment of the application, the shaper is used for carrying out phase modulation on the gaussian beam to obtain a flat-top beam with uniformly distributed energy, a spatial filtering system meeting the diffraction limit performance of the gaussian beam is arranged, and low-pass filtering is carried out on the shaped beam to remove the secondary diffraction peak of the energy distribution of the flat-top beam, so that the beam without side lobes can be obtained, and the precision processing quality of the material is improved; the spatial filtering system performs Fourier transform on the incident flat-top beam through the first Fourier lens, an image with a secondary diffraction peak is obtained at the focal plane, the image at the focal plane of the precise pinhole is subjected to low-pass filtering, the high-frequency component corresponding to the secondary diffraction peak is filtered, only the central uniform beam passes through, and the second Fourier lens performs inverse Fourier transform on the uniform beam from the image plane to output a collimated beam; the precision pinhole size range is determined according to the formula l=2.54 λf/D, where λ is the wavelength of the gaussian beam, f 1 And D is the diameter of the Gaussian beam for the focal length of the first Fourier lens, and when the size range satisfies (1+/-5%) M or (1+/-10%) L, high-frequency side lobes can be removed, and the energy distribution of the shaping light spot of the low-frequency part is not influenced.
As shown in fig. 4, the second embodiment of the present application further proposes a laser scanning processing method, for example, including steps S1 to S4. Step S1, expanding a fundamental mode Gaussian beam emitted by a laser; s2, the Gaussian beam after beam expansion is incident into a shaper serving as a diffraction device to be subjected to phase modulation, so that a flat-top beam with uniformly distributed energy is obtained through shaping; s3, imaging, low-pass filtering and collimation are carried out on the light beam after phase modulation through a spatial filtering system reaching diffraction limit optical performance so as to remove a secondary diffraction peak of the flat-top light beam; and S4, scanning and focusing the light beams emitted by the spatial filtering system to obtain light spots without side lobes.
Further, the imaging, low-pass filtering and collimating the phase modulated beam to remove the secondary diffraction peak of the energy distribution of the flat-top beam includes: carrying out Fourier transform on the light beam after phase modulation by a first Fourier lens, and obtaining a flat-top light spot with a side lobe on a focal plane of the light beam; the precision pinhole carries out low-pass filtering on the flat-top light spot with the side lobe; and performing inverse Fourier transform on the low-pass filtered light beam by a second Fourier lens to obtain a collimated light beam.
The back focal plane of the first Fourier lens is coincident with the front focal plane of the second Fourier lens, the precise pinhole is located at the coincident focal plane, and the center of the precise pinhole is coincident with the center of the flat-top light spot.
The first fourier lens uses a beam diameter such that the stark ratio of the focused beam is > 90%; the wave front distortion of the light beam after being collimated by the second Fourier lens is less than 0.25 lambda.
In one embodiment, the low pass filtering of the flat-top beam with side lobes by the precision pinhole includes, for example: the precision pinhole size range was set to (1±10%) L, l=2.54 λf/D to low-pass filter the Gaussian beam, where λ is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam after beam expansion, and is the focal length of the first Fourier lens.
In one embodiment, the ratio of the focal length of the second Fourier lens to the first Fourier lens is f 2 /f 1 =m, where m>0。
In one embodiment, the precision pinhole has the same shape as the flat top spot.
It should be noted that, the second embodiment of the present application provides a laser scanning processing method, which is suitable for the laser scanning processing system provided in the foregoing first embodiment, and the structure and function of the specific laser scanning processing system may refer to the system described in the first embodiment, so that details are omitted herein for brevity, and the beneficial effects of the laser scanning processing method provided in the present embodiment are the same as those of the laser scanning processing system provided in the first embodiment.
In addition, it should be understood that the foregoing embodiments are merely exemplary illustrations of the present application, and the technical solutions of the embodiments may be arbitrarily combined and matched without conflict in technical features, contradiction in structure, and departure from the purpose of the present application.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. A laser scanning processing system, comprising: the laser, the beam expander, the shaper, the spatial filter system and the scanning focusing system are sequentially arranged along the light path;
wherein, the laser emits a Gaussian beam of a fundamental mode;
the beam expander expands the Gaussian beam to a preset diameter and then enters the shaper;
the shaper is a diffraction device and carries out phase modulation on the Gaussian beam after beam expansion so as to shape and obtain a flat-top beam with uniformly distributed energy;
the spatial filtering system images, low-pass filters and collimates the flat-top beam after phase modulation to remove secondary diffraction peaks of energy distribution of flat-top light spots;
the scanning focusing system scans and focuses the light beams emitted by the spatial filtering system to obtain processing light spots without side lobes;
wherein, the spatial filter system includes along the light path setting gradually:
the first Fourier lens performs Fourier transform on the light beam after phase modulation to obtain a flat-top light spot with a side lobe on a focal plane;
the precise pinhole performs low-pass filtering on the flat-top beam with the side lobe;
a second Fourier lens for performing inverse Fourier transform on the low-pass filtered light beam to obtain a collimated light beam;
wherein the back focal plane of the first fourier lens coincides with the front focal plane of the second fourier lens, the precision pinhole is located at the coincident focal plane, and the center of the precision pinhole coincides with the center of the light beam;
the first fourier lens uses a beam diameter such that the starry ratio of cohesive spots is > 90%; the wave front distortion of the light beam after being collimated by the second Fourier lens is less than 0.25 lambda.
2. The laser scanning processing system of claim 1, wherein a ratio of a focal length of the second fourier lens to a focal length of the first fourier lens is f 2 /f 1 =m, where m>0。
3. The laser scanning processing system of claim 2, wherein the first fourier lens and the second fourier lens have the same optical configuration parameters and are disposed opposite the precision pinhole mirror.
4. The laser scanning processing system of claim 1, wherein the precision pinhole size range is (1±10%) L, L = 2.54 λf 1 Wherein λ is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam after beam expansion, and is the focal length of the first Fourier lens.
5. The laser scanning processing system of claim 1, wherein the precision pinhole has the same shape as the flat top spot.
6. The laser scanning processing system of claim 1, wherein the focal length f of the first fourier lens 1 In the range of 50-500mm.
7. A laser scanning processing method, comprising:
expanding the fundamental mode Gaussian beam emitted by the laser;
the base mode Gaussian beam after beam expansion is incident to a diffraction device shaper for phase modulation so as to shape and obtain a flat-top beam with uniformly distributed energy;
imaging, low-pass filtering and collimating the flat-top beam after phase modulation through a spatial filtering system to remove a secondary diffraction peak of a flat-top light spot;
scanning and focusing the light beams emitted by the spatial filtering system to obtain processing light spots without side lobes;
the imaging, low-pass filtering and collimating the flat-top beam after phase modulation to remove the secondary diffraction peak of the energy distribution of the flat-top beam comprises the following steps:
performing Fourier transform on the flat-top beam subjected to phase modulation by a first Fourier lens, and obtaining flat-top light spots with side lobes on a focal plane of the flat-top beam;
performing low-pass filtering on the flat-top beam with the side lobe by a precision pinhole; and
performing inverse Fourier transform on the low-pass filtered light beam by a second Fourier lens to obtain a collimated light beam;
the back focal plane of the first Fourier lens is coincident with the front focal plane of the second Fourier lens, the precise pinhole is positioned at the coincident focal plane, and the center of the precise pinhole is coincident with the center of the flat-top light spot;
the first fourier lens uses a beam diameter such that the stark ratio of the focused beam is > 90%; the wave front distortion of the light beam after being collimated by the second Fourier lens is less than 0.25 lambda.
8. The laser scanning processing method according to claim 7, wherein the low-pass filtering of the flat-top beam with side lobes by the precision pinhole comprises:
the precise pinhole size range is set to be (1+/-10%) L, l=2.54 λf 1 and/D, performing low-pass filtering on the flat-top beam with side lobes, wherein lambda is the wavelength of the Gaussian beam, f 1 And D is the diameter of the Gaussian beam after beam expansion, and is the focal length of the first Fourier lens.
9. The laser scanning processing method according to claim 7, wherein a ratio of a focal length of the second fourier lens to a focal length of the first fourier lens is f 2 /f 1 =m, where m>0。
10. The laser scanning processing method of claim 7, wherein the shape of the precision pinhole is the same as the shape of the flat-top spot.
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| CN202211004785.0A CN116626905A (en) | 2022-08-22 | 2022-08-22 | Laser scanning processing system and method |
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