CN106413359B - Bidirectional wave-absorbing strong electromagnetic shielding optical window with multilayer graphene grid/metal grid laminated structure - Google Patents
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Abstract
Multilayer graphite alkene net bars/metal net bars stacked structure's two-way ripples strong electromagnetic shielding light window of inhaling belongs to optical transparency spare electromagnetic shield technical field, and this electromagnetic shielding light window utilizes graphite alkene net bars film to have different printing opacity and the microwave shielding characteristic that shows when different mesh unit trompil area ratio, organically combines the strong electromagnetic reflection characteristic of the low reflection of graphite alkene net bars film and partial absorption microwave characteristic and the double-deck metal net bars of high printing opacity, arranges multilayer graphite alkene net bars film in double-deck metal net bars both sides and constitutes multilayer structure: the double-layer metal grids separated by the graphene grid films are used as transparent reflecting layers, and the graphene grid films separated by transparent media are used as transparent absorbing layers; the structure can enable radio frequency radiation on two sides of the optical window to pass through the absorption layer for multiple times and be strongly absorbed, so that the bidirectional strong shielding and low reflection characteristics are realized, and visible light only penetrates through the laminated structure once and has high light transmittance; the electromagnetic shielding optical window solves the problem that the existing transparent electromagnetic shielding method cannot give consideration to both low electromagnetic reflection, strong electromagnetic shielding and high light transmission.
Description
Technical Field
The invention belongs to the field of electromagnetic shielding of optical transparent parts, and particularly relates to a bidirectional wave-absorbing strong electromagnetic shielding optical window with a multilayer graphene grid/metal grid laminated structure.
Background
With the development of broadcasting, television, wireless communication technology and microwave technology, radio frequency equipment is equipped in a large number in various places where people move, the frequency spectrum range is continuously widened, and the intensity is multiplied, so that the radio frequency equipment not only causes interference to electronic equipment, but also threatens human health. The invisible electromagnetic pollution directly acts on machines or human bodies, is an invisible killer with serious harm, and becomes the fifth largest pollution following atmospheric pollution, water pollution, solid waste pollution and noise pollution. Electromagnetic shielding (including absorption and reflection) is a major measure for preventing and treating electromagnetic pollution, and in recent years, electromagnetic shielding technology has received much attention. The electromagnetic shielding, namely transparent electromagnetic shielding, which is required in visual observation occasions is always a difficult point and a hot point, and the application of the electromagnetic shielding, namely transparent electromagnetic shielding, comprises a medical electromagnetic isolation room observation window, a communication equipment transparent electromagnetic shielding element, an aerospace equipment optical window, an advanced optical instrument optical window, a confidential facility electromagnetic leakage prevention optical window, a liquid crystal display screen, a mobile phone touch screen, a vehicle-mounted transparent antenna and the like.
At present, the difficulty of realizing transparent electromagnetic shielding mainly lies in that most of traditional wave-absorbing materials are opaque or have poor transparency, and the transparency and the conductive shielding capability of the reflection transparent shielding technology based on transparent conductive materials or devices are mutually restricted, so that high transparency and strong electromagnetic shielding are difficult to realize simultaneously. In addition, the conductive reflective transparent shielding technology reflects electromagnetic radiation back to the space, which causes secondary pollution to the space environment and is not beneficial to the thorough prevention and treatment of electromagnetic pollution.
The transparent metal oxide film mainly made of indium tin oxide is widely applied to the visible light transparent occasions, but the light transmission waveband of the transparent metal oxide film is narrow, and the shielding capacity is not strong although the microwave shielding waveband is wide. The nano silver conductive network film can realize about 90% of light transmittance, but the nano silver wires have inevitable contact resistance, and particularly, the nano silver wires are very thin and sparse to enable the surface resistance of the nano silver wires to be higher when the nano silver wires are highly transparent, so that the shielding efficiency is reduced. The band-pass type frequency selective surface adopts a periodic resonance unit structure, can highly reflect interference microwaves outside an operating frequency band, but has poor light transmission and is difficult to realize a wide light transmission band. Therefore, the technical schemes can not meet the requirements of the electromagnetic shielding optical window on high light transmission and strong microwave shielding capability.
In contrast, the metal mesh grid with the period from millimeter to submillimeter is much shorter than the interference electromagnetic wavelength and much longer than the optical wavelength, so that the low-frequency broadband electromagnetic shielding can be realized, and meanwhile, the higher light transmittance of the visible light and the infrared band can be ensured. Therefore, the metal mesh grid with millimeter and sub-millimeter period is widely applied in the technical field of optical window electromagnetic shielding due to good transparent conductive performance:
1. patent 200810063988.0 entitled "an electromagnetic shielding optical window with double-layer square metal grid structure" describes an electromagnetic shielding optical window formed by placing square metal grids or metal wire nets with the same structural parameters in parallel on two sides of an optical window or a transparent substrate, which greatly improves the electromagnetic shielding efficiency.
2. Patent 200810063987.6 entitled "electromagnetic shielding optical window with double-layer circular ring metal grid structure" describes an electromagnetic shielding optical window formed by two layers of circular ring metal grids loaded on two sides of the optical window, which solves the problem that high light transmittance and strong electromagnetic shielding efficiency cannot be simultaneously considered.
3. Patent 201410051497.X "multi-period master-slave nested circular ring array electromagnetic shielding optical window with concentric circular rings" describes a metal mesh grid structure nested with the concentric circular rings and used for realizing the electromagnetic shielding function of the optical window, wherein the metal mesh grid structure enables stray light caused by high-level diffraction to be homogenized to a certain extent, and the influence of the mesh grid on the imaging quality of the optical window is reduced.
4. Patent 201410051496.5 entitled "electromagnetic shielding optical window with double-layer staggered multicycle metal ring nested array" describes an electromagnetic shielding optical window formed by two layers of staggered metal grids, which significantly reduces the nonuniformity of the grid diffraction light intensity distribution and the influence on imaging.
Patent 200810063988.0 and patent 200810063987.6 all adopt double-deck metal net bars parallel to place in the both sides of light window transparent substrate or substrate and constitute, and two-deck metal net bars have the same unit appearance and structural parameter, through the interval of optimizing two-layer net bars, have improved electromagnetic shielding efficiency. Patent 201410051497.X proposes a mesh grid structure with a master-slave nested circular ring array of multi-period concentric circular rings, realizes the depth homogenization of high-order diffraction, and reduces the influence on the imaging quality to a minimum. Patent 201410051496.5 makes stray light distribution more even through the selection of double-layer grid stagger angle, and has less influence on imaging quality. In the above patents, the metal mesh grid (or the metal wire mesh) is used as a core device for microwave shielding, so that a better electromagnetic shielding effect and light transmittance can be realized, but when the metal is used as a reflective electromagnetic shielding material, a reflected radio frequency signal can cause secondary pollution to the space environment, and the prevention and treatment of electromagnetic pollution is not facilitated thoroughly.
Carbon materials play a very important role in many areas of modern technology, among the many allotropes of carbon, graphene is a very typical material, graphene being formed from carbon atoms in sp2The hexagonal honeycomb lattice planar thin film formed by the hybrid tracks is a two-dimensional material with the thickness of only one carbon atom, has multiple excellent properties, one of the outstanding properties is excellent transparent conductivity, and the graphene with the two-dimensional structure has high application value in the field of transparent electromagnetic shielding due to the excellent conductivity and certain microwave absorption performance:
5. U.S. Pat. No. 20130068521, "graphene preparation method using graphene prepared by Chemical Vapor Deposition (CVD)" is loaded on a metal plate or a polymer substrate to realize Electromagnetic shielding, and compared with a metal plate or a polymer substrate which is not loaded with graphene, the Electromagnetic shielding efficiency of the whole structure is improved after the graphene is loaded.
6. Patent 201310232829. X "graphene-based structures and methods for shielding electromagnetic radiation" describes an electromagnetic shielding structure for shielding electromagnetic radiation having a frequency greater than 1 mhz, the structure being composed of one or more layers of graphene, at least one layer of graphene being doped with a dopant.
7. Patent 201420099425.8 "a transparent electromagnetic shielding film based on graphene film" describes a transparent electromagnetic shielding film with nano-silver wires arranged between a transparent substrate and a graphene film, wherein the nano-silver wires act as a charge bridge to increase the conductivity of the whole electromagnetic shielding film and improve the shielding efficiency.
8. James M. Tour et al, Rice University (Rice University) of America, used photolithography to prepare metal grids with line width of 5 μm, and transferred single-layer Graphene on the surface to make Graphene-metal grid mixed conductive Films (James M. Tour et al, "Rational Design of Hybrid Graphene Films for High-Performance transmission Electrodes". ACS Nano, 2011, 5 (8): 6472-6479), which can realize 90% transmittance and 20 Ω/sq sheet resistance.
9. Seul Ki Hong et al, Korea scientific and technical institute (KAIST), reported that the shielding efficiency of single-layer graphene was 2.27dB (Hong S K et al, "Electromagnetic interference shielding efficiency of monolayer graphene". Nanotechnology, 2012, 23 (45): 455704), with absorption and reflection losses of-4.38 dB and-13.66 dB, respectively.
10. Kim S of the University of Korea (Sungkyunkwan University) and Myeong-Gi, et al of the Korea three-star Motor company (Samsung Electro-Mechanics) use a polyetherimide/redox method to prepare a Graphene (PEI/RGO) laminate structure to achieve Electromagnetic Shielding (Kim S, et al, "Electromagnetic Interference (EMI) Transmission Shield of Reduced Graphene Oxide (RGO) Electromagnetic Interference disposed". AppACS plied materials & interfaces, Electromagnetic Shielding 2014, 6 (20): 17647 17653), the efficiencies of the double-layer PEI/RGO and single-layer PEI/RGO laminates are 6.37 and 3.09dB, respectively, and the absorption loss accounts for 96% and 92% of the total efficiency, respectively.
11. Hanjie et al, Harbin university of Industrial science, uses a copper mesh as a sacrificial layer, and prepares a plurality of graphene meshes (Han J, et al, "isolated-transmissive film based on a modulated graphene network fabric for electronic shielding". Carbon, 2015, 87: 206-type 214) by Chemical Vapor Deposition (CVD), respectively achieving 70.85% Infrared transmittance and 12.86dB shielding efficiency, and achieving 87.85% Infrared transmittance and 4dB shielding efficiency. And the graphene grid electromagnetic shielding is also dominated by absorption.
According to the scheme, the graphene is used for electromagnetic shielding, and a certain electromagnetic shielding effect can be achieved. US20130068521 uses graphene as a core device of an electromagnetic shielding device, and transfers a whole large-area graphene onto substrates such as metal and polymer by a roll-to-roll graphene transfer method, so as to achieve an excellent electromagnetic shielding effect, but the electromagnetic shielding device does not have transparency. Patent 201310232829. X "graphene-based structure and method for shielding electromagnetic radiation" uses a graphene thin film as a main body of an electromagnetic shielding structure, and at least one layer of the graphene thin film is doped to improve the electromagnetic shielding efficiency, but the doping affects the light transmittance of the whole structure. Patent 201420099425.8, "a transparent electromagnetic shielding film based on graphene thin film", utilizes nano-silver wires to increase the conductivity of the graphene thin film and increase the reflection loss to achieve the improvement of the electromagnetic shielding efficiency, but the main contribution of the electromagnetic shielding is caused by reflection. In the document 8, the graphene film is loaded on the metal mesh to form a structure in which the graphene and the metal mesh are tightly attached to each other, so that the conductivity of the metal mesh is improved, and meanwhile, the light transmittance reaches 91%, but the electromagnetic shielding of the structure is mainly reflected. The research results in the above-mentioned document 9 indicate that although the shielding efficiency of graphene increases greatly as the number of layers increases, the absorption loss increases little, and the light transmittance is lost by 2.3% per one layer of graphene, making it difficult to achieve high light transmittance, low reflection, and strong electromagnetic shielding at the same time with this structure. In the above document 10, the graphene thin film (RGO) and Polyetherimide (PEI) laminated structure prepared by the redox method realizes electromagnetic shielding, and the shielding mainly involves absorption loss, but the shielding efficiency of the double-layer PEI/RGO structure is only 6.37dB, and the light transmittance is only 62%, and it is difficult to realize both strong electromagnetic shielding and high light transmittance. The document 11 only adopts a graphene grid structure, and the shielding efficiency is low, and the strong shielding efficiency and the high light transmittance cannot be obtained at the same time.
In a word, in the prior electromagnetic shielding technology, a method mainly based on reflection-type electromagnetic shielding is easy to cause secondary electromagnetic pollution; in the electromagnetic shielding method with absorption loss, either the light transmittance is not high or the electromagnetic shielding efficiency is not strong, so that it is difficult to realize high transparency and strong electromagnetic shielding at the same time.
Disclosure of Invention
The invention aims to overcome the defects of the existing transparent electromagnetic shielding technology, in particular to the problems that the transparency and the conductive shielding capability of the existing reflective transparent shielding technology are mutually restricted, the high light transmittance and the strong microwave shielding efficiency are difficult to be considered, and electromagnetic leakage and secondary pollution are caused by reflected electromagnetic signals.
The purpose of the invention is realized as follows: the electromagnetic shielding optical window is formed by assembling a first transparent absorption layer, a transparent medium A, a metal grid A, a transparent medium B, a second transparent absorption layer, a transparent medium C, a metal grid B, a transparent medium D and a third transparent absorption layer which are sequentially overlapped and arranged in parallel; the first transparent absorption layer and the third transparent absorption layer are respectively composed of N layers of graphene grid films separated by transparent media, the second transparent absorption layer is composed of 1-6 layers of graphene grid films separated by transparent media, and the metal grid A and the metal grid B which are arranged in parallel form a transparent reflection layer.
The good effect produced by the invention is mainly focused on realizing the performance of simultaneously having bidirectional strong electromagnetic shielding, low electromagnetic reflection and high light transmittance, and specifically comprises the following steps:
firstly, electromagnetic shielding with high light transmission and absorption as main functions is realized by utilizing different light transmission and microwave shielding characteristics shown when the graphene grid film has different aperture unit opening area ratios; when the aperture area ratio t of the mesh unit of the graphene grid film is between 0.05 and 0.7, good light transmission and shielding performance can be realized by adjusting the number of layers of the graphene grid film. When the opening area ratio t of the mesh unit of the graphene grid film meets the condition that t is more than or equal to 0.3 and less than or equal to 0.7, the light transmittance which is similar to that of a single-layer graphene film is realized by utilizing the multi-layer graphene grid film, and meanwhile, the shielding performance is improved; when the opening area ratio t of the mesh unit of the graphene grid film meets the condition that t is more than or equal to 0.05 and less than 0.3, the microwave shielding performance similar to that of a single-layer graphene film is realized by utilizing the single-layer graphene grid film, and meanwhile, the light transmittance is improved; meanwhile, the microwave shielding performance of the graphene grid film is mainly microwave absorption.
Secondly, the microwave absorption characteristic of the graphene grid film and the strong microwave reflection characteristic of the double-layer metal grid are organically combined, the double-layer metal grid is used as a basic structure of the transparent reflection layer, compared with a single-layer metal grid, the microwave shielding efficiency and the reflectivity are remarkably improved on the premise that the light transmittance performance is not changed, and strong electromagnetic shielding and reflection of radio frequency radiation can be better realized; 1-6 graphene grid thin film laminated structures separated by transparent media are used as second transparent absorption layers, the second transparent absorption layers are placed between the double-layer metal grids A, B in parallel, the metal grids A passing through the first layer can be absorbed for multiple times, and microwave signals oscillating between the double-layer metal grids can be absorbed due to the strong reflection effect of the metal grids A, B, so that the electromagnetic shielding efficiency is greatly improved, and the ultra-strong electromagnetic shielding is realized; the N layers of graphene grid thin film structures separated by transparent media are used as a first transparent absorption layer and a third transparent absorption layer, so that radio frequency radiation can be partially absorbed and pass through in a low-reflection mode; the first transparent absorption layer and the third transparent absorption layer are respectively arranged at two sides of the transparent reflection layer, so that the microwave which penetrates through the transparent absorption layer is strongly reflected back to the transparent absorption layer, and good electromagnetic shielding is realized through reflection and multiple absorption; two groups of transparent absorption layers are respectively arranged on two sides of the transparent reflection layer to form an electromagnetic shielding optical window, and simultaneously absorb radio frequency radiation on the inner side and the outer side of the optical window, so that the radio frequency radiation from the two sides of the optical window is reflected and absorbed for multiple times, and finally, bidirectional low-reflection strong electromagnetic shielding is realized.
According to the multilayer graphene grid/metal grid laminated structure, on one hand, due to the existence of the first transparent absorption layer and the third transparent absorption layer, the problem that secondary electromagnetic pollution is easily caused by shielding mainly based on reflection when only a metal grid exists is solved; on the other hand, due to the existence of the transparent reflecting layer, and the metal mesh A, B of the transparent reflecting layer is arranged between the first transparent absorbing layer and the third transparent absorbing layer, microwaves to be shielded from both sides of the optical window can be reflected and absorbed for multiple times, so that the problem of low shielding efficiency when only the graphene mesh film absorbing layer exists is solved, the bidirectional shielding effect is achieved, and the bidirectional shielding effect is mainly absorption; in addition, the second transparent absorption layer is arranged between the metal grids A, B of the transparent reflection layer in parallel, so that radio frequency radiation reflected between the double-layer metal grids can be absorbed for multiple times, and the electromagnetic shielding efficiency is greatly improved; meanwhile, for light waves, the light waves only penetrate through the transparent absorption layer and the transparent reflection layer once, the loss is less, and when the aperture area ratio t of the mesh unit of the graphene grid film is between 0.05 and 0.7, the graphene grid film has a periodic aperture structure, so that the light transmission performance is improved, and the high light transmission characteristic can be realized. (ii) a And when the double-layer metal mesh grid adopts a mesh grid structure with uniform distribution of diffracted stray light, the influence of the whole laminated structure on the imaging quality is very low.
In conclusion, the invention can realize the most outstanding effects of simultaneously having bidirectional strong electromagnetic shielding, low electromagnetic reflection and high light transmittance.
Drawings
Fig. 1 is a schematic cross-sectional view of a bi-directional wave-absorbing strong electromagnetic shielding optical window with a multilayer graphene grid/metal grid laminated structure.
Fig. 2 is a schematic structural diagram of a grid unit arrangement mode of a square-hole graphene grid.
Fig. 3 is a schematic structural diagram of a grid unit arrangement mode of a circular hole graphene grid.
Fig. 4 is a schematic structural diagram of a grid unit arrangement of a grid metal grid.
Fig. 5 is a schematic structural diagram of an arrangement mode of grid units of a circular ring metal grid.
Fig. 6 is a schematic diagram of the arrangement of grid cells of the multi-period micro-ring metal grid.
Fig. 7 is a schematic cross-sectional view of a bi-directional wave-absorbing strong electromagnetic shielding optical window with a multilayer graphene grid/metal grid laminated structure according to an embodiment.
Fig. 8 is a schematic structural view of a bidirectional wave-absorbing strong electromagnetic shielding optical window with a multilayer graphene grid/metal grid laminated structure.
Description of part numbers in the figures: 1. the transparent protective layer comprises a protective layer A2, an antireflection film A3, a first transparent absorbing layer 4, a transparent medium A5, a metal grid A6, a transparent medium B7, a second transparent absorbing layer 8, a transparent medium C9, a metal grid B10, a transparent medium D11, a third transparent absorbing layer 12, an antireflection film B13, a protective layer B14, a square-hole graphene grid film A15, a transparent medium E16, a square-hole graphene grid film B17, a square-hole graphene grid film C18 and a square-hole graphene grid film D.
Detailed Description
Embodiments of the invention are described in detail below with reference to the accompanying drawings:
the electromagnetic shielding optical window is formed by assembling a first transparent absorption layer (3), a transparent medium A (4), a metal mesh grid A (5), a transparent medium B (6), a second transparent absorption layer (7), a transparent medium C (8), a metal mesh grid B (9), a transparent medium D (10) and a third transparent absorption layer (11) which are sequentially overlapped and arranged in parallel; the first transparent absorption layer (3) and the third transparent absorption layer (11) are both composed of N layers of graphene grid films separated by transparent media, the second transparent absorption layer (7) is composed of 1-6 layers of graphene grid films separated by transparent media, and the metal grid A (5) and the metal grid B (9) which are arranged in parallel form a transparent reflection layer.
Arranging a single-layer or multi-layer antireflection film A (2) and a single-layer or multi-layer protective layer A (1) in parallel on the outer side part of the first transparent absorption layer (3); a single-layer or multi-layer antireflection film B (12) and a single-layer or multi-layer protective layer B (13) are sequentially arranged in parallel on the outer side of the third transparent absorption layer (11).
When the ratio t of the open area of the mesh unit of the graphene grid film satisfies 0.3. ltoreq. t.ltoreq.0.7, the transparent absorption layer (3, 11) is composed of N layers of graphene grid films separated by a transparent medium, wherein N.ltoreq.6 { [1/(1-t) ] +1}, and [1/(1-t) ] represents the maximum positive integer not exceeding 1/(1-t).
When the ratio t of the open area of the mesh unit of the graphene grid film satisfies 0.05-t <0.3, the transparent absorption layers (3 and 11) are composed of N layers of graphene grid films separated by transparent media, wherein N is less than or equal to 6.
The metal grids A, B (5, 9) are both composed of two-dimensional plane structures with grid units arranged periodically, the period of the grid units is sub-millimeter to millimeter magnitude, the width of the metal lines is sub-micrometer to micrometer magnitude, and connecting metal for communicating the two metal lines is arranged between the adjacent grid units through metal line overlapping or at the overlapping position.
The distance between the metal mesh grid A (5) and the metal mesh grid B (9) is millimeter magnitude, and the distance is less than 0.25 time of the minimum shielding wavelength.
The number of layers of the graphene grid films forming the first, second and third transparent absorption layers (3, 7, 11) is single-layer, double-layer or three-layer, and the number of layers of the graphene grid films formed by the first, second and third transparent absorption layers (3, 7, 11) separated by the transparent medium can be the same or different.
The metal grids A, B (5, 9) are made of alloy materials with good conductivity, and the thickness of the alloy is larger than 100 nm.
The transparent reflective layer formed from metal mesh A, B (5, 9) has a light transmission greater than 90%.
The transparent medium A, B, C, D (4, 6, 8, 10) and the transparent medium manufacturing materials for separating the first, second and third transparent absorption layers (3, 7, 11) and the graphene grid film comprise common glass, quartz glass, infrared materials and transparent resin materials.
According to the bidirectional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure, the transparent reflecting layer is a core device for realizing strong reflection electromagnetic shielding, and the first transparent absorbing layer 3, the second transparent absorbing layer 7 and the third transparent absorbing layer 11 have the characteristics of low reflection and partial absorption of microwaves. Due to the existence of the second transparent absorption layer 7 between the metal grid A5 and the metal grid B7 in the transparent reflection layer, radio frequency radiation reflected for many times between double-layer metal grids is partially absorbed, and the microwave shielding capability is greatly improved. The first transparent absorption layer 3 and the third transparent absorption layer 11 are located on two sides of the transparent reflection layer, so that the electromagnetic shielding optical window of the structure can shield and absorb radio frequency radiation on two sides of the optical window at the same time. Taking a radio-frequency radiation wave source positioned outside a first transparent absorption layer 3 of an electromagnetic shielding optical window as an example, radio-frequency radiation energy irradiated to the optical window enters the first transparent absorption layer 3, the energy after being absorbed and attenuated by each layer of graphene grid film in the first transparent absorption layer 3 is highly reflected by a transparent reflection layer, and the reflected radio-frequency radiation passes through the first transparent absorption layer 3 again and is absorbed and attenuated by each layer of graphene grid film; a small amount of radio frequency radiation transmitted by the transparent reflecting layer enters the third transparent absorbing layer 11 positioned on the other side of the transparent reflecting layer, is absorbed and attenuated by each graphene grid film layer, and undergoes multiple reflection and absorption on the reflection parts of each graphene grid film layer and the transparent dielectric layer, so that most energy of the radio frequency radiation is absorbed finally. If the radio frequency radiation comes from the outside of the third transparent absorbing layer 11, the shielding and absorption effect is similar to that from the outside of the first transparent absorbing layer 3, so that the electromagnetic shielding optical window of the present invention can realize electromagnetic shielding mainly based on bidirectional absorption. And for the optical wave band needing to pass through, the optical wave band only passes through the first transparent absorption layer 3, the second transparent absorption layer 7, the third transparent absorption layer 11 and the transparent reflection layer once, the loss generated is less, and high light transmission can be realized. According to the bidirectional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure, the distance between the double-layer metal grids A5 and B9 is in millimeter order, and compared with a single-layer metal grid structure, the microwave shielding effect of the electromagnetic shielding optical window can be remarkably improved under the condition that the light transmittance is not changed.
Examples
The electromagnetic shielding optical window is formed by assembling a first transparent absorption layer 3, a transparent medium A4, a metal mesh grid A5, a transparent medium B6, a second transparent absorption layer 7, a transparent medium C8, a metal mesh grid B9, a transparent medium D10 and a third transparent absorption layer 11 which are sequentially overlapped and arranged in parallel; the first transparent absorption layer 3 is composed of a single-layer graphene grid film A14, a transparent medium E15 and a single-layer graphene grid film B16 which are sequentially arranged in parallel, the second transparent absorption layer is composed of a single-layer graphene grid film C17, the third transparent absorption layer is composed of a single-layer graphene grid film D18, and the metal grid A5 and the metal grid B9 which are arranged in parallel form a transparent reflection layer.
The invention has the technical effects that: when the electromagnetic shielding efficiency of the double-layer metal mesh grid is 29.8dB, if radio frequency radiation comes from the outer side of the first transparent absorption layer 3 of the optical window, the electromagnetic shielding efficiency of the double-layer metal mesh grid is 35.7dB, and the absorption loss accounts for 59.2 percent of the total shielding energy; if the radio frequency radiation comes from the outside of the third transparent absorbing layer 11 of the optical window, the absorption loss accounts for 49.7% of the total shielding energy; the strong electromagnetic shielding mainly based on absorption is realized for the radio frequency radiation on two sides of the light window with the structure, the light transmittance is 85.8%, and the high-transmittance characteristic is still realized. Compared with the electromagnetic shielding efficiency of 34.55dB and the light transmittance of 88.1% of the graphene/double-layer metal mesh grid transparent electromagnetic shielding device with the bidirectional wave-absorbing effect, the double-layer metal mesh grid electromagnetic shielding optical window with the graphene interlayer has the advantages that the microwave shielding performance is remarkably improved under the condition of slightly sacrificing the light transmittance, and the ultra-strong microwave shielding efficiency can be realized.
The invention also corresponds to other embodiments, changes the shape and the structural parameters of the basic unit of the double-layer metal mesh grid in the figure 7 and the arrangement mode of the basic unit, keeps the original arrangement mode of each layer unchanged, and finally can obtain similar effect; increasing or decreasing the number of layers of the graphene grid thin film separated by the transparent medium in the transparent absorption layer in fig. 7 will result in an increase in absorption loss or an increase in light transmittance; can be adjusted correspondingly according to actual needs.
Claims (5)
1. Multilayer graphite alkene net bars/metal net bars stacked structure's two-way strong electromagnetic shielding light window of inhaling, its characterized in that: the electromagnetic shielding optical window is formed by assembling a first transparent absorption layer (3), a transparent medium A (4), a metal mesh grid A (5), a transparent medium B (6), a second transparent absorption layer (7), a transparent medium C (8), a metal mesh grid B (9), a transparent medium D (10) and a third transparent absorption layer (11) which are sequentially overlapped and arranged in parallel; the first transparent absorption layer (3) and the third transparent absorption layer (11) are both composed of N layers of graphene grid films separated by transparent media, the second transparent absorption layer (7) is composed of 1-6 layers of graphene grid films separated by transparent media, and the metal grid A (5) and the metal grid B (9) which are arranged in parallel form a transparent reflection layer; when the ratio t of the open area of the mesh units of the graphene grid film satisfies 0.3 ≤ t ≤ 0.7, the first transparent absorption layer (3) and the third transparent absorption layer (11) are composed of N layers of graphene grid films separated by transparent media, wherein N ≤ 6 { [1/(1-t) ] +1}, and [1/(1-t) ] represents the maximum positive integer not exceeding 1/(1-t); when the aperture area ratio t of the mesh unit of the graphene grid film satisfies 0.05-t <0.3, the first transparent absorption layer (3) and the third transparent absorption layer (11) are formed by N layers of graphene grid films separated by transparent media, wherein N is less than or equal to 6; the number of layers of the graphene grid film forming the first transparent absorption layer (3), the second transparent absorption layer (7) and the third transparent absorption layer (11) is single-layer, double-layer or three-layer; arranging a single-layer or multi-layer antireflection film A (2) and a single-layer or multi-layer protective layer A (1) in parallel on the outer side part of the first transparent absorption layer (3); a single-layer or multi-layer antireflection film B (12) and a single-layer or multi-layer protective layer B (13) are sequentially arranged on the outer side part of the third transparent absorption layer (11) in parallel; the metal grids A (5) and B (9) are both formed by two-dimensional plane structures in which grid units are periodically arranged, the period of each grid unit is in the range of submillimeter to millimeter, the width of metal lines of each metal grid is in the range of submicrometer to micrometer, and connecting metal for communicating the two metal lines is arranged between the adjacent grid units through metal line overlapping or at the overlapping position; the distance between the metal mesh grid A (5) and the metal mesh grid B (9) is millimeter magnitude, and the distance is less than 0.25 time of the minimum shielding wavelength.
2. The bi-directional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure according to claim 1, characterized in that: the number of layers of the graphene grid thin film, which are separated by the transparent medium, of each of the first transparent absorption layer (3), the second transparent absorption layer (7) and the third transparent absorption layer (11) can be the same or different.
3. The bi-directional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure according to claim 1, characterized in that: the metal grids A (5) and B (9) are both made of alloy materials with good conductivity, and the thickness of the alloy is more than 100 nm.
4. The bi-directional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure according to claim 1, characterized in that: the light transmittance of the transparent reflecting layer consisting of the metal grids A (5) and B (9) is more than 90 percent.
5. The bi-directional wave-absorbing strong electromagnetic shielding optical window with the multilayer graphene grid/metal grid laminated structure according to claim 1, characterized in that: transparent media A (4), B (6), C (8) and D (10) for separating the transparent absorption layer and the transparent reflection layer and transparent media manufacturing materials among the graphene grid films for separating the first transparent absorption layer (3), the second transparent absorption layer (7) and the third transparent absorption layer (11) comprise common glass, quartz glass, infrared materials and transparent resin materials.
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| CN112867379B (en) * | 2021-01-08 | 2022-07-12 | 中国科学院宁波材料技术与工程研究所 | Transparent ultra-wideband electromagnetic shielding device |
| CN113056182B (en) * | 2021-01-18 | 2023-05-05 | 哈尔滨工业大学 | Transparent perfect microwave absorber based on graphene, transparent medium and ultrathin doped metal |
| CN112888288B (en) * | 2021-01-18 | 2022-10-28 | 哈尔滨工业大学 | Electromagnetic shielding curved surface optical window based on ultrathin doped metal/medium composite structure |
| CN113068387B (en) * | 2021-03-18 | 2023-04-07 | 重庆电子工程职业学院 | Ultra-wideband transparent electromagnetic protection material structure and preparation method thereof |
| CN113241510B (en) * | 2021-04-30 | 2023-02-03 | 锐石创芯(深圳)科技股份有限公司 | Microwave transmission line and radio frequency front end module |
| CN114050420A (en) * | 2021-11-29 | 2022-02-15 | 南京航空航天大学 | Heat dissipation-wave absorption integrated passive frequency selective surface wave absorber |
| CN115051157B (en) * | 2022-08-15 | 2022-10-25 | 中国人民解放军国防科技大学 | Infrared-transmitting ultra-wideband electromagnetic shielding antenna protection device based on surface plasma |
| CN116419554B (en) * | 2023-03-29 | 2023-09-15 | 西安工业大学 | Graphene precise superposition structure and preparation method and application thereof |
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