A method for manufacturing a special-shaped large-area metal mesh optical window and the window

Abstract

The application relates to a special-shaped large-area metal mesh optical window and a manufacturing method thereof, and belongs to the field of optical windows. The method comprises the following steps: manufacturing a substrate in a primary mechanical processing mode, coating photoresist on the surface of the substrate, manufacturing a mask opposite to a preset metal mesh shape on the substrate, etching a metal mesh groove, plating a metal mesh layer on the surface of the optical substrate of the metal mesh groove, plating a protective layer on the surface of the metal mesh layer to obtain a preliminary optical window, manufacturing a special-shaped large-area substrate in a secondary mechanical processing mode, stripping and cleaning a non-mesh area, then spraying a layer of photoresist on the surface of the special-shaped large-area substrate, etching a metal mesh special-shaped edge of the special-shaped large-area substrate to form an edge mesh groove, plating an edge metal mesh layer on the surface of the substrate of the edge mesh groove, plating an edge protective layer on the surface of the edge metal mesh layer, stripping and cleaning a core area, and the application has the technical effects of guaranteeing the manufacturing efficiency and uniformity of the special-shaped large-area metal mesh and being suitable for large-area and large-batch production requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical windows, in particular to a special-shaped large-area metal mesh optical window and a manufacturing method thereof. BACKGROUND

[0002] With the rapid development of radio science and radio frequency technology, a large amount of electromagnetic pollution will be generated, which not only causes electromagnetic interference to related equipment, but also has a negative impact on human health. In order to eliminate these negative effects, electromagnetic shielding materials and electromagnetic shielding technology have emerged as the times require, especially in the field of aerospace. Based on the metal mesh optical window, the electromagnetic shielding technology can enable the photoelectric detection and investigation of the internal photoelectric detection system of the instrument cabin or working cabin of aircraft weapons and equipment. At present, the metal mesh optical window is developing towards the direction of special-shaped large area, which puts forward higher requirements for the metal mesh process on the surface of the optical window substrate.

[0003] The special-shaped large-area metal mesh optical window manufactured by the traditional photolithography process will cause unevenness of the final optical window surface mesh line width size due to the unevenness of the special-shaped substrate uniformity, which will further affect the electromagnetic shielding effect of the optical window. The invention patent CN109769387A discloses a multi-layer metal mesh electromagnetic shielding optical window and a manufacturing method thereof using femtosecond laser etching. The inner-buried metal mesh is processed on the substrate material by femtosecond laser etching. This method has low efficiency and cannot be mass-produced. Moreover, the edge burr of the mesh line is more, the process is difficult to control, and finally the electromagnetic shielding effect of the optical window is affected. The invention patent CN115023129A discloses an inner-buried metal mesh optical window and a manufacturing method thereof. The metal mesh is protected by the filling material layer and the protective layer to prevent it from falling off.

[0004] For the related technologies in the above, the inventors believe that when there is a production demand for special-shaped substrate, large area, and mass production of metal mesh optical windows of various materials, the production efficiency and uniformity cannot be guaranteed. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a special-shaped large-area metal mesh optical window and a manufacturing method thereof.

[0006] One of the purposes of the present application is to provide a manufacturing method of a special-shaped large-area metal mesh optical window, which adopts the following technical scheme:

[0007] A method for manufacturing a special-shaped large-area metal mesh optical window, comprising:

[0008] The circular large-area substrate is made by a primary mechanical processing mode, which includes one or more of mechanical cutting, grinding and polishing processes;

[0009] A photoresist is coated on the surface of the circular large-area substrate, and a mask opposite to the preset metal mesh grid shape is made on the circular large-area substrate;

[0010] The metal mesh grid groove is etched, and a metal mesh grid layer is plated on the optical substrate surface of the metal mesh grid groove, and a protection layer is plated on the surface of the metal mesh grid layer to obtain a preliminary light window;

[0011] The special-shaped large-area substrate is made by a secondary mechanical processing mode, which includes cutting and polishing processes;

[0012] The non-mesh grid area is peeled off and cleaned, and then a layer of photoresist is sprayed on the surface thereof;

[0013] The metal mesh grid special-shaped edge of the special-shaped large-area substrate is etched to form an edge mesh grid groove, an edge metal mesh grid layer is plated on the optical substrate surface of the edge mesh grid groove, and an edge protection layer is plated on the surface thereof; and

[0014] The core area is peeled off and cleaned to form a special-shaped large-area substrate.

[0015] By adopting the above technical solution, the metal mesh grid groove is made on the circular large-area substrate by using a mask making, plasma beam etching and other methods, the metal layer and the protection layer are filled in the groove by using vacuum plating, and then the special-shaped large-area substrate is obtained by mechanical processing, and the uniformity of the metal mesh grid line width on the surface thereof can be significantly improved.

[0016] Preferably, the plating of the metal mesh grid layer includes:

[0017] The metal mesh grid layer is plated on the optical substrate surface etched with the metal mesh grid groove by using vacuum plating, and the material of the metal mesh grid layer includes one or more of Ni (nickel), Cr (cadmium), Cu (copper), Ag (silver), Au (copper), Al (aluminum) metal materials, or transparent conductive oxide, or a multi-layer conductive film composed of a metal thin film and a transparent conductive oxide.

[0018] Preferably, before the edge mesh grid groove is formed by etching the metal mesh grid special-shaped edge of the special-shaped large-area substrate, an edge area is made on the optical substrate by one or more of exposure, development and cleaning, and the width of the edge area is less than 1 mm.

[0019] By adopting the above technical solution, the edge ohmic connection metal line with a width of less than 1 mm can be obtained by secondary exposure, development, peeling and cleaning, which not only ensures good conductivity of the metal mesh grid layer, but also improves the effective area of the special-shaped large-area substrate.

[0020] Preferably, before coating photoresist on the surface of the circular large-area substrate or the irregularly-shaped large-area substrate, the circular large-area substrate or the irregularly-shaped large-area substrate is cleaned by using an ultrasonic cleaning machine, and the cleaned circular large-area substrate or the cleaned irregularly-shaped large-area substrate is placed on a hot plate for pre-baking to remove most of the water vapor adsorbed on the surface of the substrate, and is placed at room temperature after pre-baking.

[0021] Preferably, the edge metal mesh grid layer is made of the same material as the metal mesh grid layer.

[0022] Preferably, the method for stripping and cleaning the non-mesh grid area and then spraying a layer of photoresist on the surface of the non-mesh grid area comprises:

[0023] The photoresist spraying device is placed at the metal mesh grid window, and a layer of photoresist with a predetermined thickness is sprayed by the photoresist spraying device.

[0024] The second purpose of the present application is to provide an irregularly-shaped large-area metal mesh grid optical window, which adopts the following technical scheme:

[0025] An irregularly-shaped large-area metal mesh grid optical window comprises an irregularly-shaped large-area substrate, a mesh grid groove, a metal mesh grid layer, and a protective layer. The mesh grid groove is a microstructure groove under the surface of the irregularly-shaped large-area substrate. The metal mesh grid layer is filled in the mesh grid groove. The protective layer is attached to the upper surface of the irregularly-shaped large-area substrate.

[0026] Preferably, the irregularly-shaped large-area substrate has a polygonal irregular shape, a thickness greater than 3 mm, and a maximum diagonal length greater than 10 inches.

[0027] Preferably, the irregularly-shaped large-area substrate is made of one of the following materials: HK9L, quartz, microcrystalline, ZNS, ZNSE, Si, Ge, sapphire, and magnesium fluoride.

[0028] Preferably, the projection shape of the metal mesh grid groove is one or more of a periodic square lattice array, a periodic circular ring array, a periodic honeycomb array, and an irregular mesh pattern. The metal mesh grid layer comprises a plurality of mesh grid units arranged periodically, and each mesh grid unit is connected to each other without being disconnected.

[0029] In summary, the present application has at least one of the following beneficial technical effects:

[0030] The groove of the metal mesh grid is made on the circular large-area substrate by mask making, plasma beam etching and other methods, the metal layer and the protective layer are filled in the groove by vacuum coating, and the special-shaped large-area substrate is obtained by mechanical processing, and the uniformity of the metal mesh grid line width on the surface can be significantly improved. Through secondary exposure, development, stripping and cleaning, the edge ohmic connection metal line with a width of less than 1mm can be obtained, which can ensure good conductivity of the metal mesh grid layer and improve the effective area of the special-shaped large-area substrate. BRIEF DESCRIPTION OF DRAWINGS

[0031] Fig. 1 is a schematic diagram of a special-shaped large-area metal mesh grid optical window in the embodiment.

[0032] Fig. 2 is a basic process flow diagram of the metal mesh grid optical window in the embodiment.

[0033] Fig. 3 is a schematic diagram of special-shaped large-area metal mesh grid optical window shape processing in the embodiment.

[0034] Fig. 4 is a schematic diagram of a mechanical device for processing an edge groove structure in the embodiment.

[0035] Fig. 5 is a schematic diagram of processing an edge groove structure in the embodiment.

[0036] Fig. 6 is a microscopic diagram of a special-shaped large-area metal mesh grid optical window in the embodiment.

[0037] BRIEF DESCRIPTION OF DRAWINGS: 1, special-shaped large-area substrate; 2, mesh grid groove; 3, metal mesh grid layer; 4, protective layer; 5, photoresist; 6, circular large-area substrate; 7, upper clamping plate; 8, lower clamping plate; 9, side clamping assembly; 10, thin paper. DETAILED DESCRIPTION

[0038] The following will be described in detail in combination with the accompanying Figs. 1-6 The present application is further described in detail.

[0039] Embodiment one: the embodiment of the present application discloses a manufacturing method of a special-shaped large-area metal mesh grid optical window. Referring to Figs. 1-6 , comprising the following steps:

[0040] S1: a circular large-area substrate 6 is made by primary mechanical processing.

[0041] It includes selecting one of HK9L, quartz, microcrystalline, ZNS, ZNSE, Si, Ge, sapphire, magnesium fluoride materials, selecting materials that can be deeply processed, and making a large-size circular large-area substrate 6 by mechanical cutting first and then polishing and polishing.

[0042] S2: Clean the large circular substrate 6.

[0043] This includes cleaning a large circular substrate 6 using an ultrasonic cleaner, the method of which can be:

[0044] 1. Place the large circular substrate 6 in acetone and ultrasonically clean for 10 minutes to remove oil and organic residues;

[0045] 2. Transfer to ethanol and ultrasonically clean for 10 minutes to remove acetone residue;

[0046] 3. Place in deionized water and ultrasonically clean for 10 minutes to remove ethanol residue;

[0047] Among them, the ultrasonic frequency is 25-40kHz (25kHz is suitable for removing large particulate contaminants, and 40kHz is suitable for fine cleaning. It is necessary to avoid excessively high frequencies that may cause microstructure resonance), and the power density is 30-50W / L (excessive power may damage the coating or cause microcracks on the glass surface).

[0048] S3: Place the cleaned, large-area circular substrate 6 on a hot plate for pre-baking. After pre-baking, it needs to be placed at room temperature.

[0049] Place the large circular substrate 6 on a hot plate at 150-200°C and heat for 2-3 minutes to remove moisture. After heating, store it in a dry container as soon as possible.

[0050] S4: Coat the surface of the circular large-area substrate 6 with a photoresist of appropriate thickness 5.

[0051] Specifically, a spraying device is placed on the surface of a large circular substrate 6 to spray photoresist 5. The spraying device can be a homogenizer. The reason why the circular substrate can be homogenized more evenly is that its geometry perfectly matches the hydrodynamic characteristics of the homogenizer when it rotates, so that the photoresist 5 forms a symmetrical and stable distribution under the combined action of centrifugal force and surface tension.

[0052] S5: Create a reverse mask on a large circular base 6.

[0053] Through processes such as exposure, development, and cleaning, a mask with the opposite shape to the metal mesh is made on a large circular substrate 6; the shape of the metal mesh can be periodic or non-periodic, and the pattern can be selected according to the actual application.

[0054] Specifically:

[0055] S501, Exposure:

[0056] Mask design: The pattern on the mask = the metal grid lines themselves (transparent), and the remaining area is a chromium layer (opaque); in this way, on the positive resist, the transparent grid line area will undergo a photochemical reaction and dissolve during development; the opaque area of ​​the resist remains. At this time, the photoresist 5 opening area = metal grid lines → opposite to the grid shape (i.e., the opening corresponds to the lines). The corresponding exposure equipment can be a contact / proximity lithography machine or a projection lithography machine.

[0057] The exposure parameters are as follows:

[0058] Exposure wavelength: g line (436nm), h line (405nm) or i line (365nm);

[0059] Exposure dosage: 80~150mJ / cm² (the specific dosage needs to be optimized through experiments to ensure clear lines and no residue).

[0060] Alignment accuracy: For large-area substrates, alignment marks pre-made on the substrate are required to achieve multi-layer overlay (if necessary).

[0061] S502, Development:

[0062] After exposure, the substrate is completely immersed in the developer and gently shaken. Once the development endpoint is reached, immediately rinse with deionized water for 30 seconds to terminate the reaction. The photoresist 5 in the exposed area (grid lines) is completely dissolved, exposing the substrate. The photoresist in the unexposed area is retained.

[0063] The developer can be a TMAH (tetramethylammonium hydroxide) based developer (such as AZ300MIF, concentration 2.38%); use static immersion or spraying method, and set the temperature of the developer to 23±0.5℃ (temperature fluctuations affect linewidth); time: 40~90s (the specific time depends on the photoresist thickness and exposure dose, and is determined by the breakpoint method).

[0064] S502. Cleaning and Drying:

[0065] Rinse the substrate surface thoroughly with deionized water to remove residual developer and dissolved adhesive; dry with high-purity nitrogen or use a spin dryer (800-1000 rpm, 30 s).

[0066] S6: Etching metal mesh groove 2.

[0067] The surface of the optical substrate with the reverse mask is etched using a plasma beam to form a grid groove 2 with the same shape as the metal grid; the width and depth of the grid groove 2 should be determined according to the specific parameter requirements of the metal grid.

[0068] S7: Metal mesh layer 3 is plated.

[0069] A metal mesh layer 3 is deposited on the surface of a large circular substrate 6 with metal mesh grooves 2 using a vacuum deposition method. The material of the thin film can be one or more of the following metal materials: Ni (nickel), Cr (cadmium), Cu (copper), Ag (silver), Au (copper), Al (aluminum), etc., or transparent conductive oxides such as ITO (indium tin oxide), or a multilayer conductive film composed of a metal thin film and a transparent conductive oxide. The thickness h of the metal mesh layer 3 is less than the depth H of the mesh grooves.

[0070] S8: Protective layer 4 is plated.

[0071] Using vacuum coating, a protective layer 4 is deposited on the surface of the metal mesh layer 3. The material of the protective layer 4 is the same as or similar to that of the optical substrate material. The difference between the thickness of the protective layer 4 and the depth of the mesh groove 2 and the thickness of the metal mesh layer 3 is approximately equal to d≈Hh. After processing, a preliminary optical window is formed.

[0072] S9: The irregular large-area substrate 1 is produced by further machining.

[0073] The circular preliminary optical window after the metal mesh layer 3 and the protective layer 4 is placed in the processing center for laser processing and side polishing to finally form the required irregular large area substrate 1. At this time, the metal mesh in the irregular large area substrate 1 is uniformly distributed.

[0074] S901: Place the circular preliminary light window into the preset position and fix it to the laser processing equipment using a fixing component. The laser processing equipment can be a laser cutting machine, which cuts the circular preliminary light window.

[0075] Specifically, the fixing assembly is a combination system consisting of multi-point vacuum suction cups, elastic pressure claws, or low-temperature dispensing devices. For large-sized or ultra-thin circular preliminary light windows, conventional mechanical clamping can easily cause stress deformation or edge cracking. Therefore, a zoned vacuum adsorption platform is often used, combined with a soft sealing ring to apply pressure evenly, while avoiding obstruction of the cutting path. For spherical or aspherical circular preliminary light windows with large curvature, contour-following pressure blocks or magnetic flexible membranes are required for fixation. The fixing assembly also needs to have real-time pressure monitoring capabilities to prevent displacement or loosening caused by vibration during processing.

[0076] Depending on the material of the optical window and the processing requirements, different wavelengths of lasers can be selected: for example, CO2 lasers are suitable for cutting infrared materials such as quartz, glass, and ZnSe; ultraviolet nanosecond or femtosecond lasers are suitable for high-hardness and brittle materials such as sapphire and magnesium fluoride, which can significantly reduce the heat-affected zone; the equipment needs to be equipped with a rotary table or cross motion axes to achieve interpolation motion of circular trajectories; for irregular large-area substrates, a five-axis linkage laser cutting machine is required to ensure the perpendicularity of the edges.

[0077] 902: Polish the cut optical window. Before polishing, use a soft brush or polyurethane abrasive disc to remove obvious slag and burrs from the cut edge at low speed. Then place the optical window in a multi-frequency ultrasonic cleaning tank and use a neutral cleaning agent (pH≈8) with deionized water to remove dust, coolant residue and organic contaminants adhering to the surface. Use a non-contact 3D profilometer or high-magnification stereomicroscope to measure the chipping size of the cut edge (allowable chipping width <50μm) and the thickness of the heat-affected layer (typical value 50~200μm) to determine the subsequent polishing allowance, and then start the polishing process.

[0078] S10: Strip and clean the non-grid area.

[0079] The irregular large-area substrate 1 after laser processing and side polishing is subjected to surface stripping and cleaning. The stripping method can be ultrasonic immersion in stripping solution. It can be first coarsely cleaned with 40kHz, and then finely cleaned with 80kHz or higher frequency to balance cleanliness and surface protection.

[0080] S11: Apply adhesive to protect the core area.

[0081] The large-area irregularly shaped substrate 1, cleaned in S10, is placed into a photoresist spraying device, and a certain thickness of photoresist 5 is sprayed onto its surface. The thickness of the photoresist 5 is usually between 2 micrometers and 10 micrometers. The spraying method can be either spraying or spin coating. Spraying is used on both flat and uneven surfaces, and the thickness accuracy is usually ≤±10%. Spin coating is mainly used on flat surfaces, and the accuracy can reach ≤±3%.

[0082] S12: Photolithographic irregular edge.

[0083] By going through processes such as exposure, development, and cleaning again, an edge region is created on the substrate of the irregular large-area substrate 1, with the edge region width being less than 1mm.

[0084] S13: Plasma beam etching of irregular edges.

[0085] After the protective layer 4 is plated in S8, a thin paper 10 is attached to the non-grid surface of the large circular base 6. The edge of the thin paper 10 is cut so that it is the same size as the large circular base 6 and the two are attached to each other. The center position of the thin paper 10 is found and marked.

[0086] The irregularly shaped large-area substrate 1 is clamped by a clamping assembly, which includes an upper clamping plate 7 and a lower clamping plate 8. The upper clamping plate 7 and the lower clamping plate 8 are symmetrically arranged and both can rotate, thereby driving the irregularly shaped large-area substrate 1 to rotate horizontally during subsequent processing. Before being clamped by the upper clamping plate 7 and the lower clamping plate 8, the irregularly shaped large-area substrate 1 is clamped and fed between the upper clamping plate 7 and the lower clamping plate 8 by a side clamping assembly 9. The side clamping plate can be a gripper. A positioning laser is provided at the rotation center of the lower clamping plate 8. First, the upper clamping plate 7 and the lower clamping plate 8 are separated. The irregularly shaped large-area substrate 1 is fed between the upper clamping plate 7 and the lower clamping plate 8 by the side clamping assembly 9. Then, the position is adjusted so that the positioning laser irradiates the marked position in the middle of the thin paper 10. At this time, the upper clamping plate 7 and the lower clamping plate 8 are engaged to clamp the irregularly shaped large-area substrate 1.

[0087] The plasma beam etching track is set up in the radial direction of a large circular metal mesh window. Then, using a second set of laser positioning, one edge groove structure is etched first. Then, by rotating the upper clamping plate 7 or the lower clamping plate 8, the next edge groove structure is processed. This process continues until the processing is completed. After that, the adjacent edge groove structures are connected to each other to form an edge groove structure that is connected to the internal metal mesh groove 2.

[0088] S14: Edge metal thin film plating.

[0089] A metal thin film is deposited on the surface of the optical substrate of the edge groove of the irregular large-area substrate 1 using vacuum deposition. The material of the thin film can be one or more of the following metals: Ni (nickel), Cr (cadmium), Cu (copper), Ag (silver), Au (copper), Al (aluminum), etc., or transparent conductive oxides such as ITO (indium tin oxide), or a multilayer conductive film composed of a metal thin film and a transparent conductive oxide. The metal thin film is the same as in step S7, which can achieve ohmic connection for all metal mesh structures.

[0090] S15: Edge protection film coating.

[0091] A protective film is deposited on the surface described in step S14 using a vacuum deposition method. The material of the protective film is the same as or similar to that of the optical substrate material, and the film thickness is the same as that in S8.

[0092] S16: Peel and clean the internal core area to form a large-area irregularly shaped metal mesh light window.

[0093] Example 2: This application discloses an irregularly shaped large-area metal mesh optical window, referring to... Figs. 1-3It includes an irregularly shaped large-area substrate 1, a mesh groove 2, a metal mesh layer 3, and a protective layer 4. The mesh groove 2 is a microstructure groove below the surface of the irregularly shaped large-area substrate 1. The metal mesh layer 3 is filled in the mesh groove 2, and the protective layer 4 is attached to the upper surface of the irregularly shaped large-area substrate 1.

[0094] The irregularly shaped large-area substrate 1 has a polygonal irregular shape, a thickness greater than 3 mm, and a maximum diagonal length greater than 10 inches. The irregularly shaped large-area substrate 1 is made of one of the following materials: HK9L, quartz, microcrystalline, ZNS, ZNSE, Si, Ge, sapphire, and magnesium fluoride. The mesh groove 2 is a mesh-like microstructure formed below the surface of the irregularly shaped large-area substrate 1, and the sidewall verticality error of the microstructure is less than ±5%. The projected shape of the metal mesh groove 2 is one or more of the following: a periodically arranged square array, a circular array, a honeycomb array, and an irregular mesh pattern. The metal mesh layer 3 includes multiple periodically arranged mesh units, and each mesh unit is interconnected without being separated. The arrangement period of the mesh units in the metal mesh layer 3 is 100–1000 micrometers, the linewidth is 1–10 micrometers, and the ratio of the linewidth to the arrangement period is less than 0.1. The uniformity error of the metal mesh linewidth is within ±5%.

[0095] Employing a large-area substrate with an irregular polygonal shape, a thickness exceeding 3mm, and a diagonal exceeding 10 inches, this design meets the assembly and usage requirements of large-diameter, non-standard geometric contour optical windows, making it particularly suitable for aerospace optoelectronic pods, shipborne optoelectronic tracking systems, and large vehicle-mounted optoelectronic equipment. The greater thickness enhances the substrate's mechanical strength and thermal shock resistance, reducing the risk of deformation and breakage in harsh environments, thus ensuring the structural stability and long-term reliability of the metal mesh layer 3. Matching optical materials can be selected based on specific applications: for example, sapphire and quartz are suitable for high-hardness, scratch-resistant windows; ZnS / ZnSe is suitable for infrared thermal imaging; Si / Ge is suitable for long-wave infrared; and magnesium fluoride is suitable for ultraviolet to mid-infrared. Appropriate selection of substrate materials ensures high light transmittance while also considering thermal expansion matching, chemical stability, and processing performance, thereby improving the environmental adaptability and optical efficiency of the mesh window.

[0096] The high-precision (sidewall verticality error ≤ ±5%) microstructure of the grid groove 2 ensures that the subsequently filled metal grid layer 3 has a rectangular or near-rectangular cross-sectional shape, thereby significantly reducing the additional resistance changes and electromagnetic wave reflection losses caused by sidewall tilting during electromagnetic shielding. Simultaneously, the vertical sidewalls help maintain the set linewidth and periodic parameters, avoiding the deterioration of optical diffraction effects and ensuring the consistency of the window's transmittance and electromagnetic shielding effectiveness in the target wavelength band (such as infrared and visible light). Different projection shapes can be optimized for different electromagnetic interference frequency bands and incident angles: square arrays provide balanced shielding performance across a wide frequency range; circular arrays are suitable for circularly polarized wave interference environments; cellular arrays can achieve higher aperture ratios (thus improving optical transmittance) under equal linewidth conditions; irregular mesh patterns can avoid moiré fringes or coherent noise caused by periodic structures, making them particularly suitable for focal plane array detection systems. By flexibly selecting or combining these shapes, multiple targets requiring high transmittance, low stray light, and strong electromagnetic shielding can be addressed.

[0097] All grid cells form a continuous conductive network, constituting a complete low-impedance conductive path, avoiding local current interruptions or antenna effects caused by cell open circuits. This continuous structure effectively suppresses the circulation blockage of induced currents, achieving uniform and efficient electromagnetic shielding across the entire window area (e.g., shielding effectiveness exceeding 30dB in the 1–18 GHz range), while avoiding scattering hotspots caused by broken lines, maintaining the cleanliness of infrared or visible light images. This parameter range represents the optimal balance between optical transmittance and electromagnetic shielding effectiveness: a period less than 100 μm easily leads to enhanced diffraction effects, while a period greater than 1000 μm results in decreased shielding effectiveness; a linewidth of 1–10 μm ensures sufficiently low resistivity (typically using Cu, Au, or Ag materials), while a linewidth / period ratio of less than 0.1 ensures that the metal blocking area is less than 10%, thereby maintaining optical transmittance above 90% (for mid-wave infrared) or higher (for long-wave infrared). This design effectively avoids the severe energy loss of traditional wide-line-width grids.

[0098] Strict linewidth uniformity control (within ±5%) ensures that each grid cell has nearly identical resistivity and optical diffraction characteristics, thereby eliminating parasitic capacitance differences and diffraction efficiency inhomogeneities caused by local linewidth deviations. This directly translates into a highly consistent transmission wavefront and stable electromagnetic shielding effectiveness across the entire window (e.g., shielding effectiveness fluctuations less than ±1.5 dB), avoiding "grid shadows" or "bright and dark stripes" artifacts on the imaging system, making it particularly suitable for optical systems of high-resolution, large-area detectors.

[0099] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for fabricating an irregularly shaped, large-area metal mesh optical window, characterized in that, include: A large circular base (6) is made by means of initial machining, wherein the initial machining includes one or more of the following processes: mechanical cutting, grinding and polishing. Photoresist (5) is coated on the surface of a large circular substrate (6), and a mask with the opposite shape to the preset metal mesh is made on the large circular substrate (6). Etch a metal mesh groove (2); deposit a metal mesh layer (3) on the optical substrate surface of the metal mesh groove (2), and deposit a protective layer (4) on the surface of the metal mesh layer (3) to obtain a preliminary optical window; Irregular large-area substrates are produced by further machining (1), wherein the further machining includes cutting and polishing processes; The non-grid area was stripped and cleaned, and then a layer of photoresist was sprayed onto its surface (5); An edge mesh trench is formed by etching the edge of the irregularly shaped large-area substrate (1). An edge metal mesh layer (3) is deposited on the optical substrate surface of the edge mesh trench; and an edge protective layer (4) is deposited on its surface; and The core area was peeled off and cleaned to form a large, irregularly shaped base.

2. The method for manufacturing an irregularly shaped large-area metal mesh optical window according to claim 1, characterized in that, The plating of the metal mesh layer (3) includes: A metal mesh layer (3) is deposited on the surface of an optical substrate with engraved metal mesh grooves (2) using a vacuum deposition method. The material of the metal mesh layer (3) includes one or more of the following metal materials: Ni (nickel), Cr (cadmium), Cu (copper), Ag (silver), Au (copper), and Al (aluminum), or a transparent conductive oxide, or a multilayer conductive film composed of a metal thin film and a transparent conductive oxide.

3. The method for manufacturing an irregularly shaped large-area metal mesh optical window according to claim 1, characterized in that: Before forming edge grid grooves on the metal grid irregular edge of the etched large-area substrate (1), an edge region is made on the optical substrate by one or more of the following methods: exposure, development, and cleaning. The width of the edge region is less than 1 mm.

4. The method for manufacturing an irregularly shaped large-area metal mesh optical window according to claim 1, characterized in that: Before coating the surface of the circular large-area substrate (6) or the irregular large-area substrate (1) with photoresist (5), the circular large-area substrate (6) or the irregular large-area substrate (1) is cleaned with an ultrasonic cleaner. The cleaned circular large-area substrate (6) or the irregular large-area substrate (1) is placed on a hot plate for pre-baking to remove most of the moisture adsorbed on the substrate surface. After pre-baking, it is placed at room temperature.

5. The method for manufacturing an irregularly shaped large-area metal mesh optical window according to claim 1, characterized in that: The edge metal mesh layer (3) is made of the same material as the metal mesh layer (3).

6. The method for fabricating an irregularly shaped large-area metal mesh optical window according to claim 1, Its features are: The method of stripping and cleaning the non-grid area, and then spraying a layer of photoresist (5) on its surface includes: A photoresist of a predetermined thickness was applied by placing a glue spraying device at the metal mesh window (5).

7. An irregularly shaped large-area metal mesh optical window, prepared by the method described in any one of claims 1-6, characterized in that: It includes an irregular large-area substrate (1), a mesh groove (2), a metal mesh layer (3) and a protective layer (4). The mesh groove (2) is a microstructure groove under the surface of the irregular large-area substrate (1). The metal mesh layer (3) is filled in the mesh groove (2). The protective layer (4) is attached to the upper surface of the irregular large-area substrate (1).

8. The irregularly shaped large-area metal mesh optical window according to claim 7, characterized in that: The irregular large-area base (1) is polygonal and irregular in shape, with a thickness greater than 3mm and a maximum diagonal length greater than 10 inches.

9. The irregularly shaped large-area metal mesh optical window according to claim 7, characterized in that: The irregular large-area substrate (1) is made of one of the following materials: HK9L, quartz, microcrystalline, ZNS, ZNSE, Si, Ge, sapphire, or magnesium fluoride.

10. The irregularly shaped large-area metal mesh optical window according to claim 7, characterized in that: The projected shape of the metal mesh groove (2) is one or more of the following: a periodically arranged square array, a circular array, a honeycomb array, and an irregular mesh pattern; the metal mesh layer (3) includes a plurality of periodically arranged mesh units, and each mesh unit is continuously connected to the others.

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