A method for fabricating high-energy laser micro / nano structures based on patterned design of external optical path glass

Abstract

This invention discloses a method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical glass, belonging to the field of metal material surface processing technology. The method includes the following steps: coating an energy-absorbing material with a specific pattern onto the surface of optical glass according to the target micro / nano structure to prepare patterned optical glass; placing the patterned optical glass at a specific position in the external optical path between the converging laser emitter of a laser shock device and the target material; and performing laser shock treatment on the target material surface to generate the target micro / nano structure. This invention enables the simple construction of complex micro / nano structures, allows for cross-scale control of micro / nano structure dimensions, significantly reduces processing difficulty, has low cost, and allows for high flexibility by changing the position of the patterned optical glass according to actual scaling requirements.

Description

Technical Field

[0001] This invention relates to the field of metal material surface processing technology, and in particular to a method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical glass. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Laser micro-nano manufacturing technology, as one of the core technologies in modern precision machining, has shown great application potential in fields such as medicine and aerospace. Traditional top-down laser micro-nano manufacturing processes mainly rely on photolithography to form micro-nano structures, and their process accuracy is limited by the beam resolution and etching uniformity of the photolithography stage. However, photolithography has stringent requirements for laser beam quality (such as beam size and energy distribution uniformity), resulting in high equipment costs and low process economics.

[0004] Patent CN113967796B discloses a method for preparing superhydrophobic surfaces of aluminum alloy surfaces using laser shock embossing of micro / nanoparticles. This patent relies on complex pre- and post-processing techniques, and its use of a mixing ratio of micro / nanoparticles to control the formed micro / nano structures can easily lead to uneven distribution in practical applications, resulting in poor consistency of the surface micro / nano structures. Patent CN115703167B utilizes an ultra-high strain rate multi-step laser shock embossing process and a hard, vertically channeled, high-precision surface mold to manufacture ultra-fine metal micro / nano structures. This patent requires the use of hard ceramic or alloy molds, demands extremely high processing precision, has high manufacturing costs, and is prone to wear, making large-scale production difficult. Furthermore, it requires two steps for shock embossing, resulting in a long process cycle and high energy consumption.

[0005] Therefore, developing new micro-nano manufacturing technologies that are low-cost, easy to implement, and highly flexible has become a pressing technical challenge for the industry. Summary of the Invention

[0006] In view of this, the present invention provides a high-energy laser micro / nano structure manufacturing method based on the patterned design of external optical glass. The present invention "pre-positions" the micro / nano structure design in the laser propagation path, breaks through the dependence of traditional processes on direct processing of the target surface, and realizes low-cost and high-flexibility manufacturing of micro / nano structures in a high-energy laser environment.

[0007] This invention provides a method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass, comprising the following steps:

[0008] Patterned optical glass is fabricated by coating the surface of optical glass with energy-absorbing materials in specific patterns according to the target micro / nano structure.

[0009] Patterned optical glass is placed at a specific position in the external optical path between the converging laser emitter and the target material of the laser shock device; the target material is located between the converging laser emitter and the theoretical focal point of the converging laser.

[0010] An absorption layer and a constraint layer are sequentially set on the surface of the target material, and laser shock treatment is performed on the surface of the target material to generate the target micro-nano structure.

[0011] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0012] (1) In this invention, patterned optical glass is set in the external optical path. The area without energy-absorbing material will not affect the laser propagation path. After the laser impacts, a concave structure is formed on the surface of the target material. The area coated with energy-absorbing material will block the laser from passing through, and thus form a protruding structure on the corresponding target material surface. Therefore, this invention can realize the simple construction of complex micro-nano structures. At the same time, based on the focusing characteristics of the laser, the pattern size of the patterned optical glass is larger than the target micro-nano structure size of the target material. There is a certain scaling ratio relationship. Therefore, this invention can realize cross-scale control of the micro-nano structure size, greatly reduce the processing difficulty, lower the cost, and change the position of the patterned optical glass according to the actual scaling requirements, which is more flexible.

[0013] (2) This invention eliminates the need for complex pre-processing / post-processing steps, directly achieving energy regulation through the patterned design of the external optical path glass. This eliminates steps such as precision mold processing, particle mixing, and ultrasonic cleaning, significantly reducing equipment and consumable costs. Furthermore, this invention generates micro / nano structures in one step through energy modulation at the optical path end, avoiding multi-step laser impact, improving processing efficiency, and reducing processing energy consumption. Attached Figure Description

[0014] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0015] Figure 1 This is a schematic diagram of the high-energy laser micro / nano structure manufacturing process according to an embodiment of the present invention;

[0016] In the figure, 1 is the laser; 2 is the external optical path; 3 is the patterned optical glass; 4 is the area to be processed on the target surface; and 5 is the micro / nano structure. Detailed Implementation

[0017] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] This invention provides a method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass, comprising the following steps:

[0019] Patterned optical glass is fabricated by coating the surface of optical glass with energy-absorbing materials in specific patterns according to the target micro / nano structure.

[0020] Patterned optical glass is placed at a specific position in the external optical path between the converging laser emitter and the target material of the laser shock device; the target material is located between the converging laser emitter and the theoretical focal point of the converging laser.

[0021] An absorption layer and a constraint layer are sequentially set on the surface of the target material, and laser shock treatment is performed on the surface of the target material to generate the target micro-nano structure.

[0022] In this invention, the laser emitted by the laser is a converging beam, and the target material is located in front of the theoretical focal point of the laser. Therefore, the beam diameter gradually decreases with the propagation distance. During laser impact, the converging laser forms a focal spot on the target surface. This invention first precisely coats an energy-absorbing material onto the surface of optical glass based on the geometric characteristics (protrusions or depressions) of the target micro / nano structure, forming an enlarged pattern corresponding to the target micro / nano structure. The patterned optical glass is arranged in the converging external optical path between the laser and the target material. Utilizing the natural convergence characteristics of the laser beam, the energy-absorbing pattern is projected proportionally onto the target surface. If a protruding structure is required in a specific area of ​​the target surface, the energy-absorbing material covers the corresponding position on the optical glass; if a concave structure is required in a specific area of ​​the target surface, the energy-absorbing material is distributed in its peripheral area. The energy-absorbing material locally absorbs laser energy, forming a non-uniform plasma shock wave distribution on the target surface, driving selective plastic deformation of the material and directly generating the target micro / nano structure, enabling the precise manufacturing of specific target micro / nano structures. By adjusting the scaling factor, continuous scaling from micrometer to nanometer scale structures can be achieved in a single operation, enabling cross-scale control of micro / nano structure dimensions. This significantly reduces processing difficulty, lowers costs, and increases flexibility. This invention revolutionizes traditional laser micro / nano manufacturing by replacing "target-end design" with "optical path-end energy modulation." Through a three-pronged approach—the fabrication of patterned optical glass, dynamic position adjustment, and coordinated laser focusing—it solves the core problems of existing processes, such as reliance on physical molds, low processing freedom, and poor material adaptability. This achieves low-cost, high-precision, cross-scale manufacturing of micro / nano structures under high-energy laser conditions.

[0023] In this invention, the energy-absorbing material is black paint or black tape, with a coating thickness of 500 μm or more. Under laser irradiation, the energy-absorbing material absorbs laser energy in a specific area, resulting in localized energy attenuation and thus generating a non-uniform plasma shock wave distribution on the target surface. The thickness of the energy-absorbing material quantitatively affects the attenuation of pulsed laser energy, thereby indirectly adjusting the degree of micro / nano structure undulation through shock wave intensity: there is a threshold value for the thickness of the energy-absorbing material that prevents complete ablation, which is specifically determined by the laser energy set by the laser shock; the higher the laser energy value, the more energy-absorbing material is consumed, resulting in a larger threshold value for complete ablation; when the energy-absorbing material is thick enough, exceeding the threshold value, the laser energy is completely consumed at the patterned optical glass of the external optical path, and at this time, there is no laser shock wave effect on the area of ​​the target surface corresponding to the energy-absorbing material coating, and the height difference between the protrusions and depressions depends only on the amount of plastic deformation of the area of ​​the target surface corresponding to the uncoated energy-absorbing material; when the thickness of the energy-absorbing material does not exceed the threshold value, the laser energy cannot be completely consumed at the external optical path glass, and at this time, there is an attenuated laser shock wave effect on the area of ​​the target surface corresponding to the energy-absorbing material coating, and the height difference between the protrusions and depressions depends on the difference in the amount of plastic deformation of the area of ​​the target surface corresponding to the uncoated and coated energy-absorbing material.

[0024] In this invention, the side of the patterned optical glass coated with the energy-absorbing material faces away from the converging laser emitter to reduce the impact of energy-absorbing material ablation on laser energy penetration in the surrounding area. Furthermore, the coating thickness error is below 5% to avoid energy distribution distortion. The formula for the coating thickness error is as follows:

[0025]

[0026] In this invention, the coating step is implemented using direct writing, spraying, or photolithography. This invention does not impose any special limitations on specific implementation methods; any method commonly used in the art can be employed.

[0027] In this invention, the size of the patterned optical glass is y, the size of the target micro / nano structure on the target surface is x, the scaling factor is M, M = x / y, the distance between the focusing laser emitter of the laser impact device and the target is L2, and the theoretical focal length of the focusing laser of the laser impact device is f. Therefore, the formula for calculating the distance L1 between the patterned optical glass and the target is as follows:

[0028]

[0029] It should be noted that the theoretical focal length of the converging laser refers to the distance between the emitting end of the converging laser and the position where the laser focusing area is a point without area (the theoretical focus). Based on the characteristics of the converging laser, x < y, so M < 1. When the value of M is larger, the values of x and y are closer, and the distance L1 between the patterned optical glass and the target is closer; when the value of M is larger, y is larger, and the distance L1 between the patterned optical glass and the target is farther. Since the target is located between the emitting end of the converging laser and the theoretical focus of the converging laser, L2 < f. The present invention can select the scaling factor M as needed, and then determine the placement position of the patterned optical glass according to the theoretical focal length f of the converging laser and the distance L2 between the emitting end of the converging laser and the target.

[0030] In the present invention, 0.02 < M < 0.8, and further preferably 0.05 < M < 0.5. The value of M should not be too large. If it is too large, the distance L1 between the patterned optical glass and the target will be too close, which will not only significantly weaken the scaling effect, but also cause the patterned optical glass to receive too much laser impact energy, possibly causing damage to the optical glass.

[0031] In the present invention, corresponding to the morphological size of the micro-nano structure, the diameter of the laser spot on the surface of the target is preferably 50 - 1000 μm, and more preferably 100 - 500 μm.

[0032] In the present invention, the diameter of the spot at the emitting end of the converging laser of the laser shock device is 10 - 30 mm.

[0033] In the present invention, the optical glass is K9 glass. K9 glass has high light transmittance, low dispersion and good stability, and is suitable for optical requirements in high-precision imaging, laser technology and harsh environments. Further, the thickness of the optical glass is 1 - 3 mm.

[0034] In the present invention, the material of the absorption layer is black paint or black tape. The absorption layer is the material basis for laser-induced ablation to form plasma, and the plasma forms an impact effect within a limited time and space; the material of the constraint layer is K9 glass or deionized water. If K9 glass is used, it needs to be mechanically pressed on the absorption layer material, and bubbles should be avoided between the K9 glass and the absorption layer material; if deionized water is used, the water flow rate needs to be controlled to keep the water flow on the surface of the absorption layer stable and the thickness uniform.

[0035] The technical solution of the present invention will be further described below with specific embodiments.

[0036] Embodiment

[0037] This embodiment provides a method for manufacturing high-energy laser micro-nano structures based on the patterned design of an external optical path optical glass. The schematic diagram of the manufacturing process is as Figure 1 shown.

[0038] (1) Target material and laser parameters:

[0039] Target material: 304 stainless steel plate, 1mm thick, surface roughness Ra≤0.1μm.

[0040] Laser type 1: Nd:YAG pulsed laser; wavelength: 1064nm; pulse energy: 5J; pulse width: 18ns; repetition rate: 10Hz; emitter spot diameter: 20mm; theoretical laser focal length: f = 304.5mm (naturally converging beam).

[0041] (2) Preparation of patterned optical glass

[0042] ① Pattern design:

[0043] Target micro / nano structure: rectangular recessed array, unit size 200μm×80μm, recess spacing 2μm.

[0044] Based on the target recessed array, a 4mm×1.6μm rectangular energy-absorbing region is designed on the optical glass surface, with a spacing of 0.4mm between the energy-absorbing regions (scaled at M=0.05).

[0045] ② Coating process:

[0046] Using laser direct writing technology, a pyrolytic graphite coating is applied to the surface of optical glass with a thickness of 600μm±18μm (3% error); the edge sharpness of the coating is ≤2μm to ensure accurate energy distribution.

[0047] (2) Optical path arrangement and calibration

[0048] Target position: L2 = 300mm (located between the laser and the focal point, L2) <f);

[0049] The patterned optical glass 3 is placed in the laser external optical path 2. Installation location:

[0050]

[0051] The patterned optical glass 3 is 85.5 mm away from the target surface of the processing area 4 and 214.5 mm away from the laser 1.

[0052] Patterned optical glass 3 is fixed: The patterned optical glass 3 is installed on an electric translation stage with a positioning accuracy of ±0.05mm.

[0053] Laser beam alignment: Real-time monitoring using a CCD camera to ensure that the center of the patterned optical glass 3 coincides with the center of the laser spot (deviation ≤ 5μm).

[0054] (3) Laser shock treatment

[0055] An absorption layer and a constraint layer are coated from the inside out on the surface of the target material. The absorption layer material is 3M black tape, and the constraint layer material is K9 glass. A single laser impact (the laser spot diameter on the target surface is about 300μm) causes the laser to pass through the patterned optical glass 3. The energy-absorbing area absorbs energy and generates a local shock wave. The energy is reflected / scattered in the non-energy-absorbing area. The corresponding position of the target material is subjected to the pressure of the shock wave to form a micro-nano structure 5 (recessed array), which corresponds to the pattern on the patterned optical glass 3.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass, characterized in that, Includes the following steps: Patterned optical glass is fabricated by coating the surface of optical glass with energy-absorbing materials in specific patterns according to the target micro / nano structure. Patterned optical glass is placed at a specific position in the external optical path between the converging laser emitter and the target material of the laser shock device; the target material is located between the converging laser emitter and the theoretical focal point of the converging laser. An absorption layer and a constraint layer are sequentially deposited on the surface of the target material, and laser shock treatment is performed on the surface of the target material to generate the target micro-nano structure. The dimensions of the patterned optical glass are y The size of the target micro / nano structure on the target surface is x Scaling factor is M , M = x / y The distance between the laser converging emitter of the laser shock device and the target material is... L 2. The theoretical focal length of the focusing laser in the laser shock device is: f Then, the distance between the patterned optical glass and the target material... L The formula for calculating 1 is as follows: ； Among them, 0.02 <M<0.8。 2. The high-energy laser micro / nano structure manufacturing method based on patterned design of external optical path glass as described in claim 1, characterized in that, The energy-absorbing material is black paint or black tape, with a coating thickness of 500 μm or more.

3. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The coating thickness error value is below 5%, and the formula for the coating thickness error value is as follows: 。 4. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The coating step is achieved using direct writing, spraying, or photolithography.

5. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The diameter of the laser spot on the target surface is 50~1000μm.

6. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The diameter of the laser spot at the converging laser emitter of the laser shock device is 10-30 mm.

7. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The optical glass is K9 glass, and the thickness of the optical glass is 1~3 mm.

8. The method for manufacturing high-energy laser micro / nano structures based on patterned design of external optical path glass as described in claim 1, characterized in that, The absorbent layer is made of black paint or black tape, and the constraining layer is made of K9 glass or deionized water.

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