A two-photon high-throughput direct writing device and method based on controllable multi-dot grayscale writing

Abstract

The present invention discloses a two-photon high-throughput direct writing device and method based on controllable multi-dot grayscale writing. The device obtains a focal array with uniform intensity by coordinating the microlens array and the digital micromirror array, and controls the rotation angle of the parallel direct writing spot array through the image rotation module, and realizes high-precision grayscale writing by controlling the rotation angle and the spacing between the lines. The method can adjust the writing strategy of the device according to the actual grayscale writing needs, and the displacement 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, and making full use of the pupil energy of the femtosecond laser spot, so that the method has the advantages of high-throughput large area and 2.5D high-precision grayscale writing, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser direct writing, and in particular relates to a two-photon high-throughput direct writing device and method based on controllable multi-dot grayscale writing. Background Art

[0002] At present, the manufacturing of large-area complex micro-nano structures has broad practical application prospects at the level of major national strategies and industrial needs, such as aircraft bionic drag reduction, large-size flexible touch, space film lenses, etc. However, there are many problems in its preparation, such as how to achieve efficient photolithography processing of micro / nano-scale feature structures at a size above the millimeter level, and how to flexibly manufacture and arrange various microstructures without frequently changing mask plates and other devices.

[0003] Traditional projection exposure lithography technology is difficult to manufacture complex three-dimensional micro-nano structures. Before each manufacturing, it is necessary to design and process the corresponding mask, which is expensive and inefficient. Although electron / ion beam lithography has a higher lithography resolution, it is limited by its own low writing speed and it is difficult to complete the efficient manufacturing of large-area micro-nano structures. Laser direct writing has the advantages of low cost, high writing freedom, and low working environment requirements, but it is limited to single-point writing and it is still difficult to efficiently manufacture large-area micro-nano structures.

[0004] The literature [Optics&Laser Technology, 2019, 113:407-415] realized a 70×110 spot array through a digital micromirror array DMD and a bilateral microlens spatial filter array, which greatly improved the flux, and controlled the dose of each spot through DMD for grayscale lithography, realizing parallel processing of arbitrary free-form surface structures with high flux. However, the imaging quality of the light source microlens itself is poor, and single-photon lithography is used, with a writing resolution of only 3 microns, which is difficult to meet the general lithography needs.

[0005] The invention patent application with publication number CN112596349A discloses a two-photon parallel direct writing device and method based on multi-dot array generation and independent control. It uses a microlens array MLA to generate a light spot array, and modulates the amplitude and wavefront of each light spot through the DMD and spatial light modulator SLM respectively to control the intensity and position of each light spot in the focal plane of the objective lens, which can achieve high-throughput super-resolution parallel flexible processing of arbitrary curved surface structures and true three-dimensional microstructures with high uniformity. However, due to the pixel size of the SLM itself, its control accuracy is limited. It is difficult to achieve accurate spot scanning for a large number of laser dot arrays, and the refresh rate of the SLM itself is slow, making it difficult to achieve fast scanning; in addition, the system is essentially still step lithography, which can only write a single field of view at a time, and is inefficient when writing over a large area. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing, which can achieve high-throughput super-resolution parallel grayscale processing at extremely high scanning speed.

[0007] The present invention provides a two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing, which includes a femtosecond laser, a beam expander, an angular dispersion compensation module, a digital micromirror array, a second 4F system, a microlens array, a fifth lens, an image rotation module, a first dichroic mirror and an objective lens according to the direction of light advance;

[0008] The microlens array focuses each unit light spot from the digital micromirror array to form a focal array, and the focal array is used to form parallel light transmitted at different angles through a fifth lens, so as to form a parallel direct-writing light spot array on the two-photon photoresist;

[0009] The image rotation module is used to change the transmission direction of the parallel light so as to control the rotation angle of the parallel direct writing light spot array.

[0010] Preferably, the angular dispersion compensation module comprises a blazed grating and a first 4F system;

[0011] The blazed grating is used to compensate for the angular dispersion of the light beam emitted from the digital micromirror array. The position and posture of the blazed grating are adjusted so that the angular dispersion of the light beam is suppressed after the light beam is emitted from the DMD through the first 4F system.

[0012] Further preferably, the first 4F system includes a first convex lens and a second convex lens.

[0013] The first 4F system is used to image the light field of the blazed grating onto the digital micromirror array DMD. The focal lengths F1 and F2 of the first convex lens and the second convex lens satisfy F1 / F2=dθ2 / dθ1, where dθ1 and dθ2 are the role dispersion of the blazed grating and the digital micromirror array DMD, respectively.

[0014] Preferably, the digital micromirror array comprises m×n micromirror array units, and the light beam passes through each micromirror array unit to form a corresponding unit light spot.

[0015] The present invention provides that each micromirror array unit includes a plurality of micromirrors, and the intensity and uniformity of a unit light spot are regulated by switching the independent "on" and "off" states of each micromirror, so as to obtain a unit light spot with uniform intensity, thereby improving the photolithography accuracy of the photoresist.

[0016] Preferably, the second 4F system includes a third convex lens, a fourth convex lens and a reflecting mirror.

[0017] The second 4F system is used to image the light field on the digital micromirror array DMD onto the plane of the microlens array MLA, so that the k×k micromirrors contained in each micromirror array unit of the digital micromirror array DMD can independently and correspondingly control the microlens light beams on the MLA, and by controlling the k×k microlens light beams passing through the microlens, the intensity of the focus formed by each microlens is made uniform.

[0018] Preferably, the microlens array MLA comprises m×n microlenses, and the unit light spots correspond to the microlenses one by one. The microlens array is used to focus the incident m×n unit light spots, and one unit light spot corresponds to one microlens, and at most an m×n focus array can be generated on the MLA focal plane.

[0019] Preferably, the fifth convex lens and the microlens array MLA form a third 4F system. The focal array generated by the microlens array MLA is converted into parallel light transmitted at different angles after passing through the fifth convex lens, and the light spots overlap at the entrance pupil plane of the objective lens, and finally focused on the focal plane of the objective lens to form a parallel direct-writing light spot array.

[0020] Preferably, the image rotation module is a Dove prism-like structure, and the light is reversed 180° after passing through this module. When this module rotates with its optical axis as the axis, the rotation angle of the image is twice the rotation angle of the prism. By controlling the image rotation module, the rotation angle of the light spot array can be controlled, thereby controlling the writing overlap area during scanning, and realizing grayscale writing with controllable grayscale.

[0021] Preferably, the two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing further comprises an imaging unit, and the imaging unit comprises a second dichroic mirror, a beam splitter, an illumination light-emitting diode LED and a charge-coupled device CCD imaging module;

[0022] The illumination light emitted by the illumination LED is irradiated to the focal plane through the beam splitter, the second dichroic mirror, the first dichroic mirror, and the objective lens, and then returns to the CCD imaging module along the original path to form an image.

[0023] Preferably, the two-photon high-throughput direct writing device based on controllable multi-dot grayscale engraving further includes a focus locking module, which generates a focus locking laser that sequentially passes through a second dichroic mirror, a first dichroic mirror, and an objective lens to irradiate a focal plane, and then returns to the focus locking module along the original path, and determines the position of the focal plane by detecting the returned light. The present invention ensures that the excitation light is always focused on the photoresist on a large-area high-precision displacement stage through detection by the focus locking module.

[0024] Preferably, the relationship between the grayscale level x, the column number n of the direct writing spot array, and the rotation angle θ is as follows:

[0025] tanθ=(x-1) / n

[0026] Among them, θ≤45°, and the number of columns n is divisible by x-1.

[0027] The present invention uses an image rotation module to control the rotation angle of the laser array, thereby controlling the lateral uniform distribution of the scribed lines when the large-area high-precision displacement stage is uniformly scanned, and grayscale writing of different grayscales is achieved. In order to ensure that each scribed line has the same grayscale level, the number of columns n of the spot array needs to be divisible by x-1. If the situation of non-divisibility occurs, the present invention can also eliminate the light beam of a certain column through the micromirror switch control in the digital micromirror array to achieve divisibility, thereby achieving the purpose of redundant design and improving the stability of control.

[0028] Preferably, the two-photon photoresist comprises a photoinitiator, a film-forming resin and a solvent;

[0029] The photoinitiator is 7-diethylamino-3-thenoyl coumarin, the film-forming resin is methacrylic acid-zirconium oxide composite, and the solvent is propylene glycol monomethyl ether acetate;

[0030] The photoinitiator component ratio in the photoresist ranges from 0.01 wt% to 3 wt%, the film-forming resin component ratio in the photoresist ranges from 5 wt% to 30 wt%, and the solvent component ratio in the photoresist ranges from 70 wt% to 95 wt%.

[0031] The present invention converts a single beam of femtosecond laser into ten thousand beams of laser, and the energy of the laser is significantly reduced. The present invention reduces the difficulty of initiating the photochemical reaction of the overall photoresist by introducing a methacrylic acid-zirconia complex that can efficiently perform chemical reactions into the photoresist, and regulating the content of the photoinitiator in the photoresist, so that the two-photon photoresist provided by the present invention can still successfully complete photoinitiation and perform photolithography under lower femtosecond laser energy. Specifically, the photoinitiator in the photoresist decomposes under the irradiation of a lower energy femtosecond laser, and the generated active species can further efficiently initiate a polymerization / agglomeration chemical reaction of the methacrylic acid-zirconia complex, thereby changing the solubility of the photoresist in the photolithography area in the developer, and realizing two-photon direct writing lithography.

[0032] The present invention also provides a two-photon direct writing method, which uses the two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing to perform direct writing, comprising:

[0033] The femtosecond laser is expanded by a beam expander and then irradiated onto the blazed grating;

[0034] After being pre-compensated for angular dispersion, the light is irradiated onto the digital micromirror array (DMD) through the first 4F system;

[0035] The digital micromirror array DMD performs amplitude modulation on the incident light spot, and then images it onto the microlens array MLA through the second 4F system and the reflector, and generates a focus dot matrix on the focal plane of the microlens array MLA;

[0036] The focal point array then passes through the fifth convex lens, the image rotation module, the dichroic mirror and the objective lens, and finally forms an image in the focal plane of the objective lens on the translation stage, and performs high-throughput super-resolution two-photon direct writing processing;

[0037] The illumination light generated by the LED is irradiated to the focal plane through the beam splitter, the second dichroic mirror, the first dichroic mirror, and the objective lens, and then returns to the CCD imaging module for imaging.

[0038] The focus locking laser generated by the focus locking module passes through the second dichroic mirror, the first dichroic mirror, and the objective lens in sequence to irradiate the focal plane, and then returns to the focus locking module along the original path. The position of the focal plane is determined by detecting the returned light.

[0039] Preferably, an image rotation module is used to control the rotation angle of the laser array, thereby controlling the lateral distribution of the scribed lines when the translation stage scans at a uniform speed, thereby achieving grayscale writing of different gray levels.

[0040] This method can adjust the writing strategy of the equipment according to the actual writing requirements, so that it has the advantages of both high throughput and 2.5D high-precision grayscale writing.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention achieves a focal array with uniform intensity by coordinated regulation of the microlens array and the digital micromirror array, thereby achieving precise regulation of the number of columns and beam spacing of the parallel direct-writing spot array, achieving the purpose of precisely controlling the spacing between the lines, and realizing large-area, high-throughput arbitrary pattern writing exposure. The present invention also controls the rotation angle of the parallel direct-writing spot array through an image rotation module, and achieves high-precision grayscale writing by controlling the rotation angle and the spacing between the lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the principle of a two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing provided by a specific embodiment of the present invention;

[0044] Figure 2 A schematic diagram of an embodiment of an image rotation module provided in a specific embodiment of the present invention;

[0045] Figure 3 A specific embodiment of the present invention provides a photolithography pattern with different grayscale levels achieved by adjusting the handedness angle. DETAILED DESCRIPTION

[0046] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0047] In order to achieve high-throughput super-resolution parallel grayscale processing at an extremely high scanning speed, a specific embodiment of the present invention uses the synergistic effect of a digital micromirror array DMD and a microlens array MLA to form a parallel direct-writing spot array with uniform spot intensity at an extremely high scanning speed and high-throughput super-resolution on a two-photon photoresist. The image rotation module controls the angle of the focus array output by the MLA to control the rotation angle of the parallel direct-writing spot array, thereby controlling the area where the spots overlap and efficiently controlling the grayscale order. In order to achieve the above functions, a specific embodiment of the present invention provides a two-photon high-throughput direct-writing device based on controllable multi-dot grayscale engraving, such as Figure 1 As shown, the specific description is as follows:

[0048] A femtosecond laser 1, a beam expander 2, a blazed grating 3, a first convex lens 4, a second convex lens 5, a digital micromirror array DMD6, a third convex lens 7, a fourth convex lens 8, a reflector 9, a microlens array MLA10, a fifth convex lens 11, an image rotation module 12, a first dichroic mirror 13, an objective lens 14 and a large-area displacement stage 15 are arranged in sequence according to the direction of light travel.

[0049] The blazed grating 3, the first convex lens 4 and the second convex lens 5 provided in the specific embodiment of the present invention constitute an angular dispersion compensation module, wherein the first convex lens 4 and the second convex lens 5 constitute a first 4F system, and the first 4F system is used to image the light field of the blazed grating 3 to the digital micromirror array DMD6, and compensate for the angular dispersion generated by the digital micromirror array DMD6 as a grating element itself. The focal lengths F1 and F2 of the first convex lens 4 and the second convex lens 5 satisfy F1 / F2=dθ2 / dθ1, wherein dθ1 and dθ2 are the angular dispersions of the blazed grating 3 and the digital micromirror array DMD6, respectively; the position and posture of the blazed grating 3 are adjusted so that the angular dispersion of the light beam is suppressed after the light beam is emitted from the digital micromirror array DMD6 through the 4F system.

[0050] The digital micromirror array DMD6 provided in a specific embodiment of the present invention performs amplitude modulation on the incident light spot. The digital micromirror array DMD6 divides the effective pixel area into m×n micromirror array units, one micromirror array unit corresponds to one unit light spot, and each micromirror array unit includes k×k micromirrors. The k×k micromirrors contained in each micromirror array unit of the digital micromirror array DMD6 are independently switched between "on" and "off" states, thereby independently adjusting the intensity and uniformity of each unit light spot.

[0051] The third convex lens 7, the fourth convex lens 8 and the reflector 9 provided in the specific embodiment of the present invention form a second 4F system, which is used to image the light field on the digital micromirror array DMD6 onto the plane of the microlens array MLA10, so that the k×k micromirrors contained in each micromirror array unit of the digital micromirror array DMD6 can independently and correspondingly control the microlens light beam on the microlens array MLA10, and by controlling the microlens light beam, the intensity of the focus obtained by each microlens is made uniform, so that a higher lithography accuracy is achieved. The selection of the k value is jointly determined by the parameters such as the array, the system aperture, and the objective lens entrance pupil required for actual engraving.

[0052] The microlens array MLA10 provided in a specific embodiment of the present invention comprises m×n microlenses for focusing incident m×n unit light spots. One unit light spot corresponds to one microlens, and at most m×n focus arrays can be generated on the focal plane of the microlens array MLA10.

[0053] The fifth convex lens 11 provided in the specific embodiment of the present invention and the microlens array MLA10 form a third 4F system. The focal array generated by the microlens array MLA10 is converted into parallel light transmitted at different angles after passing through the fifth convex lens 11, and the light spots are overlapped at the entrance pupil plane of the objective lens 14, and finally focused on the focal plane of the objective lens 14 to form a parallel direct-writing light spot array.

[0054] The image rotation module 12 provided in the specific embodiment of the present invention adopts a Dove prism-like structure, which is composed of three plane mirrors, such as Figure 2 As shown, the light is reversed 180° after passing through this module. When this module rotates with its optical axis as the axis, the rotation angle of the image is twice the rotation angle of the prism. By controlling the image rotation module 12, the rotation angle of the light spot array can be controlled, thereby controlling the writing overlap area during scanning, and realizing grayscale writing with controllable grayscale.

[0055] On the other hand, a specific embodiment of the present invention further provides a two-photon direct writing method, which uses the two-photon high-throughput direct writing device based on controllable multi-dot grayscale engraving to perform grayscale direct writing, including: the femtosecond laser is expanded by the beam expander 2 and irradiated onto the blazed grating 3, which is pre-compensated for angular dispersion and then irradiated onto the digital micromirror array DMD6 through the first 4F system, the digital micromirror array DMD6 performs amplitude modulation on the incident light spot, and then images it onto the microlens array MLA10 through the second 4F system and the reflector 9, and generates a focal dot matrix on the focal plane of the microlens array MLA10, which then passes through the fifth convex lens 11, the image rotation module 12, and the dichroic mirror 13. and objective lens 14, and finally imaged in the focal plane of the objective lens on the large-area high-precision displacement stage 15, and high-throughput super-resolution two-photon direct writing processing is performed; the illumination light generated by LED19 is irradiated to the focal plane through the beam splitter 18, the second dichroic mirror 16, the first dichroic mirror 13, and the objective lens 14, and then returns to the CCD imaging module 20 for imaging; the focus locking module 17 generates a focus locking laser that passes through the second dichroic mirror 16, the first dichroic mirror 13, and the objective lens 14 in sequence to irradiate the focal plane, and then returns to the focus locking module 17 along the same route, and the position of the focal plane is determined by detecting the returned light, so as to ensure that the excitation light is always focused on the photoresist on the large-area high-precision displacement stage 15.

[0056] Based on the above system, the present invention also provides a large-area high-throughput two-photon grayscale direct writing method, which uses an image rotation module 12 to control the rotation angle of the laser array, thereby controlling the lateral distribution of the engraved lines when the large-area high-precision translation stage 15 scans at a uniform speed, thereby achieving grayscale writing of different gray levels.

[0057] like Figure 3 As shown in , assume that the number of direct writing spot arrays is m×n, the distance between adjacent lasers is a, the array rotation angle is θ, and the final scanning line spacing is b. Figure 3 As shown in (a), in the case of no grayscale writing, that is, 2 grayscales (on and off), that is, one line is scanned by one beam, in order to ensure uniform spacing between the lines, the spacing between the beam in the first row and the first column and the beam in the last column of the second row should be equal to the spacing between other lines, that is: , simplifies to: tanθ=1 / n. It can be obtained that, under the condition of gray level determination, the rotation angle is only related to the number of columns of the laser array.

[0058] When the image rotation module is controlled to rotate the array by θ, the scanning line width will just meet the condition of uniform spacing. At this time, the large-area high-precision displacement stage 15 is manipulated to move at a uniform speed in the horizontal direction, and a total of m×n uniformly distributed lines can be engraved at one time at the focal plane of the objective lens 14. While maintaining the uniform motion of the large-area high-precision displacement stage 15, the pixel switches of the corresponding unit area of ​​the digital micromirror array DMD6 are controlled, and the switches of each light beam are manipulated to complete high-throughput large-area arbitrary pattern engraving exposure.

[0059] like Figure 3 As shown in (b), at 3 grayscale levels, in order to ensure uniform spacing between the lines, the spacing between the first row and the first column of the beam and the last column of the third row should be equal to the spacing between other lines, thereby ensuring that two beams scan each line to achieve 3-level grayscale control. At this time, Simplified, we get: tanθ=2 / n. Similarly, when the number of grayscale levels required to be written by the system is x, the angle θ of the laser array image rotation needs to satisfy tanθ=(x-1) / n. At this time, the spot array is divided into two areas with the same number of columns, namely p1 and p2, which respectively represent a group of spots that control the grayscale writing level. Grayscale exposure writing is achieved by switching the exposure times of the corresponding spot positions in sequence.

[0060] The large-area high-throughput two-photon grayscale direct writing method provided by the specific embodiment of the present invention uses an image rotation module to control the upper limit of the angle θ of the laser array image rotation to 45°, and the selected x-1 must be a factor of the number of laser columns n, that is, n can be divided by x-1. When x-1 required for actual writing cannot be divided by n, several columns of light beams in the laser array can be eliminated (that is, the digital micromirror array DMD6 corresponding to the conjugate position of the light beam is set to 0) until x-1 can divide n, thereby ensuring that all engraved lines correspond to the same number of light beams.

[0061] This method can adjust the writing strategy of the equipment according to the actual grayscale writing needs, and during the writing exposure process, the large-area high-precision translation stage 15 only needs to maintain a uniform scanning speed, saving the time of repeated acceleration and deceleration of the platform. At the same time, it makes full use of the entrance pupil energy of the femtosecond laser spot, so that this method has the advantages of high-throughput large-area and 2.5D high-precision grayscale writing, and has broad application prospects.

[0062] Based on the above system, the present invention also provides a two-photon photoresist, comprising 7-diethylamino-3-thenoyl coumarin (photoinitiator), methacrylic acid-zirconium oxide composite (film-forming resin) and propylene glycol monomethyl ether acetate (solvent).

[0063] In some embodiments, the component ratio of the photoinitiator can be 0.01 wt%~3 wt%, or can be 0.02 wt%, 0.03 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.25 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, etc.

[0064] In some embodiments, the component proportion of the film-forming resin can be 5 wt%~30 wt%, or can be 6 wt%, 6.5 wt%, 7 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 22 wt%, 26 wt%, 29 wt%, 29.5 wt%, etc.

Claims

1. A two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing, characterized in that: According to the direction of light travel, it includes a femtosecond laser, a beam expander, an angular dispersion compensation module, a digital micromirror array, a second 4F system, a microlens array, a fifth lens, an image rotation module, a first dichroic mirror and an objective lens; The microlens array focuses each unit light spot from the digital micromirror array to form a focal array, and the focal array is used to form parallel light transmitted at different angles through a fifth lens, so as to form a parallel direct-writing light spot array on the two-photon photoresist; The image rotation module is used to change the transmission direction of the parallel light so as to control the rotation angle of the parallel direct writing spot array; The relationship between the grayscale level x and the number of columns n and the rotation angle θ of the direct writing spot array is shown in the following formula: tanθ=(x-1) / n, where θ≤45°, the number of columns n can be divided by x-1, and the rotation angle θ is the angle between the engraving direction and the arrangement direction of the columns of the spot array.

2. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The angular dispersion compensation module includes a blazed grating and a first 4F system; The blazed grating is suitable for compensating for angular dispersion of a light beam emerging from the digital micromirror array.

3. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The digital micromirror array includes m×n micromirror array units, and a light beam passes through each micromirror array unit to form a corresponding unit light spot.

4. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The micromirror array includes m×n microlenses, and the unit light spots correspond to the microlenses one by one.

5. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing also includes an imaging unit, which includes a second dichroic mirror, a beam splitter, an illumination LED and a CCD imaging module; The illumination light emitted by the illumination LED is irradiated to the focal plane through the beam splitter, the second dichroic mirror, the first dichroic mirror, and the objective lens, and then returns to the CCD imaging module along the original path to form an image.

6. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The two-photon high-throughput direct writing device based on controllable multi-dot grayscale engraving also includes a focus locking module, which generates a focus locking laser that passes through a second dichroic mirror, a first dichroic mirror, and an objective lens in sequence to irradiate a focal plane, and then returns to the focus locking module along the original path, and determines the position of the focal plane by detecting the returned light.

7. The two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing according to claim 1 is characterized in that: The two-photon photoresist comprises a photoinitiator, a film-forming resin and a solvent; The photoinitiator is 7-diethylamino-3-thenoyl coumarin, the film-forming resin is methacrylic acid-zirconium oxide composite, and the solvent is propylene glycol monomethyl ether acetate; The photoinitiator component ratio in the photoresist ranges from 0.01 wt% to 3 wt%, the film-forming resin component ratio in the photoresist ranges from 5 wt% to 30 wt%, and the solvent component ratio in the photoresist ranges from 70 wt% to 95 wt%.

8. A two-photon direct writing method, characterized in that: Direct writing is performed using a two-photon high-throughput direct writing device based on controllable multi-dot grayscale writing as described in any one of claims 1 to 7, comprising: The femtosecond laser is expanded by a beam expander and then irradiated onto the blazed grating; After being pre-compensated for angular dispersion, the light is irradiated onto the digital micromirror array (DMD) through the first 4F system; The digital micromirror array DMD performs amplitude modulation on the incident light spot, and then images it onto the microlens array MLA through the second 4F system and the reflector, and generates a focus dot matrix on the focal plane of the microlens array MLA; The focal point array then passes through a fifth convex lens, an image rotation module, a dichroic mirror and an objective lens, and finally forms an image in the focal plane of the objective lens on a large-area high-precision translation stage, and performs high-throughput super-resolution two-photon direct writing processing; The illumination light generated by the LED is irradiated to the focal plane through the beam splitter, the second dichroic mirror, the first dichroic mirror, and the objective lens, and then returns to the CCD imaging module for imaging. The focus locking module generates a focus locking laser which passes through the second dichroic mirror, the first dichroic mirror, and the objective lens in sequence to irradiate the focal plane, and then returns to the focus locking module along the original path, and the position of the focal plane is determined by detecting the returned light; The image rotation module is used to control the rotation angle of the laser array, thereby controlling the lateral distribution of the scribed lines when the translation stage is scanning at a uniform speed, and realizing grayscale writing of different gray levels; The relationship between the grayscale level x and the number of columns n and the rotation angle θ of the direct writing spot array is shown in the following formula: tanθ=(x-1) / n, where θ≤45°, the number of columns n can be divided by x-1, and the rotation angle θ is the angle between the engraving direction and the arrangement direction of the columns of the spot array.

Images