optical filter

Abstract

The application relates to an optical filter, which relates to the technical field of optics. The optical filter comprises a substrate, a first antireflection film arranged on one side of the substrate, a dielectric black film, a transparent conductive layer and a second antireflection film which are sequentially arranged on the other side of the substrate, and positive and negative electrodes which are arranged on the transparent conductive layer and between the transparent conductive layer and the second antireflection film; wherein the first antireflection film comprises a first film stack, a second film stack, a third film stack and a fourth film stack which are sequentially arranged on the substrate; the dielectric black film comprises a first film layer, a second film layer and a fifth film stack which are sequentially arranged on the substrate; the first film stack, the second film stack, the third film stack, the fourth film stack and the fifth film stack are respectively formed by stacking at least three dielectric film layers, and the refractive indexes of the adjacent two dielectric film layers are different. When the optical filter is used as a laser radar cover, the optical filter can adapt to a cold environment, can reduce light signal interference and can improve optical performance.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, in particular to an optical filter. Background Art

[0002] With the rapid development of autonomous driving in the automotive industry, the application of lidar for adaptive cruise control is becoming more and more widespread. Among them, the importance of the radar cover installed in front of the lidar for protection is gradually becoming prominent.

[0003] Conventional radomes have poor adaptability to cold and harsh environments and are easily affected by ice, snow, fog, and frost in cold conditions. Therefore, heated radomes have emerged. To address this issue, existing technology provides a radome that uses heating wires located on the front of the front cover for heating. However, existing radomes heated with heating wires affect the penetration and imaging quality of the LiDAR, fail to meet the low reflectivity requirements of the LiDAR radome, and have poor resistance to optical signal interference. Summary of the Invention

[0004] An object of the present invention is to provide an optical filter which, when used as a laser radar cover, can adapt to cold environments, reduce optical signal interference, and improve optical performance.

[0005] The embodiment of the present invention is achieved as follows:

[0006] In one aspect, the present invention provides an optical filter comprising a substrate, a first antireflection film disposed on one side of the substrate, and a dielectric black film, a transparent conductive layer, and a second antireflection film stacked sequentially on the other side of the substrate. A positive electrode and a negative electrode are plated between the transparent conductive layer and the second antireflection film. The first antireflection film comprises a first film stack, a second film stack, a third film stack, and a fourth film stack stacked sequentially on the substrate. The dielectric black film comprises a first film layer, a second film layer, and a fifth film stack stacked sequentially on the substrate. The first, second, third, fourth, and fifth film stacks are each formed by stacking at least three dielectric film layers, with adjacent dielectric film layers having different refractive indices. When used as a lidar cover, this filter can adapt to cold environments, reduce optical signal interference, and improve optical performance.

[0007] Optionally, the first membrane stack is formed by stacking in a first preset stacking structure, and the first preset stacking structure is in the form of: (LM) n The second membrane stack is formed by stacking a second preset stacking structure, and the second preset stacking structure is: (HL) n H; the third membrane stack is formed by stacking a third preset stacking structure, and the third preset stacking structure is: (ML) nM; the fourth membrane stack is formed by stacking a fourth preset stacking structure, and the fourth preset stacking structure is: (HML) n ; Among them, H, M, and L are three dielectric film layers with different refractive indices, and the refractive index of M is greater than the refractive index of L and less than the refractive index of H, n is the number of cycles, and n is an integer greater than or equal to 1.

[0008] Optionally, the thickness of each dielectric film layer of the first antireflection film is between 0 nm and 200 nm, and / or the number of dielectric film layers of the first antireflection film is between 15 and 25.

[0009] Optionally, the fifth membrane stack is formed by stacking in a fifth preset stacking structure, and the fifth preset stacking structure is in the form of: (LH) n L; and the refractive index of the first film layer is less than the refractive index of the second film layer.

[0010] Optionally, the refractive index of the H dielectric film layer is between 3.0 and 6.0, the refractive index of the M dielectric film layer is between 1.8 and 3.0, and the refractive index of the L dielectric film layer is between 1.2 and 1.6.

[0011] Optionally, the material of the H dielectric film layer is SiH, the material of the M dielectric film layer is at least one of SiN, SiOH, SiON, SiO, TiO2, Ta2O5, Ti3O5 and Nb2O5, and the material of the L dielectric film layer is any one of SiO2, silicon-aluminum mixture or a mixture of the two.

[0012] Optionally, the second antireflection film is an L dielectric film layer or a multilayer film, wherein the multilayer film is stacked in a sixth preset stacking structure, and the sixth preset stacking structure is in the form of: (LM) n L or (LH) n L, wherein H, M, and L are three dielectric film layers with different refractive indices, the refractive index of the H dielectric film layer is between 3.0 and 6.0, the refractive index of the M dielectric film layer is between 1.8 and 3.0, and the refractive index of the L dielectric film layer is between 1.2 and 1.6, and n is the number of cycles, and n is an integer greater than or equal to 1.

[0013] Optionally, the thickness of each dielectric film layer of the dielectric black film and the thickness of each dielectric film layer of the second antireflection film are respectively between 0 nm and 500 nm, and the sum of the number of dielectric film layers of the dielectric black film, the number of transparent conductive layers and the number of dielectric film layers of the second antireflection film is between 20 and 50.

[0014] Optionally, the optical filter further includes a waterproof film located on a side of the first anti-reflection film away from the substrate.

[0015] Optionally, the optical filter further includes an ink layer covering the positive electrode and the negative electrode on a side away from the transparent conductive layer, wherein the ink layer is located between the positive electrode and the second antireflection film.

[0016] The beneficial effects of the present application include:

[0017] The filter provided by the present application comprises a substrate, a first antireflection film arranged on one side of the substrate, a dielectric black film, a transparent conductive layer and a second antireflection film arranged in sequence on the other side of the substrate, and a positive electrode and a negative electrode arranged on the transparent conductive layer; wherein the first antireflection film comprises a first film stack, a second film stack, a third film stack and a fourth film stack arranged in sequence on the substrate; the dielectric black film comprises a first film layer, a second film layer and a fifth film stack arranged in sequence on the substrate; the first film stack, the second film stack, the third film stack, the fourth film stack and the fifth film stack are each formed by stacking at least three dielectric film layers, and the refractive indexes of adjacent two dielectric film layers are different. When the filter of the present application is used as a radome of a laser radar, the positive electrode and the negative electrode can be connected to a power supply, so as to heat the transparent conductive layer by electrification, thereby realizing the heating of the substrate to remove surface water mist or ice layer and the like; and the filter of the present application has low reflectivity and high transmissivity in the near-infrared light wave band, and is cut off in the visible light wave band (i.e. has low reflectivity and transmissivity in the visible light wave band), so that the filter provided by the present application can solve the problem of the damage of the penetration and imaging capability of the laser radar caused by heating in the prior art under the condition of being applicable to cold environment, so that the filter has excellent optical properties, can reduce the light interference of the radome on the laser radar, and thereby improves the precision of the laser radar. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0019] Figure 1 The structural schematic diagram of the filter provided by some embodiments of the present application;

[0020] Figure 2 The structural schematic diagram of the positive electrode, the negative electrode and the transparent conductive layer provided by some embodiments of the present application;

[0021] Figure 3 The structural schematic diagram of the positive electrode, the negative electrode, the transparent conductive layer and the ink layer provided by some embodiments of the present application;

[0022] Figure 4 The structural schematic diagram of the positive electrode, the negative electrode, the transparent conductive layer, the ink layer and the second antireflection film provided by some embodiments of the present application;

[0023] Figure 5 A graph showing the relationship between reflectivity and wavelength at various angles after film formation on both sides of an optical filter provided by some embodiments of the present invention;

[0024] Figure 6 A graph showing the relationship between transmittance and wavelength at various angles after film formation on both sides of an optical filter provided by some embodiments of the present invention;

[0025] Figure 7 A graph showing the relationship between the reflectivity and wavelength at various angles of the first antireflection film provided in some embodiments of the present invention;

[0026] Figure 8 A graph showing the relationship between reflectivity and wavelength at various angles for filter stacks provided in some embodiments of the present invention;

[0027] Figure 9 A comparison diagram of the relationship between the reflectivity and wavelength curves at various angles and the transmittance and wavelength curves of the filter stacks provided in some embodiments of the present invention.

[0028] Icon: 10-substrate; 20-first antireflection film; 30-dielectric black film; 40-transparent conductive layer; 50-second antireflection film; 61-positive electrode; 62-negative electrode; 70-waterproof film; 80-ink layer. DETAILED DESCRIPTION

[0029] The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present invention and will recognize applications of these concepts not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of the present invention and the appended claims.

[0030] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to regionally divide one element from another element. For example, without departing from the scope of the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] It should be understood that when an element (such as a layer, region or substrate) is referred to as being "on another element" or "extending onto another element", it may be directly on the other element or directly extending onto the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly onto another element", there are no intervening elements. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as being "above another element" or "extending over another element", it may be directly on the other element or directly extending over the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly on another element" or "extending directly over another element", there are no intervening elements. It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0032] Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical", may be used herein to describe the relationship of one element, layer or region to another element, layer or region, as illustrated in the figures. It should be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0033] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0034] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless otherwise explicitly defined herein.

[0035] Please refer to Figure 1This embodiment provides an optical filter including a substrate 10, a first antireflection film 20 arranged on one side of the substrate 10, and a dielectric black film 30, a transparent conductive layer 40, and a second antireflection film 50 stacked in sequence on the other side of the substrate 10, wherein a positive electrode 61 and a negative electrode 62 located on the transparent conductive layer 40 are plated between the transparent conductive layer 40 and the second antireflection film 50; wherein the first antireflection film 20 includes a first film stack, a second film stack, a third film stack, and a fourth film stack stacked in sequence on the substrate 10; the dielectric black film 30 includes a first film layer, a second film layer, and a fifth film stack stacked in sequence on the substrate 10; the first film stack, the second film stack, the third film stack, the fourth film stack, and the fifth film stack are respectively formed by stacking at least three dielectric film layers, and the refractive indices of two adjacent dielectric film layers are different.

[0036] It should be noted that the optical filter provided in this application can be used as a protective cover in applications where optical signal interference reduction is required. For example, the filter can serve as a radome for a LiDAR (Lidar). Of course, the radome is merely an example provided in this application and should not be considered the sole limitation on the application of the optical filter provided in this application.

[0037] For example, in this embodiment, the substrate 10 may be made of any one of tempered glass, plastic, and composite materials.

[0038] A first antireflection film 20 is provided on one side of the substrate 10, and a dielectric black film 30 is provided on the other side. In this embodiment, the first antireflection film 20 is a stack formed by stacking a first film stack, a second film stack, a third film stack, and a fourth film stack. The first film stack is in direct contact with the substrate 10, and the second film stack, the third film stack, and the fourth film stack are sequentially stacked on the first film stack. In this embodiment, the first film stack, the second film stack, the third film stack, and the fourth film stack are each also a stacked structure. Specifically, each stack can be a stacked structure formed by stacking at least three dielectric film layers. Furthermore, the refractive indices of the two adjacent dielectric film layers in each film stack are different.

[0039] Similarly, the dielectric black film 30 also has a stacked structure. However, unlike the first anti-reflection film 20, it is composed of a first film layer, a second film layer, and a fifth film stack. The first film layer is in direct contact with the side of the substrate 10 facing away from the first anti-reflection film 20, while the second film layer and the fifth film stack are sequentially formed on the first film layer. In short, the dielectric black film 30 is composed of two single film layers and a film stack. Similar to the first, second, third, and fourth film stacks, the fifth film stack is also a stacked structure consisting of at least three dielectric film layers, and the refractive indices of the two adjacent dielectric film layers in the fifth film stack are also different.

[0040] The transparent conductive layer 40 can be made of indium tin oxide. In this embodiment, after the dielectric black film 30 and the transparent conductive layer 40 are coated, they can be annealed in a nitrogen-filled oven. Nitrogen is injected into the oven to reduce the oxygen content to below 0.1% before annealing. The annealing temperature can be between 250°C and 350°C, and the annealing time can be between 2 and 3 hours. This minimizes the sheet resistance of the transparent conductive layer 40.

[0041] The positive electrode 61 and the negative electrode 62 are respectively transferred to the opposite ends of the transparent conductive layer 40. Figure 2 It should be noted that, in this embodiment, the positive electrode 61 and the negative electrode 62 need to be annealed and cured after being transferred to the two ends of the transparent conductive layer 40. Optionally, the material of the positive electrode 61 and the negative electrode 62 can be silver.

[0042] It should be noted that the positive electrode 61 and the negative electrode 62 are respectively connected to power, so that the transparent conductive layer 40 can be electrically heated, thereby increasing the temperature of the substrate 10 to remove surface water mist or ice.

[0043] To reduce the surface reflection of the positive electrode 61 and the negative electrode 62, optionally, in this embodiment, the filter may further include an ink layer 80 covering the positive electrode 61 and the negative electrode 62 on the side away from the transparent conductive layer 40, wherein the ink layer 80 is located between the positive electrode 61 and the second antireflection film 50. Figure 3 It should be noted that the ink layer 80 is directly transferred onto the positive electrode 61 and the negative electrode 62 , and after the ink layer 80 is transferred, it also needs to be annealed and cured.

[0044] The second antireflection film 50 is located on the side of the transparent conductive layer 40 away from the dielectric black film 30. The second antireflection film 50 can reduce the reflection of the side surface inside the visible area. It should be noted that when the filter is provided with an ink layer 80, the second antireflection film 50 should be plated after the ink layer 80 is printed. Figure 4 As shown, at this time, the second antireflection film 50 will cover the ink layer 80, so as to reduce the surface reflection of the ink layer 80.

[0045] Please refer to Figure 5 As shown in Table 1, Figure 5 The graph is a curve showing the relationship between the reflectivity and wavelength at each angle after the film is formed on both sides of the filter. Table 1 is a corresponding table showing the relationship between the reflectivity and wavelength at each angle after the film is formed on both sides of the filter. Figure 5As can be seen from Table 1, the optical filter provided by the present application has a low reflectivity in the range of 400nm to 700nm, and in a certain wavelength range of near-infrared light (for example, in the range of 870nm to 960nm), it also has a low reflectivity when the incident angle is 0° to 70°. For example, the optical filter provided by the present application has a reflectivity of R<0.2%at (i.e., the reflectivity of the light is less than 0.2%) between 0° and 20° in the near-infrared light band of 870nm to 960nm, Rs<0.3%at (i.e., the reflectivity of the light is less than 0.3%) at 30°, Rs<3.0%at (i.e., the reflectivity of the light is less than 3%) at 30°, and Rs<10%at (i.e., the reflectivity of the light is less than 10%) at 70°. In this way, the filter has excellent optical properties. For example, when the filter is used as a radar cover, it can reduce the optical interference of the radar cover to the laser radar and increase the accuracy of the laser radar system.

[0046] Table 1:

[0047]

[0048] Please refer to Figure 6 As shown in Table 2, Figure 6 The graph is a curve showing the relationship between transmittance and wavelength at each angle after the film is formed on both sides of the filter. Table 2 is a corresponding table showing the relationship between transmittance and wavelength at each angle after the film is formed on both sides of the filter. Figure 6 As can be seen from Table 2, the optical filter provided by the present application has low transmittance in the 300nm to 800nm ​​range, but has higher transmittance in a certain wavelength range of near-infrared light (for example, in the 870nm to 960nm range) at an incident angle of 0° to 70°. For example, at an incident angle of 0°, the optical filter provided by the present application has an overall average transmittance of less than 0.1% in the 300nm to 800nm ​​band, and a transmittance of greater than 95% in the 870nm to 960nm band.

[0049] Table 2:

[0050]

[0051] from Figure 5 and Figure 6 As can be seen from Tables 1 and 2, the optical filter provided by the present application has low reflectivity and high transmittance in the near-infrared light band (the figure only illustrates one of the near-infrared light bands, namely the 870nm to 960nm band; in fact, the same characteristics are also exhibited in the 1270nm to 1330nm or 1510nm to 1590nm bands), and is cut off in the visible light band (i.e., its reflectivity and transmittance are both low in the visible light band). In this way, the optical filter provided by the present application can have excellent optical properties, can reduce light interference, and improve optical performance.

[0052] In summary, the optical filter provided in the present application includes a substrate 10, a first anti-reflection film 20 arranged on one side of the substrate 10, and a dielectric black film 30, a transparent conductive layer 40 and a second anti-reflection film 50 stacked in sequence on the other side of the substrate 10, and a positive electrode 61 and a negative electrode 62 located on the transparent conductive layer 40 are also plated between the transparent conductive layer 40 and the second anti-reflection film 50; wherein, the first anti-reflection film 20 includes a first film stack, a second film stack, a third film stack and a fourth film stack stacked in sequence on the substrate 10; the dielectric black film 30 includes a first film layer, a second film layer and a fifth film stack stacked in sequence on the substrate 10; the first film stack, the second film stack, the third film stack, the fourth film stack and the fifth film stack are respectively formed by stacking at least three dielectric film layers, and the refractive indices of two adjacent dielectric film layers are different. When the filter of the present application is used as a radar cover of a laser radar (it should be understood that the use of the filter as a radar cover is only an example of its application scenario, which is for the purpose of explaining and understanding its technical effects and should not be regarded as a limitation of the present application), it can connect the positive electrode 61 and the negative electrode 62 to a power source, thereby electrically heating the transparent conductive layer 40, thereby causing the substrate 10 to heat up to remove surface water mist or ice, etc.; and the present application has low reflectivity and high transmittance in the near-infrared light band, and cuts off in the visible light band (that is, its reflectivity and transmittance are low in the visible light band). In this way, the filter provided by the present application can solve the problem of impaired penetration and imaging capabilities of the laser radar due to heating in the prior art while being applicable to cold environments, so that the filter has excellent optical properties, can reduce the optical interference of the radar cover to the laser radar, and thus improve the accuracy of the laser radar.

[0053] Optionally, the first membrane stack is formed by stacking in a first preset stacking structure, and the first preset stacking structure is in the form of: (LM) n The second membrane stack is formed by stacking a second preset stacking structure, and the second preset stacking structure is: (HL) n H; the third membrane stack is formed by stacking a third preset stacking structure, and the third preset stacking structure is: (ML) n M; the fourth membrane stack is formed by stacking a fourth preset stacking structure, and the fourth preset stacking structure is: (HML) n ; Among them, H, M, and L are three dielectric film layers with different refractive indices, and the refractive index of M is greater than the refractive index of L and less than the refractive index of H, n is the number of cycles, and n is an integer greater than or equal to 1.

[0054] It should be noted that the number of cycles n in the stacking structures of the first film stack, the second film stack, the third film stack, and the fourth film stack can be the same or different. In this way, the film system structure of the first antireflection film 20 is (LM) n (HL) nH(ML) n M(HML) n , the four n in the film structure can be the same or different.

[0055] Optionally, the thickness of each dielectric film layer of the first antireflection film 20 is between 0 nm and 200 nm, and / or the number of dielectric film layers of the first antireflection film 20 is between 15 and 25.

[0056] In this embodiment, the thicknesses of the dielectric film layers of the first antireflection film 20 may be the same or different. The total number of dielectric film layers of the first antireflection film 20 is between 15 and 25. For example, the total number of dielectric film layers may be 15, 17, 20, or 25, etc., which are not listed here.

[0057] Please refer to Figure 7 As shown in Table 3, Figure 7 The curve relationship diagram of the reflectivity and wavelength of the first antireflection film 20 at various angles provided by the present application is shown in Table 3. The corresponding relationship table of the reflectivity and wavelength of the first antireflection film 20 at various angles provided by the present application is shown in Table 4. Figure 7 As can be seen from Table 3, the first antireflection film 20 provided by the present application has an extremely low reflectivity in the range of 870 nm to 960 nm, and a relatively low reflectivity in the range of 420 nm to 680 nm.

[0058] Table 3:

[0059]

[0060] Optionally, the fifth membrane stack is formed by stacking in a fifth preset stacking structure, and the fifth preset stacking structure is in the form of: (LH) n L; and the refractive index of the first film layer is less than the refractive index of the second film layer.

[0061] In this way, the dielectric black film 30 is composed of two single film layers (i.e., the first film layer and the second film layer) and a fifth film stack. For example, the first film layer of the dielectric black film 30 can be an L dielectric film layer, and the second film layer can be an M dielectric film layer. In this way, the film structure of the dielectric black film 30 is LM (LH). n L.

[0062] Optionally, the refractive index of the H dielectric layer is between 3.0 and 6.0, the refractive index of the M dielectric layer is between 1.8 and 3.0, and the refractive index of the L dielectric layer is between 1.2 and 1.6. That is, the H dielectric layer is a high-refractive-index material layer, the M dielectric layer is a medium-refractive-index material layer, and the L dielectric layer is a low-refractive-index material layer. Thus, the first antireflection film 20 and the dielectric black film 30 provided herein can each be formed by stacking layers of different high and low refractive indices.

[0063] For example, the material of the H dielectric film layer can be SiH, the material of the M dielectric film layer can be at least one of SiN, SiOH, SiON, SiO, TiO2, Ta2O5, Ti3O5, and Nb2O5, and the material of the L dielectric film layer can be any one of SiO2, a silicon-aluminum mixture, or a mixture thereof. In other words, the materials of the dielectric film layers of the optical filter provided herein can be selected from the aforementioned materials. Specifically, this application does not impose any restrictions, and those skilled in the art can determine the materials themselves.

[0064] Furthermore, in this embodiment, optionally, the second antireflection film 50 may be an L dielectric film layer or a multilayer film, wherein the multilayer film is stacked in a sixth preset stacking structure, and the sixth preset stacking structure is in the form of: (LM) n L or (LH) n L, where H, M, and L are three dielectric film layers with different refractive indices, the refractive index of the H dielectric film layer is between 3.0 and 6.0, the refractive index of the M dielectric film layer is between 1.8 and 3.0, and the refractive index of the L dielectric film layer is between 1.2 and 1.6, and n is the number of cycles, and n is an integer greater than or equal to 1. That is, the second antireflection film 50 has three forms. The first is a single-layer film formed by the L dielectric film layer, and the second is a film system structure (LM) n L multilayer film, the third type is the film structure (LH) n Multilayer film of L.

[0065] When the second antireflection film 50 is a multilayer film, the H dielectric film layer is a high refractive index material film layer, the M dielectric film layer is a medium refractive index material film layer, and the L dielectric film layer is a low refractive index material film layer. In this way, the second antireflection film 50 provided by the present application can also be formed by stacking film layers with different high and low refractive indices.

[0066] Optionally, the thickness of each dielectric film layer of the dielectric black film 30 and the thickness of each dielectric film layer of the second antireflection film 50 are respectively between 0 nm and 500 nm.

[0067] Furthermore, the sum of the number of dielectric film layers of the dielectric black film 30, the number of transparent conductive layers 40, and the number of dielectric film layers of the second antireflection film 50 is between 20 and 50. For example, the sum of the number of layers can be 20, 30, 40, or 50.

[0068] It should be noted that the material of the dielectric film layer of the second antireflection film 50 is the same as that mentioned above. The material of the H dielectric film layer can be SiH, the material of the M dielectric film layer can be at least one of SiN, SiOH, SiON, SiO, TiO2, Ta2O5, Ti3O5 and Nb2O5, and the material of the L dielectric film layer can be any one of SiO2, a silicon-aluminum mixture, or a mixture of the two.

[0069] Please refer to Figure 8 、 Figure 9 As shown in Table 4, Figure 8 This is a graph showing the relationship between the reflectivity at various angles and wavelength for the filter stack provided by the present application (i.e., the stack formed by the dielectric black film 30, the transparent conductive layer 40, and the second anti-reflection film 50). Table 4 shows the relationship between the reflectivity at various angles and wavelength for the filter stack formed by the dielectric black film 30, the transparent conductive layer 40, and the second anti-reflection film 50 provided by the present application. Figure 9 The curves of reflectivity and wavelength at various angles and the curves of transmittance and wavelength of the filter stack provided by this application are compared. Figure 8 、 Figure 9 As can be seen from Table 4, the filter stack provided by the present application has low transmittance and reflectance in the visible light band, and low reflectance and high transmittance in the near-infrared light band (870-960 nm).

[0070] Table 4:

[0071]

[0072] To protect the optical filter and prevent it from being affected by the external environment, optionally, in this embodiment, the optical filter further includes a waterproof film 70 located on a side of the first anti-reflection film 20 away from the substrate 10 .

[0073] The foregoing description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0074] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A filter, characterized in that: The device comprises a substrate, a first antireflection film provided on one side of the substrate, and a dielectric black film, a transparent conductive layer, and a second antireflection film stacked in sequence on the other side of the substrate, wherein a positive electrode and a negative electrode located on the transparent conductive layer are plated between the transparent conductive layer and the second antireflection film; Among them, the first anti-reflection film includes a first film stack, a second film stack, a third film stack and a fourth film stack stacked in sequence on the substrate; the dielectric black film includes a first film layer, a second film layer and a fifth film stack stacked in sequence on the substrate; the first film stack, the second film stack, the third film stack, the fourth film stack and the fifth film stack are respectively formed by stacking at least three layers of dielectric film layers, and the refractive indices of two adjacent layers of the dielectric film layers are different.

2. The optical filter according to claim 1, wherein The first membrane stack is formed by stacking in a first preset stacking structure, and the first preset stacking structure is in the form of: (LM) n ; The second membrane stack is formed by stacking in a second preset stacking structure, and the second preset stacking structure is in the form of: (HL) n H; the third membrane stack is formed by stacking a third preset stacking structure, and the third preset stacking structure is: (ML) n M; the fourth membrane stack is formed by stacking a fourth preset stacking structure, and the fourth preset stacking structure is: (HML) n ; Among them, H, M, and L are three dielectric film layers with different refractive indices, and the refractive index of M is greater than the refractive index of L and less than the refractive index of H, n is the number of cycles, and n is an integer greater than or equal to 1.

3. The optical filter according to claim 2, wherein The thickness of each dielectric film layer of the first antireflection film is between 0 nm and 200 nm, and / or the number of dielectric film layers of the first antireflection film is between 15 and 25.

4. The optical filter according to claim 2, wherein The fifth membrane stack is formed by stacking in a fifth preset stacking structure, and the fifth preset stacking structure is in the form of: (LH) n L; and the refractive index of the first film layer is less than the refractive index of the second film layer.

5. The optical filter according to claim 4, wherein The refractive index of the H dielectric film layer is between 3.0 and 6.0, the refractive index of the M dielectric film layer is between 1.8 and 3.0, and the refractive index of the L dielectric film layer is between 1.2 and 1.

6.

6. The optical filter according to claim 5, wherein The material of the H dielectric film layer is SiH, the material of the M dielectric film layer is at least one of SiN, SiOH, SiON, SiO, TiO2, Ta2O5, Ti3O5 and Nb2O5, and the material of the L dielectric film layer is any one of SiO2, a silicon-aluminum mixture or a mixture of the two.

7. The optical filter according to any one of claims 1 to 6, characterized in that The second antireflection film is an L dielectric film layer or a multilayer film, wherein the multilayer film is stacked in a sixth preset stacking structure, and the sixth preset stacking structure is in the form of: (LM) n L or (LH) n L, wherein H, M, and L are three dielectric film layers with different refractive indices, the refractive index of the H dielectric film layer is between 3.0 and 6.0, the refractive index of the M dielectric film layer is between 1.8 and 3.0, and the refractive index of the L dielectric film layer is between 1.2 and 1.6, and n is the number of cycles, and n is an integer greater than or equal to 1.

8. The optical filter according to claim 1, wherein The thickness of each dielectric film layer of the dielectric black film and the thickness of each dielectric film layer of the second antireflection film are respectively between 0 nm and 500 nm, and the sum of the number of layers of each dielectric film layer of the dielectric black film, the number of layers of the transparent conductive layer, and the number of layers of each dielectric film layer of the second antireflection film is between 20 and 50.

9. The optical filter according to claim 1, wherein The optical filter further includes a waterproof film located on a side of the first anti-reflection film away from the substrate.

10. The optical filter according to claim 1 or 9, characterized in that The optical filter further includes an ink layer covering the positive electrode and the negative electrode on a side away from the transparent conductive layer, wherein the ink layer is located between the positive electrode and the second antireflection film.

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