Directional small-angle radiation regulation and control device with mid-infrared micro lens combined with micropore array

Abstract

The invention provides a directional small-angle radiation regulation and control device combining a mid-infrared micro lens and a micropore array, which comprises a micro lens array part and a micropore array part which are arranged at an interval from top to bottom, and is characterized in that the micro lens array part comprises a mid-infrared transparent layer and a micro lens array layer which are sequentially arranged from bottom to top; the micro-lens array layer is provided with a plurality of micro-lenses which are arranged in an array, the micro-pore array part comprises an intermediate infrared reflecting layer, an intermediate infrared absorbing layer and a substrate layer which are sequentially arranged from top to bottom, a micro-pore array is formed on the intermediate infrared reflecting layer, the micro-pore array is provided with micro-pores which are arranged in an array and are in one-to-one correspondence with the plurality of micro-lenses, and the micro-pore array part is provided with a plurality of micro-pores which are in one-to-one correspondence with the micro-lenses. The diameter of each micropore is smaller than that of the corresponding microlens, the central axis of each micropore and the optical axis of the corresponding microlens are coaxially arranged, and the focal plane of each microlens is higher than the lower surface of the intermediate infrared absorption layer and not higher than the upper surface of the intermediate infrared absorption layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation cooling, and in particular relates to a directional small-angle radiation control device combining a mid-infrared microlens with a microhole array. Background Art

[0002] Radiative cooling is a passive cooling method that can achieve temperatures below ambient without relying on external power, thus attracting widespread attention from academia and industry. The basic principle of radiative cooling can be expressed by the following formula:

[0003] P neT (T, θ) = P rad (T, θ)-P suu -P atm (T amb ,θ)-P couv (T,T amb )

[0004]

[0005] P conv (T,T amb )=Ah c (T amb -T)

[0006]

[0007] It can be seen from the above formula that the net radiation power Pnet is inversely related to the atmospheric radiation power Patm and is positively related to the radiation power Prad of the radiation cooler. Therefore, from the perspective of radiation control, the way to increase the net radiation power is to increase the net radiation power Prad and reduce the radiation power Patm of the radiation cooler.

[0008] The main principle of the radiant cooler is to reflect the energy in the solar band as completely as possible, while increasing the mid-infrared radiation energy. When the outward radiation energy is greater than the external input energy, the net radiation power can be greater than zero, thereby achieving the radiant cooling effect.

[0009] At present, most radiation cooling devices have omnidirectional radiation cooling effects, and there are few studies on directional radiation cooling. Most radiation cooling devices use materials with high emissivity at the atmospheric window, such as multilayer inorganic films, porous organic polymers, and super-surface micro-nano structures. These materials have no selectivity for emissivity at different angles, and the hemispherical emissivity is high at 0-180°. This type of radiator without angle selectivity is not conducive to further improving the net radiation power, nor is it suitable for the harsh working environment of the radiation cooler. For example, radiation coolers are mostly used in non-open environments with many buildings around. At this time, large-angle thermal radiation can be easily blocked by surrounding obstacles, thereby greatly reducing the effective outward radiation energy.

[0010] To achieve directional radiation cooling structure, researchers proposed a multilayer one-dimensional photonic crystal based on gradient ENZ materials. ENZ metamaterials achieve symmetrical directional radiation in two directions beyond zero-degree incidence through artificial construction of near-zero refractive index, but cannot achieve normal directional radiation perpendicular to the material surface, and cannot achieve radiation cooling at small normal angles, which limits the improvement of radiation cooling power. Summary of the invention

[0011] In order to solve the above-mentioned deficiencies of the prior art, the main purpose of the present invention is to provide a directional small-angle radiation control device combining a mid-infrared microlens with a microhole array.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] The present invention provides a directional small-angle radiation control device of a mid-infrared microlens combined with a microhole array, which has the following characteristics: a microlens array portion and a microhole array portion arranged in an upper and lower interval, wherein the microlens array portion comprises a mid-infrared transparent layer and a microlens array layer arranged in sequence from bottom to top, the microlens array layer has a plurality of microlenses arranged in an array, the microhole array portion comprises a mid-infrared reflection layer, a mid-infrared absorption layer and a substrate layer arranged in sequence from top to bottom, a microhole array is formed on the mid-infrared reflection layer, the microhole array has microholes arranged in an array and corresponding to the plurality of microlenses one by one, the diameter of the microhole is smaller than the diameter of the corresponding microlens, the central axis of the microhole is coaxially arranged with the optical axis of the corresponding microlens, and the focal plane of the microlens is higher than the lower surface of the mid-infrared absorption layer and not higher than the upper surface of the mid-infrared absorption layer.

[0014] In the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention, it can also have the following characteristics: it also includes: a supporting connection part, which is used to install the microlens array part at a predetermined height position above the microhole array part, wherein the supporting connection part includes a plurality of supporting columns arranged at circumferential intervals along the microlens array part and the microhole array part.

[0015] The directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention may also have the following feature: wherein the support column is a support column with adjustable height.

[0016] The directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention may also have the following characteristics: wherein the microlens array portion further includes a mid-infrared anti-reflection layer located on the upper surface of the microlens array layer.

[0017] The directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention may also have the following characteristics: wherein the mid-infrared anti-reflection layer is a multilayer film composed of alternating ZnSe films and ZnS films.

[0018] In the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention, it can also have the following characteristics: wherein, the mid-infrared reflection layer is set as the upper mid-infrared reflection layer, and the microhole array part also includes a mid-infrared reflection layer as the lower mid-infrared reflection layer, and the lower mid-infrared reflection layer is arranged between the substrate layer and the mid-infrared absorption layer.

[0019] The directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention may also have the following characteristics: wherein the upper mid-infrared reflection layer and the lower mid-infrared reflection layer are both made of aluminum film or silver film with a thickness of 0.1 to 0.5 μm.

[0020] The directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention may also have the following feature: wherein the diameter of the microhole is 90-10% of the diameter of the microlens.

[0021] In the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention, it can also have the following characteristics: wherein the microlens array layer is made of fluoride glass or zinc selenide, the convex surface diameter of the plano-convex lens of the microlens is 140-560μm, and the focal length is 50-200μm.

[0022] In the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array provided by the present invention, it can also have the following characteristics: the mid-infrared absorption layer adopts a black paint film with a thickness of 10 to 100 μm, a polydimethylsiloxane (PDMS) film with a thickness of 100 μm to 1 mm, or a SiO2 / Si3N4 multilayer film with a thickness of 0.1562 μm, 0.3266 μm, 0.6944 μm, or 0.2414 μm.

[0023] Function and Effect of the Invention

[0024] According to the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array involved in the present invention, since it has a microlens array part and a microhole array part arranged at intervals from top to bottom, the microlens array part includes a mid-infrared transparent layer and a microlens array layer arranged in sequence from bottom to top, the microlens array layer has a plurality of microlenses arranged in an array, the microhole array part includes a mid-infrared reflection layer, a mid-infrared absorption layer and a substrate layer arranged in sequence from top to bottom, a microhole array is formed on the mid-infrared reflection layer, the microhole array has microholes arranged in an array and corresponding to the plurality of microlenses one by one, the diameter of the microhole is smaller than the diameter of the corresponding microlens, the central axis of the microhole is coaxially arranged with the optical axis of the corresponding microlens, and the focal plane of the microlens is higher than the lower surface of the mid-infrared absorption layer and not higher than the upper surface of the mid-infrared absorption layer, so that the light focused on the center of the microhole can be absorbed, and the light focused outside the microhole is reflected, thereby achieving the effect of directional radiation cooling, and improving the efficiency and environmental adaptability of the radiation control device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a directional small-angle radiation control device of a mid-infrared microlens combined with a microhole array in the present invention;

[0026] Figure 2 is a schematic diagram of a plano-convex lens of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the microlens and microhole array unit of the present invention;

[0028] Figure 4 is a flow chart of the propagation of incident light of the present invention;

[0029] Figure 5 The present invention is 100 μm thick pdms, SiO2 / Si3N4 four-layer film structure designed by genetic algorithm and black paint absorption rate;

[0030] Figure 6 is a top view of a microlens array and a microhole array arranged in a quadrilateral close-packed array in an embodiment of the present invention;

[0031] Figure 7 is the absorptivity of the embodiment of the present invention under incident light at different angles;

[0032] Figure 8 is the absorptivity of the embodiment of the present invention at different wavelengths and different angles; and

[0033] Fig. 9 It is a top view of a microlens array and a microhole array arranged in a hexagonal close-packed array in a first variation of the present invention. DETAILED DESCRIPTION

[0034] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention.

[0035] Figure 1 It is a structural schematic diagram of a directional small-angle radiation control device of a mid-infrared microlens combined with a microhole array in the present invention.

[0036] like Figure 1 As shown, the directional small-angle radiation control device 100 of the mid-infrared microlens combined with the microhole array includes a microlens array portion 10 and a microhole array portion 20 which are arranged in an upper and lower interval, and a supporting connection portion 30.

[0037] like Figure 1 As shown, the microlens array portion 10 includes a mid-infrared transparent layer 11 and a microlens array layer 12 which are sequentially arranged from bottom to top.

[0038] The mid-infrared transparent layer 11 is used as a substrate for the microlens array layer 12 and is made of Ge or fluoride glass, with a typical thickness ranging from 0.5 mm to several millimeters. The thickness of the substrate should be thin enough to ensure the lowest possible absorption loss in the required mid-infrared band.

[0039] The microlens array layer 12 is made of fluoride glass or zinc selenide (ZnSe) material, and has a plurality of microlenses 121 arranged in an array.

[0040] like Figure 1 As shown, the micro-hole array portion 20 includes a mid-infrared reflection layer 21, a mid-infrared absorption layer 22 and a substrate layer 23 which are sequentially arranged from top to bottom.

[0041] The mid-infrared reflection layer 21 is an aluminum film or a silver film with a thickness of 0.1 to 0.5 μm, which has a wide-band infrared reflection performance, is low in cost and easy to prepare. A micropore array 211 is formed on the mid-infrared reflection layer 21, and the micropore array 211 has a plurality of micropores 211a arranged in a row array. The plurality of micropores 211a correspond one-to-one to the plurality of microlenses 121, and the central axis of each micropore 211a is coaxially arranged with the optical axis of the corresponding microlens 121; the diameter of the micropore 211a is smaller than the diameter of the corresponding microlens 121, and preferably the diameter of the micropore 211a is 10 to 90% of the diameter of the microlens 121.

[0042] The mid-infrared absorption layer 22 can be a black paint film with a thickness of 10 to 100 μm, a polydimethylsiloxane (PDMS) film with a thickness of 100 μm to 1 mm, or a Sio2 / Si3N4 multilayer film with a thickness of 0.1562 μm, 0.3266 μm, 0.6944 μm, or 0.2414 μm.

[0043] The substrate layer 23 is a metal substrate made of aluminum or stainless steel, and has a thickness of 0.5 to 5 mm.

[0044] like Figure 1 As shown, the supporting connection part 30 is used to install the microlens array part 10 at a predetermined height position above the microhole array part 20 , and includes four supporting columns 31 .

[0045] Four support columns 31 are arranged at intervals along the circumference of the microlens array portion 10 and the microhole array portion 20 ; the support columns 31 are straight rods made of plastic or aluminum alloy, and have a height of 100 μm.

[0046] Figure 2 Schematic diagram of the plano-convex lens of the present invention.

[0047] like Figure 2 As shown, let the radius of the sphere corresponding to the convex surface of the plano-convex lens be r, and its center be C. Light AD is incident on the convex surface, CD is the normal, and the incident angle is α (very small); let the refractive index of the plano-convex lens be n, then its refraction angle is approximately nα. Let OC be r, OF be f, then tan(α)≈α=OD / r, tan[(n-1)α]≈(n-1)α=OD / f, so f=r / (n-1). If n=1.5, then f=2r, that is, the larger the radius of the sphere, the larger the focal length of the lens.

[0048] Figure 3 Schematic diagram of the structure of the microlens and microhole array unit of the present invention; wherein, (a) is a schematic diagram of light propagation when the incident light angle is greater than the structural absorption cutoff angle; (b) is a schematic diagram of light propagation when the incident light angle is equal to the structural absorption cutoff angle.

[0049] Figure 3 It shows that incident light at different angles is focused by the microlens 121 to different parts of the microhole 211a, thereby achieving the effect that large-angle incident light is reflected and small-angle incident light is absorbed. Specifically: Figure 3 As shown in (a), when the incident angle is vertical, the incident light is focused by the microlens 121 to the bottom of the center of the microhole 211a, and is absorbed by the mid-infrared absorption layer 22; Figure 3 As shown in (b), when the incident light angle is large, the incident light is focused by the microlens 121 to the portion of the mid-infrared reflective layer 21 other than the microhole 211a, and is reflected by the mid-infrared reflective layer 21, that is, in a low absorption state; Figure 3 As shown in (c), when the incident angle is equal to the absorption cutoff angle, the incident light is focused by the microlens 121 onto the side wall of the microhole 211a. At this time, the absorption cutoff angle |θmax|=arctan(D / 2 / f), where D is the diameter of the microhole 211a and f is the focal length of the microlens 121.

[0050] Figure 4 It is a propagation flow chart of incident light of the present invention.

[0051] Figure 4 The process of selective absorption of incident light at different angles is shown, specifically: when incident vertically, electromagnetic waves in the 8-14μm mid-infrared band can be almost completely absorbed by the mid-infrared absorption layer 22 below the microhole 211a; when deviating from the vertical direction, the focal spot partially deviates from the microhole 211a, and as the deviation angle increases to a certain extent, until the focal spot completely deviates from the microhole 211a, it is completely irradiated on the mid-infrared reflection layer 21, and this part of the energy is almost completely reflected by the mid-infrared reflection layer 21, thereby passing through the upper microlens 121. According to Kirchhoff's principle of thermal radiation, the above analysis process is reversible, that is, the inverse process of the light absorption process is the thermal radiation process, thereby achieving the angle selectivity of polarization-insensitive light absorption, that is, the angle selectivity of thermal radiation. The above process describes the propagation direction of light when it is incident from above the microlens array 12, that is, the normally incident light can enter the mid-infrared absorption layer 22 under the metal micropore 211a and be almost completely absorbed, and the deviation angle increases to a certain extent until the focal spot completely deviates from the micropore 211a, thereby completely irradiating the mid-infrared reflection layer 21, and this part of the energy is almost completely reflected by the mid-infrared reflection layer 21. According to the principle of reversibility of the optical path and Kirchhoff's principle of thermal radiation, the energy radiated by the mid-infrared absorption layer 22 will be mainly concentrated in the small angle direction of the normal, and the radiated light deviating from the normal will not be able to radiate outward through the microlens array 12.

[0052] Based on the above-mentioned characteristic that the focal spot position of the focal plane of the microlens 121 shifts with the change of the incident angle of the electromagnetic wave, the following further describes how to design the microhole array 211 and the mid-infrared absorption layer 22 that match the microlens array 12 .

[0053] Figure 5 The invention discloses a 100 μm thick pdms, a SiO2 / Si3N4 four-layer film structure designed by a genetic algorithm, and a black paint absorptivity.

[0054] The transfer matrix algorithm is used to calculate the absorbance of the mid-infrared absorption layer 22 using 100 μm thick PDMS and the substrate layer 23 using A1. The SiO2 / Si3N4 four-layer film structure as the mid-infrared absorption layer 22 is designed using the genetic algorithm combined with the transfer matrix algorithm. The film thicknesses are 0.1562, 0.3266, 0.6944, and 0.2414 μm, respectively. Their absorbances in the mid-infrared band are as follows: Figure 5As shown. It can be seen that these materials can be used to form the mid-infrared high absorption part, and metal such as Al and Ag thin films can be plated on the high absorption structure as the mid-infrared reflection layer, and a periodic microhole array can be etched on the film through photolithography and etching processes. The mid-infrared light focused by the microlens array to the microhole part will be absorbed by the high absorption layer, and the large-angle light focused on the metal film will be reflected by the metal film.

[0055] <Example>

[0056] In this embodiment, the mid-infrared transparent substrate layer 11 is made of ZnSe with a thickness ranging from 0.5 mm to several millimeters.

[0057] Figure 6 FIG. 4 is a top view of a microlens array and a microhole array arranged in a quadrilateral close-packed array in an embodiment of the present invention.

[0058] In this embodiment, the microlens array layer 12 is made of ZnSe material and is formed by hot-melting photoresist. The specific manufacturing method is as follows: ZnSe is used as the substrate, and the photoresist thermal reflow technology is used. The cylindrical target pattern is used as the exposure group, and the photoresist on the ZnSe substrate is exposed by using the mask. The photoresist cylindrical array is heated to a temperature exceeding the melting temperature, and the photoresist begins to melt. Due to the different surface tensions, the photoresist is processed into a spherical plano-convex lens under the action of the interfacial tension. The photoresist pattern is transferred to the ZnSe substrate through ion etching technology, so that the ZnSe is prepared as follows. Figure 6 The plano-convex lens array shown in a square close-packed arrangement and with a focal length of 100 μm is the microlens array layer 12. The convex radius is based on the formula f=r / (n-1), and the refractive index of ZnSe in the mid-infrared band (10-14 μm) is about 2.4, so the convex radius is 140 μm. According to |θmax|=arctan(D / 2 / f), it can be obtained that the limited directional radiation angle of the radiation control device of this embodiment is ±15°.

[0059] In this embodiment, the substrate of the mid-infrared reflective layer 21 is an Al film with a thickness of 0.1 μm, and its manufacturing method is: first, photolithography is used to form a photoresist mask, and then ion dry etching is used to etch a microhole array 211 with a central diameter D of 53.6 μm and a period P of 100 μm.

[0060] In this embodiment, the mid-infrared absorption layer 22 is a PDMS film with a thickness of 100 μm.

[0061] In this embodiment, the substrate layer 23 is made of an aluminum alloy film with a thickness of 0.5 mm to 5 mm.

[0062] In this embodiment, the height of the support pillar 31 is 100 μm.

[0063] Figure 7 is the absorptivity of the embodiment of the present invention under different incident angles.

[0064] like Figure 7 As shown in the figure, θ represents the angle between the incident light and the direction parallel to the surface, where 90° represents a small angle of incidence when the incident light is perpendicular to the surface of the structure, and the absorption rate is 0.97. When the incident angle is 15° to the central optical axis, the absorption rate is 0.2425 when it is 75° parallel to the structure surface.

[0065] Figure 8 It is the absorption rate of the embodiment of the present invention at different wavelengths and different angles.

[0066] Figure 8 The graph shows the relationship between the absorbance and the angle θ between the incident light and the structure surface at 8, 10, and 12 μm wavelengths. Figure 8 It can be seen that the incident light in the vertical direction of the atmospheric window band and close to the central optical axis has a high absorption rate, while in the direction deviating from the vertical incidence, the absorption rate of the structure drops rapidly to zero, thereby achieving a directional selective radiation effect in the atmospheric window band.

[0067] Example Function and Effect

[0068] According to the directional small-angle radiation control device of the mid-infrared microlens combined with the microhole array involved in this embodiment, since it has a microlens array part and a microhole array part arranged at intervals from top to bottom, the microlens array part includes a mid-infrared transparent layer and a microlens array layer arranged in sequence from bottom to top, the microlens array layer has a plurality of microlenses arranged in an array, the microhole array part includes a mid-infrared reflection layer, a mid-infrared absorption layer and a substrate layer arranged in sequence from top to bottom, a microhole array is formed on the mid-infrared reflection layer, the microhole array has microholes arranged in an array and corresponding to the plurality of microlenses one by one, the diameter of the microhole is smaller than the diameter of the corresponding microlens, the central axis of the microhole is coaxially arranged with the optical axis of the corresponding microlens, and the focal plane of the microlens is higher than the lower surface of the mid-infrared absorption layer and not higher than the upper surface of the mid-infrared absorption layer, so that the light focused on the center of the microhole can be absorbed, and the light focused outside the microhole is reflected, thereby achieving the effect of directional radiation cooling, and improving the efficiency and environmental adaptability of the radiation control device.

[0069] <Modification 1>

[0070] This modification example 1 is a further improvement of the embodiment. The same symbols are given to the same structures as those in the embodiment, and the same descriptions are omitted.

[0071] Fig. 9It is a top view of a microlens array and a microhole array arranged in a hexagonal close-packed array in a first variation of the present invention.

[0072] like Fig. 9 As shown, the difference between this modification example 1 and the embodiment is that the multiple microlenses 121 and the multiple microholes 211a are arranged in a hexagonal close-packed array.

[0073] In this embodiment, in addition to the functions and effects of the embodiment, because the multiple microlenses and the multiple microholes are arranged in a hexagonal close-packed array, the effective through-hole area accounts for 90.69% when the hexagonal close-packed arrangement is arranged, and the effective through-hole area is 78.54% when the tetragonal close-packed arrangement is arranged, which effectively increases the convergence and collection capabilities of the incident light, thereby improving the optical efficiency and directional control of the system.

[0074] <Modification 2>

[0075] This variant example 2 is a further improvement of the embodiment and variant example 1. The same symbols are given to the same structures as those in the embodiment and variant example 1, and the same descriptions are omitted.

[0076] like Figure 1 As shown, the difference between this modification example 2 and the embodiment and the modification example 1 is that the microlens array portion 10 further includes a mid-infrared anti-reflection layer 13 located on the upper surface of the microlens array layer 12 .

[0077] In the second variation, the mid-infrared anti-reflection layer 13 is a multilayer film composed of ZnSe films and ZnS films arranged alternately.

[0078] In this variation example 2, in addition to having the same functions and effects as the embodiment and variation example 1, since ZnSe is used as the mid-infrared lens material in the embodiment, its reflectivity is still relatively large. By coating an anti-reflection film composed of ZnSe and ZnS materials on the surface of the microlens array, the radiation cooling power of the system is further increased.

[0079] <Variation 3>

[0080] This variant example 3 is a further improvement of the embodiment and variant examples 1 and 2. The same symbols are given to the same structures as those in the embodiment, variant example 1 and variant example 2, and the same descriptions are omitted.

[0081] like Figure 1 As shown, compared with the embodiment, the first modification, and the second modification, the third modification is different in that the micropore array portion 20 further includes a mid-infrared reflection layer 24 disposed between the substrate layer 23 and the mid-infrared absorption layer 22. The mid-infrared reflection layer 24 also uses an aluminum film or a silver film with a thickness of 0.1 to 0.5 μm, and the difference between the two is that no micropores are formed on the mid-infrared reflection layer 24.

[0082] In the third modification example, in addition to having the functions and effects of the embodiment and the first and second modification examples, since a mid-infrared reflection layer is further provided between the substrate layer and the mid-infrared absorption layer, a very small amount of light transmitted through the mid-infrared absorption layer can be reflected and absorbed by the mid-infrared absorption layer again, further improving the radiation cooling power of the system.

[0083] <Fourth Modification Example>

[0084] The fourth modification example is a further improvement of the embodiment and the first to third modification examples. The same symbols are given to the same structures as in the embodiment and the first to third modification examples, and the same descriptions are omitted.

[0085] Compared with the embodiment and the first to third modification examples, the difference in the fourth modification example is that the support column 31 has a height-adjustable structure.

[0086] In the fourth modification example, in addition to having the functions and effects of the embodiment and the first to third modification examples, since the support column is a support column with adjustable height, it is convenient to adjust the height of the microlens array relative to the microhole array. By adjusting the height of the microlens array relative to the microhole array, the focal plane position of the microlens can be no longer limited to the upper surface of the mid-infrared absorption layer. Specifically: when the height of the support column is adjusted towards the upper surface of the mid-infrared absorption layer, the focal plane will be located within the upper surface; when the support column is adjusted upwards, the focal plane will be located between the upper surface and the lower surface and gradually deviate from the upper surface of the mid-infrared absorption layer. This adjustment method can further enhance the angle selectivity in the embodiment, and then the angle selectivity in the embodiment will be further increased, that is, |θmax| < arctan(D / 2 / f), and the directional radiation cooling angle is further reduced and biased towards the normal direction, so that the directional radiation cooling angle selectivity can be more conveniently adjusted, facilitating the selection of the directional angle to obtain the maximum radiation cooling power in practical applications.

[0087] <Fifth Modification Example>

[0088] The fifth modification example is a further improvement of the embodiment and the first to fourth modification examples. The same symbols are given to the same structures as in the embodiment and the first to fourth modification examples, and the same descriptions are omitted.

[0089] Compared with the embodiment and the first to fourth modification examples, the difference in the fifth modification example is that the mid-infrared absorption layer 22 is replaced with a SiO2 / Si3N4 multi-layer film structure designed by the differential evolution algorithm, and a 200nm Ag film is additionally deposited below the multi-layer film structure to achieve reflection in the sunlight band.

[0090] In this variant example 5, in addition to the functions and effects of the embodiment and variant examples 1 to 4, a SiO2 / Si3N4 structure of 257.3nm, 216.7nm, 421.1nm, 291.9nm, 417.9nm, 257.2nm, and 56.3nm is adopted, and there is a 200nm Ag film under the multilayer film. This design achieves a wavelength selectivity effect with high emissivity in the atmospheric window band 8-14μm and high reflectivity in the solar band 0.3-2.5μm, so as to achieve a better cooling effect.

[0091] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

Claims

1. A directional small-angle radiation control device combining a mid-infrared microlens with a microhole array, characterized in that: include: The microlens array part and the microhole array part are arranged in an up-and-down manner. The microlens array portion includes a mid-infrared transparent layer and a microlens array layer arranged in sequence from bottom to top. The microlens array layer has a plurality of microlenses arranged in an array. The micro-hole array portion comprises a mid-infrared reflection layer, a mid-infrared absorption layer and a substrate layer arranged in sequence from top to bottom. A microhole array is formed on the mid-infrared reflective layer, and the microhole array has microholes arranged in an array and corresponding to the plurality of microlenses one by one. The diameter of the microhole is smaller than the diameter of the corresponding microlens, The central axis of the microhole is coaxially arranged with the optical axis of the corresponding microlens, and the focal plane of the microlens is higher than the lower surface of the mid-infrared absorption layer and not higher than the upper surface of the mid-infrared absorption layer.

2. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: Also includes: A supporting connection portion, used to mount the microlens array portion at a predetermined height position above the microhole array portion, Wherein, the supporting connection part includes a plurality of supporting columns arranged at intervals along the circumference of the microlens array part and the microhole array part.

3. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 2 is characterized in that: in, The support column is a support column with adjustable height.

4. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The microlens array portion further includes a mid-infrared anti-reflection layer located on the upper surface of the microlens array layer.

5. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 4, characterized in that: in, The mid-infrared anti-reflection layer is a multilayer film composed of ZnSe films and ZnS films arranged alternately.

6. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The mid-infrared reflection layer is set as an upper mid-infrared reflection layer, The micropore array portion further comprises a mid-infrared reflection layer as a lower mid-infrared reflection layer, The lower mid-infrared reflection layer is disposed between the substrate layer and the mid-infrared absorption layer.

7. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The upper mid-infrared reflection layer and the lower mid-infrared reflection layer are both made of aluminum film or silver film with a thickness of 0.1-0.5 μm.

8. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The diameter of the microhole is 90-10% of the diameter of the microlens.

9. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The microlens array layer is made of fluoride glass or zinc selenide. The convex surface diameter of the plano-convex lens of the microlens is 140-560 μm, and the focal length is 50-200 μm.

10. The directional small-angle radiation control device of mid-infrared microlens combined with microhole array according to claim 1, characterized in that: in, The mid-infrared absorption layer adopts a black paint film with a thickness of 10 to 100 μm, a polydimethylsiloxane (PDMS) film with a thickness of 100 μm to 1 mm, or a SiO2 / Si3N4 multilayer film with a thickness of 0.1562 μm, 0.3266 μm, 0.6944 μm, or 0.2414 μm.

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