A radiation-cooled integrated filter and its preparation method

Abstract

This invention discloses a radiation-cooled integrated filter and its fabrication method, comprising a color filter film, a transparent substrate, and an all-solid-state diffuse reflection unit arranged sequentially from top to bottom, forming a monolithic integrated structure without air cavities. The color filter film selectively filters the solar spectrum; the all-solid-state diffuse reflection unit diffusely reflects light transmitted through the color filter film back into the incident space to avoid thermal gain caused by absorption of transmitted light by the material. The all-solid-state diffuse reflection unit, from top to bottom, includes: a rough surface at the bottom of the transparent substrate, a solid support layer, and a metal reflective layer; the solid support layer tightly fills the space between the rough surface and the metal reflective layer to fill the micro-grooves of the rough surface and form a flat surface at the bottom. This invention, through its all-solid-state monolithic integrated structure and aerogel solid support layer, effectively suppresses SPR heat loss while achieving lightweight and high-reliability integration.

Description

Technical Field

[0001] This invention belongs to the field of radiation cooling and micro-nano optics technology, specifically relating to a radiation-cooled integrated filter and its preparation method. Background Technology

[0002] Structured color filters, by avoiding the high absorption loss of traditional dyes or inks in the solar band, possess advantages such as high solar radiation stability and low thermal gain, showing great application potential in passive radiative cooling and all-weather passive thermal control. However, in existing color radiative cooling filter designs, a double-substrate adhesive encapsulation process is typically used to achieve specific diffuse reflectance spectrum modulation. This involves applying adhesive material to the edges of two substrates to maintain the internal air cavity structure. This double-substrate hollow structure has significant physical defects in practical applications: in harsh environments such as aviation, drastic changes in external air pressure can create a huge pressure difference between the inside and outside of the cavity, easily causing substrate deformation or even rupture, leading to complete failure of the device's optical performance. Simultaneously, the double-layer substrate and encapsulation material significantly increase the device weight, severely restricting its lightweight design. Furthermore, due to the lack of solid support inside the air cavity, the adhesive layer is prone to cracking or film peeling under high-frequency vibration or mechanical impact.

[0003] In addition to the fragility of its physical structure, this hollow structure also suffers from severe optical thermal management defects. In this structure, the metallic reflective layer is directly exposed within the air cavity, and its rough interface readily excites surface plasmon resonance (SPR). This effect induces undesirable photothermal absorption, introducing additional thermal gain in the solar spectrum and severely weakening the overall efficiency of passive radiative cooling.

[0004] In summary, there is a current need to develop a novel radiation-cooled device structure that can achieve efficient spectral control and stable cooling performance, meet the stringent requirements of aerospace applications for lightweight, high strength, and vibration resistance, and effectively suppress additional photothermal losses from a mechanistic perspective. This is also the original design intention of the radiation-cooled integrated filter of this invention.

[0005] Therefore, how to solve the problems of existing double-substrate hollow structures being prone to deformation and breakage under harsh environments, having large weight, poor vibration resistance, and additional photothermal absorption caused by surface plasmon resonance, and how to provide a lightweight, high-strength, pressure-resistant, vibration-resistant, and mechanism-suppressive SPR photothermal loss radiation-cooled integrated filter are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0006] The first objective of this invention is to provide a radiation-cooled integrated filter, addressing the problems in the prior art.

[0007] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0008] A radiation-cooled integrated filter includes a color filter film, a transparent substrate, and an all-solid-state diffuse reflection unit arranged closely from top to bottom, forming a monolithic integrated structure without air cavities. The color filter film is used to selectively filter the solar spectrum; the all-solid-state diffuse reflection unit is used to diffusely reflect the light transmitted through the color filter film back into the incident space to avoid thermal gain caused by the absorption of transmitted light by the material.

[0009] The all-solid-state diffuse reflection unit comprises, from top to bottom: a rough surface at the bottom of the transparent substrate, a solid support layer, and a metal reflective layer;

[0010] The solid support layer is tightly filled between the rough surface and the metal reflective layer to fill the micro-grooves of the rough surface and form a flat surface at the bottom.

[0011] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0012] As a preferred technical solution of the present invention: the solid support layer is made of a low refractive index solid material, which is used to physically isolate the direct contact between the metal reflective layer and the rough interface, so as to eliminate the photothermal absorption caused by surface plasmon resonance.

[0013] As a preferred technical solution of the present invention: the transparent substrate serves as a thermal radiation energy conversion layer, with an average transmittance of more than 95% in the visible-near infrared band and a high absorption rate in the mid-infrared band to achieve radiative heat dissipation.

[0014] As a preferred technical solution of the present invention: the solid support layer is an aerogel coating, and the material of the aerogel coating is selected from one of silica aerogel, alumina aerogel, titanium dioxide aerogel or organic polymer aerogel;

[0015] Alternatively, the aerogel coating is preferably a nanoporous silica aerogel coating.

[0016] As a preferred technical solution of the present invention: the color filter film is formed by alternating stacking of low refractive index materials and high refractive index materials, and its absorption rate in the visible-near infrared band is less than 5%.

[0017] As a preferred embodiment of the present invention: the low refractive index material is silicon dioxide, and the high refractive index material is titanium dioxide.

[0018] As a preferred embodiment of the present invention: a metal bonding layer with a thickness of 2~5nm is provided between the flat bottom of the solid support layer and the metal reflective layer, and the material of the metal bonding layer is selected from titanium or chromium.

[0019] As a preferred technical solution of the present invention: the material of the metal reflective layer is selected from gold, silver, aluminum, copper, platinum and their alloys, the thickness is 50~200nm, and the reflectivity in the visible-near infrared band is greater than 95%.

[0020] As a preferred technical solution of the present invention: a dielectric protective layer is also tightly attached to the side of the metal reflective layer away from the solid support layer, and the dielectric protective layer material is selected from one of silicon oxide, titanium oxide, and aluminum oxide, with a thickness of 10~50nm.

[0021] As a preferred technical solution of the present invention: the material of the transparent substrate is selected from inorganic materials such as K9 glass and fused silica, or organic polymer materials such as polymethyl methacrylate and polycarbonate, and its thickness is 0.5~5mm.

[0022] The second objective of this invention is to provide a method for preparing a radiation-cooled integrated filter, addressing the problems in the prior art.

[0023] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0024] The method for preparing the radiation-cooled integrated filter includes the following steps:

[0025] S1, roughen the lower side of the transparent substrate to form a rough surface with micro-nano undulations;

[0026] S2, depositing a color filter film on the smooth surface of the upper side of the transparent substrate;

[0027] S3, a solid support layer is prepared on the rough surface of the lower side of the transparent substrate, so that the solid support layer fills the micro-grooves of the rough surface and forms a flat surface at the bottom.

[0028] S4. A metal bonding layer, a metal reflective layer, and a dielectric protective layer are sequentially deposited on the flat bottom of the solid support layer to obtain a fully solid monolithically integrated cooling filter.

[0029] Compared with the prior art, the radiation-cooled integrated filter and its preparation method of the present invention have the following beneficial effects:

[0030] First, this invention utilizes an all-solid-state monolithic integrated structure. By sequentially setting a rough surface, a low-refractive-index solid support layer, and a metal reflective layer at the bottom of a transparent substrate, the solid support layer fills the microscopic grooves of the rough surface and isolates the metal reflective layer from direct contact with the rough interface. This solves the problem of undesirable photothermal absorption caused by interfacial surface plasmon resonance in existing diffuse reflection filters. Simultaneously, this invention reflects transmitted light back to the incident space almost without loss through a diffuse reflection mechanism, fundamentally avoiding the risk of transmitted light being absorbed and converted into heat energy. While maintaining a structural color appearance, it achieves extremely low solar band absorptivity. Combined with the high infrared emissivity of the substrate, it achieves a significant radiative cooling effect.

[0031] Secondly, this invention adopts an all-solid-state monolithic integrated structure, completely abandoning the traditional double-substrate bonded hollow structure. This solves the technical problems of substrate deformation or cracking caused by drastic changes in external air pressure, as well as adhesive layer cracking or film peeling caused by high-frequency vibration. This significantly improves the structural stability and vibration resistance of the device in harsh environments such as aerospace. Simultaneously, removing the bottom packaging substrate greatly reduces the device weight, meeting the stringent lightweight requirements of aerospace payloads.

[0032] Third, the preparation method of this invention eliminates the need for the second substrate alignment and UV bonding steps in traditional processes, simplifying the process steps, reducing equipment requirements, and greatly reducing manufacturing and process complexity. Simultaneously, this method avoids defects such as bubbles and misalignment that may occur during the double-substrate bonding process, resulting in a high yield rate. Furthermore, the all-solid-state structure requires no subsequent encapsulation after one-time molding, making it extremely suitable for large-scale mass production and facilitating widespread application.

[0033] This invention achieves lightweight and highly reliable integration through an all-solid monolithic integrated structure and an aerogel solid support layer, while effectively suppressing SPR heat loss. Combined with the high emissivity of the mid-infrared, it achieves efficient radiative cooling, which has broad application prospects in aerospace optical payloads, UAV detection windows, and outdoor building thermal management. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the radiation-cooled integrated filter according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the color filter film structure according to an embodiment of the present invention, which is composed of alternating stacks of high and low refractive index materials;

[0036] Figure 3 This is a schematic diagram of the structure of the all-solid-state diffuse reflection unit of the present invention; wherein, the solid support layer fills the rough surface at the bottom of the transparent substrate, the metal reflective layer is integrated on the flat surface at the bottom of the solid support layer through the metal adhesive layer, and a dielectric protective layer is provided on the side of the metal reflective layer away from the solid support layer.

[0037] Figure 4 The simulated visible light specular reflection spectrum of the color filter film in Application Example 1 without the integration of the all-solid-state diffuse reflection unit;

[0038] Figure 5 The actual diffuse reflectance spectrum of the radiation-cooled integrated filter in the visible light band is shown in Application Example 1.

[0039] Figure 6 The image shows the reflectance spectrum of the radiation-cooled integrated filter in Application Example 1 in the near-infrared band (700~2500nm), reflecting the high reflectance shielding characteristics of the device against solar heat load.

[0040] Figure 7 The absorption spectrum of the radiation-cooled integrated filter in Application Example 1 in the mid-infrared band (8~14μm) reflects the high radiation heat dissipation characteristics of the device in the atmospheric transparent window.

[0041] Figure 8 This is a comparison chart of the radiation cooling temperature reduction test curves of the radiation-cooled integrated filter in Application Example 1 under direct sunlight conditions. Detailed Implementation

[0042] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0043] To address the technical problems of existing diffuse reflection filters in radiation cooling applications, such as undesirable photothermal absorption caused by surface plasmon resonance (SPR) at the interface, which severely weakens the cooling efficiency, and the structural failure of traditional double-substrate bonded structures due to air pressure changes and high-frequency vibrations in harsh aerospace environments, this invention provides a radiation cooling integrated filter with efficient photothermal control through a monolithic all-solid-state integrated structure and its fabrication method.

[0044] A radiation-cooled integrated filter includes a color filter film, a transparent substrate, and an all-solid-state diffuse reflection unit arranged closely from top to bottom, forming a monolithic integrated structure without air cavities.

[0045] Light is incident from the side of a color filter film, which is a multi-layered thin film structure made of alternating stacks of high and low refractive index materials, deposited on the smooth top of a transparent substrate, for selective filtering of the solar spectrum.

[0046] Traditional reflective color filters, while reflecting light of a specific wavelength, absorb the remaining transmitted light using materials. This absorption loss generates significant thermal gain, greatly impairing the radiative cooling effect. To achieve efficient passive cooling, this invention does not absorb transmitted light. Instead, it uses a bottom-mounted all-solid-state diffuse reflection unit to diffusely reflect the transmitted light back to the incident medium with almost no loss. This design, while exhibiting a structural color appearance, fundamentally eliminates the risk of transmitted light being absorbed and converted into heat energy.

[0047] To further block solar heat load, the absorption rate of each layer of the color filter film is extremely low (less than 5%) in the visible-near infrared band (0.3~2.5μm). Common coating materials include silicon dioxide, titanium dioxide, and aluminum oxide, and the extinction coefficient of these materials in this band is almost 0.

[0048] As a preferred option, the low-refractive-index material is silicon dioxide, and the high-refractive-index material is titanium dioxide.

[0049] The color filter film preferably has 1 to 20 layers (i.e., 0.5 to 10 pairs of alternating high and low refractive index units), and the thickness of each layer is 10 to 400 nm.

[0050] The transparent substrate, serving as the core thermal radiation energy conversion layer, possesses high transmittance in the visible-near-infrared band, preferably with an average transmittance greater than 95%. Simultaneously, it must exhibit a large absorptivity (i.e., high emissivity) within the atmospheric transparency window in the mid-infrared band (8~14μm) to achieve efficient outward radiative heat dissipation. The substrate can be an inorganic material such as K9 glass or fused silica, or a single-layer polymer material such as PMMA, CR-39, PC, PS, polyethylene, polytetrafluoroethylene, or polydimethylsiloxane, with a preferred thickness of 0.5~5mm.

[0051] As a core improvement of the present invention, the all-solid diffuse reflection unit comprises, from top to bottom, a rough surface, a solid support layer, a metal bonding layer, a metal reflective layer, and a dielectric protective layer.

[0052] The rough surface is obtained by polishing the bottom of the transparent substrate with 280-mesh fine sandpaper. The solid support layer is made of a low-refractive-index solid material and is tightly disposed between the rough surface and the metal bonding layer; preferably, the solid support layer is an aerogel coating, and more preferably a nanoporous silica aerogel coating.

[0053] The solid support layer perfectly fills the micro-grooves of the rough surface in terms of physical structure and forms an absolutely flat surface at the bottom. Optically, it effectively isolates the direct contact between the metal reflective layer and the rough surface by using an extremely low refractive index, thereby preserving the physical mechanism of eliminating surface plasmon resonance (SPR) photothermal absorption and avoiding additional thermal gain of the device in the solar spectrum band.

[0054] To further enhance the mechanical strength of the monolithic integrated structure, a titanium or chromium metal bonding layer with a thickness of 2-5 nm is provided between the flat bottom of the solid support layer and the metal reflective layer to enhance the adhesion of the metal reflective layer.

[0055] The metal reflective layer material is selected from gold, silver, aluminum, copper, platinum and their alloys, preferably silver, and its thickness is preferably 80~120nm, with a reflectivity greater than 95% in the visible-near infrared band.

[0056] The metal reflective layer has a dielectric protective layer on the side opposite to the solid support layer. The material is selected from one of silicon oxide, titanium oxide, and aluminum oxide, and the thickness is 10~50nm.

[0057] The present invention also provides a method for preparing the above-mentioned radiation-cooled integrated filter, comprising the following steps:

[0058] (1) Based on the refrigeration spectral characteristics and the requirements of thermal management, the material and thickness of the color filter film are optimized and selected to design a membrane structure that meets the requirements of low absorption.

[0059] (2) Grind the lower side of the transparent substrate to form a rough surface with micro-nano undulations;

[0060] (3) Electron beam evaporation deposition is used to deposit a color filter film onto the smooth surface of the upper side of a transparent substrate;

[0061] (4) On the rough surface of the lower side of the transparent substrate, a low refractive index solid support layer is prepared by spin-coating an aerogel (such as nanoporous silica aerogel) liquid phase precursor and curing it, so that the solid support layer fills the grooves of the rough surface and forms a flat surface at its bottom.

[0062] (5) Using physical vapor deposition technology, a metal bonding layer, a metal reflective layer, and a dielectric protective layer are sequentially deposited on the flat bottom of the solid support layer to finally obtain a fully solid monolithically integrated cooling filter. This fabrication method completely eliminates the second substrate alignment and UV bonding process in the traditional process, making the fabrication process simple, the device strong, and extremely suitable for large-scale mass production.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] This invention avoids the absorption loss of transmitted light through diffuse reflection and suppresses the undesirable energy loss caused by the interface SPR effect. The device has extremely low absorptivity in the solar band, and combined with the high infrared emissivity of the substrate, it can achieve a significant cooling effect (a cooling effect of 13.4°C in Application Example 1).

[0065] The all-solid-state monolithic structure solves the deformation and breakage problems of traditional air-cavity designs in aerospace environments. Removing the bottom packaging substrate reduces the device weight by approximately 50%, significantly improving shock resistance and meeting aerospace payload application standards.

[0066] Example 1

[0067] like Figure 1 As shown, a radiation-cooled integrated filter consists of three modules: a transparent substrate 1, a color filter film 2, and an all-solid-state diffuse reflection unit 3. The color filter film 2, the transparent substrate 1, and the all-solid-state diffuse reflection unit 3 are stacked tightly from top to bottom to form a monolithic integrated structure without air cavities.

[0068] Traditional reflective color filters typically absorb transmitted light while reflecting specific wavelengths, leading to severe parasitic absorption and thermal gain under strong light, thus compromising cooling performance. This invention's radiation-cooled integrated filter comprises three modules forming a synergistic cooling system. Its core objective is to significantly reduce the absorption of incident solar radiation while ensuring specific color output.

[0069] The structure of color filter film 2 is as follows Figure 2 As shown, this is a multilayer thin-film structure composed of alternating stacks of high and low refractive index materials (201, 202). After incident light passes through the color filter film 2, most of the transmitted light enters the bottom all-solid-state diffuse reflection unit 3 and is uniformly reflected back to the incident medium, with only a small amount of incident light being reflected by the specular surface. To ensure radiative cooling performance, the coating material is preferably silicon dioxide, titanium dioxide, aluminum oxide, etc., with an extinction coefficient approaching zero.

[0070] The transparent substrate 1 serves as both the physical support layer and the core energy conversion layer for radiative cooling. Its materials are selected from inorganic materials such as K9 glass and fused silica, or organic polymer materials such as PMMA and PC. Because these materials have extremely high absorptivity / emissivity in the mid-infrared band (8~14μm), they can radiate heat into deep space through the atmospheric transparency window. Simultaneously, the substrate maintains extremely high transparency in the visible-near-infrared band, ensuring that transmitted light reaches the bottom reflective layer without damage.

[0071] like Figure 3 As shown, the all-solid-state diffuse reflection unit 3 of the present invention completely abandons the traditional hollow air cavity structure, and is composed of five tightly integrated parts from top to bottom:

[0072] 301 Rough Surface: Formed by mechanical polishing of the bottom of transparent substrate 1, providing a micro-nano undulating interface for diffuse reflection.

[0073] 302 Solid Support Layer: A low-refractive-index solid material is used to fill the grooves and form a flat bottom surface. The solid support layer is preferably an aerogel coating, and more preferably a nanoporous silica aerogel. This layer physically achieves monolithic compaction and optically eliminates the additional heat loss caused by surface plasmon resonance (SPR) by utilizing its extremely low refractive index, thereby reducing the thermal gain in the solar band.

[0074] 303 bonding layer: a 2-5nm titanium or chromium transition layer, which significantly enhances the structural stability and anti-detachment strength of the device under aerospace vibration environment.

[0075] 304 metal reflective layer: The preferred material is silver, with a thickness of 50-200nm, which realizes efficient back diffuse reflection of transmitted light, and the monolithic integrated design achieves the ultimate lightweight of the device.

[0076] 305 dielectric protective layer: with a thickness of 10-50nm, used to isolate the external environment and prevent the metal layer from oxidizing and failing.

[0077] In this embodiment, a K9 glass substrate (2 mm thick) is used, and the back side is polished with 280-grit sandpaper. After spin-coating a nanoporous silica aerogel precursor to form a solid support layer (302) on the surface, a 3 nm thick titanium bonding layer (303), a 100 nm thick silver reflective layer (304), and a 20 nm thick silica protective layer (305) are vacuum-deposited in sequence.

[0078] From bottom to top of the transparent substrate to the incident side, the specific film structure of the color filter is as follows:

[0079] membrane Material Thickness (nm) 1 <![CDATA[TiO2]]> 17.3 2 <![CDATA[SiO2]]> 19.0 3 <![CDATA[TiO2]]> 68.8 4 <![CDATA[SiO2]]> 91.6 5 <![CDATA[TiO2]]> 102.9 6 <![CDATA[SiO2]]> 106.2 7 <![CDATA[TiO2]]> 58.9 8 <![CDATA[SiO2]]> 103.3 9 <![CDATA[TiO2]]> 104.4 10 <![CDATA[SiO2]]> 89.7 11 <![CDATA[TiO2]]> 58.2 12 <![CDATA[SiO2]]> 90.7 13 <![CDATA[TiO2]]> 109.0 14 <![CDATA[SiO2]]> 89.3 15 <![CDATA[TiO2]]> 57.2 16 <![CDATA[SiO2]]> 119.9 17 <![CDATA[TiO2]]> 101.3

[0080] The simulated visible light specular reflection spectrum of this film system without the integrated all-solid-state diffuse reflection unit is as follows: Figure 4 As shown. After adding the all-solid-state diffuse reflection unit, the actually fabricated filter avoids absorption in the transmission band, and the color it exhibits is the complementary color of the specular reflection color of the colored filter film, that is, it appears green. Its diffuse reflection spectrum is as follows. Figure 5 As shown.

[0081] The reflectance spectrum of this radiation-cooled integrated filter in the near-infrared band of 700~2500nm is as follows: Figure 6 As shown, its reflectivity is close to 100%, ensuring highly efficient shielding against solar radiation. Its reflection / absorption spectrum in the mid-infrared band (8~14μm) is as follows... Figure 7As shown, the average absorptivity is greater than 95%, which can make full use of the atmospheric transparency window to radiate heat into deep space and achieve efficient radiative cooling.

[0082] like Figure 8 As shown in the radiation cooling characteristic curve, compared with the traditional absorption-loss type dye green filter, the all-solid-state monolithic integrated structure used in this embodiment achieves a significant cooling effect of 13.4℃ under the same sunlight conditions. This fully demonstrates that by eliminating interfacial surface plasmon resonance (SPR) and adopting an all-solid-state integrated design, the photothermal control performance and environmental adaptability of the device can be significantly improved.

[0083] This invention discloses a radiation-cooled integrated optical filter and its fabrication method. The device consists of a color filter film, a transparent substrate, and an all-solid-state diffuse reflection unit tightly integrated from top to bottom, forming a monolithic integrated structure without air cavities. By introducing an aerogel coating as a solid support layer to replace the traditional double-substrate and air-cavity structure, the device achieves lightweight and high-reliability integration, effectively solving the structural failure problems caused by cavity deformation and high-frequency vibration due to sudden pressure changes in harsh environments such as aerospace. Optically, the solid support layer effectively suppresses undesirable heat loss caused by surface plasmon resonance (SPR) by physically isolating the metal reflective layer from direct contact with the rough interface, ensuring that transmitted light returns to the incident space via efficient diffuse reflection from the bottom unit. Combined with the high mid-infrared emissivity of the transparent substrate, the device exhibits extremely low absorptivity in the visible to near-infrared band, demonstrating excellent radiation-cooling performance and showing broad application prospects in aerospace optical payloads, UAV detection windows, and outdoor building thermal management.

[0084] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A radiation-cooled integrated filter, characterized in that, The device comprises a color filter film, a transparent substrate, and an all-solid-state diffuse reflection unit arranged in a tightly packed manner from top to bottom, forming a monolithic integrated structure without air cavities. The color filter film is used to selectively filter the solar spectrum; the all-solid-state diffuse reflection unit is used to diffusely reflect the light transmitted through the color filter film back into the incident space to avoid thermal gain caused by the absorption of transmitted light by the material. The all-solid-state diffuse reflection unit comprises, from top to bottom: a rough surface at the bottom of the transparent substrate, a solid support layer, and a metal reflective layer; The solid support layer is tightly filled between the rough surface and the metal reflective layer to fill the micro-grooves of the rough surface and form a flat surface at the bottom.

2. The radiation-cooled integrated filter as described in claim 1, characterized in that, The solid support layer is made of a low-refractive-index solid material, which is used to physically isolate the metal reflective layer from direct contact with the rough interface, so as to eliminate photothermal absorption caused by surface plasmon resonance.

3. The radiation-cooled integrated filter as described in claim 1, characterized in that, The transparent substrate serves as a thermal radiation energy conversion layer, with an average transmittance of over 95% in the visible-near-infrared band and a high absorption rate in the mid-infrared band to achieve radiative heat dissipation. Alternatively, the transparent substrate may be made of inorganic materials such as K9 glass or fused silica, or organic polymer materials such as polymethyl methacrylate or polycarbonate, with a thickness of 0.5 to 5 mm.

4. The radiation-cooled integrated filter as described in claim 1, characterized in that, The solid support layer is an aerogel coating, and the material of the aerogel coating is selected from one of silica aerogel, alumina aerogel, titanium dioxide aerogel or organic polymer aerogel. Alternatively, the aerogel coating is preferably a nanoporous silica aerogel coating.

5. The radiation-cooled integrated filter as described in claim 1, characterized in that, The color filter film is composed of alternating stacks of low-refractive-index and high-refractive-index materials, and its absorption rate in the visible-near-infrared band is less than 5%.

6. The radiation-cooled integrated filter as described in claim 5, characterized in that, The low-refractive-index material is silicon dioxide, and the high-refractive-index material is titanium dioxide.

7. The radiation-cooled integrated filter as described in claim 1, characterized in that, Between the flat bottom of the solid support layer and the metal reflective layer, a metal bonding layer with a thickness of 2~5nm is also provided, and the material of the metal bonding layer is selected from titanium or chromium.

8. The radiation-cooled integrated filter as described in claim 1, characterized in that, The material of the metal reflective layer is selected from gold, silver, aluminum, copper, platinum and their alloys, with a thickness of 50~200nm and a reflectivity of greater than 95% in the visible-near infrared band.

9. The radiation-cooled integrated filter as described in claim 1, characterized in that, The side of the metal reflective layer opposite to the solid support layer is also tightly attached to a dielectric protective layer. The dielectric protective layer material is selected from one of silicon oxide, titanium oxide, and aluminum oxide, and the thickness is 10~50nm.

10. A method for preparing a radiation-cooled integrated filter as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1, roughen the lower side of the transparent substrate to form a rough surface with micro-nano undulations; S2, depositing a color filter film on the smooth surface of the upper side of the transparent substrate; S3, a solid support layer is prepared on the rough surface of the lower side of the transparent substrate, so that the solid support layer fills the micro-grooves of the rough surface and forms a flat surface at the bottom. S4. A metal bonding layer, a metal reflective layer, and a dielectric protective layer are sequentially deposited on the flat bottom of the solid support layer to obtain a fully solid monolithically integrated cooling filter.

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