Method and device for photoetching circular ring microstructure array on curved surface

Abstract

The invention discloses a method and a device for photoetching a ring microstructure array on a curved surface, and belongs to the technical field of laser direct writing exposure machines. The invention provides an exposure method and a corresponding photoetching device, aiming at solving the problems of difficulty in processing and low efficiency when a metasurface, a frequency selective surface, a metal mesh and the like consisting of circular ring microstructures are manufactured on the surface of a curved substrate such as a spherical surface and the like in the prior art. A light path structure of the device is composed of a hollow circular ring light beam generation part and a hollow circular ring light beam miniature part, and an incident collimated light beam is modulated into a hollow circular ring light beam for exposure. The exposure light beam modulated by the exposure method has the advantages of thinner circular ring width, longer focal depth and longer working distance, the influence of the height change of the substrate on the exposure circular ring is reduced, the requirement for the positioning error of a mechanical displacement table is reduced, the pulse type laser beam can directly expose the complete single circular ring, and the exposure efficiency is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser direct writing exposure machines, and particularly relates to a direct writing exposure method and a corresponding device for photolithography of a circular ring microstructure array on a curved surface. The prepared circular ring microstructure array can be used as a basic structural unit for applications such as supersurfaces, frequency selective surfaces, and electromagnetic shielding metal grids. Background Art

[0002] In today's era, the research and development process of various electronic products pays more and more attention to the compatibility, shielding and protection of electromagnetic waves. Electromagnetic functional devices such as electromagnetic shielding metal grids, frequency selective surfaces, and electromagnetic metasurfaces composed of microstructure arrays have increasingly highlighted their application value because of their functions of electromagnetic wave shielding and protection, electromagnetic wave regulation, etc. However, in the current research status at home and abroad, such electromagnetic wave functional devices composed of microstructure arrays are mostly in the form of flat substrates, while the research on curved substrates is relatively small. In practical applications, devices and devices with curved outer contours occupy a high proportion, especially electromagnetic shielding light windows with spherical surfaces as substrates, which have more inherent advantages in applications. In terms of optical imaging, the spherical light window allows the internal camera to use a lens with a larger field of view, expand the imaging range, and reduce image distortion; in terms of mechanical properties, spherical and streamlined surfaces can withstand greater pressure, and the contours conform to aerodynamic characteristics, reduce the resistance of high-speed aircraft, and enhance aerodynamic performance. By covering the microstructure array on the spherical light window, the electromagnetic functional device can match the outer contour of the applied equipment to adapt to the working conditions of electromagnetic waves incident at multiple angles. In addition, relevant research on microstructure units shows that for transparent electromagnetic shielding metal grids, using circular ring-shaped symmetrical microstructures as their basic units can effectively reduce the impact of high-order diffraction spots on imaging; in addition, applying this type of microstructure unit to metasurfaces can effectively improve the device's insensitivity to electromagnetic wave polarization. Therefore, electromagnetic wave functional devices that combine circular ring-shaped symmetrical microstructures with curved substrates have extremely high application value. However, there are still great difficulties in processing and preparing circular ring microstructures on curved optical transparent substrates.

[0003] Although there are some cases of using laser direct writing method to prepare microstructures on spherical surfaces, the practicality of related results is still relatively low. Its technical difficulties and problems are mainly reflected in the following three aspects: First, the spherical surface is a three-dimensional structure. The multiple rotating axes and translation stages equipped in the exposure device increase the source of positioning errors in the equipment. The accumulation of errors will be obviously reflected in the defocus distance of the lithography system, resulting in blurred light spots and reduced lithography quality; second, the optical path of conventional laser direct writing lithography equipment uses a microscope objective to reduce the spot size of the exposure beam. In order to obtain a smaller line width, a high-magnification microscope objective is usually used. Its numerical aperture is large, the working distance of the objective lens is short, and it is easy to collide with the surface of the substrate during movement; third, conventional spherical laser direct writing equipment generates a single point-shaped exposure spot, which relies on the continuous uniform motion of the multi-axis translation stage to connect the single points into a line, and the exposure efficiency is low. The above difficulties are widely present in the microstructure of the spherical substrate exposed by the existing laser direct writing equipment, not to mention the streamlined curved substrate with more complex surface undulations.

[0004] At present, among the methods and devices for processing microstructures such as mesh, grating, frequency selective surface, etc. by laser direct writing method on spherical substrate, the representative achievements and patents are as follows:

[0005] Patent publication number: CN1101722362A "Laser direct writing method for deep concave spherical surface with intersecting latitude grid patterns", patent publication number: CN1488997A "A concave spherical surface photolithography ruling machine", patent publication number: CN216990334U "A longitude and latitude spherical surface laser processing machine", patent publication number: CN113172335A "A method for etching non-developable FSS surfaces with a multi-axis precision laser processing machine" and papers: "Realization of laser direct writing control of deep concave spherical grid with constant exposure", "Research on curved surface grid writing technology", "Research on curved surface laser direct writing system and key technologies", "Laser direct writing technology for convex spherical grid", "Research on curved surface laser direct writing system and key technologies", etc., use a multi-axis translation stage to drive the sample to move continuously so that a single point spot can expose lines. This exposure method affects the consistency of line width and has low exposure efficiency. In addition, the short working distance of the microscope objective leads to spatial structure conflicts, which limits the application of the technology.

[0006] The paper "Research on Key Technologies for High-efficiency Curved Surface Laser Direct Writing Lithography" adopts a nonlinear optical lever structure to change the focal length of the optical system in real time according to the surface height of the spherical sample, thereby increasing the height range of the spherical surface that can be exposed. However, this technology still does not avoid the problems of low efficiency of laser single-point exposure and short working distance of the microscope objective. In addition, there is still the problem of reduced exposure quality for positions with large edge slopes of spherical samples.

[0007] The paper "Laser-lithography on Non-planar Surfaces" modified the equipment platform based on a commercial laser direct writer and added a mechanical structure that can drive the substrate to rotate. However, this achievement is limited by the original equipment hardware, and the exposure angle in the inclined area is limited. It still uses the method of direct writing in different areas, which easily produces more graphic splicing marks.

[0008] Patent publication number: CN111077741B "Curved surface lithography method using DMD and liquid crystal modulation" can theoretically realize universal maskless lithography on curved surfaces, but because of the use of DMD and liquid crystal spatial light modulators, the cost is relatively high, the structure is highly complex, and the projection objective lens used still has high positioning accuracy requirements and is prone to collision with the substrate.

[0009] Patent publication number: CN102097296A "A method for preparing semiconductor nano-rings" uses the principle of generating annular light spots as diffraction Poisson light spots, which is different from the principle of the method used in the present invention. Summary of the invention

[0010] The purpose of the present invention is to overcome the difficulties existing in the process of preparing spherical microstructures in the above-mentioned prior art, especially the microstructures represented by laser direct writing metal grids, which have the problems of difficulty in increasing line width, poor line width consistency, low manufacturing efficiency, equipment structure conflict, etc., and propose a method for photolithography of circular ring microstructure arrays on spherical surfaces and complex curved surfaces and a corresponding photolithography device, which has the advantages of finer line width, good line width consistency, large tolerance for defocus, high processing efficiency, and high cost-effective equipment, and can better meet the processing requirements of metal grids, metasurfaces, frequency selective surfaces and other applications.

[0011] The technical solution adopted by the present invention is: a method and device for photolithography of circular ring microstructure array on a curved surface, characterized in that: the photolithography device is composed of a laser light source, a hollow circular ring beam generating part, a hollow circular ring beam miniaturization part, a curved surface sample and a numerically controlled multi-axis displacement stage, the surface of the curved surface sample is coated with photoresist, and circular ring microstructure units arranged on the surface of the curved surface sample are generated by sequential exposure to form a circular ring microstructure array; before each circular ring microstructure unit is exposed, the numerically controlled multi-axis displacement stage adjusts the rotation angle and coordinates of the curved surface sample so that the surface area to be exposed of the curved surface sample enters the set exposure position; a collimated light beam is emitted from the laser light source, passes through the hollow circular ring beam generating part to generate a hollow circular ring beam with a fixed ring width, and then passes through the hollow circular ring beam miniaturization part to generate a miniaturized hollow circular ring beam, the ring width of the miniaturized hollow circular ring beam is gradually reduced during the propagation process, and is located at a working distance Z WThe area to be exposed is transformed into a circular spot for photolithography, which exposes the photoresist coated on the surface of the curved sample to produce a single circular microstructure unit. After each circular microstructure unit is exposed, the curved sample is rotated and moved to the next area to be exposed by the CNC multi-axis translation stage, and the above exposure steps are repeated until the exposure of the circular microstructure array set on the surface of the curved sample is completed.

[0012] In the technical solution of the above invention content: the hollow ring beam generating part is composed of a hollow cone beam diffusion element and a hollow cone beam focusing element; the distance between the hollow cone beam diffusion element and the hollow cone beam focusing element is Z A , Z A It is proportional to the diameter of the hollow ring beam; the hollow ring beam generating part adopts any one of the following two combinations: the first is two convex cone lenses, and the second is a concave cone lens and a convex cone lens.

[0013] In the technical solution of the above invention content: the hollow ring light beam miniaturization part is composed of a positive lens front group and a positive lens rear group, the focal length f1 of the positive lens front group is greater than the focal length f2 of the positive lens rear group, the spherical aberration of the positive lens rear group is greater than the spherical aberration of the positive lens front group, and the hollow ring light beam miniaturization part relies on the spherical aberration of the internal optical element to make the light rays of different radial heights converge before reaching the focus of the positive lens rear group, thereby modulating into a ring light spot; the distance Z between the positive lens front group and the positive lens rear group C Used to adjust the divergence of the outgoing beam, Z C Smaller than f1+f2; the annular spot has a ring width of micrometer or submicrometer order; the miniaturized part of the hollow annular beam has a focal depth of hundreds of micrometers, exposing the annular microstructure unit whose surface height fluctuation range of the curved sample is smaller than the focal depth length.

[0014] In the technical solution of the above invention content: the types of optical elements used in the hollow ring beam generating part and the hollow ring beam miniaturization part include solid lenses made of optical glass, diffractive optical elements, holograms loaded on reflective and transmissive spatial light modulators, and metasurface lenses.

[0015] In the technical solution of the above invention, the optical elements of the hollow ring beam generating part and the hollow ring beam miniaturization part are installed on the linear translation stage, and the distance Z between the elements is changed by the host computer during the exposure process. A and Z C , adjust the exposure size of the circular spot.

[0016] In the technical solution of the above invention content: a combination of an achromatic cemented lens and a single lens with achromatic function is used in the positive lens front group and the positive lens rear group.

[0017] In the technical solution of the above invention content: the components in the laser light source include a laser, a shutter, a beam collimator, and a beam expander.

[0018] In the technical solution of the above invention content: an adjustable shading plate is arranged between the hollow ring beam generating part and the hollow ring beam miniaturization part to block part of the light of the hollow ring beam, so that the modulated ring light spot becomes a ring with a gap.

[0019] In the technical solution of the above invention content: the types of lithography applicable to the method include: ultraviolet lithography using conventional positive photoresist and negative photoresist, additive manufacturing using the principle of photocuring, and using high-power laser to ablate or denature the material coated on the surface of the curved sample.

[0020] The innovation and good effects of the present invention are:

[0021] 1. The present invention uses the spherical aberration in the aberration characteristics of the spherical convex lens as the dominant factor for the convergence of the circular ring light beam. Compared with the traditional photolithography method that uses a microscope objective to scale the light beam, this method reduces the convergence angle of the light beam, which can produce two advantages. On the one hand, the exposure light beam avoids the limitation of the numerical aperture of the objective lens, which greatly improves the focal depth range of the optical system; this advantage can not only prevent the exposure of the circular ring structure from being deteriorated due to the defocus of the objective lens, and improve the tolerance range of the device, but also use this focal depth range to ignore the fluctuations of the surface profile of the curved surface, and realize the preparation of the circular ring structure on the complex curved surface. On the other hand, the reduced beam convergence angle can provide a longer working distance. For concave spherical surfaces and curved surface structures with obstructions on the edges, the extension of the working distance can effectively avoid the spatial conflict of objects between the objective lens and the curved surface, and prevent collisions.

[0022] 2. The optical system of the device of the present invention causes light rays of different radial heights in the incident light beam to be deflected due to spherical aberration. After being emitted, the light rays extend in a straight line along the propagation direction and cross one another in sequence near the image plane, converging into a circular ring light spot with a thin ring width, which can reach the micron and submicron levels. However, the traditional photolithography device using a microscope objective follows the principle of imaging optics, and the limit of the spot size generated is the product of the incident light beam size and the vertical magnification of the optical system.

[0023] 3. The device of the present invention can adjust the diameter of the ring or the position and width of the notch of the ring during the exposure process by adjusting the position of the linear translation stage of the optical element and the opening size of the light shielding plate, so that the device of the present invention can be applied to the unit structure requirements of various grid, metasurface and other applications.

[0024] 4. The exposure method of the present invention is specially designed for circular microstructures. A complete circular ring can be generated at one time each time the exposure is performed. There is no need to move the curved surface sample and the direct writing head during the exposure process, that is, the formation of the circular ring lines no longer depends on mechanical movement. Therefore, the exposure efficiency is higher, and the continuity of mechanical movement is avoided to affect the consistency of line width, thereby improving the exposure quality.

[0025] 5. The advantages of the present invention, such as large tolerance of the defocus error and fixed position of a single exposure, can reduce the accuracy requirements of other components in the device, such as the translation stage and the focusing and adjusting system, reduce costs, and be more suitable for production and manufacturing.

[0026] In summary, the present invention makes full use of the spherical aberration characteristics of the spherical lens to generate a circular ring-shaped light beam, which can be used to photolithography a circular ring-shaped microstructure on a curved substrate, and has the characteristics of large focal depth, thin and uniform ring width. The circular ring lines generated by this method are of high quality, have low precision requirements on other parts of the equipment, and have good economy and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the pictures described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The present invention is a schematic diagram of the functional division of the internal components of a device having an array of circular microstructures photolithographically formed on a curved surface.

[0029] Figure 2 The present invention is a schematic diagram of components arranged in a device for photolithography of a circular microstructure array on a curved surface according to a specific embodiment 1.

[0030] Figure 3 It is a schematic diagram of the last spherical convex lens of the device in specific embodiment 1 using spherical aberration to converge the light beam.

[0031] Figure 4 This is a diagram of the intensity distribution of the annular light spot simulated by the optical element used in specific embodiment 1.

[0032] Figure 5 3 is an intensity profile diagram of the annular light spot using specific embodiment 1.

[0033] Figure 6 The circular ring microstructure is obtained by exposing the sample coated with photoresist using the prototype of specific embodiment 1.

[0034] Figure 7The light radial height distribution diagrams are obtained by using the optical path tracing method to calculate the optical elements used in Example 1 and Example 2 at the image plane position. The horizontal axis is the image plane position of the light path along the optical axis, the vertical axis is the height along the optical axis section, and the straight lines in the figure are the propagation trajectories of light of different wavelengths at the position. Part number description in the figure: 1. Laser light source; 2. Hollow ring beam generating part; 3. Hollow ring beam miniaturization part; 4. Curved surface sample; 5. CNC multi-axis translation stage; 6. Ring light spot for photolithography; 7. Collimated beam emitted by the light source; 8. Hollow ring beam with fixed ring width; 9. Miniaturized hollow ring beam; 10. Focus depth range of the ring beam for exposure; 11. First cone lens; 12. Second cone lens; 13. First convex lens; 14. Second convex lens; 21. Hollow conical beam diffusion element; 22. Hollow conical beam focusing element; 31. Positive lens front group; 32. Positive lens rear group; Z A . The distance between the hollow cone beam diffusing element and the hollow cone beam focusing element; Z C .The distance between the front and rear groups of the positive lens; Z W .Working distance of the objective lens. DETAILED DESCRIPTION

[0035] The present invention is further described below with reference to the accompanying drawings and preferred embodiments:

[0036] The purpose of the present invention is achieved in this way: the optical path system in the present invention is the core of the device for realizing circular microstructure lithography. Figure 2 The invention is a most basic implementation form of a method and device for photolithography of a circular ring microstructure array on a curved surface, and the parameters of the optical elements are shown in the specific embodiment 1. In the embodiment, two convex cone lenses are used as the hollow circular ring beam generating part, and two spherical plano-convex lenses are used as the hollow circular ring beam shrinking part.

[0037] The laser light source emits a collimated light beam. After passing through the first cone lens, the light beam is deflected along the central symmetry axis, first converged and then diverged to form a hollow cone-shaped light beam. The second cone lens shapes the hollow cone-shaped light beam, and the light beam converges again in the propagation direction to form a hollow cylindrical light beam. After passing through the hollow ring light beam generation part composed of the cone lens, the light beam then enters the hollow ring light beam miniaturization part. In principle, for a spherical convex lens, the incident light beam will cause the light near the axis of the lens to focus at a position slightly away from the lens due to the spherical aberration of the lens, while the light near the edge of the lens will focus at a position slightly closer to the lens, and there is an area where the light rays intersect between the two. The present invention utilizes this principle and uses a spherical plano-convex lens with a large spherical aberration (small focal length) as the rear group of the positive lens. Before the annular light beam reaches the focus, the light rays near the inner diameter and the outer diameter of the annular light beam converge due to the spherical aberration. The ring width of the light beam is thin in a section during the propagation process, which can be used for photolithography exposure. In addition, another spherical plano-convex lens with a larger focal length (smaller spherical aberration) is used as the front group of the positive lens. The two plano-convex lenses are used together, and the appropriate distance between the plano-convex lenses is adjusted. The ray tracing cross-section of the hollow circular ring beam formed at the end is as follows Figure 3 As shown in . This structure is similar to an inverted telescope optical path, which can proportionally reduce the overall size of the incident light beam to reach the target set diameter, and the scaling ratio is related to the focal length of the two plano-convex lenses; the difference is that the distance between the two plano-convex lenses is less than the sum of the focal lengths of the two plano-convex lenses, so that the diameter of the outgoing light beam remains stable in the area with a thinner ring width. The present invention generates a fine annular spot through spherical aberration convergence, and the light beam convergence process is slower, so it has a longer focal depth and working distance than the traditional objective lens focusing method. Therefore, the present device does not use a traditional objective lens, avoiding the problem that the advantages of spot size, focal depth, and working distance cannot coexist.

[0038] Based on the modulation method of the circular light beam, the present invention is equipped with a multi-axis translation stage with translation and rotation functions, and a curved surface sample coated with photoresist is fixed on the translation stage. Before each exposure, the CNC multi-axis translation stage moves the position of the curved surface sample to be exposed to the area of ​​the fine circular spot generated by the optical path. After each exposure of a circular spot, the multi-axis translation stage will move to the next position to be exposed, and the above process will be repeated until all circular units are photolithographically completed. Relying on the above working principle, the device can not only avoid the problem of changes in defocus distance and reduced exposure quality caused by positioning errors of the translation stage, but also allow the surface contour of curved surface samples of any shape to change within the focal depth range, and is compatible with curved surfaces of more shapes.

[0039] The above two advantages enable the surface of the curved sample coated with photoresist to be exposed smoothly to form a circular microstructure array. The following describes the innovation and function of the present invention by improving the parameters of a specific embodiment.

[0040] Embodiment 1:

[0041] According to an embodiment 1 of a method and device for photolithography of a circular ring microstructure array on a curved surface of the present invention, the parameters of the components used are: laser wavelength 405nm; the first conical lens material is quartz, the bottom angle α=10°, and the diameter d=12.5mm; the second conical lens material is quartz, the bottom angle α=10°, and the diameter d=25mm; the first plano-convex lens material is N-BK7, the focal length f=500mm, the diameter d=25.4mm, and the radius of curvature R=258.4mm; the second plano-convex lens material is N-BK7, the focal length f=20mm, the diameter d=6.3mm, and the radius of curvature R=10.36mm. According to Snell's law n1sinθ1=n2sinθ2, ray tracing calculations are performed, and the corresponding optical path is built on the experimental equipment. It can be seen that: when the diameter of the target ring is 0.8mm, the distance Z between the two conical lenses A =124.8mm; the distance between the two plano-convex lenses is Z C =525.6mm; working distance Z of the second plano-convex lens W =31.8mm.

[0042] The test method of this embodiment in the laboratory is: install a CMOS camera on the multi-axis translation stage, adjust the distance between the camera sensor and the center of the last surface of the second plano-convex lens to the working distance Z W , can be photographed Figure 4 The energy intensity distribution of the circular spot in the image. By taking the horizontal and vertical energy intensity values ​​through the center of the circular ring, we can obtain Figure 5 The normalized energy intensity distribution profile in the figure. From the two figures, we can see that the energy distribution of the circular spot is smooth, the edge is sharp, and the ring width is relatively uniform. The output power and exposure time of the exposure light source are controlled by the host computer, and the sample coated with photoresist is exposed. After collecting the surface morphology of the photoresist with a laser confocal microscope, the Figure 6 The height diagram of the ring structure is shown. Through the measurement of laser confocal microscopy, it can be seen that when the diameter of the ring is 0.8mm, the ring width can be maintained at 3μm-4μm. The verticality between the exposed area and the non-exposed area is good, which is conducive to the subsequent process flow such as metal deposition.

[0043] Embodiment 2:

[0044] Embodiment 2 of a method and device for photolithography of a circular microstructure array on a curved surface is based on Embodiment 1, and the plano-convex lens of the rear group of the positive lens is replaced with a double-cemented achromatic lens. The parameters of the double-cemented achromatic lens are: the first surface curvature radius R1 = 12.363mm, the second surface curvature radius R2 = -8.703mm, the third surface curvature radius R3 = -24.846mm, the material of the double convex lens is H-K9, the material of the meniscus lens is H-ZF2, the focal length f = 20mm, and the diameter d = 6mm. Other lens parameters remain unchanged.

[0045] It can be known from the theoretical calculation using the optical path tracing method that after eliminating the chromatic aberration of the positive lens rear group on the basis of Example 1, the ring width caused by chromatic aberration can be reduced by 17.8% in theory. It can be seen that adding a chromatic aberration correction lens made of flint glass to the positive lens front group and the positive lens rear group of the hollow circular ring beam micro-contraction part can effectively control the chromatic aberration generated by the optical path in the present invention and improve the quality of the circular ring light spot.

[0046] The above cases prove that the present invention has high advantages and practicality. Obviously, after understanding the content and principle of the present invention, professionals in this field may make various modifications and changes in form and details without departing from the principle and structure of the present invention, but these modifications and changes based on the idea of ​​the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A method and device for photolithography of a circular microstructure array on a curved surface, characterized in that: The photolithography device is composed of a laser light source (1), a hollow circular ring beam generating part (2), a hollow circular ring beam miniaturization part (3), a curved surface sample (4) and a numerically controlled multi-axis displacement stage (5). The surface of the curved surface sample (4) is coated with photoresist. Through sequential exposure, circular ring microstructure units arranged on the surface of the curved surface sample (4) are generated to form a circular ring microstructure array. Before each circular ring microstructure unit is exposed, the numerically controlled multi-axis displacement stage (5) adjusts the rotation angle and coordinates of the curved surface sample (4) so ​​that the surface area to be exposed of the curved surface sample (4) enters a set exposure position. A collimated light beam (7) is emitted from the laser light source (1), passes through the hollow circular ring beam generating part (2) to generate a hollow circular ring beam (8) with a fixed ring width, and then passes through the hollow circular ring beam miniaturization part (3) to generate a miniaturized hollow circular ring beam (9). The ring width of the miniaturized hollow circular ring beam (9) is gradually reduced during the propagation process and is located at a working distance Z. W The area to be exposed is transformed into a circular ring light spot (6) for photolithography, and the circular ring light spot (6) exposes the photoresist coated on the surface of the curved surface sample (4) to produce a single circular ring microstructure unit; after each circular ring microstructure unit is exposed, the curved surface sample (4) is rotated and moved to the next area to be exposed by a numerically controlled multi-axis translation stage (5), and the above exposure steps are repeated until the circular ring microstructure array set on the surface of the curved surface sample (4) is completely exposed.

2. A method and device for photolithography of a circular microstructure array on a curved surface according to claim 1, characterized in that: The hollow annular beam generating part (2) is composed of a hollow conical beam diffusion element (21) and a hollow conical beam focusing element (22); the distance between the hollow conical beam diffusion element (21) and the hollow conical beam focusing element (22) is Z A , Z A The diameter of the hollow ring light beam (8) is proportional to the diameter of the hollow ring light beam (8); the hollow ring light beam generating part (2) adopts any one of the following two combinations: the first is two convex cone lenses, and the second is a concave cone lens and a convex cone lens.

3. The method and device for photolithography of a circular microstructure array on a curved surface according to claim 1, characterized in that: The hollow annular light beam miniaturization part (3) is composed of a positive lens front group (31) and a positive lens rear group (32). The focal length f1 of the positive lens front group (31) is greater than the focal length f2 of the positive lens rear group (32). The spherical aberration of the positive lens rear group (32) is greater than the spherical aberration of the positive lens front group (31). The hollow annular light beam miniaturization part (3) relies on the spherical aberration of the internal optical element to make the light rays of different radial heights converge before reaching the focus of the positive lens rear group (32), thereby modulating into an annular light spot (6). The distance Z between the positive lens front group (31) and the positive lens rear group (32) is C Used to adjust the divergence of the outgoing beam, Z C The circular ring light spot (6) has a ring width of micrometer or submicrometer order; the hollow circular ring light beam micro-shrinkage portion (3) has a focal depth of hundreds of micrometers order, exposing the circular ring microstructure unit of the curved surface sample (4) whose surface height fluctuation range is less than the focal depth length.

4. The method and device for photolithography of a circular microstructure array on a curved surface according to claim 1, characterized in that: The types of optical elements used in the hollow ring beam generating part (2) and the hollow ring beam miniaturizing part (3) include solid lenses made of optical glass, diffractive optical elements, holograms loaded on reflective and transmissive spatial light modulators, and metasurface lenses.

5. The method and device for photolithography of circular microstructure array on curved surface according to claim 1, characterized in that: The optical elements of the hollow ring beam generating part (2) and the hollow ring beam miniaturization part (3) are mounted on a linear displacement stage, and the distance Z between the elements is changed by the host computer during the exposure process. A and Z C , adjust the exposure size of the circular spot (6).

6. The method and device for photolithography of circular microstructure array on a curved surface according to claim 1, characterized in that: A combination of an achromatic cemented lens and a single lens with an achromatic function is used in the positive lens front group (31) and the positive lens rear group (32).

7. The method and device for photolithography of a circular microstructure array on a curved surface according to claim 1, characterized in that: The components in the laser light source (1) include a laser, a shutter, a beam collimator and a beam expander.

8. The method and device for photolithography of circular microstructure array on a curved surface according to claim 1, characterized in that: An adjustable light shielding plate is arranged between the hollow circular ring light beam generating part (2) and the hollow circular ring light beam miniaturization part (3) to shield part of the light of the hollow circular ring light beam (8) so that the modulated circular ring light spot (6) becomes a circular ring with a notch.

9. The method and device for photolithography of circular microstructure array on a curved surface according to claim 1, characterized in that: The photolithography types applicable to the method include: ultraviolet photolithography using conventional positive photoresist and negative photoresist, additive manufacturing using the principle of photocuring, and using high-power laser to ablate or denature the material coated on the surface of the curved sample (4).

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