A high-throughput multi-slot two-photon laser direct writing system and method

Abstract

This invention discloses a high-throughput multi-slot two-photon laser direct writing system and method. The system utilizes a beam-expanding and homogenizing module to expand the femtosecond laser beam while simultaneously shaping the laser intensity from a Gaussian distribution to a flat-top beam. These two aspects ensure that the multiple generation modules produce a sufficient number of uniformly intense sub-slots. Furthermore, this invention uses a beam-combining module to combine multiple sub-slots according to a predetermined arrangement to form a multi-slot. Thus, under the action of the laser direct writing module, extremely high-throughput large-area three-dimensional micro / nano fabrication can be achieved. This system enables extremely high-throughput large-area three-dimensional micro / nano fabrication.

Description

Technical Field

[0001] This invention belongs to the field of laser direct writing technology, specifically relating to a high-throughput multi-slot two-photon laser direct writing system and method. Background Technology

[0002] Currently, the fabrication of large-area complex micro / nano structures has broad practical application prospects at both the national strategic level and industrial demand level, such as biomimetic drag reduction for aircraft, large-size flexible touch screens, and space thin-film lenses. However, its fabrication faces many challenges, such as how to achieve efficient photolithography processing of micro / nano-scale feature structures at millimeter-scale or larger dimensions, and how to flexibly fabricate and arrange various microstructures without frequently changing masks and other devices.

[0003] Traditional projection lithography is difficult to manufacture complex three-dimensional micro and nanostructures. It requires the design and fabrication of a corresponding mask before each fabrication, which is expensive and inefficient. Although electron / ion beam lithography has high lithographic resolution, it is limited by its low writing speed and cannot efficiently manufacture large-area micro and nanostructures. Laser direct writing has the advantages of low cost, high degree of freedom in writing, and low requirements for working environment, but it is still difficult to efficiently manufacture large-area micro and nanostructures due to its single-point writing limitation.

[0004] Patent application CN112596349A discloses a two-photon parallel direct-writing device and method based on multi-point array generation and independent control. This patent application utilizes a microlens array (MLA) to generate a spot array, and modulates the amplitude and wavefront of each spot using a digital lens modulator (DMD) and a spatial light modulator (SLM) to control the intensity and position of each spot on the objective lens focal plane. This enables high-throughput, super-resolution, parallel, and flexible processing of highly uniform arbitrary curved surface structures and true three-dimensional microstructures. However, limited by the pixel size of the SLM itself, its control precision is limited, making precise spot scanning difficult for a large number of laser points. Furthermore, the SLM's refresh rate is slow, hindering rapid scanning. In addition, this system is essentially still a step-step lithography system, capable of writing only a single field of view at a time, resulting in insufficient efficiency for large-area writing.

[0005] Patent application CN118778380A discloses a two-photon high-throughput direct writing device and method based on controllable multi-dot grayscale writing. This method can adjust the writing strategy of the device according to actual grayscale writing requirements, and the stage only needs to maintain a uniform scanning speed during the writing exposure process, saving the time of repeated acceleration and deceleration of the platform. It also fully utilizes the entrance pupil energy of the femtosecond laser spot, giving this method the advantages of both high throughput and large area writing, as well as 2.5D high-precision grayscale writing. However, this system uses only one DMD, limiting the number of parallel focal points and making it difficult to further increase the throughput. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art. This invention proposes a high-throughput multi-slot two-photon laser direct writing system, which can realize extremely high-throughput large-area three-dimensional micro-nano processing.

[0007] A specific embodiment of the present invention provides a high-throughput multi-slot two-photon laser direct writing system, which, according to the direction of light propagation, is sequentially arranged a femtosecond laser, a beam expanding and homogenizing module, a beam splitting module, a multi-slot generation module, a beam combining module, and a laser direct writing module; The femtosecond laser is used to generate femtosecond lasers; The beam expanding and homogenizing module is used to expand the femtosecond laser beam and to distribute the laser intensity of the femtosecond laser in a flat-top distribution. The beam splitting module is used to split the femtosecond laser beam into multiple sub-beams of equal intensity; The multi-point array generation module is used to convert each sub-beam into a corresponding sub-multi-point array; The beam combining module is used to combine multiple sub-multi-point arrays into a multi-point array according to a set arrangement. The laser direct writing module is used to converge multiple points onto the displacement stage to realize a high-throughput multi-point array two-photon laser direct writing system.

[0008] Preferably, the multi-point array generation module includes multiple sub-multi-point array generation modules, each sub-multi-point array generation module being used to receive a corresponding sub-beam and convert the sub-beam into a corresponding sub-multi-point array.

[0009] More preferably, the sub-multi-point array generation module is arranged in sequence according to the direction of light propagation, consisting of a digital micromirror array, a 4F imaging lens group, a microlens array, and an image rotator; The digital micromirror array is used to modulate the amplitude of the sub-beam to obtain multiple unit spots; The 4F imaging lens group is used to image multiple unit light spots onto the microlens array; The microlens array is used to focus the multiple unit light spots to obtain multiple focal point arrays; The image rotator is used to adjust the rotation angle of multiple focal arrays to obtain a sub-multi-point array.

[0010] More preferably, the digital micromirror array comprises m×n micromirror array units, and the sub-beam passes through the m×n micromirror array units to obtain m×n unit light spots.

[0011] More preferably, each micromirror array unit includes k×k micromirrors. By independently switching the k×k micromirrors on and off, the intensity and uniformity of the light spot in each unit can be independently controlled.

[0012] More preferably, the microlens array includes m×n microlenses for focusing the incident m×n unit light spots to generate an m×n focal array.

[0013] Preferably, the beam combining module is a polarizing beam splitter (PBS), which is used to combine sub-multi-point arrays with different polarization directions and arrange them sequentially and synchronously out of the array along a set direction.

[0014] Preferably, the laser direct writing module is arranged in sequence with a tube lens module, an image rotation module, and a photolithography objective lens according to the direction of light propagation; The tube-scope module is used to perform wavefront modulation on the multi-point array, so that the beams of the multi-point array can all enter the entrance pupil of the lithography objective. The image rotation module is used to adjust the rotation angle of the entire multi-point array, thereby meeting the requirements of the writing strategy.

[0015] More preferably, the field of view (FOV) and entrance pupil diameter (D) of the photolithography objective are: FOV≥N×L D = NA × f × 2 Where N is the number of sub-multi-point arrays, L is the diagonal length of the sub-multi-point arrays, NA is the numerical aperture of the multiple sub-multi-point arrays generated by the multi-point array generation module, and f is the equivalent optical focal length of the tube-scope module.

[0016] On the other hand, the present invention also provides a high-throughput multi-slot two-photon laser direct writing method, which uses the aforementioned high-throughput multi-slot two-photon laser direct writing system for direct writing, including: The femtosecond laser generated by the femtosecond laser is expanded by a beam expanding and homogenizing module, and the laser intensity of the femtosecond laser is distributed in a flat-top shape. The expanded, flat-top distributed femtosecond laser beam is split into multiple sub-beams of equal intensity using a beam-splitting module. Multiple sub-beams are generated by a multi-point matrix generation module to obtain corresponding multiple sub-multi-point matrices; Multiple sub-multi-point arrays are combined into a multi-point array by a beam-combining module according to a set arrangement. High-throughput multi-segment two-photon laser direct writing is achieved by focusing multiple points onto a displacement stage using a laser direct writing module.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a beam-expanding and homogenizing module to expand the femtosecond laser beam while simultaneously shaping the laser intensity from a Gaussian distribution to a flat-top beam. These two aspects ensure that the multi-point generation module produces a sufficient number of sub-multi-point arrays with uniform intensity. Furthermore, this invention uses a beam-combining module to combine multiple sub-multi-point arrays according to a set arrangement to form a multi-point array. Thus, under the action of the laser direct writing module, it is possible to achieve extremely high throughput large-area three-dimensional micro-nano processing. Attached Figure Description

[0018] Figure 1 A schematic diagram of a high-throughput multi-slot two-photon laser direct writing system provided for a specific embodiment of the present invention; Figure 2 A schematic diagram of a sub-multi-point matrix generation module provided in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the optical path of the beam combining module provided in a specific embodiment of the present invention; Figure 4 This is a schematic diagram of a sub-multi-point array arrangement provided in a specific embodiment of the present invention; Figure 5 An example diagram of a multi-dot scanning and writing method provided in a specific embodiment of the present invention. Detailed Implementation

[0019] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, a specific embodiment of the present invention provides a high-throughput multi-slot two-photon laser direct writing system. According to the direction of light propagation, a femtosecond laser 1, a beam expanding and homogenizing module 2, a beam splitting module 3, a multi-slot generation module 4, a beam combining module 5, a laser direct writing module, and a displacement stage 9 are arranged in sequence. The laser direct writing module includes a tube lens module 6, an image rotation module 7, and a lithography objective lens 8.

[0021] The femtosecond laser 1 provided in the specific embodiment of the present invention can generate femtosecond lasers of a specific wavelength. After passing through the beam expansion and homogenization module 2, the laser diameter is expanded to a suitable size for the subsequent multi-point array generation module 4 to generate multiple sub-point arrays. At the same time, the laser intensity is transformed from a Gaussian distribution to a flat-top distribution, and the wavefront at each point of the laser cross section remains perpendicular to the principal optical axis.

[0022] In a specific embodiment of the present invention, to ensure the femtosecond pulse width characteristics of the femtosecond laser and minimize pulse width broadening, the beam expanding and homogenizing module 2 needs to ensure that the total optical path of the light at any point on the laser cross-section remains consistent or nearly horizontal after passing through the beam expanding and homogenizing module 2; that is, the wavefront at all points on the laser cross-section remains perpendicular to the principal optical axis. The laser is collimated both before and after entering the beam expanding and homogenizing module 2.

[0023] The beam-splitting module 3 provided in this specific embodiment of the invention splits the expanded femtosecond laser beam into N sub-beams of equal intensity (N≥2), with each sub-beam corresponding to a multi-point array generation sub-module. The beam-splitting module 3 divides the laser into N beams of equal intensity according to design requirements, wherein the direction and position of each sub-beam can be freely adjusted to match each multi-point array generation sub-module.

[0024] The multi-point array generation module 4 provided in the specific embodiment of the present invention includes N sub-multi-point array generation modules. Each sub-multi-point array generation module provided in the specific embodiment of the present invention has the same optical path structure, which is to convert the sub-beams they input into sub-multi-point arrays, and then enter the beam combining module 5 together. The beam combining module 5 arranges all the sub-multi-point arrays into a larger multi-point array in a certain arrangement.

[0025] In one specific embodiment, such as Figure 2 As shown, the multi-point array generation module provided in this embodiment is arranged sequentially according to the light propagation direction, consisting of a digital micromirror array (DMD) 401, a 4F imaging lens group 402, a microlens array 403, and an image rotator 404. The DMD 401 modulates the amplitude of the incident light, which is then imaged proportionally onto the front focal plane of the microlens array 403 by the 4F imaging lens group. After modulation by the microlens array 403, the laser light converges into a focal array, and then the image rotator 404 adjusts the rotation angle of the array, thereby obtaining a sub-multi-point array at an arbitrary angle.

[0026] Specifically, the digital micromirror array (DMD401) provided in this embodiment divides the effective pixel area into m×n micromirror array units. Each micromirror array unit corresponds to a unit light spot. Each micromirror array unit includes k×k micromirrors. The k×k micromirrors in each micromirror array unit of the digital micromirror array (DMD401) are independently switched between "on" and "off" states, thereby independently controlling the intensity and uniformity of each unit light spot.

[0027] Specifically, the microlens array 403 provided in the specific embodiment of the present invention includes m×n microlenses for focusing m×n incident unit light spots. One unit light spot corresponds to one microlens, and a maximum of m×n focal arrays can be generated on the focal plane of the microlens array 403.

[0028] Specifically, the beam combining module 5 provided in this embodiment combines the sub-multi-point arrays of each sub-multi-point array generation module. Each sub-multi-point array is an m×n focal array. The number N of the sub-multi-point arrays and their relative positions determine the system's direct writing strategy.

[0029] In one specific embodiment, when the number of sub-multi-point arrays is 4, such as Figure 3 As shown, in this embodiment, the beam combining module 5 consists of a polarizing beam splitter PBS 501. Sub-multi-point arrays 1 and 3 are in the same polarization direction and are incident on the PBS at a certain distance apart. Sub-multi-point arrays 2 and 4 are in perpendicular polarization directions and are also incident on the PBS at a certain distance apart. The sub-multi-point arrays are combined by the PBS and emitted synchronously, arranged sequentially along the long side, with adjacent sub-multi-point arrays closely arranged. The arrangement on the objective lens focal plane is as follows: Figure 4 As shown.

[0030] It should be noted that the number N of sub-multiple arrays in this embodiment is not limited to 4. When N is more than 4, the sub-multiple arrays can continue to be arranged along the PBS direction to complete the bundle.

[0031] The endoscope module 6 provided in this specific embodiment modulates the wavefront of the multi-point array, ensuring that all multi-point array beams enter the entrance pupil of the lithography objective lens 8 precisely. The image rotation module 7 provided in this specific embodiment can adjust the overall rotation direction of the multi-point array to meet the requirements of various writing strategies. After passing through the lithography objective lens 8, the multi-point array converges on the displacement stage 9, achieving high-throughput multi-point array two-photon laser direct writing.

[0032] The field of view of the lithography objective 8 provided in this embodiment is determined by the number N of sub-multi-dot arrays, the multi-dot array generation module 4, and the arrangement of the sub-multi-dot arrays. In this embodiment, the size of the sub-multi-dot arrays in the multi-dot array generation module 4 is determined by the size of the digital micromirror array 401 and the microlens array 403. The N sub-multi-dot arrays after a specific arrangement need to be within the field of view of the lithography objective 8.

[0033] The field of view (FOV) of the lithography objective 8 provided in this embodiment is ≥ N×L. Where N is the number of sub-arrays and L is the diagonal length of the sub-arrays.

[0034] The entrance pupil size of the lithography objective 8 provided in this embodiment is jointly determined by the multi-dot array generation module 4 and the tube mirror module 6, and the formula is: D=NA×f×2, where NA is the numerical aperture of the sub-multi-dot array generated by the multi-dot array generation module 4, f is the equivalent optical focal length of the tube mirror module 6, and D is the entrance pupil diameter of the lithography objective 8.

[0035] On the other hand, specific embodiments of the present invention also provide a large-area, high-throughput two-photon direct writing method. This method uses an image rotation module 7 to control the overall rotation angle of the laser multi-point array, thereby controlling the lateral distribution of the scribing lines during uniform scanning of the large-area, high-precision displacement stage 9, achieving pixel-dense two-photon writing. Figure 5 As shown.

[0036] The high-throughput multi-slot two-photon laser direct writing method provided in this specific embodiment of the invention uses the high-throughput multi-slot two-photon laser direct writing system as described above for direct writing, including: The femtosecond laser generated by the femtosecond laser is expanded by a beam expanding and homogenizing module, and the laser intensity of the femtosecond laser is distributed in a flat-top manner.

[0037] The expanded, flat-top femtosecond laser beam is split into multiple sub-beams of equal intensity using a beam-splitting module.

[0038] Multiple sub-beams are generated by a multi-point matrix generation module to obtain corresponding multiple sub-multi-point matrices.

[0039] Multiple sub-multi-point arrays are combined into a multi-point array by a beam-combining module according to a set arrangement.

[0040] High-throughput multi-segment two-photon laser direct writing is achieved by focusing multiple points onto a displacement stage using a laser direct writing module.

Claims

1. A high-throughput multi-spot array two-photon laser direct writing system, characterized in that, According to the direction of light propagation, the femtosecond laser, beam expansion and homogenization module, beam splitting module, multi-point array generation module, beam combining module and laser direct writing module are set up in sequence. The femtosecond laser is used to generate femtosecond lasers; The beam expanding and homogenizing module is used to expand the femtosecond laser beam and to distribute the laser intensity of the femtosecond laser in a flat-top distribution. The beam splitting module is used to split the femtosecond laser beam into multiple sub-beams of equal intensity; The multi-point array generation module is used to convert each sub-beam into a corresponding sub-multi-point array; The beam combining module is used to combine multiple sub-multi-point arrays into a multi-point array according to a set arrangement. The laser direct writing module is used to converge multiple points onto the displacement stage to realize a high-throughput multi-point array two-photon laser direct writing system.

2. The high-throughput multi-slot two-photon laser direct writing system according to claim 1, characterized in that, The multi-point array generation module includes multiple sub-multi-point array generation modules. Each sub-multi-point array generation module is used to receive the corresponding sub-beam and convert the sub-beam into the corresponding sub-multi-point array.

3. The high-throughput multipoint-array two-photon laser direct writing system according to claim 2, wherein, The sub-multi-point array generation module is arranged in sequence according to the direction of light propagation: digital micromirror array, 4F imaging lens group, microlens array and image rotator; The digital micromirror array is used to modulate the amplitude of the sub-beam to obtain multiple unit spots; The 4F imaging lens group is used to image multiple unit light spots onto the microlens array; The microlens array is used to focus the multiple unit light spots to obtain multiple focal point arrays; The image rotator is used to adjust the rotation angle of multiple focal arrays to obtain a sub-multi-point array.

4. The high-throughput multipoint-array two-photon laser direct writing system according to claim 3, wherein, The digital micromirror array comprises m×n micromirror array units, and the sub-beam passes through the m×n micromirror array units to obtain m×n unit light spots.

5. The high-throughput multi-slot two-photon laser direct writing system according to claim 4, characterized in that, Each micromirror array unit includes k×k micromirrors. By independently switching the k×k micromirrors on and off, the intensity and uniformity of the light spot in each unit can be independently controlled.

6. The high-throughput multipoint-array two-photon laser direct writing system according to claim 4, wherein, The microlens array includes m×n microlenses, which are used to focus the incident m×n unit light spots to generate an m×n focal array.

7. The high-throughput multipoint-array two-photon laser direct writing system according to claim 1, wherein, The beam combining module is a polarizing beam splitter (PBS), which is used to combine sub-multi-point arrays with different polarization directions and arrange them sequentially and emit them synchronously along a set direction.

8. The high-throughput multipoint-array two-photon laser direct writing system according to claim 1, wherein, The laser direct writing module is arranged in sequence with a tube lens module, an image rotation module, and a photolithography objective lens according to the direction of light propagation; The tube-scope module is used to perform wavefront modulation on the multi-point array, so that the beams of the multi-point array can all enter the entrance pupil of the lithography objective. The image rotation module is used to adjust the rotation angle of the entire multi-point array, thereby meeting the requirements of the writing strategy.

9. The high-throughput multi-slot two-photon laser direct writing system according to claim 8, characterized in that, The field of view (FOV) and entrance pupil diameter (D) of the photolithography objective are: FOV≥N×L D = NA × f × 2 Where N is the number of sub-multi-point arrays, L is the diagonal length of the sub-multi-point arrays, NA is the numerical aperture of the multiple sub-multi-point arrays generated by the multi-point array generation module, and f is the equivalent optical focal length of the tube-scope module.

10. A high-throughput multipoint array two-photon laser direct writing method, characterized by, Direct writing is performed using the high-throughput multi-slot two-photon laser direct writing system as described in any one of claims 1-9, including: The femtosecond laser generated by the femtosecond laser is expanded by a beam expanding and homogenizing module, and the laser intensity of the femtosecond laser is distributed in a flat-top shape. The expanded, flat-top distributed femtosecond laser beam is split into multiple sub-beams of equal intensity using a beam-splitting module. Multiple sub-beams are generated by a multi-point matrix generation module to obtain corresponding multiple sub-multi-point matrices; Multiple sub-multi-point arrays are combined into a multi-point array by a beam-combining module according to a set arrangement. High-throughput multi-segment two-photon laser direct writing is achieved by focusing multiple points onto a displacement stage using a laser direct writing module.

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