Infrared cut-off filter

Abstract

The utility model discloses an infrared ray cut-off filter which comprises a substrate, a hard protective film, a multilayer interference film and an anti-reflection coating are sequentially deposited on one surface of the substrate according to the direction from the air side to the substrate, the multilayer interference film is composed of at least five high refractive index material layers and at least five low refractive index material layers, and the high-refractive-index material layers and the low-refractive-index material layers are alternately stacked. According to the utility model, a plurality of layers of dielectric films are deposited on the surface of the substrate, selective transmission and reflection characteristics for light in a specific wavelength range are formed based on a thin film interference principle, and a strong reflection band is formed in a near-infrared region while high transmittance is effectively kept in a visible light range, so that the purpose of cutting off infrared rays is achieved.

Description

Technical Field

[0001] This utility model relates to the field of filter technology, and in particular to an infrared cut-off filter. Background Technology

[0002] An optical filter is an optical element used to select the desired wavelength of radiation. It is widely used in various fields, including cameras. In digital cameras, images are converted from analog signals to digital signals by CMOS or CCD sensors. To ensure image quality, an infrared cutoff filter is typically installed in front of these sensors. The function of this filter is to prevent infrared light from entering the sensor, because if infrared light is captured, it may interfere with the color accuracy of the image, causing information imperceptible to the naked eye to affect the imaging effect.

[0003] Therefore, a high-quality IR filter is crucial for ensuring the quality of captured images. Based on this requirement, this utility model aims to provide a filter structure that can effectively block infrared rays. Utility Model Content

[0004] The purpose of this utility model is to provide an infrared cutoff filter in order to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An infrared cutoff filter includes a substrate arranged in a direction from the air side to the substrate. A hard protective film, a multilayer interference film, and an anti-reflective coating are sequentially deposited on one surface of the substrate. The multilayer interference film consists of at least five layers of high-refractive-index material and low-refractive-index material, which are alternately stacked.

[0007] As a further description of the above technical solution:

[0008] A waterproof membrane is attached to the surface of the rigid protective film.

[0009] As a further description of the above technical solution:

[0010] The surface of the waterproof membrane is coated with a dustproof membrane.

[0011] As a further description of the above technical solution:

[0012] The substrate is made of optical glass.

[0013] As a further description of the above technical solution:

[0014] Both the anti-reflective coating and the low-refractive-index material layer are made of SiO2.

[0015] As a further description of the above technical solution:

[0016] The hard protective film is made of diamond-like carbon coating, and the high refractive index material layer is made of Ta2O5.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0018] 1. In this invention, a multilayer dielectric film is deposited on the surface of the substrate. Based on the principle of thin film interference, selective transmission and reflection characteristics of light within a specific wavelength range are formed. This effectively maintains high transmittance in the visible light range while forming a strong reflection band in the near-infrared region, thereby achieving the purpose of blocking infrared rays.

[0019] 2. In this utility model, an anti-reflective coating is designed to reduce the reflection loss of light when it passes through the surface of the filter, thereby improving the transmittance.

[0020] 3. In this utility model, a rigid protective film is designed to increase the durability of the filter and its ability to resist scratches, corrosion and other problems.

[0021] 4. In this invention, a solution containing a specific molecular structure is used to coat the surface of the filter, and then cured into a waterproof film by heating or other means, which effectively prevents water from adhering to the surface of the filter and avoids image blurring or other optical performance degradation caused by water droplets.

[0022] 5. In this utility model, nanotechnology is used to form a very thin but extremely smooth dustproof film on the surface of the filter, which reduces the adhesion of dust particles to the surface of the filter and makes it easy to clean. Attached Figure Description

[0023] Figure 1 An exploded view of an infrared cutoff filter according to an embodiment of the present invention is shown.

[0024] Figure 2 A three-dimensional structural schematic diagram of an infrared cutoff filter provided according to an embodiment of the present utility model is shown;

[0025] Figure 3 It shows Figure 1 Enlarged diagram of point A in the middle.

[0026] Legend:

[0027] 1. Substrate; 2. Anti-reflective coating; 3. Multilayer interference film; 31. High refractive index material layer; 32. Low refractive index material layer; 4. Hard protective film; 5. Waterproof film; 6. Dustproof film. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0029] Please see Figure 1-3 This utility model provides a technical solution: an infrared cutoff filter, including a substrate 1, arranged in a direction from the air side to the substrate 1. A dustproof film 6, a waterproof film 5, a hard protective film 4, a multilayer interference film 3, and an anti-reflection coating 2 are sequentially deposited (e.g., by physical vapor deposition) on one surface of the substrate 1. The multilayer interference film 3 is composed of at least five layers of high refractive index material 31 and low refractive index material 32, which are stacked alternately. Based on the principle of thin film interference, it forms selective transmission and reflection characteristics of light within a specific wavelength range, effectively maintaining high transmittance in the visible light range while forming a strong reflection band in the near-infrared region, thereby achieving the purpose of cutting off infrared rays.

[0030] It's important to note that the number of layers in designing an infrared cutoff filter depends primarily on the required optical performance parameters, such as the cutoff wavelength, transmittance profile, and the specific application requirements. For simple infrared cutoff functionality, at least 5 to 10 layers of alternating high- and low-refractive-index materials are needed. This structure can meet basic infrared filtering requirements but may not provide an optimized transmittance profile or a particularly steep cutoff characteristic. For higher performance requirements, such as a very smooth and efficient transmittance profile or a very steep cutoff edge, the number of layers may need to be increased to 15 or more. High-performance infrared cutoff filters sometimes contain up to 20 or more layers to ensure optimal performance within a specified wavelength range.

[0031] Specifically, substrate 1 is made of optical glass, such as BK7 or BK20, which has good light transmittance and mechanical hardness; anti-reflective coating 2 is made of SiO2, which improves transmittance by reducing the reflection loss of light when passing through the filter surface; high refractive index material layer 31 is made of Ta2O5, and low refractive index material layer 32 is made of SiO2, which achieves selective reflection or transmission of infrared rays; hard protective film 4 is made of diamond-like carbon coating, which increases the durability of the filter and its ability to resist environmental influences (such as scratches and corrosion); a solution containing a specific molecular structure (such as fluoropolymers) is coated on the filter surface, and then cured by heating to form a waterproof film 5, which effectively prevents moisture from adhering to the filter surface and avoids image blurring or other optical performance degradation caused by water droplets; a very thin but extremely smooth dustproof film 6 is formed on the filter surface using nanotechnology, which reduces the adhesion of dust particles to the filter surface and is easy to clean.

[0032] Furthermore, when designing the filter structure, the thickness of each layer is crucial for achieving specific optical performance. Specifically, the thickness of the optical glass is determined according to the specific application requirements, typically a few millimeters. The thickness of the anti-reflective coating 2, the high-refractive-index material layer 31, and the low-refractive-index material layer 32 is based on the principle of one-quarter of the wavelength (λ / 4n), where λ is the design wavelength and n is the refractive index of the material. For example, for a center wavelength λ = 700nm (a common infrared cutoff wavelength), the thickness of the anti-reflective coating 2 and the low-refractive-index material layer 32 is approximately 120nm, and the thickness of the high-refractive-index material layer 31 is approximately 83nm. The actual thickness needs to be adjusted according to the specific transmittance requirements and cutoff wavelength.

[0033] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An infrared cut filter comprising a substrate (1), characterized in that, One surface of the substrate (1) is sequentially deposited with a hard protective film (4), a multilayer interference film (3) and an anti-reflection coating (2) in the direction from the air side to the substrate (1), the multilayer interference film (3) is composed of at least five layers of high refractive index material layer (31) and low refractive index material layer (32), the high refractive index material layer (31) and the low refractive index material layer (32) are alternately stacked.

2. An infrared cut filter according to claim 1, wherein The surface of the hard protective film (4) is connected with a waterproof film (5).

3. An infrared cut filter according to claim 2, wherein The surface of the waterproof film (5) is coated with a dustproof film (6).

4. The infrared cut filter according to claim 1, wherein The substrate (1) is selected from optical glass.

5. The infrared cut filter according to claim 1, wherein The anti-reflection coating (2) and the low refractive index material layer (32) are both selected from SiO2.

6. The infrared cut filter according to claim 1, wherein The hard protective film (4) is selected from diamond-like carbon coating, and the high refractive index material layer (31) is selected from Ta2O5.

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