Electromagnetic stealth wide-angle-domain high-transmittance functional light window and method

Abstract

The invention discloses an electromagnetic stealth wide-angle-domain high-transmittance functional light window and method, and belongs to the technical field of photoelectric detection and electromagnetic stealth. Comprising a light window substrate, cone-shaped body surface microstructures arranged on the outer surface of the light window substrate in a periodic array mode, and metal periodic meshes, and a microstructure light window is formed. A single cone surface microstructure array unit is surrounded by a single metal periodic mesh array unit to form a periodic array structure in which a cone surface microstructure and a metal periodic mesh are coupled with each other, namely, a gradient refractive index area is formed on the surface of the light window. The metal periodic mesh is in conductive lap joint with a gold film plated on the side face of the light window substrate, and the optical transmission function is achieved while continuous conduction of the light transmission surface of the light window is guaranteed. The invention provides an optical window with both an electromagnetic stealth function and an omnidirectional detection function, and is an effective solution for realizing an ultra-oblique incident light window of stealth photoelectric equipment.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detection technology and electromagnetic stealth technology, and specifically relates to an electromagnetic stealth wide-angle high-transmittance functional optical window and a method. Background Art

[0002] With the development trend of transparent optoelectronic sensing equipment in the future, the requirements for electromagnetic shielding devices are not limited to the basic function of electromagnetic signal shielding, but also include good visual effects and mechanical toughness. They have important application value and prospects in fields including precision instrument displays, medical electromagnetic isolation observation windows, wearable electronic system touch screens, space detection windows, laser radar windows, infrared detection imaging, etc. Especially in the field of cutting-edge optical windows, in order to meet the detection of target objects, high optical transmittance is required while also having good optical imaging quality.

[0003] It is difficult for traditional transparent electromagnetic shielding films to simultaneously ensure high light transmittance, high shielding efficiency, and mechanical toughness, while also taking into account optical imaging quality. Therefore, how to manufacture an optical window that has high light transmittance over a wide angle and spectrum, high mechanical toughness, high optical imaging quality, and high electromagnetic shielding efficiency is the primary problem that needs to be solved. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides an electromagnetic stealth wide-angle high-transmittance functional optical window and method, the optical window couples the cone surface microstructure and the metal periodic grid on the surface, the cone surface microstructure arranged in a periodic array forms a gradient refractive index area on the optical window surface, and the metal periodic grid arranged in a periodic array surrounds the cone surface microstructure, through the cooperation of the two, while improving the wide-angle and wide-band high optical transmittance, the strength of the surface structure can be guaranteed, and the mechanical toughness is improved. The present invention is an optical window with both electromagnetic stealth function and omnidirectional detection function, which is an effective solution to realize the ultra-oblique incident optical window of stealth optoelectronic equipment.

[0006] The technical solution of the present invention is: an electromagnetic stealth wide-angle high-transmittance functional light window, including a light window substrate and a cone surface microstructure and a metal periodic grid arranged in a periodic array on its outer surface to form a microstructure light window; a single cone surface microstructure array unit is surrounded by a single metal periodic grid array unit to form a periodic array structure in which the cone surface microstructure and the metal periodic grid are mutually coupled, that is, a gradient refractive index area is formed on the surface of the light window; the metal periodic grid is conductively overlapped with the gold film plated on the side of the light window substrate to ensure that the light-transmitting surface of the light window is conductively continuous while realizing the optical transmission function.

[0007] A further technical solution of the present invention is: the cone surface microstructure is prepared by photolithography of an anti-reflection film layer plated on the outer surface of the light window substrate, and a single cone surface microstructure array unit presents a pyramidal structure morphology with an aspect ratio lower than 10 / 1, which can achieve a gradual change in optical refractive index; the typical period value of the cone surface microstructure is 0.4μm-2μm.

[0008] A further technical solution of the present invention is that the structure of the microstructure on the surface of the cone should meet the following conditions:

[0009] λ>Λ·(max(n s , n i )+n i sinθ)

[0010] Where: λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle, and Λ represents the microstructure period.

[0011] A further technical solution of the present invention is: the metal periodic grid is made on the outer surface of the light window substrate by laser direct writing, presenting a square, circular or honeycomb periodic structure; the metal periodic grid and the cone surface microstructure are complementary in position on the light window substrate.

[0012] A further technical solution of the present invention is that the material of the metal periodic grid is usually nickel alloy, the typical period value is 100 μm-400 μm, and the line width is 1 μm-5 μm.

[0013] A further technical solution of the present invention is that the metal periodic grid electromagnetic screen efficiency satisfies the following conditions:

[0014]

[0015] Where: λ′ is the wavelength of the electromagnetic wave, w is the grid line width, and p is the grid period.

[0016] A further technical solution of the present invention is that the light window substrate is made of sapphire.

[0017] A design method for an electromagnetic stealth wide-angle high-transmittance functional optical window, the specific steps are as follows:

[0018] An anti-reflection film layer is plated on the outer surface of the light window substrate;

[0019] An array periodic cone surface microstructure is fabricated on the anti-reflection film layer by photolithography, and the structure of the cone surface microstructure should meet the following conditions:

[0020] λ>Λ·(max(n s , n i)+n i sinθ) where λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle, and Λ represents the microstructure period;

[0021] A metal periodic grid is fabricated on the outer surface of the optical window substrate by laser direct writing and deep etching, and the electromagnetic screen efficiency of the metal periodic grid satisfies the following conditions:

[0022]

[0023] Where: λ′ is the wavelength of the electromagnetic wave, w is the line width of the grid, and p is the grid period;

[0024] A gold film is plated on the side of the light window substrate to be conductively overlapped with the metal periodic grid.

[0025] An application of an electromagnetic stealth wide-angle high-transmittance functional light window, wherein the electromagnetic stealth wide-angle high-transmittance functional light window is installed on an optical window of an optoelectronic device through a light window installation frame, wherein the installation hole profile of the light window installation frame is consistent with the non-light-transmitting annular surface of the light window, the light window is embedded in the installation hole, and is fixed by bonding with a sealant having both conductivity and sealing properties;

[0026] A plurality of light window pressing blocks are installed on the circumference of the outer edge of the mounting hole of the light window mounting frame through a connecting piece to press and fix the light window embedded in the mounting hole, and a gasket of flexible material is arranged between the light window pressing block and the light window surface for flexible pressing.

[0027] A further technical solution of the present invention is: the mounting hole of the light window mounting frame is a conical hole, and the light window is axially mounted and limited by the conical circumference, and the outer surface of the light window is located at the small diameter end of the conical hole; the inner surface of the light window mounting frame is coplanar with or smoothly transitioned to the inner surface of the light window; and a plurality of light window pressing blocks are circumferentially installed on the outer edge of the large diameter end of the mounting hole of the light window mounting frame to flexibly press and fix the inner surface of the light window.

[0028] Beneficial Effects

[0029] The beneficial effect of the present invention is that the present invention proposes an optical window that combines the electromagnetic stealth function with the high transmittance function in a wide angle range and wide spectrum. Compared with the traditional dielectric coated optical window, the optical transmittance in a wide angle range and wide spectrum is improved, and the electromagnetic stealth of the window is achieved without affecting the optical performance. The specific advantages are as follows:

[0030] 1. The present invention organically combines the surface pyramidal microstructure and the periodic metal grid, and utilizes the molecular binding force between the grid metal and the film layer microstructure to improve the strength of the surface micro-nano structure and enhance the environmental adaptability.

[0031] 2. The present invention prepares a periodic array of cone microstructures on the surface of the light window substrate, which can form a gradient refractive index area on the light window surface and achieve high optical transmittance in a wide angle range and wide band.

[0032] 3. The metal periodic grid prepared on the surface of the light window substrate of the present invention is overlapped with the gold film plated on the side of the light window, realizing the optical transmission function while achieving the conductive continuity of the light-transmitting surface of the microstructure light window; at the same time, the mesh metal periodic grid supports the microstructure of the cone surface, enhancing the strength of the micro-nano structure on the window surface.

[0033] 4. In the application of the light window, the light window mounting frame installs the microstructure light window in the form of a four-sided surround, and its mounting hole is a conical hole structure, that is, the contact with the microstructure light window is a protective chamfered edge design, which facilitates the installation and positioning of the light window. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural diagram of an electromagnetic stealth wide-angle high-transmittance functional optical window in an embodiment of the present invention.

[0035] Figure 2 Schematic diagram of the surface micro-nano morphology of the microstructured light window in an embodiment of the present invention.

[0036] Figure 3 This is a scanning electron microscope image of the micro-nano morphology of the light window surface in an embodiment of the present invention.

[0037] Figure 4 It is a comparison chart of the wide-angle transmittance test of the microstructure in the embodiment of the present invention and the traditional dielectric film light window.

[0038] Explanation of the reference numerals: 1. Light window mounting frame, 2. Microstructure light window, 3. Sealant, 4. Light window pressing block, 5. Conical surface microstructure, 6. Metal periodic grid, 7. Gold film. DETAILED DESCRIPTION

[0039] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] Based on the problem that traditional transparent electromagnetic shielding films cannot simultaneously ensure high light transmittance, high shielding effectiveness, and mechanical toughness, and take into account the optical imaging quality, the present invention provides an electromagnetic stealth wide-angle high-transmittance functional light window, including a light window substrate and a cone surface microstructure and a metal periodic grid arranged in a periodic array on its outer surface to form a microstructure light window; a single cone surface microstructure array unit is surrounded by a single metal periodic grid array unit to form a periodic array structure in which the cone surface microstructure and the metal periodic grid are coupled to each other, that is, a gradient refractive index area is formed on the surface of the light window; the metal periodic grid is conductively overlapped with the gold film plated on the side of the light window substrate to ensure that the light-transmitting surface of the light window is conductively continuous while realizing the optical transmission function.

[0042] Specifically, the cone surface microstructure is prepared by photolithography of an anti-reflection film layer plated on the outer surface of the light window substrate. A single cone surface microstructure array unit has a pyramidal structure morphology with an aspect ratio of less than 10 / 1, which can achieve a gradual change in optical refractive index. The typical period value of the cone surface microstructure is 0.4μm-2μm.

[0043] Specifically, the metal periodic grid is made on the outer surface of the light window substrate by laser direct writing, and is in a square, circular or honeycomb periodic structure; the metal periodic grid and the cone surface microstructure are complementary in position on the light window substrate.

[0044] Specifically, the material of the metal periodic grid is usually nickel alloy, the typical period value is 100 μm-400 μm, and the line width is 1 μm-5 μm.

[0045] Specifically, the light window substrate is made of sapphire.

[0046] The present invention provides a design method for an electromagnetic stealth wide-angle high-transmittance functional optical window, and the specific steps are as follows:

[0047] Step 1: coating an anti-reflection film layer on the outer surface of the light window substrate;

[0048] Step 2: fabricating an array periodic cone surface microstructure on the anti-reflection film layer by photolithography, wherein the structure of the cone surface microstructure should meet the following conditions:

[0049] λ>Λ·(max(n s , n i )+n i sinθ)

[0050] Where: λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle, and Λ represents the microstructure period;

[0051] Step 3: A metal periodic grid is fabricated on the outer surface of the light window substrate by laser direct writing and deep etching. The electromagnetic screen efficiency of the metal periodic grid satisfies the following conditions:

[0052]

[0053] Where: λ′ is the wavelength of the electromagnetic wave, w is the line width of the grid, and p is the grid period;

[0054] Step 4: A gold film is plated on the side of the light window substrate to form an electrically conductive connection with the metal periodic grid.

[0055] The present invention provides an application of an electromagnetic stealth wide-angle high-transmittance functional light window, wherein the electromagnetic stealth wide-angle high-transmittance functional light window is installed on an optical window of an optoelectronic device through a light window mounting frame, the mounting hole profile of the light window mounting frame is consistent with the non-light-transmitting annular surface of the light window, the light window is embedded in the mounting hole and fixed by bonding with a sealant having both electrical conductivity and sealing properties; a plurality of light window pressing blocks are installed on the circumference of the outer edge of the mounting hole of the light window mounting frame through a connecting piece, the light window embedded in the mounting hole is pressed and fixed, and a gasket of a flexible material is arranged between the light window pressing block and the light window surface for flexible pressing.

[0056] Specifically, the mounting hole of the light window mounting frame is a conical hole, and the light window is axially mounted and limited by the conical circumference, and the outer surface of the light window is located at the small diameter end of the conical hole; the inner surface of the light window mounting frame is coplanar with or smoothly transitions to the inner surface of the light window; and a plurality of light window pressing blocks are circumferentially installed on the outer edge of the large diameter end of the mounting hole of the light window mounting frame to flexibly press and fix the inner surface of the light window.

[0057] The above technical solution is further described below in conjunction with the accompanying drawings:

[0058] Reference Figure 1 As shown, the optical window of this embodiment with electromagnetic stealth, wide-angle and high-transmittance functions includes a light window mounting frame 1, a microstructure light window 2, a sealant 3, and a light window pressing block 4.

[0059] The light window installation frame 1 surrounds the microstructure light window 2 on all four sides, and the outer surface of the light window installation frame 1 needs to be coplanar or smoothly transitioned with the surface of the microstructure light window 2. The outer surface of the light window installation frame 1 is sprayed with stealth conductive paint, and the contact with the microstructure light window 2 has a protective chamfered edge design, and is bonded and fixed by a sealant 3 that has both conductivity and sealing properties. The light window installation frame 1, the sealant 3, and the metal periodic grid 6 and the gold film 7 of the microstructure light window 2 form a conductive continuous layer on the outer surface of the structure to achieve electromagnetic continuity and stealth shielding effectiveness.

[0060] Reference Figure 2As shown, the microstructure light window of this embodiment includes a cone surface microstructure 5, a metal periodic grid 6 and a gold film 7 coated on the side mounting surface. The specific surface microstructure morphology and manufacturing method are as follows:

[0061] The outer surface of the microstructure light window 2 is plated with an anti-reflection film layer, and an array of periodic cone surface microstructures 5 are made on the film layer by photolithography. The structure of the cone surface microstructure 5 should meet the following conditions:

[0062] λ>Λ·(max(n s , n i )+n i sinθ) where λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle; the typical period value of the surface microstructure 5 is 0.4 μm-2 μm. The surface microstructure can usually be manufactured by laser interference exposure technology, nanoimprint technology, etc.

[0063] The outer surface of the microstructure light window 2 is provided with a metal periodic grid 6 located at the groove of the surface microstructure 5. The grid material is usually a nickel alloy, including but not limited to nickel metal, nickel-gold alloy and nickel-silver alloy. It can be made into a square, circular or honeycomb periodic structure by laser direct writing and deep etching. Its electromagnetic screen efficiency meets the following conditions:

[0064]

[0065] Where: λ′ is the wavelength of the electromagnetic wave, w is the grid line width, and p is the grid period; the typical structural period value is 100μm-400μm, and the typical grid line width is 1μm-5μm. Laser direct writing technology can usually be used to manufacture metal periodic grid structures.

[0066] Figure 3 This is a scanning electron microscope image of the surface micro-nano morphology of the light window of this embodiment, and the period of the micro-nano structure is 0.8μm. Figure 4 This is a comparison chart of the wide-angle transmittance of the microstructured light window of this embodiment and the traditional dielectric film light window. The test sample light window is 1 mm thick sapphire, and the test band is 3.5 μm-5 μm. It can be seen from the figure that with the increase of the incident angle, the transmittance of the traditional dielectric film decreases significantly, while the microstructured light window of the present invention can be maintained above 90%.

[0067] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. An electromagnetic stealth wide-angle high-transmittance functional optical window, characterized by: The invention comprises a light window substrate and a cone surface microstructure and a metal periodic grid arranged in a periodic array on its outer surface, forming a microstructure light window; a single cone surface microstructure array unit is surrounded by a single metal periodic grid array unit, forming a periodic array structure in which the cone surface microstructure and the metal periodic grid are mutually coupled, that is, a gradient refractive index region is formed on the surface of the light window; the metal periodic grid is conductively overlapped with the gold film plated on the side of the light window substrate, ensuring that the light-transmitting surface of the light window is conductively continuous while realizing the optical transmission function.

2. According to claim 1, an electromagnetic stealth wide-angle high-transmittance functional optical window is characterized by: The cone surface microstructure is prepared by photolithography of an anti-reflection film layer plated on the outer surface of the light window substrate. A single cone surface microstructure array unit presents a pyramidal structure morphology with an aspect ratio lower than 10 / 1, which can achieve a gradual change in optical refractive index. The typical period value of the cone surface microstructure is 0.4μm-2μm.

3. According to claim 2, an electromagnetic stealth wide-angle high-transmittance functional optical window is characterized by: The structure of the cone surface microstructure should meet the following conditions: λ>Λ·(max(n s ,n i )+n i sinθ) Where: λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle, and Λ represents the microstructure period.

4. According to claim 1, the electromagnetic stealth wide-angle high-transmittance functional optical window is characterized by: The metal periodic grid is made on the outer surface of the light window substrate by laser direct writing, and presents a square, circular or honeycomb periodic structure; the metal periodic grid and the cone surface microstructure are complementary in position on the light window substrate.

5. According to claim 4, the electromagnetic stealth wide-angle high-transmittance functional optical window is characterized by: The material of the metal periodic grid is usually nickel alloy, with a typical period value of 100 μm-400 μm and a line width of 1 μm-5 μm.

6. The electromagnetic stealth wide-angle high-transmittance functional optical window according to claim 5, characterized in that: The metal periodic grid electromagnetic screen efficiency meets the following conditions: Where: λ′ is the wavelength of the electromagnetic wave, w is the grid line width, and p is the grid period.

7. According to claim 1, the electromagnetic stealth wide-angle high-transmittance functional optical window is characterized by: The light window substrate is made of sapphire.

8. A design method for the electromagnetic stealth wide-angle high-transmittance functional optical window according to any one of claims 1 to 7, characterized in that The specific steps are as follows: An anti-reflection film layer is plated on the outer surface of the light window substrate; An array periodic cone surface microstructure is fabricated on the anti-reflection film layer by photolithography, and the structure of the cone surface microstructure should meet the following conditions: λ>Λ·(max(n s ,n i )+n i sin θ) Where: λ is the optical wavelength, n s is the substrate refractive index, n i is the refractive index of air, θ is the incident angle, and Λ represents the microstructure period; A metal periodic grid is fabricated on the outer surface of the optical window substrate by laser direct writing and deep etching, and the electromagnetic screen efficiency of the metal periodic grid satisfies the following conditions: Where: λ′ is the wavelength of the electromagnetic wave, w is the line width of the grid, and p is the grid period; A gold film is plated on the side of the light window substrate to be conductively overlapped with the metal periodic grid.

9. An application of the electromagnetic stealth wide-angle high-transmittance functional optical window according to any one of claims 1 to 7, characterized in that: The electromagnetic stealth wide-angle high-transmittance functional light window is installed on the optical window of the optoelectronic device through a light window installation frame, the installation hole profile of the light window installation frame is consistent with the non-light-transmitting annular surface of the light window, the light window is embedded in the installation hole, and is fixed by bonding with a sealant that has both conductivity and sealing properties; A plurality of light window pressing blocks are installed on the circumference of the outer edge of the mounting hole of the light window mounting frame through a connecting piece to press and fix the light window embedded in the mounting hole, and a gasket of flexible material is arranged between the light window pressing block and the light window surface for flexible pressing.

10. Application of the electromagnetic stealth wide-angle high-transmittance functional optical window according to claim 9, characterized in that: The mounting hole of the light window mounting frame is a conical hole, and the light window is axially mounted and limited by the conical circumference, and the outer surface of the light window is located at the small diameter end of the conical hole; the inner surface of the light window mounting frame is coplanar with or smoothly transitioned to the inner surface of the light window; and a plurality of light window pressing blocks are circumferentially installed on the outer edge of the large diameter end of the mounting hole of the light window mounting frame to flexibly press and fix the inner surface of the light window.

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