Large-slope conformal curved surface electromagnetic shielding transparent light window giving consideration to infrared visible light laser

Abstract

The invention belongs to the technical field of electromagnetic shielding of optical transparent parts, and particularly relates to a large-slope conformal curved surface electromagnetic shielding transparent light window considering infrared visible light laser, which consists of a curved surface optical glass substrate, an electromagnetic shielding layer and a surface protection layer, the electromagnetic shielding layer is of a multi-layer electromagnetic shielding structure composed of a conductive polymer transparent film and a randomly-distributed metal mesh film. The electromagnetic shielding transparent light window has high shielding characteristics in X and S wave bands, keeps excellent optical transmission performance, and can meet the requirements of high imaging quality and high stealth characteristics of a high-performance seeker. Meanwhile, the appearance of the light window is trimmed and the design parameters of the shielding layer are adjusted, so that the service requirements of the seeker in different combat scenes can be met, and the electromagnetic shielding transparent light window with excellent performance is provided for the seeker of weapon equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic shielding of optical transparent parts, and in particular relates to a large-slope conformal curved surface electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers. Background Art

[0002] The transparent light window is an important component for the weapon and equipment seeker to achieve accurate reconnaissance and detection of targets. With the gradual improvement of the combat performance of weapons and equipment, the performance requirements for transparent light windows are getting higher and higher. In addition to having high transmittance in visible light, infrared light, laser and other working bands, it must also have a high level of electromagnetic wave shielding capability in the microwave band. While showing high transmittance in the optical band to achieve precise observation, it must ensure strong electromagnetic shielding characteristics in the microwave band to achieve the purpose of electromagnetic protection and radar stealth.

[0003] Transparent electromagnetic shielding materials are an important method for transparent light windows to achieve electromagnetic protection. Since light and microwaves are both electromagnetic waves, the essence of transparent electromagnetic shielding is to achieve the passband of the optical band and the stopband of the microwave frequency band. The main method at present is to add a transparent and conductive film layer to the transparent light window. The transparent conductive film layer is generally made of conductive fine wire mesh coating with a metal line width in the micron range or a transparent conductive coating. The above two methods are called metal grid frequency filtering technology and transparent conductive film technology respectively.

[0004] Metal mesh films generally have a periodic structure. Changing the parameters of its periodic structure can achieve filtering functions in specific bands. This is because the line width of the metal mesh film is in the micron or submicron order, and the period is in the submillimeter order. The electromagnetic shielding wavelength in the visible and infrared bands is much smaller than the period length of the metal mesh, and the electromagnetic wavelength in the microwave and radar bands is much larger than the mesh period. The optical window with a metal mesh film on the surface has both high transmittance in the optical band and excellent electromagnetic shielding properties in the microwave / radar band, and has become one of the more commonly used technical means to achieve electromagnetic shielding of optical windows. However, as a non-continuous transparent conductive film, the metal mesh will inevitably diffract the incident light when it is loaded on the optical window. The diffracted light will become stray light in the optical system, thereby affecting the imaging effect and imaging quality of the optical system, resulting in a decrease in system resolution and detection sensitivity.

[0005] Transparent electromagnetic shielding technology is mainly realized by transparent conductive films. Currently, the most studied transparent conductive films include indium tin oxide (ITO), F-doped SnO 2 (FTO), Co-doped SnO 2(CTO), Al-doped ZnO (AZO), Ga-doped ZnO (GZO), CuS, PbO and other films. Among them, ITO film is the most mature and commercially used transparent conductive film. ITO film has the characteristics of low square resistance (<10Ω / sq) and high transmittance (>90%), but according to the molecular thermodynamics principle of film growth, in order to allow the ITO grains sputtered onto the substrate to have enough energy to migrate to a better lattice during the film growth process, the substrate temperature should be 300℃ or even higher to obtain ITO film with good quality, low resistivity and high transmittance. In addition, ITO film is expensive and has poor flexibility. These factors limit the further application of ITO film.

[0006] With the continuous improvement of the performance of weapon seekers, the transparent light window electromagnetic shielding technology has been greatly challenged. On the one hand, when using flat optical glass to make the transparent light window of the seeker, multiple pieces of glass need to be assembled to meet the multi-angle and wide time domain use requirements of the seeker, but more boundaries will be generated during assembly, which affects both the imaging quality and the overall RCS of the seeker. Therefore, the transparent light windows of high-performance seekers are mostly large-slope special-shaped curved surface structures, but the design and production difficulty of conformal curved surface light window electromagnetic shielding is greatly increased, and there are problems such as low efficiency, high cost, and small processing size; on the other hand, with the development of detection radar technology, the electromagnetic shielding of light windows is required to develop towards multi-band broadband shielding, and the broadband electromagnetic shielding efficiency of existing materials is relatively low.

[0007] Conductive polymer film is a new type of transparent conductive film material developed in recent years. Common conductive polymers include polyaniline, polythiophene, polyphenylene vinylene, polypyrrole, etc. Conductive polymer film has excellent light transmittance and flexibility, and the preparation process is simple and low-cost. It has outstanding advantages in the field of conformal surface electromagnetic shielding. However, there are relatively few related studies at present, and its electromagnetic shielding performance is relatively low, the environmental stability is poor, and it is easy to cause performance degradation, which makes it difficult to meet the electromagnetic shielding needs of high-performance transparent light windows. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] The technical problem to be solved by the present invention is how to provide a large-slope conformal curved electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers, so as to solve the problems of low broadband electromagnetic shielding efficiency, poor electromagnetic shielding effect, poor environmental stability, complex process, and difficulty in conforming to special-shaped surfaces of existing transparent light windows, improve system resolution and detection sensitivity, and meet the needs of precise detection and strike of missiles and weapons and equipment in future complex battlefield environments.

[0010] (II) Technical solution

[0011] In order to solve the above technical problems, the present invention provides a large-slope conformal curved electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers, and the electromagnetic shielding transparent light window comprises: a curved optical glass substrate, an electromagnetic shielding layer and a surface protection layer;

[0012] Among them, the electromagnetic shielding layer is a multilayer heterogeneous electromagnetic shielding structure composed of a conductive polymer transparent film and a randomly distributed metal grid film. The two films are alternately stacked. Through the multiple reflections of electromagnetic waves by the multilayer heterogeneous electromagnetic shielding structure, the electromagnetic wave energy is attenuated and the shielding effectiveness of the shielding layer is improved.

[0013] Among them, in the electromagnetic shielding layer, the flexible conductive polymer transparent film can be perfectly conformally prepared on the special-shaped curved surface, and the conductive polymer is doped and modified by the nano absorber, which effectively improves the electromagnetic shielding effect of the conductive polymer film, so that it has excellent electromagnetic shielding performance in the X-band;

[0014] The randomly distributed metal grid film layer avoids the diffraction interference problem caused by the periodic metal grid and has excellent electromagnetic shielding performance in the S band;

[0015] Through the synergistic shielding effect of multi-layer heterogeneous electromagnetic shielding structures, the shielding effect of the transparent light window in the X and S dual bands is further improved.

[0016] The surface protection layer is used for barrier protection and improving the environmental stability of the conductive polymer transparent film.

[0017] The multi-layer heterogeneous electromagnetic shielding structure is composed of N layers of conductive polymer transparent films and N layers of randomly distributed metal grid films alternately, where 2≤N≤5.

[0018] Wherein, the conductive polymer transparent film is one of polyethylene dioxythiophene film, polyaniline film, poly 3-butylthiophene film and polypyrrole film.

[0019] The conductive polymer transparent film is modified by doping with a nano absorber, wherein the nano absorber is nano Ni, Ag, Fe 3 O 4 、Co 3 O 4 、LeFeO 3 The nano absorber is used in an amount of 0.5% to 7% of the mass fraction of the conductive polymer.

[0020] The conductive polymer transparent film is prepared by a solution spraying and curing process, and the film thickness is 300 μm to 600 μm.

[0021] Wherein, the randomly distributed metal grid film is one of a Cu-Ag metal grid film, a Cu-Au metal grid film, a Ni-Ag metal grid film, and an Al-Ta metal grid film.

[0022] The randomly distributed metal grid film is a triangular random grid structure with a line width of 4 μm to 7 μm, an average period of 130 μm to 190 μm, and a thickness of 120 μm to 230 μm.

[0023] Wherein, the surface protection layer is an organic polymer coating, and the organic polymer used is one of methyl polysilazane, vinyl polysilazane and polymethyl methacrylate.

[0024] (III) Beneficial effects

[0025] Compared with the prior art, the present invention provides a large-slope conformal curved electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers. The transparent light window is composed of a curved optical glass substrate, an electromagnetic shielding layer, and a surface protective layer. In the design of the electromagnetic shielding layer, a multi-layer electromagnetic shielding structure composed of a conductive polymer transparent film and a randomly distributed metal grid film is adopted. Through the self-shielding effect of each layer of film and the multiple reflection effect of the multi-layer electromagnetic shielding structure on the electromagnetic wave, the electromagnetic wave energy is attenuated to achieve high shielding characteristics in the X and S dual bands. At the same time, the electromagnetic shielding layer is mainly composed of a conductive polymer transparent film, and maintains excellent optical transmittance under the condition of high shielding characteristics, which can meet the requirements of high imaging quality and high stealth characteristics of high-performance seekers. At the same time, the transparent light window electromagnetic shielding design scheme provided by the present invention solves the problems of low wide-band electromagnetic shielding efficiency, poor electromagnetic shielding effect, poor environmental stability, complex process, and difficulty in conforming to special-shaped surfaces of transparent light windows with irregular curved surfaces. By trimming the shape of the light window and adjusting the design parameters of the shielding layer, the requirements for the use of seekers in different combat scenarios can be met, providing a transparent light window with excellent electromagnetic shielding performance for the seeker of weapons and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic cross-sectional diagram of a transparent light window with a large slope conformal surface for electromagnetic shielding that takes into account both infrared and visible light lasers.

[0027] Figure 2 Schematic diagram of the electromagnetic shielding structure of the transparent light window.

[0028] Figure 3 Schematic diagram of randomly distributed metal grids in triangular structures.

[0029] Numbers in the figure: 1-surface protection layer; 2-electromagnetic shielding layer; 3-curved optical glass substrate; 4-conductive polymer transparent film; 5-randomly distributed metal grid film. DETAILED DESCRIPTION

[0030] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0031] In order to solve the above technical problems, the present invention provides a large-slope conformal curved electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers, and the electromagnetic shielding transparent light window comprises: a curved optical glass substrate, an electromagnetic shielding layer and a surface protection layer;

[0032] Among them, the electromagnetic shielding layer is a multilayer heterogeneous electromagnetic shielding structure composed of a conductive polymer transparent film and a randomly distributed metal grid film. The two films are alternately stacked. Through the multiple reflections of electromagnetic waves by the multilayer heterogeneous electromagnetic shielding structure, the electromagnetic wave energy is attenuated and the shielding effectiveness of the shielding layer is improved.

[0033] Among them, in the electromagnetic shielding layer, the flexible conductive polymer transparent film can be perfectly conformally prepared on the special-shaped curved surface, and the conductive polymer is doped and modified by the nano absorber, which effectively improves the electromagnetic shielding effect of the conductive polymer film, so that it has excellent electromagnetic shielding performance in the X-band;

[0034] The randomly distributed metal grid film layer avoids the diffraction interference problem caused by the periodic metal grid and has excellent electromagnetic shielding performance in the S band;

[0035] Through the synergistic shielding effect of multi-layer heterogeneous electromagnetic shielding structures, the shielding effect of the transparent light window in the X and S dual bands is further improved.

[0036] The surface protection layer is used for barrier protection and improving the environmental stability of the conductive polymer transparent film.

[0037] Through the design of the present invention, the problems of low broadband electromagnetic shielding efficiency, poor electromagnetic shielding effect, poor environmental stability, complex process, and difficulty in conforming to the irregular curved surface and the like of transparent light windows with irregular curved surfaces are solved. At the same time, the electromagnetic shielding layer is mainly composed of a conductive polymer transparent film, which maintains excellent optical transmittance under high shielding characteristics, thereby providing a high-performance electromagnetic shielding transparent light window for weapon equipment seekers.

[0038] The multi-layer heterogeneous electromagnetic shielding structure is composed of N layers of conductive polymer transparent films and N layers of randomly distributed metal grid films alternately, where 2≤N≤5.

[0039] Wherein, the conductive polymer transparent film is one of polyethylene dioxythiophene film, polyaniline film, poly 3-butylthiophene film and polypyrrole film.

[0040] The conductive polymer transparent film is modified by doping with a nano absorber, wherein the nano absorber is nano Ni, Ag, Fe 3 O 4 、Co 3 O 4 、LeFeO 3 The nano absorber is used in an amount of 0.5% to 7% of the mass fraction of the conductive polymer.

[0041] The conductive polymer transparent film is prepared by a solution spraying and curing process, and the film thickness is 300 μm to 600 μm.

[0042] Wherein, the randomly distributed metal grid film is one of a Cu-Ag metal grid film, a Cu-Au metal grid film, a Ni-Ag metal grid film, and an Al-Ta metal grid film.

[0043] The randomly distributed metal grid film is a triangular random grid structure with a line width of 4 μm to 7 μm, an average period of 130 μm to 190 μm, and a thickness of 120 μm to 230 μm.

[0044] Wherein, the surface protection layer is an organic polymer coating with high optical properties, and the organic polymer used is one of methyl polysilazane, vinyl polysilazane and polymethyl methacrylate.

[0045] Example 1

[0046] This embodiment provides a hemispherical electromagnetic shielding transparent light window, the inner surface diameter of which is 220 mm, the transparent glass substrate thickness is 7.6 mm, the outer surface of the transparent glass substrate is an electromagnetic shielding layer formed by alternating stacking of 3 layers of polyethylene dioxythiophene film and 3 layers of Cu-Ag metal grid film, and the outer surface of the electromagnetic shielding layer is a vinyl polysilazane transparent coating, which is the outer surface of the hemispherical electromagnetic shielding transparent light window and provides protection for the light window.

[0047] The polyethylene dioxythiophene film of the hemispherical electromagnetic shielding transparent light window is prepared by solution spraying and curing process, and the thickness of each layer is controlled at 320μm to 380μm. 3 O 4 Doping modification, nano-Fe 3 O 4 The amount used is 5% of the mass fraction of polyethylene dioxythiophene. At the same time, the triangular random Cu-Ag metal grid film of the hemispherical electromagnetic shielding transparent light window has a line width of 4.2 μm, an average period of 170 μm, and a thickness of 120 μm.

[0048] Example 2

[0049] This embodiment provides an arc-shaped plate-shaped electromagnetic shielding transparent light window, with an inner surface diameter of 360 mm, an arc of 230°, a width of 240 mm, a transparent glass substrate thickness of 6.8 mm, and an outer surface of the transparent glass substrate being an electromagnetic shielding layer formed by alternating stacking of 5 layers of poly 3-butylthiophene film and 5 layers of Ni-Ag metal grid film, and an outer surface of the electromagnetic shielding layer being a polymethyl methacrylate coating, which is the outer surface of the arc-shaped plate-shaped electromagnetic shielding transparent light window and provides protection for the light window.

[0050] The poly(3-butylthiophene) film of the arc-shaped plate-shaped electromagnetic shielding transparent light window is prepared by a solution spraying and curing process, and the thickness of each layer is controlled at 540 μm to 600 μm. 3 and Fe 3 O 4 Doping modification, nano-LeFeO 3 and Fe 3 O 4 The usage amount is 3% and 3.5% of the mass fraction of poly 3-butylthiophene respectively. At the same time, the triangular random Ni-Ag metal grid film of the arc-shaped plate-shaped electromagnetic shielding transparent light window has a line width of 5.8μm, an average period of 165μm, and a thickness of 150μm.

[0051] Example 3

[0052] This embodiment provides a hemispherical electromagnetic shielding transparent light window, the inner surface diameter of which is 170 mm, the transparent glass substrate thickness is 5.4 mm, the outer surface of the transparent glass substrate is an electromagnetic shielding layer formed by alternating stacking of 2 layers of polypyrrole film and 2 layers of Cu-Au metal grid film, and the outer surface of the electromagnetic shielding layer is a methyl polysilazane transparent coating, which is the outer surface of the hemispherical electromagnetic shielding transparent light window and provides protection for the light window.

[0053] The polypyrrole film of the hemispherical electromagnetic shielding transparent light window is prepared by solution spraying and curing process, and the thickness of each layer is controlled at 430μm to 490μm. 3 O 4 Doping modification, nano Co 3 O 4 The amount used is 2.3% of the mass fraction of polypyrrole. At the same time, the triangular random Cu-Au metal grid film of the hemispherical electromagnetic shielding transparent light window has a line width of 6.4 μm, an average period of 130 μm, and a thickness of 220 μm.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A large-slope conformal curved electromagnetic shielding transparent light window that takes into account both infrared and visible light lasers, characterized in that: The electromagnetic shielding transparent light window comprises: a curved optical glass substrate, an electromagnetic shielding layer and a surface protection layer; Among them, the electromagnetic shielding layer is a multilayer heterogeneous electromagnetic shielding structure composed of a conductive polymer transparent film and a randomly distributed metal grid film. The two films are alternately stacked. Through the multiple reflections of electromagnetic waves by the multilayer heterogeneous electromagnetic shielding structure, the electromagnetic wave energy is attenuated and the shielding effectiveness of the shielding layer is improved.

2. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: In the electromagnetic shielding layer, the flexible conductive polymer transparent film can be perfectly conformally prepared on the irregular curved surface, and the conductive polymer is doped and modified by the nano absorber, so as to effectively improve the electromagnetic shielding effect of the conductive polymer film, so that it has excellent electromagnetic shielding performance in the X-band; The randomly distributed metal grid film layer avoids the diffraction interference problem caused by the periodic metal grid and has excellent electromagnetic shielding performance in the S band; Through the synergistic shielding effect of multi-layer heterogeneous electromagnetic shielding structures, the shielding effect of the transparent light window in the X and S dual bands is further improved.

3. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The surface protection layer is used for barrier protection and improves the environmental stability of the conductive polymer transparent film.

4. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The multi-layer heterogeneous electromagnetic shielding structure is composed of N layers of conductive polymer transparent films and N layers of randomly distributed metal grid films alternately, wherein 2≤N≤5.

5. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The conductive polymer transparent film is one of polyethylene dioxythiophene film, polyaniline film, poly 3-butylthiophene film and polypyrrole film.

6. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The conductive polymer transparent film is doped and modified with a nano absorber, which is a mixture of one or two of nano Ni, Ag, Fe3O4, Co3O4, and LeFeO3, and the amount of the nano absorber used is 0.5% to 7% of the mass fraction of the conductive polymer.

7. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The conductive polymer transparent film is prepared by a solution spraying and curing process, and the film thickness is 300 μm to 600 μm.

8. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The randomly distributed metal grid film is one of a Cu-Ag metal grid film, a Cu-Au metal grid film, a Ni-Ag metal grid film, and an Al-Ta metal grid film.

9. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The randomly distributed metal grid film is a triangular random grid structure with a line width of 4 μm to 7 μm, an average period of 130 μm to 190 μm, and a thickness of 120 μm to 230 μm.

10. The large-slope conformal curved electromagnetic shielding transparent light window for both infrared and visible light lasers as claimed in claim 1, characterized in that: The surface protection layer is an organic polymer coating, and the organic polymer used is one of methyl polysilazane, vinyl polysilazane and polymethyl methacrylate.

Images