Multi-channel optical anti-counterfeiting pattern based on hierarchical structure as well as preparation method and application of multi-channel optical anti-counterfeiting pattern

Abstract

The invention belongs to the technical field of optical anti-counterfeiting, and particularly relates to a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure and a preparation method and application of the multi-channel optical anti-counterfeiting pattern. The preparation method comprises the following steps: respectively prefabricating a nickel impression with a periodic nanostructure and a nickel impression with a periodic micron structure; and the aluminum base with the work hardening effect is sequentially impressed through the nanometer nickel impression die and the micron nickel impression die. Through the method, the multi-channel optical anti-counterfeiting pattern based on the hierarchical structure is successfully prepared. Due to the fact that the periodic nanometer structures and the periodic micrometer structures have independent and different diffraction peaks respectively, people can decode different encrypted pattern information at different observation angles, and special tools or extra environmental stimulation do not need to be used. The characteristic is expected to play a key role in information security fields such as anti-counterfeiting, information encryption and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical anti-counterfeiting, and in particular relates to a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure, and a preparation method and application thereof. Background Art

[0002] In today's society, the problem of counterfeiting and shoddy products has significantly escalated and gradually penetrated into all aspects of daily life, causing huge economic losses and posing a serious threat to national security. In order to meet this challenge, researchers have developed various information encryption technologies, such as digital anti-counterfeiting technology, biological anti-counterfeiting technology, chemical anti-counterfeiting technology, and optical anti-counterfeiting technology. Among them, optical anti-counterfeiting technology has great application prospects in the field of information encryption due to its unique optical phenomena, such as reflection, absorption, transmission, diffraction and scattering, and intuitive visual impact effects. However, traditional single-channel optical anti-counterfeiting technology is extremely easy to imitate and copy. In order to achieve a higher level of encryption and reduce counterfeiting, researchers have further proposed multi-channel optical anti-counterfeiting technology.

[0003] Among these technologies, multiplexed holography allows multiple encryption channels to be embedded in the hologram to improve data security and anti-counterfeiting performance, and has become one of the most commonly used encryption methods. According to the size of the hologram, it can be divided into macroscopic holograms and holographic metasurfaces. The former is formed by recording multiple coherent interference patterns of object light and reference light using the principles of interference and diffraction of light. Although holographic images have excellent readability, their complex preparation process, strict environmental requirements, and the need for complex three-dimensional reconstruction technology limit their practical development in anti-counterfeiting applications. Holographic metasurfaces decode various hidden optical images by manipulating the degrees of freedom of light (such as wavelength, amplitude, or polarization), so that subwavelength structures with different arrangements and shapes produce unique variable electromagnetic responses. However, the fabrication of metasurfaces usually relies on technologies such as electron beam lithography or focused ion beam etching, which requires a lot of cost and preparation time. In addition, the pattern area of ​​holographic metasurfaces is extremely small, which poses a challenge to readability, so professional equipment such as microscopes / projectors must be used in conjunction with specific light sources, such as specific wavelengths or polarized light. These limitations hinder the practical applications of metasurfaces in the real world.

[0004] On the other hand, environmentally responsive metamaterials have emerged as another promising multi-channel optical anti-counterfeiting approach. By inducing changes in environmental factors (such as stress, humidity, gas composition, and ultraviolet light), parameters such as lattice spacing, observation angle, relative refractive index, and reflectivity (including fluorescence) of these metamaterials can be dynamically adjusted. This makes it possible to encrypt and decode various images by manipulating the brightness or chromaticity of the metamaterials. Although these materials have commendable modulation capabilities, their switching between different states usually takes a long time (ranging from seconds to minutes) and the number of switching times is limited, a limitation that may lead to reduced efficiency in practical applications. In addition, the integration of multiple materials into these systems will complicate their preparation process, which will seriously limit their widespread application.

[0005] Recent studies have shown that multi-channel encrypted patterns constructed with three-dimensional hierarchical structures have the potential to increase information complexity. This combination of precise arrangements from nanometers to micrometers enables more flexible manipulation of light and can present a variety of pattern information in real time. However, their preparation is limited to specific materials with relatively low-quality images. Therefore, designing an economical and effective strategy for multi-channel optical anti-counterfeiting patterns remains a difficult problem in the current research field. Summary of the invention

[0006] The technical problem to be solved by the present invention is to design a method for preparing multi-channel optical anti-counterfeiting patterns based on multi-step embossing technology by utilizing the work hardening phenomenon of the aluminum-based surface in view of the above-mentioned deficiencies in the prior art. This preparation method not only improves the complexity of optical information encryption, but also has the advantages of high readability and good material compatibility. It is suitable for a wide range of security identification and authentication needs, and realizes the rapid, large-scale, low-cost and scalable production of optical anti-counterfeiting patterns. It has important application prospects in future optical anti-counterfeiting material technology.

[0007] To achieve the above object, the present invention adopts the following technical solution: a method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure, comprising the following steps:

[0008] S1. Preparation of a nano-nickel stamp having a coding pattern A1:

[0009] A silicon plate with a periodically arranged nanopore array is used as a silicon template, a noble metal layer is deposited on the surface of the silicon template where the nanopore array is located, and then the template is placed in an electrolyte as a working electrode for nickel electrochemical deposition. After the deposition is completed, the deposited film on the surface is removed to obtain a nano-nickel stamp with a nano-protrusion array;

[0010] An aluminum foil pretreated by electrochemical polishing is taken, and the nano-nickel stamp having the nano-protrusion array structure is used for imprinting, and then the imprinted aluminum foil is engraved with a laser to remove the nano-structure in the redundant area to obtain the desired coding pattern A1, and then the foil is placed in an electrolyte as a working electrode for nickel electrochemical deposition, and after the deposition is completed, the deposited film on the surface is removed to obtain a nano-nickel stamp having a nano-protrusion array and the array is distributed in the coding pattern A1;

[0011] Alternatively, repeat the above steps to prepare nano-nickel stamps having coding patterns A2-Am respectively;

[0012] S2. Preparation of a micron nickel stamp having a coding pattern B1:

[0013] An ordered and densely packed single-layer PS microsphere array is prepared on the surface of a silicon wafer by a gas-liquid interface self-assembly process, and then the single-layer PS microsphere array on the surface of the silicon wafer is treated with a laser to remove the PS microspheres in the redundant area, so as to obtain a single-layer PS microsphere array distributed in the coding pattern B1, and then a PDMS solution is coated on the single-layer PS microsphere array distributed in the coding pattern 2, and the PDMS film layer is peeled off after curing to obtain a PDMS template having a micron hole array and the array is distributed in the coding pattern 2; the above-mentioned PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition, and after the deposition is completed, the deposited film on the surface is removed to obtain a micron nickel stamp having a micron protrusion array and the array is distributed in the coding pattern B1;

[0014] Alternatively, a layer of photoresist film is spin-coated on a clean silicon wafer, and after baking and curing, a mask plate is covered on the surface and exposed, the mask plate has a coding pattern B1, and after development treatment, a micrometer hole array penetrating the photoresist film is obtained on the photoresist film, and the array is distributed in the coding pattern B1, the mask plate is removed, and a PDMS solution is coated on the developed photoresist film. After curing, the PDMS film layer is peeled off to obtain a PDMS template having a micrometer hole array and the array is distributed in the coding pattern B1; the above-mentioned PDMS template is used for nickel electrochemical deposition, and after the deposition is completed, the deposited film on the surface of the working electrode is removed, which is a micrometer nickel stamp having a micrometer protrusion array and the array is distributed in the coding pattern B1;

[0015] Alternatively, repeat the above steps to prepare micron nickel stamps having coding patterns B2-Bn respectively;

[0016] S3. Select one or more of the nano-nickel stamps prepared in step S1 to perform the first imprinting on the aluminum sheet, and then select one or more of the micron nickel stamps prepared in step S2 to perform the second imprinting. The centers of the two imprinted coding patterns correspond to each other, and a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure can be obtained on the aluminum sheet.

[0017] As a further improvement of the preparation method of the multi-channel optical anti-counterfeiting pattern based on the hierarchical structure:

[0018] Preferably, in step S3, two of the nano-nickel stamps with different coding patterns obtained in step S1 are selected and sequentially imprinted on an aluminum sheet, and the structures in the two nano-nickel stamps are both nano-grating arrays, and the grating arrays imprinted twice on the plane of the aluminum sheet are perpendicular to each other; then two of the micron-nickel stamps with different coding patterns obtained in step S2 are selected and sequentially imprinted on an aluminum sheet, and the structures in the two micron-nickel stamps are both micron-grating arrays, and the grating arrays imprinted twice on the plane of the aluminum sheet are perpendicular to each other; when imprinting multiple times, the centers of the coding patterns correspond to each other, and a four-channel optical anti-counterfeiting pattern based on a hierarchical structure can be obtained on the aluminum sheet.

[0019] Preferably, the electrolyte contains an aqueous solution of 0.12M NiCl2, 0.12M NiSO4 and 0.5M H3BO3, and the nickel electrochemical deposition is carried out at 2mA cm -2 The current density lasts for 18-24h.

[0020] Preferably, the arrangement of the nanopores in the nanopore array on the silicon template in step S1 is quadrilateral, hexagonal or grating arrangement; when the nano-nickel stamp with a nano-protrusion array structure is used to emboss the pre-treated aluminum foil in step S1, the applied pressure is 12-20MPa; when the aluminum foil or the single-layer PS microsphere array after engraving is performed using a laser, the wavelength is 360nm, the power is 0.4W, and the tool spacing is 5μm; in step S2, the particle size of the PS microspheres is 2.5μm, and the PS microspheres in excess areas are removed by laser processing, the laser wavelength is 360nm, the power is 0.4W, and the tool spacing is 5μm.

[0021] Preferably, the PDMS solution described in step S2 is produced by mixing the prepolymer polydimethylsiloxane PDMS and the cross-linking agent in a mass ratio of 5:1, the coating thickness is more than 5 mm, and then placed at 60° C. for curing for 2-4 hours; the model of the photoresist in step S2 is AR 5350, and the thickness of the photoresist film is 5-10 μm.

[0022] Preferably, in step S2, a double-sided alignment lithography machine is used to expose the surface with a mask plate, and the exposure dose is 50-56 mJ cm -2 .

[0023] Preferably, the specific steps of the development treatment in step S2 are: placing in a developer having a volume ratio of AR300-26 to water of 1:7 for development for 40-45 seconds, and then drying.

[0024] Preferably, the pressure of the first printing press is 12-20 MPa, and the pressure of the second printing press is 1-5 MPa.

[0025] A second object of the present invention is to provide a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure obtained by the preparation method based on the multi-step imprinting technology described in any one of the above.

[0026] A third object of the present invention is to provide an application of any of the above-mentioned multi-channel optical anti-counterfeiting patterns based on a hierarchical structure in optical anti-counterfeiting.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The present invention provides a method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure, and the technical principles based on each step are as follows:

[0029]

[0030] Wherein, λ is the diffraction center wavelength, m and n are the diffraction order and the medium refractive index, d is the period spacing, and α and θ are the incident and reflection angles of light, respectively. When other conditions are the same, since the microstructure and the nanostructure have different period spacings d, different diffraction wavelengths λ will be displayed at different angles. Therefore, patterns based on micro-nano hierarchical structures will display different patterns at different angles. The present invention can easily obtain a micro-nano composite nickel stamp for one-step imprinting by electrochemically depositing anti-counterfeiting patterns that have been imprinted multiple times, and achieve high-precision pattern transfer under the action of pressure. This preparation method not only provides a new idea for the preparation of high-performance multi-channel optical anti-counterfeiting patterns based on hierarchical structures, but also has extremely important significance for promoting its practical application, and can be used for large-scale production of micro-nano composite nickel stamps.

[0031] 2) The multi-channel optical anti-counterfeiting pattern based on the hierarchical structure prepared by the present invention has the following excellent properties:

[0032] (1) Powerful encryption capability. On the one hand, since the nano and micro array structures in the hierarchical structure exhibit different independent diffraction peaks, when illuminated by white light, we can directly decode the dual-channel encrypted pattern from different observation angles. On the other hand, by introducing mutually perpendicular nano and micro grating structures, the present invention can realize a more complex four-channel coding pattern, and each channel can independently encode and customize different anti-counterfeiting information, thereby greatly improving the information capacity and security performance of the optical anti-counterfeiting pattern.

[0033] (2) Excellent readability. The prepared multi-channel optical anti-counterfeiting patterns based on hierarchical structures can be observed directly under sunlight or with simple light sources such as flashlights, without the assistance of special light sources and tools such as microscopes / projectors. In addition, these multi-channel patterns can be decoded immediately without the need for environmental stimulation such as stress, voltage (current), humidity, temperature, gas or ultraviolet light;

[0034] (3) Wide material applicability. Based on the unique multi-step imprinting method of surface work hardening, the preparation process does not require photoresist or complex optical systems and is applicable to a variety of materials such as aluminum, zinc, silver, copper, PET, etc., enhancing its potential for practical application;

[0035] (4) It can be produced quickly, on a large scale, and at low cost. On the one hand, the proposed multi-channel optical anti-counterfeiting pattern based on the hierarchical structure can be easily replicated on a large scale through an improved roll-to-roll imprinting method. On the other hand, the nano- and micro-nickel stamps used for multi-step imprinting can not only be replicated hundreds of times through electrochemical deposition, but can also be reused hundreds of times in the actual imprinting process. Therefore, the production cost of these optical anti-counterfeiting patterns can be less than 1 cent / square centimeter, which has the advantages of simple process, high reliability, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is based on the coding principle of preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure based on multiple imprinting. When white light is irradiated at a specific angle, the hierarchical structure can be N1,N2,N3... The observation angle range shows a completely independently encoded nanoimprint pattern, denoted as “KEY 1”; while in θ M1,M2,M3... The observation angle range shows a completely independently encoded micro-embossed pattern, denoted as "KEY 2".

[0037] Figure 2 The schematic diagram of the preparation process of a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure using a multi-step imprinting method and the optical and morphological characterization of the product obtained in Example 1. Figure 2 A is a schematic diagram of the optical anti-counterfeiting pattern preparation process. Figure 2 B is an optical photograph of the structural color pattern produced by the nanostructure at different observation angles. Figure 2 C is an optical photograph of the structural color pattern produced by the microstructure at different observation angles. Figure 2 E is a scanning electron microscope (SEM) image of the connection area between the hierarchical structure and the nanostructure. Figure 2 D is the magnified SEM image of the nanostructure. Figure 2 F is the magnified SEM image of the hierarchical structure.

[0038] Figure 3SEM images of various hierarchical structures consisting of nano- and micro-structures of varying periods and arrangements were obtained for Examples 2-5. Figure 3 A to Figure 3 D shows the SEM images of the hierarchical structures composed of 600nm squares + 4μm hexagons, 400nm squares + 4μm hexagons, 360nm gratings + 4μm hexagons, and 600nm squares + 4μm arranged gratings.

[0039] Figure 4 The figure is a comparison of the diffraction spectra of the hierarchical structure formed by the 600 nm periodic nanostructure, the 2.5 μm periodic microstructure and their combination prepared in Example 1.

[0040] Figure 5 This is a four-channel coding pattern prepared by multi-step embossing in Example 6, wherein each channel can be independently encoded with different customized anti-counterfeiting information. Figure 5 A is the conceptual design of a four-channel angle light encryption pattern. The left side is a schematic diagram of the grating alignment direction from top to bottom, and the right side is an observation diagram. Figure 5 B is the simulated angle-resolved spectrum mapping of the nanograting with a period of 360 nm. Figure 5 C is the simulated angular resolved spectral mapping of a micron grating with a period of 4 μm. Figure 5 D shows the observation results under different incident light and viewing angles.

[0041] Figure 6 The invention provides a scalable manufacturing method for the optical anti-counterfeiting pattern and a demonstration of its practical application. Figure 6 a is a schematic diagram of the improved roll-to-roll embossing machine for large-scale production. Figure 6 b shows a photograph of the anti-counterfeiting pattern prepared on an aluminum coil several meters long. Figure 6 c shows the anti-counterfeiting pattern embossed on the aluminum coil and the information encoded at different viewing angles. Figure 6 d shows the thermal stability of the anti-counterfeiting pattern. Figure 6 e demonstrates the reproducibility of the anti-counterfeiting pattern on different materials. Figure 6 f is an example diagram of the application of anti-counterfeiting products in real life. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for preparing a dual-channel optical anti-counterfeiting pattern, and the specific steps are as follows:

[0045] S1. Preparation of a nano-nickel stamp having a coding pattern A1:

[0046] A photolithographic silicon wafer with a periodic nanopore array arranged in a square pattern and a period of 600 nm was used as a template. Electron beam evaporation was used to deposit a 10 nm thick nanopore on the surface of the silicon template where the nanopore openings were located (deposition rate was 0.1 nm s -1 ) and then placed in an electrolyte as a working electrode for nickel electrochemical deposition (where the silicon template is used as the cathode, the Ni plate is used as the anode, the electrolyte is composed of 0.12MNiCl2, 0.12MNiSO4 and 0.5M H3BO3, and the current density is 2mAcm -2 , deposition time is 24h), to obtain a nano-nickel stamp with a nano-protrusion array;

[0047] Take the aluminum foil pretreated by electrochemical polishing, and use the above-mentioned nano-nickel stamp with a nano-protrusion array structure to imprint (the applied pressure is 12-20MPa, and the imprinting time is 10s), and then use a laser (wavelength of 360nm, power of 0.4W) to engrave the imprinted aluminum foil (the knife spacing is 5μm), remove the nanostructure in the redundant area, and obtain the required coding pattern A1; then place the above-mentioned aluminum foil with the coding pattern A1 in an electrolyte as a working electrode and perform nickel electrochemical deposition again (the electrolyte composition and deposition parameters are the same as above), and after the deposition is completed, remove the deposited film on the surface to obtain a nano-nickel stamp with a nano-protrusion array and the array is distributed in the coding pattern A1;

[0048] S2. Preparation of a micron nickel stamp having a coding pattern B1:

[0049] A single-layer orderly arranged PS microsphere array (PS microspheres with a particle size of 2.5 μm, uniform distribution, hexagonal arrangement, and a period of 2.5 μm) was prepared on the surface of a silicon wafer by a gas-liquid interface self-assembly process. The single-layer PS microsphere array was treated with a laser (wavelength of 360 nm, power of 0.4 W) to remove the PS microspheres in the redundant area to obtain a single-layer PS microsphere array with a coded pattern B1 distribution. Then, a PDMS solution (prepolymer polydimethylsiloxane) was coated on the single-layer PS microsphere array with a coded pattern B1 distribution. PDMS and a cross-linking agent are mixed in a mass ratio of 5:1, with a thickness of more than 5 mm, and cured at 60°C for 2-4 hours, and the PDMS film layer is peeled off after curing to obtain a PDMS template having a micron hole array and the array is distributed in a coding pattern B1; the above PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition (the electrolyte and deposition parameters are the same as above), and after the deposition is completed, the deposited film on the surface of the working electrode is removed to obtain a micron nickel stamp having a micron protrusion array and the array is distributed in a coding pattern B1;

[0050] S3. Imprint nano and micro structures

[0051] First, the nano-nickel imprint film prepared as above is used to perform the first imprint on the aluminum sheet (the applied pressure is 12-20Mpa), and then the micron nickel imprint film prepared in step S2 is used to perform the second imprint (the applied pressure is 1-5Mpa). The coding patterns of the two imprints correspond to each other, and the patterns on the nano-nickel imprint and the micron nickel imprint can be imprinted on the aluminum sheet at the same time, and finally a dual-channel optical anti-counterfeiting pattern based on a hierarchical structure is obtained.

[0052] Example 2

[0053] This embodiment provides a method for preparing a dual-channel optical anti-counterfeiting pattern, and the specific steps are as follows:

[0054] S1. Preparation of a nano-nickel stamp having a coding pattern A2:

[0055] A photolithographic silicon wafer with a periodic nanopore array arranged in a square pattern and a period of 600 nm was used as a template. Electron beam evaporation was used to deposit a 10 nm thick nanopore on the surface of the silicon template where the nanopore openings were located (deposition rate was 0.1 nm s -1 ) and then placed in an electrolyte as a working electrode for nickel electrochemical deposition (where the silicon template is used as the cathode, the Ni plate is used as the anode, the electrolyte is composed of 0.12MNiCl2, 0.12MNiSO4 and 0.5M H3BO3, and the current density is 2mAcm -2 , deposition time is 24h), to obtain a nano-nickel stamp with a nano-protrusion array;

[0056] Take the aluminum foil pretreated by electrochemical polishing, and use the above-mentioned nano-nickel stamp with a nano-protrusion array structure to imprint (the applied pressure is 12-20MPa, and the imprinting time is 10s), and then use a laser (wavelength of 360nm, power of 0.4W) to engrave the imprinted aluminum foil (the knife spacing is 5μm), remove the nanostructure in the redundant area, and obtain the required coding pattern A2; then place the above-mentioned aluminum foil with the coding pattern A2 in an electrolyte as a working electrode and perform nickel electrochemical deposition again (the electrolyte composition and deposition parameters are the same as above), and after the deposition is completed, remove the deposited film on the surface to obtain a nano-nickel stamp with a nano-protrusion array and the array is distributed in the coding pattern A2;

[0057] S2. Preparation of a micron nickel stamp having a coding pattern B2:

[0058] The cleaned silicon wafer was placed on a coating machine and a layer of photoresist film (AR 5350, 30 seconds, 5 μm thickness) was spin-coated at 6000 rpm and pre-dried at 105 °C for 4 minutes. Then, the mask was covered and exposed (53 mJ cm -2 The photoresist film is exposed to light (exposure dose), and then placed in a developer (AR300-26 and water in a volume ratio of 1:7) for development for 40 seconds, and a micrometer hole array with a hexagonal arrangement and a period of 4 μm is formed on the photoresist film, and the array is distributed in the coding pattern B2; a PDMS solution (prepolymer polydimethylsiloxane (PDMS) and a cross-linking agent are mixed in a mass ratio of 5:1, with a thickness of more than 5 mm, and cured at 80°C for 2 hours) is coated on the developed photoresist film, and the PDMS film layer is peeled off after curing to obtain a PDMS template with a micrometer hole array and an array distributed in the coding pattern B2; the above-mentioned PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition (the electrolyte and deposition parameters are the same as above), and after the deposition is completed, the deposited film on the surface of the working electrode is removed to obtain a micron nickel stamp with a micrometer hole array and an array distributed in the coding pattern B2.

[0059] S3. Imprint nano and micro structures

[0060] First, the nano-nickel imprint film prepared as above is used to perform the first imprint on the aluminum sheet (the applied pressure is 12-20Mpa), and then the micron nickel imprint film prepared in step S2 is used to perform the second imprint (the applied pressure is 1-5Mpa). The coding patterns of the two imprints correspond to each other, and the patterns on the nano-nickel imprint and the micron nickel imprint can be imprinted on the aluminum sheet at the same time, and finally a dual-channel optical anti-counterfeiting pattern based on a hierarchical structure is obtained.

[0061] Example 3

[0062] This embodiment provides a method for preparing a dual-channel optical anti-counterfeiting pattern. The specific steps refer to Example 2, except that when preparing the nano-nickel stamp with the coding pattern A2 in step S1, the period of the periodic nanohole array on the silicon template used is changed from 600nm to 400nm.

[0063] Example 4

[0064] This embodiment provides a method for preparing a dual-channel optical anti-counterfeiting pattern. The specific steps refer to Example 2, except that when preparing a nano-nickel stamp with a coding pattern A2 in step S1, the periodic nanostructure on the silicon template used is changed from a nanohole array with a period of 600nm to a one-dimensional grating array with a period of 360nm.

[0065] Example 5

[0066] This embodiment provides a method for preparing a dual-channel optical anti-counterfeiting pattern. The specific steps refer to Example 2, except that when preparing a micron nickel stamp with a coding pattern B2 in step S2, the structure formed on the photoresist film is changed from the original micron hole array to a one-dimensional grating array with the same period.

[0067] Example 6

[0068] This embodiment provides a method for preparing a four-channel optical anti-counterfeiting pattern, and the specific steps are as follows:

[0069] S1. Preparation of a nano-nickel stamp having a coding pattern A3:

[0070] A photolithographic silicon wafer with a nano-grating array with a period of 360 nm was used as a template. The surface of the nano-grating array on the silicon template was deposited with a thickness of 10 nm by electron beam evaporation (deposition rate was about 0.1 nm s -1 ) as a conductive layer, and then placed in an electrolyte as a working electrode for nickel electrochemical deposition (where the silicon template is used as the cathode, the Ni plate is used as the anode, the electrolyte is composed of 0.12MNiCl2, 0.12M NiSO4 and 0.5M H3BO3, and the current density is 2mA cm -2 , deposition time is 24h), to obtain a nano-nickel stamp with a nano-protrusion array;

[0071] Take the aluminum foil pretreated by electrochemical polishing, and use the above-mentioned nano-nickel stamp with a nano-protrusion array structure to imprint (the applied pressure is 12-20MPa, and the imprinting time is 10s), and then use a laser (wavelength of 360nm, power of 0.4W) to engrave the imprinted aluminum foil (the knife spacing is 5μm), remove the nanostructure in the redundant area, and obtain the required coding pattern A3; then place the above-mentioned aluminum foil with the coding pattern A3 in an electrolyte as a working electrode and perform nickel electrochemical deposition again (the electrolyte composition and deposition parameters are the same as above), and after the deposition is completed, remove the deposited film on the surface to obtain a nano-nickel stamp with a nano-protrusion array and the array is distributed in the coding pattern A3;

[0072] S2. Preparation of a nano-nickel stamp having a coding pattern A4:

[0073] A photolithographic silicon wafer with a nano-grating array with a period of 360 nm was used as a template. The surface of the nano-grating array on the silicon template was deposited with a thickness of 10 nm by electron beam evaporation (deposition rate was about 0.1 nm s -1 ) as a conductive layer, and then placed in an electrolyte as a working electrode for nickel electrochemical deposition (where the silicon template is used as the cathode, the Ni plate is used as the anode, the electrolyte is composed of 0.12MNiCl2, 0.12M NiSO4 and 0.5M H3BO3, and the current density is 2mA cm -2 , deposition time is 24h), to obtain a nano-nickel stamp with a nano-protrusion array;

[0074] Take the aluminum foil pretreated by electrochemical polishing, and use the above-mentioned nano-nickel stamp with a nano-protrusion array structure to imprint (the applied pressure is 12-20MPa, and the imprinting time is 10s), and then use a laser (wavelength of 360nm, power of 0.4W) to engrave the imprinted aluminum foil (the knife spacing is 5μm), remove the nanostructure in the redundant area, and obtain the required coding pattern A4; then place the above-mentioned aluminum foil with the coding pattern A4 in an electrolyte as a working electrode and perform nickel electrochemical deposition again (the electrolyte composition and deposition parameters are the same as above), and after the deposition is completed, remove the deposited film on the surface to obtain a nano-nickel stamp with a nano-protrusion array and the array is distributed in the coding pattern A4;

[0075] S3, preparing a micron nickel stamp having a coding pattern B3:

[0076] The cleaned silicon wafer was placed on a coating machine and a layer of photoresist film (AR 5350, 30 seconds, 5 μm thickness) was spin-coated at 6000 rpm and pre-dried at 105 °C for 4 minutes. Then, the mask was covered and exposed (53 mJ cm -2The photoresist film is placed in a developer (AR300-26 and water in a volume ratio of 1:7) for 40 seconds, and a micron grating array (period of 4 μm) is formed on the photoresist film, and the array is distributed in a coding pattern B3; a PDMS solution (prepolymer polydimethylsiloxane (PDMS) and a cross-linking agent are mixed in a mass ratio of 5:1, with a thickness of more than 5 mm, and cured at 80°C for 2-4 hours) is coated on the developed photoresist film, and the PDMS film layer is peeled off after curing to obtain a PDMS template having a micron grating array and an array distributed in a coding pattern B3; the PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition (the electrolyte and deposition parameters are the same as above), and after the deposition is completed, the deposited film on the surface of the working electrode is removed to obtain a micron nickel stamp having a micron grating array and an array distributed in a coding pattern B3.

[0077] S4, preparing a micron nickel stamp having a coding pattern B4:

[0078] The cleaned silicon wafer was placed on a coating machine and a layer of photoresist film (AR 5350, 30 seconds, 5 μm thickness) was spin-coated at 6000 rpm and pre-dried at 105 °C for 4 minutes. Then, the mask was covered and exposed (53 mJ cm -2 The photoresist film is placed in a developer (AR300-26 and water in a volume ratio of 1:7) for 40 seconds, and a micron grating array (period of 4 μm) is formed on the photoresist film, and the array is distributed in a coding pattern B4; a PDMS solution (prepolymer polydimethylsiloxane (PDMS) and a cross-linking agent are mixed in a mass ratio of 5:1, with a thickness of more than 5 mm, and cured at 80°C for 2-4 hours) is coated on the developed photoresist film, and the PDMS film layer is peeled off after curing to obtain a PDMS template having a micron grating array and an array distributed in a coding pattern B4; the PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition (the electrolyte and deposition parameters are the same as above), and after the deposition is completed, the deposited film on the surface of the working electrode is removed to obtain a micron nickel stamp having a micron grating array and an array distributed in a coding pattern B4.

[0079] S5. Imprint nano and micro structures

[0080] The nano-nickel imprint films prepared in the above steps S1 and S2 are respectively embossed twice on the aluminum sheet (the pressure applied is 12-20 MPa, and the nano-gratings on the nano-nickel imprint films must be ensured to be perpendicular to each other during the two embossing processes), and then the micron nickel imprint films prepared in steps S3 and S4 are embossed twice (the pressure applied is 1-5 MPa, and the micron gratings on the micron nickel imprint films must be ensured to be perpendicular to each other during the two embossing processes). The coding patterns A3 and A4 on the nano-nickel imprint and the coding patterns B3 and B4 on the micron nickel imprint can be simultaneously embossed on the aluminum sheet, and finally a four-channel optical anti-counterfeiting pattern based on a hierarchical structure is obtained.

[0081] Performance tests and test results:

[0082] (1) The present invention uses multi-step embossing to prepare a dual-channel optical anti-counterfeiting pattern based on a hierarchical structure. Figure 1 As shown. The anti-counterfeiting pattern consists of a periodic nanostructure, a periodic microstructure and a periodic nano / micro hierarchical structure. Since the periodic nanostructure and the periodic microstructure have completely different diffraction spectra, the hierarchical structure composed of the two has these two independent and different diffraction spectra at the same time. This makes such a hierarchical structure suitable for the design of dual-channel optical anti-counterfeiting patterns. Therefore, when white light is irradiated onto the hierarchical structure at a specific angle, it can be diffracted in the diffraction angle range θ n1 (θ n2 ,θ n3 …) shows a completely independent encrypted nanoimprint image “KEY 1”, and in the diffraction angle area θ m1 (θ m2 ,θ m3 …) displays a completely independent encrypted micro-imprint image “KEY 2”.

[0083] (2) Figure 2 Schematic diagram of the preparation process of a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure prepared by a multi-step imprinting method in Example 1, as well as the optical and morphological characterizations.

[0084] in, Figure 2 A in the figure is a schematic diagram of the optical anti-counterfeiting pattern preparation process. Figure 2Figure A shows in detail the preparation process of the dual-channel optical anti-counterfeiting pattern. First, by imprinting a nano-nickel stamp with a coding pattern A1 (e.g., a circle) onto an aluminum sheet, an initial periodic nanostructure was successfully constructed on the surface of the aluminum sheet. Subsequently, the work hardening phenomenon of the aluminum base during the nanoimprinting process was utilized, and the micron-nickel stamp with a coding pattern B1 (e.g., a butterfly) was also accurately imprinted onto the aluminum sheet, thereby further constructing a periodic micron structure based on the initial nanostructure. This work hardening phenomenon ensures that the nanostructure can be effectively retained and replicated during the subsequent microimprinting process. Finally, through this simple two-step imprinting step, a pattern structure with dual-channel optical anti-counterfeiting characteristics was successfully prepared. It is worth noting that these nano- and micron-nickel stamps used for imprinting can be reused more than hundreds of times. The entire imprinting process takes only a few seconds, without the use of photoresist and a complex light source system, which significantly reduces the time required to prepare a hierarchical structure.

[0085] Figure 2 B is an optical photograph of the structural color pattern produced by the nanostructure at different observation angles. Figure 2 (C) is an optical photograph of the structural color pattern produced by the microstructure at different observation angles. Figure 2 Medium B and Figure 2 C in the middle was taken with a Nikon Z6 camera under white light on a self-made optical platform. The platform can adjust the height (H) and angle (θ) of the camera, the position (x, y) and direction of the sample and the direction of the incident light (α) to ensure that photos can be taken in all situations. The white light is parallelized by a series of concave and convex lenses. Since the periodic nano- and micro-structures exhibit different diffraction spectra, the encrypted information designed in the hierarchical structure can be decoded into different patterns at different observation angles. Figure 2 As shown in Figure B, under 45° white light illumination, when the observation angle changes from 0° to 20°, circular coding patterns of different colors are displayed on the hierarchical structure sample composed of 600nm periodic nanostructures and 2.5μm periodic microstructures, which are blue, cyan, green, gray, yellow and red in sequence. Figure 2 As shown in C, when the observation angle changes from -10° to -18°, or from -60° to -68°, the sample shows a butterfly coding pattern of different colors, red, yellow and blue, or orange, green and blue. In addition, the pattern can also be decoded by changing the direction of the light source.

[0086] The surface morphology of the samples was characterized by scanning electron microscopy (Zeiss Gemini 450, Germany) and atomic force microscopy (Bruker Dimension ICON, USA). Figure 2 D in the figure is the magnified SEM image of the nanostructure. Figure 2 (E) is a scanning electron microscope (SEM) image of the connection area between the hierarchical structure and the nanostructure. Figure 2 F is the enlarged SEM image of the hierarchical structure. Figure 2 Figure E shows a scanning electron microscope (SEM) image of the edge of the butterfly. It can be clearly seen that the area not stamped by the micron nickel stamp remains unchanged, and is still a periodic nanostructure formed after one stamping, such as Figure 2 As shown in D. The area further stamped by the micron nickel stamp is transformed into a regular hierarchical structure composed of periodic nano- and micro-structures, as shown in Figure 2 As shown in F.

[0087] (3) The microscopic morphology of the sample surface was characterized using scanning electron microscopy (Zeiss Gemini 450, Germany) and atomic force microscopy (Bruker Dimension ICON, USA). Figure 3 SEM images of various hierarchical structures composed of nano- and micro-structures with different periods and arrangements. Figure 3 A to D show 600nm square + 4μm hexagon ( Figure 3 A, Example 2), 400nm square + 4μm hexagon ( Figure 3 Middle B, Example 3), 360nm grating + 4μm hexagon ( Figure 3 C, Example 4) and 600nm square + 4μm grating ( Figure 3 (D), SEM image of the hierarchical structure of the composition of Example 5).

[0088] Depend on Figure 3 It can be seen that this two-step imprinting method can also be used to quickly prepare a series of other hierarchical structures with different periodic nano- and micro-structure combinations. The well-preserved morphology and clear boundaries of the hierarchical structures demonstrate the reliability and wide applicability of the two-step imprinting method.

[0089] (4) Spectral simulation: In order to accurately predict the decoding angle of the pattern, a simulation analysis method combining the Matrix Laboratory and the Finite-Difference Time-Domain is used to accurately predict the diffraction spectrum angle and intensity of the periodic nano, micron and hierarchical structures obtained in Example 1. Spectral test: The backscattering spectrum (i.e., diffraction spectrum) of the sample was measured using a micro-area angle-resolved spectrometer (Shanghai Ideaoptics Corp., Ltd.). The white light from the halogen lamp was irradiated onto the sample surface, and then the reflected signal was collected by a Princeton Instrument 300 spectrometer using a 100× / 0.9NA objective lens. After Fourier transformation and removal of the influence of the background and incident light source, the angularly resolved spectral data was finally obtained.

[0090] like Figure 4 As shown in A to C, their angle-resolved spectral mappings in the visible spectrum under 45° white light incidence are simulated. Figure 4 As shown in Figure A, the nanostructure with a period of 600 nm exhibits an extremely strong specular reflection peak at -45° (also called zero-order diffraction, marked as "0"), a relatively strong first-order nano-diffraction peak shift line between 0° and 25° (marked as "N1"), and a relatively weak second-order nano-diffraction peak shift line above 40° (marked as "N2"). Figure 4 As shown in Figure B, for a micron structure with a period of 2.5 μm, a strong reflection peak (marked as "0") is observed at -45°, accompanied by multi-order micron diffraction peak shift lines in different angle ranges (marked as "M1", "M2", "M3" ... "MX"), and the light intensity decreases with the increase of the diffraction order. Figure 4 As shown in C, for the hierarchical structure composed of nanostructures and microstructures, its angle-resolved diffraction peak shift line is almost a combination of the diffraction peak shift lines of the two structures. In addition, Figure 4 The relative relationship between the diffraction angle and reflection intensity of the hierarchical structure in Figure 3 intuitively demonstrates the different diffraction effects in different angle regions, such as the nano-pattern region, micro-pattern region, and mirror reflection region, which can be used to decode information. It is worth noting that in the spectral mapping of the hierarchical structure ( Figure 4 In Figure C), although high-order micron diffraction (M3 to MX) is observed within the nanopattern angle range, its reflection intensity is relatively low compared to N1, and its effect on the display of the nanopattern is small, so it can be ignored. Here, the present invention defines a standard: if the color intensity of the microstructure in a given area is less than 1 / 10 of the color intensity of the nanostructure, the area is classified as a nanopattern area; otherwise, it is classified as a mixed pattern area. Further, as Figure 4As shown in E to H, the experimentally measured peak positions are basically consistent with the simulation results, which proves the reliability and feasibility of the above simulation method in predicting diffraction spectra.

[0091] In addition, N1 and M1 are considered to be the best observation areas due to their highest optical intensity and can be extracted from the above mapping. According to the spectral information, the diffraction peak of the nanostructure with a period of 600nm red-shifts from about 420nm to about 650nm ( Figure 4 I), which differs from the spectrum displayed by the hierarchical structure by only about 2° ( Figure 4 Similarly, the diffraction peak of the microstructure with a period of 2.5 μm is red-shifted from -29° to -25° in the visible range ( Figure 4 J), which differs from the spectrum displayed by the hierarchical structure by only about 1° ( Figure 4 This result also explains why the entire sample area can maintain uniform color at a given angle (nano, micro, and hierarchical structures exist in the sample at the same time). In summary, the combination of micro and nano structures with different periods can be designed for dual-channel anti-counterfeiting patterns.

[0092] (5) Preparation and anti-counterfeiting effect of four-channel anti-counterfeiting pattern:

[0093] In order to enhance the anti-counterfeiting ability of the pattern, the dual-channel can be further expanded into a more complex four-channel response mode based on the above optical diffraction principle, corresponding to Example 6. To prove this point, Figure 5 Figure A shows a four-in-one anti-counterfeiting pattern that is stamped by different nickel stamps in sequence. From top to bottom, it is a butterfly, maple leaf, pine tree, and umbrella pattern. The periodic nanostructure (360nm) and periodic microstructure (4μm) in the nickel stamp are both one-dimensional (1D) grating arrays and are arranged perpendicular to each other ( Figure 5 (A). Since the one-dimensional grating only diffracts in a single plane, this vertical arrangement provides additional degrees of freedom for observation in different orientations. For example, in the yoz plane, two different coding patterns consisting of pattern A3 encoded by nanostructures and pattern B3 encoded by microstructures can be observed; while in the xoz plane, two other different coding patterns consisting of pattern A4 encoded by nanostructures and pattern B4 encoded by microstructures can be observed.

[0094] In order to predict the optimal observation angle, the present invention uses a previously established simulation method to simulate the angle-resolved spectra of its constituent units (i.e., individual nano- and micro-structures). Figure 5 As shown in Figures B and C, under 30° white light illumination, the best observation angle for nanostructures is -16° to -20°, while the best observation angle for microstructures is 40° or above. Figure 5 As shown on the right side of A in Figure 1, a beam of light is incident on the sample surface at different angles, and the observer observes from different directions. When light source 1 illuminates the yoz plane, the observer can see a maple leaf pattern on the upper right of the sample, and an umbrella pattern on the upper left. Similarly, when light source 2 illuminates the xoz plane, a butterfly pattern can be seen on the upper back, and a pine tree pattern can be seen on the upper front. This information is summarized in Figure 5 In Figure D, the effectiveness and reliability of the four-channel encryption pattern are fully demonstrated. Therefore, the present invention successfully verifies the four-channel encryption pattern based on the same optical principle and improves the security of information.

[0095] Example 7

[0096] This embodiment provides an example of scalable manufacturing and application of anti-counterfeiting patterns, and the equipment used specifically includes the following structure: The present invention develops a roll-to-roll rolling instrument. The instrument mainly includes a feeding unit, a cleaning unit, a flattening unit, an embossing unit, a flattening unit and a receiving unit. Among them, the core embossing unit is composed of two parallel rollers. In order to relieve internal stress and extend service life, the upper unit uses a stainless steel roller with a chrome-plated surface, and the lower surface uses a stainless steel roller with a plastic patina (thickness 1mm).

[0097] like Figure 6 As shown in A, by fixing the nano / micro structured nickel film on the upper roller and then applying pressure during the sliding process with the lower roller, a complex hierarchical structure is directly extruded. In this way, the present invention can produce a large number of optical anti-counterfeiting patterns in a short time, thereby meeting the needs of large-scale production. In addition, this roll-to-roll embossing method is not only simple to operate, but also energy-saving and environmentally friendly. Compared with traditional optical anti-counterfeiting technology, this method does not require complex equipment and high material costs, greatly reduces production costs, and provides a new solution for the development of optical anti-counterfeiting technology. Figure 6 Figure B shows an aluminum roll several meters long, with a series of QR code anti-counterfeiting patterns with preset security codes embossed on its surface. Figure 6 As shown in C, QR code 1 encoded as Key: 654321 will be decoded in the nano pattern angle area, while QR code 2 encoded as Key: 123456 will be decoded in the micro pattern angle area. However, in the diffracted light mixing area or under the multi-directional mixing of light sources, a mixed pattern that cannot be scanned will appear. Since the nickel film used in the above process can be repeatedly embossed hundreds of times, this manufacturing method not only saves a lot of production time but also has low cost. Excluding fixed costs such as embossing equipment, the average cost of this anti-counterfeiting pattern is less than 1 cent per square centimeter.

[0098] Furthermore, to demonstrate the broad applicability of the method, we further found that these patterns imprinted on the aluminum coils remained intact even when the samples were directly exposed to flames, e.g. Figure 6 As shown in D. At the same time, due to the presence of nano, micro and hierarchical structures, the hydrophobicity of the material is also enhanced, which undoubtedly improves the self-cleaning ability of the prepared anti-counterfeiting pattern material. In addition, Figure 6 As shown in Figure E, these anti-counterfeiting patterns can also be quickly replicated on other metal / polymer materials, such as zinc, silver, copper, and polyethylene terephthalate (PET). Figure 6 As shown in Figure F, these multi-channel anti-counterfeiting patterns are expected to be directly printed or attached to the surface of valuables as labels. In the future, we expect this method to be widely used in various fields that require anti-counterfeiting measures, such as product labels and document anti-counterfeiting, so as to effectively combat counterfeit and shoddy products and be widely used in real life.

[0099] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure, characterized in that: It is prepared based on a multi-step imprinting method, which specifically includes the following steps: S1. Preparation of a nano-nickel stamp having a coding pattern A1: A silicon plate with a periodically arranged nanopore array is used as a silicon template, a noble metal layer is deposited on the surface of the silicon template where the nanopore array is located, and then the template is placed in an electrolyte as a working electrode for nickel electrochemical deposition. After the deposition is completed, the deposited film on the surface is removed to obtain a nano-nickel stamp with a nano-protrusion array; An aluminum foil pretreated by electrochemical polishing is taken, and the nano-nickel stamp having the nano-protrusion array structure is used for imprinting, and then the imprinted aluminum foil is engraved with a laser to remove the nano-structure in the redundant area to obtain the desired coding pattern A1, and then the foil is placed in an electrolyte as a working electrode for nickel electrochemical deposition, and after the deposition is completed, the deposited film on the surface is removed to obtain a nano-nickel stamp having a nano-protrusion array and the array is distributed in the coding pattern A1; Alternatively, repeat the above steps to prepare nano-nickel stamps having coding patterns A2-Am respectively; S2. Preparation of a micron nickel stamp having a coding pattern B1: An ordered and densely packed single-layer PS microsphere array is prepared on the surface of a silicon wafer by a gas-liquid interface self-assembly process, and then the single-layer PS microsphere array on the surface of the silicon wafer is treated by laser to remove the PS microspheres in the redundant area, and a single-layer PS microsphere array distributed in the coding pattern B1 is obtained, and then a PDMS solution is coated on the single-layer PS microsphere array distributed in the coding pattern 2, and the PDMS film layer is peeled off after curing to obtain a PDMS template having a micron hole array and the array is distributed in the coding pattern 2; The PDMS template is placed in an electrolyte as a working electrode for nickel electrochemical deposition, and after the deposition is completed, the deposited film on the surface is removed to obtain a micron nickel stamp having a micron protrusion array and the array is distributed in a coding pattern B1; Alternatively, a layer of photoresist film is spin-coated on a clean silicon wafer, and after baking and curing, a mask plate is covered on the surface and exposed, the mask plate has a coding pattern B1, and after development treatment, a micrometer hole array penetrating the photoresist film is obtained on the photoresist film, and the array is distributed in the coding pattern B1, the mask plate is removed, and a PDMS solution is coated on the developed photoresist film. After curing, the PDMS film layer is peeled off to obtain a PDMS template having a micrometer hole array and the array is distributed in the coding pattern B1; The PDMS template is used for nickel electrochemical deposition. After the deposition is completed, the deposited film on the surface of the working electrode is removed, which is a micron nickel stamp having a micron protrusion array and the array is distributed in a coding pattern B1; Alternatively, repeat the above steps to prepare micron nickel stamps having coding patterns B2-Bn respectively; S3. Select one or more of the nano-nickel stamps prepared in step S1 to perform the first imprinting on the aluminum sheet, and then select one or more of the micron nickel stamps prepared in step S2 to perform the second imprinting. The centers of the two imprinted coding patterns correspond to each other, and a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure can be obtained on the aluminum sheet.

2. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: In step S3, two of the nano-nickel stamps with different coding patterns obtained in step S1 are selected and sequentially imprinted on an aluminum sheet, and the structures in the two nano-nickel stamps are both nano-grating arrays, and the grating arrays imprinted twice on the plane of the aluminum sheet are perpendicular to each other; then two of the micron-nickel stamps with different coding patterns obtained in step S2 are selected and sequentially imprinted on an aluminum sheet, and the structures in the two micron-nickel stamps are both micron-grating arrays, and the grating arrays imprinted twice on the plane of the aluminum sheet are perpendicular to each other; when imprinting multiple times, the centers of the coding patterns correspond to each other, and a four-channel optical anti-counterfeiting pattern based on a hierarchical structure can be obtained on the aluminum sheet.

3. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: The electrolyte contained an aqueous solution of 0.12 M NiCl2, 0.12 M NiSO4 and 0.5 M H3BO3. The nickel electrochemical deposition was carried out at 2 mA cm -2 The current density lasts for 18-24h.

4. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: In step S1, the arrangement of the nanopores in the nanopore array on the silicon template is quadrilateral, hexagonal or grating arrangement; when the nano-nickel stamp with the nano-protrusion array structure is used to emboss the pre-treated aluminum foil in step S1, the applied pressure is 12-20MPa; when the aluminum foil or the single-layer PS microsphere array after the embossing is engraved by laser, the wavelength is 360nm, the power is 0.4W, and the tool spacing is 5μm; in step S2, the particle size of the PS microsphere is 2.5μm, and the PS microspheres in the excess area are removed by laser treatment, and the wavelength of the laser is 360nm, the power is 0.4W, and the tool spacing is 5μm.

5. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: The PDMS solution described in step S2 is produced by mixing the prepolymer polydimethylsiloxane PDMS and the cross-linking agent in a mass ratio of 5:1, with a coating thickness of more than 5 mm, and then placed at 60° C. for curing for 2-4 hours; the model of the photoresist in step S2 is AR5350, and the thickness of the photoresist film is 5-10 μm.

6. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: In step S2, a double-sided alignment lithography machine is used to expose the surface with a mask plate, and the exposure dose is 50-56mJcm -2 .

7. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: The specific steps of the development treatment in step S2 are: placing in a developer having a volume ratio of AR300-26 to water of 1:7 for 40-45 seconds, and then drying.

8. The method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to claim 1, characterized in that: The pressure of the first printing press is 12-20MPa, and the pressure of the second printing press is 1-5MPa.

9. A multi-channel optical anti-counterfeiting pattern based on a hierarchical structure obtained by the method for preparing a multi-channel optical anti-counterfeiting pattern based on a hierarchical structure according to any one of claims 1 to 8.

10. Application of the multi-channel optical anti-counterfeiting pattern based on hierarchical structure as claimed in claim 9 in optical anti-counterfeiting.

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