Filtering system and imaging system

Abstract

The utility model discloses a filtering system and an imaging system, the filtering system comprises a first metal reflection layer, a second metal reflection layer and a metasurface layer, the first metal reflection layer and the second metal reflection layer are both arranged to be a sub-wavelength film structure, the metasurface layer is arranged between the first metal reflection layer and the second metal reflection layer, and the metasurface layer is arranged between the first metal reflection layer and the second metal reflection layer. The first metal reflection layer and the second metal reflection layer are arranged to be of a monolithic continuous structure and cover the multiple elements of the metasurface layer. According to the filtering system, the excellent stray light suppression effect of the metal reflecting layer is utilized, the filtering wavelength can be finely adjusted by the metasurface layer to obtain a very accurate spectrum channel, and the structure and the manufacturing process are simplified while the processing error between the layers in the system is reduced through the structure that the single metal reflecting layer covers a plurality of elements.

Description

Technical Field

[0001] The utility model relates to the field of optical devices for regulating electromagnetic waves, in particular to a filtering system and an imaging system. Background Art

[0002] The filtering system is one of the key components of the imaging system and is widely used in fields such as spectral imaging, color correction, and signal processing. The filtering system realizes the optimization and enhancement of the image signal by selectively transmitting or reflecting light in a specific wavelength band. At present, the main implementation methods of the filtering system include dielectric filters, metal mirrors, and metasurface structures. However, the existing filtering systems have certain limitations in terms of manufacturing complexity, cost, and performance.

[0003] For example, existing multispectral filtering systems usually achieve filtering through multiple coatings. The multiple coating process is complex, which affects the production yield. The production process is complex and the production cost is high. Moreover, the produced filtering system also has insufficient performance in terms of stray light suppression and signal-to-noise ratio, and it is difficult to meet the requirements of high-precision imaging. As Figure 1 shown, the figure shows a schematic diagram of the filtering effects of different wavelengths of an existing filtering system. This filtering system only has filtering effects in the vicinity of 500 - 550 nm and 600 - 675 nm, but it cannot suppress stray light in the ranges less than 475 nm and greater than 750 nm, and the filtering effect is not ideal enough. Summary of the Invention

[0004] To solve the problems in the prior art that the production process of the filtering system is complex, the production cost is high, and the performance of the finished product is insufficient, the purpose of the utility model is to provide a filtering system and an imaging system that can reduce costs and improve performance.

[0005] To achieve the above-mentioned utility model purpose, an embodiment of the utility model provides a filtering system, which includes a first metal reflection layer, a second metal reflection layer, and a metasurface layer. Both the first metal reflection layer and the second metal reflection layer are set as sub-wavelength thin film structures. The metasurface layer is disposed between the first metal reflection layer and the second metal reflection layer. The metasurface layer includes an elementary layer, and the elementary layer includes a plurality of elementary units with sub-wavelength structures. The sizes and arrangement manners of the plurality of elementary units are determined according to the target wavelength band. Both the first metal reflection layer and the second metal reflection layer are set as single-piece continuous structures and cover the plurality of elementary units.

[0006] As a further improvement of the utility model, the filtering system includes multiple groups of narrowband filtering partitions. Each group of narrowband filtering partitions corresponds to a different narrowband wavelength band, and the parameters of the plurality of elementary units in each narrowband filtering partition are determined according to the narrowband wavelength band corresponding to each group of narrowband filtering partitions.

[0007] As a further improvement of the present utility model, the filtering system includes multiple groups of broadband filtering partitions. Each group of the broadband filtering partitions corresponds to a different broadband band. Each group of the broadband filtering partitions corresponds to a group of the first metal reflection layer and the second metal reflection layer. The distances between the first metal reflection layer and the second metal reflection layer of different broadband filtering partitions are different. The parameters of the first metal reflection layer, the second metal reflection layer, and multiple elementary units of each broadband filtering partition are determined according to the broadband band corresponding to each group of the broadband filtering partitions.

[0008] As a further improvement of the present utility model, one of the first metal reflection layer and the second metal reflection layer is shared by the multiple groups of broadband filtering partitions, and the other of the first metal reflection layer and the second metal reflection layer includes multiple sub-reflection layers with different heights. Each group of the broadband filtering partitions corresponds to its respective sub-reflection layer.

[0009] As a further improvement of the present utility model, both the first metal reflection layer and the second metal reflection layer are provided as multiple sheets. Each group of the broadband filtering partitions respectively corresponds to one of the first metal reflection layer and one of the second metal reflection layer.

[0010] As a further improvement of the present utility model, the metasurface layer further includes a filling layer, and the filling layer at least partially fills between the multiple elementary units.

[0011] As a further improvement of the present utility model, the filtering system further includes a buffer layer, and the buffer layer is disposed between the metasurface layer and the first metal reflection layer.

[0012] and / or

[0013] the buffer layer is disposed between the metasurface layer and the second metal reflection layer.

[0014] As a further improvement of the present utility model, each elementary unit is composed of multiple materials, and in the direction from the first metal reflection layer to the second metal reflection layer, each material of the elementary unit is arranged in sequence.

[0015] To achieve one of the above utility model purposes, an embodiment of the present utility model provides an imaging system. The imaging system further includes the above filtering system and an image sensor layer. The first metal reflection layer is located on the light incident side of the filtering system, the second metal reflection layer is located on the light exiting side of the filtering system, and the image sensor layer is disposed on a side of the filtering system close to the second metal reflection layer.

[0016] As a further improvement of the present utility model, the imaging system further includes a protective layer and a substrate. The protective layer is disposed between the image sensor layer and the second metal reflection layer, and the substrate is disposed on the side of the image sensor layer away from the filtering system.

[0017] Compared with the conventional technology, the present utility model has the following beneficial effects: The filtering system combines the metasurface layer with two metal reflection layers to achieve the filtering effect. On the one hand, by utilizing the excellent stray light suppression effect of the metal reflection layer, its optical performance is more uniform and stable, so that the filtering system improves the signal-to-noise ratio; on the other hand, by utilizing the structure of multiple primitive elements of the sub-wavelength structure of the metasurface layer, the filtering wavelength is finely adjusted to allow light of a specific frequency to pass through, obtaining a very precise spectral channel; on the third hand, through the structure of a single metal reflection layer covering multiple primitive elements, while simplifying the structure and manufacturing process, the processing error between layers in the system can be reduced, improving the reliability of the filtering system. Description of the Drawings

[0018] Figure 1 is a schematic diagram of the filtering effects of different wavelengths of an existing filtering system;

[0019] Figure 2 is a schematic structural diagram in the sectional direction of the imaging system according to the first embodiment of the present utility model;

[0020] Figure 3 is a schematic diagram of the filtering effects of different wavelengths of the filtering system according to the first embodiment of the present utility model;

[0021] Figure 4 is a schematic structural diagram in the top view direction of the metasurface layer according to the first embodiment of the present utility model;

[0022] Figure 5 is a partial schematic structural diagram in the top view direction of the metasurface layer according to the first embodiment of the present utility model;

[0023] Figure 6 is a schematic structural diagram in the sectional direction of the filtering system according to the second embodiment of the present utility model;

[0024] Figure 7 is a schematic structural diagram in the sectional direction of the filtering system according to the third embodiment of the present utility model;

[0025] Figure 8 is a schematic structural diagram in the sectional direction of the filtering system according to the fourth embodiment of the present utility model;

[0026] Among them, 100 is a filtering system; 110 is a narrowband filtering partition; 120 is a wideband filtering partition; 200 is an imaging system; 10 is a first metal reflection layer; 20 is a second metal reflection layer; 30 is a metasurface layer; 31 is a primitive layer; 311 is a primitive; 32 is a filling layer; 40 is a buffer layer; 41 is a first buffer layer; 42 is a second buffer layer; 50 is an image sensor layer; 60 is a protective layer; 70 is a substrate; 80 is an antireflection layer. Detailed implementation manners

[0027] The following will describe the present utility model in detail in conjunction with the specific implementation manners shown in the accompanying drawings. However, these implementation manners do not limit the present utility model, and structural, method, or functional transformations made by those of ordinary skill in the art based on these implementation manners are all included in the protection scope of the present utility model.

[0028] It should be understood that terms indicating relative spatial positions such as "above", "upper", "below", "lower" used herein are for the purpose of facilitating description of the relationship of one unit or feature to another unit or feature as shown in the accompanying drawings. Terms indicating relative spatial positions may be intended to include different orientations of the device in use or operation other than the orientation shown in the figures.

[0029] An embodiment of the present utility model provides a filtering system 100 and an imaging system 200 that reduce costs and improve performance.

[0030] The following describes the filtering system 100 in multiple embodiments. Embodiment 1 is as Figures 2 to 5 shown, showing the basic structure of the filtering system 100; Embodiment 2 is as Figure 6 shown, and Embodiment 3 is as Figure 7 shown.

[0031] Embodiment 1

[0032] A filtering system 100 of this embodiment, as Figure 2 shown, includes a first metal reflection layer 10, a second metal reflection layer 20, and a metasurface layer 30. Both the first metal reflection layer 10 and the second metal reflection layer 20 are set as sub-wavelength thin film structures.

[0033] The working principle of the filtering system 100 is to form a Fabry - Perot (F - P) resonator. The first metal reflective layer 10 and the second metal reflective layer 20 can both be made of metal thin films, which are produced by coating. The materials include but are not limited to aluminum, copper, silver, gold, etc. Preferably, silver is used as the material. The thicknesses of the first metal reflective layer 10 and the second metal reflective layer 20 can be the same or different, and the materials can also be the same or different. The thicknesses of the first metal reflective layer 10 and the second metal reflective layer 20 are both in the sub - wavelength range, that is, the size is smaller than the wavelength of light. When the filtering system 100 is applied to the visible light band, the thicknesses of the first metal reflective layer 10 and the second metal reflective layer 20 are less than the wavelength of visible light. When the filtering system 100 is applied to the near - infrared light band, the thicknesses of the first metal reflective layer 10 and the second metal reflective layer 20 are less than the wavelength of near - infrared light.

[0034] Due to the excellent stray light suppression effect of the metal reflective layer, only part of the expected band can pass through the first metal reflective layer 10 and the second metal reflective layer 20, and other non - expected bands can be completely reflected and cannot pass through. Therefore, the optical performance is more uniform and stable, and the signal - to - noise ratio of the filtering system 100 is improved.

[0035] The metasurface layer 30 is disposed between the first metal reflective layer 10 and the second metal reflective layer 20. The metasurface layer 30 includes an elementary layer 31, and the elementary layer 31 includes a plurality of elements 311 with sub - wavelength structures. The sizes and arrangement manners of the plurality of elements 311 are determined according to the target band. The material of the element 311 can be any dielectric material such as TiO2, Si, Si3N4, Ge, etc., and the specific material is determined according to the target band. In addition, the element 311 can also be a phase - change material, and the refractive index can be changed by other means such as temperature control or electrical control.

[0036] The metasurface layer 30 serves the purpose of adjusting the equivalent refractive index. By using the structures of the plurality of elements 311 with sub - wavelength structures in the metasurface layer 30, the filtering wavelength can be finely adjusted by changing the size of the nanostructures, allowing light of a specific frequency to pass through, generating a narrow - band filtering effect with different central wavelengths, and obtaining a very precise spectral channel.

[0037] The metasurface layer 30 is used to form a high-transmission region. Through the expected wavelength band, the refractive index and thickness of the metasurface layer 30 determine the position of the expected wavelength band; the first metal reflection layer 10 and the second metal reflection layer 20 are used to form a high-reflection region to prevent as much light as possible from passing through the wavelength bands other than the expected one. The specific thicknesses of the first metal reflection layer 10 and the second metal reflection layer 20 can be further optimized according to the relationship of refractive index matching. Specifically, since the upper part of the first metal reflection layer 10 is generally air and the lower part of the second metal reflection layer 20 is generally other media, such as the protective layer 60 below, the equivalent refractive index of the combination of the first metal reflection layer 10 and air, and the equivalent refractive index of the combination of the second metal reflection layer 20 and the protective layer 60 are considered here. When the two equivalent refractive indices are closer, the transmittance of the light in the expected wavelength band is higher, and the refractive index matching effect is better at this time. Of course, the specific thicknesses of the first metal reflection layer 10 and the second metal reflection layer 20 can be different under different optimization conditions, and can even be directly determined according to experience, as long as the transmittance of the light with wavelengths within a certain range is satisfied.

[0038] Both the first metal reflection layer 10 and the second metal reflection layer 20 are set as a single-piece continuous structure and cover multiple elements 311. The single-piece continuous structure means that the first metal reflection layer 10 and the second metal reflection layer 20 covering multiple elements 311 are not interrupted and are a whole-piece structure. On the one hand, this simplifies the overall structure of the filtering system 100, reduces the complexity of independently processing the metal layer of each element 311, simplifies the coating and etching steps of the metal layer corresponding to each element 311 during the manufacturing process, reduces the alignment and positioning requirements, and improves the production efficiency; on the other hand, it reduces the alignment and positioning errors of the filtering structures corresponding to each element 311, improves the consistency and reliability of the system; on the third hand, in this way, a higher density of elements 311 can be integrated, making the filtering system 100 have better optical performance.

[0039] During the filtering process of the filtering system 100, the distance between the first metal reflection layer 10 and the second metal reflection layer 20 can meet the requirements of a relatively wide wavelength band. First, determine the position of the approximate center wavelength, and then by adjusting the size and layout of the elements 311 of the metasurface layer 30 and adjusting the equivalent refractive index of the metasurface layer 30, a more refined change in the center wavelength of the passband can be obtained.

[0040] Finally, through the design of using the first metal reflection layer 10 and the second metal reflection layer 20 with a single-piece continuous structure to cover multiple elements 311 in the filtering system 100, the efficient transmission of the light in the target wavelength band and the effective suppression of stray light are realized, the signal-to-noise ratio of the imaging system 200 is improved, and the image color is more restored.

[0041] The schematic diagram of the filtering effects of different wavelengths of the filtering system 100 in this embodiment is as Figure 3As shown, the filtering system 100 produces a good filtering effect in the wavelength bands of 580 - 610 nm, 610 - 660 nm, and 660 - 720 nm, and has an excellent suppression effect on the sideband intervals less than 550 nm and greater than 750 nm, with an ideal filtering effect.

[0042] Further, as Figure 4 shown, the filtering system 100 includes multiple groups of narrow - band filtering partitions 110. Each group of narrow - band filtering partitions 110 corresponds to a different narrow - band wavelength band, and the parameters of multiple primitive elements 311 within the narrow - band filtering partition 110 are determined according to the narrow - band wavelength band corresponding to each group of narrow - band filtering partitions 110.

[0043] Figure 4 In

[0044] which, λ1, λ2, λ3, etc. respectively represent different narrow - band wavelength bands corresponding to the narrow - band filtering partition 110. The distances between the first metal reflection layer 10 and the second metal reflection layer 20 corresponding to these narrow - band filtering partitions 110 are the same. That is to say, based on the common distance between the first metal reflection layer 10 and the second metal reflection layer 20, the requirements of a certain interval of wavelength bands can be met, and these different narrow - band wavelength bands are all within this certain interval.

[0045] In addition, as Figure 2 and 4 shown, the metasurface layer 30 further includes a filling layer 32, and the filling layer 32 at least partially fills the space between multiple primitive elements 311. The filling layer 32 plays a role in supporting and weakening resonance. The filling layer 32 can be made of materials including but not limited to silicon dioxide, titanium dioxide, silicon nitride, silicon, glue, or polymers, etc., or can be a temperature - controlled or electrically - controlled material with variable refractive index.

[0046] The distance d between the first metal reflection layer 10 and the second metal reflection layer 20 can be calculated according to the formula: nd = m * λ / 2, where m is a positive integer 1, 2, 3... The equivalent refractive index of several layers between the first metal reflection layer 10 and the second metal reflection layer 20, and the calculation method is: n TE =[(1 - f)*n1 2 +f * n2 2 ^(1 / 2), n TM =[(1 - f) / n1 2 +f / n2 2 ^(-1 / 2), where, n TE and n TMrespectively represent the equivalent refractive indices of TE wave and TM wave, n1 is the refractive index of the filling layer 32, n2 is the refractive index of the primitive layer 31, and f is the filling ratio of the primitive 311 in the metasurface layer 30.

[0047] The basic shape of each primitive 311 in the primitive layer 31 can be expanded from a circle, a circular hole, a square, a square hole, a cross to other free shapes. The arrangement of the primitives 311 can be as Figure 5 shown, which can be a square lattice arrangement, a hexagonal lattice arrangement, a polar coordinate arrangement, or any other non-periodic arrangement that can play a role in changing the equivalent refractive index inside the structure, or even various free shapes.

[0048] Furthermore, the structure of the primitive 311 can also be other structures. For example, as Figure 6 shown, each primitive 311 is composed of multiple materials. In the direction from the first metal reflection layer 10 to the second metal reflection layer 20, each material of the primitive 311 is arranged in sequence. That is to say, each primitive 311 is a multi-layer structure to further improve the overall transmittance and increase the multi-spectral coverage range.

[0049] Continuing as Figure 2 shown, the filtering system 100 further includes a buffer layer 40. The buffer layer 40 is disposed between the metasurface layer 30 and the first metal reflection layer 10, and / or the buffer layer 40 is disposed between the metasurface layer 30 and the second metal reflection layer 20. The buffer layer 40 of this embodiment includes a first buffer layer 4140 and a second buffer layer 4240. The first buffer layer 4140 is disposed between the metasurface layer 30 and the first metal reflection layer 10, and the second buffer layer 4240 is disposed between the metasurface layer 30 and the second metal reflection layer 20. The materials of the first buffer layer 4140 and the second buffer layer 4240 can be various materials such as silicon dioxide, silicon nitride, and silicon, which are used to play a supporting and buffering role.

[0050] To achieve one of the above-mentioned utility model purposes, an embodiment of the present utility model provides an imaging system 200. As Figure 2 shown, the imaging system 200 further includes the above-mentioned filtering system 100 and an image sensor layer 50. The first metal reflection layer 10 is located on the light incident side of the filtering system 100, the second metal reflection layer 20 is located on the light exiting side of the filtering system 100, and the image sensor layer 50 is disposed on the side of the filtering system 100 close to the second metal reflection layer 20.

[0051] The image sensor layer 50 can be CMOS (Complementary Metal Oxide Semiconductor). The filtering system 100 of this embodiment can be compatible with the traditional CMOS process. The entire filtering system 100 can be grown on the CMOS surface directly through the film coating and etching process to achieve the multi-spectral imaging effect, meet the imaging requirements of the miniaturized integrated system, and is very easy to achieve mass production and processing.

[0052] Further, continuing as Figure 2 shown, the imaging system 200 further includes a protective layer 60 and a substrate 70. The protective layer 60 is disposed between the image sensor layer 50 and the second metal reflection layer 20, and the substrate 70 is disposed on the side of the image sensor layer 50 away from the filtering system 100. The setting of the protective layer 60 can effectively protect the image sensor from the influence of the external environment. The substrate 70 is disposed on the side of the image sensor away from the filtering system 100, providing a solid support, improving the overall structural stability and seismic resistance of the system. The protective layer 60 and the substrate 70 further improve the durability and stability of the system.

[0053] Embodiment 2

[0054] The difference between this embodiment and Embodiment 1 is that the filtering system 100 further includes multiple groups of broadband filtering partitions 120 in addition to the narrowband filtering partitions 110. As Figure 6 shown in this embodiment, each group of broadband filtering partitions 120 corresponds to a different broadband wavelength band. Each group of broadband filtering partitions 120 corresponds to a group of the first metal reflection layer 10 and the second metal reflection layer 20. The distances between the first metal reflection layer 10 and the second metal reflection layer 20 of different broadband filtering partitions 120 are different. The parameters of the first metal reflection layer 10, the second metal reflection layer 20, and the multiple elementary units 311 are determined according to the broadband wavelength band corresponding to each group of broadband filtering partitions 120.

[0055] Because when the distance between the first metal reflection layer 10 and the second metal reflection layer 20 is fixed, the adjustable range of the central wavelength is relatively limited. To obtain a wider wavelength adjustment range, this embodiment sets several groups of different broadband filtering partitions 120, corresponding to different wavelength bands respectively, such as 400 - 600nm, 600 - 800nm, and 800 - 1000nm respectively. The distances between the first metal reflection layer 10 and the second metal reflection layer 20 corresponding to each group of broadband filtering partitions 120 are different. Within the same broadband filtering partition 120, the first metal reflection layer 10 and the second metal reflection layer 20 of the monolithic continuous structure can still correspond to the multiple elementary units 311, and within one broadband filtering partition 120, there can be multiple groups of narrowband filtering partitions 110.

[0056] Therefore, through different broadband filtering partitions 120, a wider band selection can be achieved, improving the flexibility and applicability of the filtering system 100, optimizing the filtering performance and optical control ability of the system, enabling it to better adapt to various filtering requirements, and further enabling the imaging system 200 to operate efficiently within a wider spectral range.

[0057] Continuing as Figure 6 shown, one of the first metal reflection layer 10 and the second metal reflection layer 20 in this embodiment is shared by multiple groups of broadband filtering partitions 120, and the other of the first metal reflection layer 10 and the second metal reflection layer 20 includes multiple sub-reflection layers of different heights, and each group of broadband filtering partitions 120 corresponds to its respective sub-reflection layer.

[0058] By sharing one of the first metal reflection layer 10 and the second metal reflection layer 20 by multiple broadband filtering partitions 120, the structural design of the filtering system 100 is simplified, the manufacturing efficiency is improved, the required materials and manufacturing steps are reduced, and the stability and consistency of the system are improved.

[0059] Embodiment 3

[0060] This embodiment and Embodiment 2 both include multiple groups of broadband filtering partitions 120. The difference from Embodiment 2 is that, as Figure 7 shown, both the first metal reflection layer 10 and the second metal reflection layer 20 are provided as multiple sheets, and each group of broadband filtering partitions 120 respectively corresponds to one first metal reflection layer 10 and one second metal reflection layer 20.

[0061] In this way, different broadband filtering partitions 120 can be flexibly adjusted according to the needs of the partition, further refining the filtering effect, enabling each broadband filtering partition 120 to be optimized according to its specific requirements, and improving the filtering accuracy and optical performance of the imaging system 200.

[0062] Embodiment 4

[0063] The difference between this embodiment and Embodiment 1 is that in addition to including the structure in Embodiment 1, an anti-reflection layer 80 is further provided above the first metal reflection layer 10, that is, on the side where the incident light enters, as Figure 8 shown, the anti-reflection layer 80 can be one of a band-pass, high-pass, or low-pass filter, or a superposition of multiple ones. On the one hand, the anti-reflection layer 80 can increase the transmittance of the incident light and eliminate stray light. On the other hand, it can protect the first metal reflection layer 10 and prevent the first metal reflection layer 10 from being oxidized by contact with the air above, especially when the first metal reflection layer 10 is provided as a silver film, it can more effectively prevent the formation of an oxide layer on the surface of silver.

[0064] In addition, the first metal reflection layer 10 is in contact with the first buffer layer 4140 below, the second metal reflection layer 20 is in contact with the second buffer layer 4240 above, and the second metal reflection layer 20 is in contact with the protective layer 60 below, so that the surface of no metal reflection layer is in contact with air and oxidized, thereby ensuring a high light transmittance.

[0065] Compared with the prior art, the present embodiment has the following beneficial effects:

[0066] The filtering system 100 combines the metasurface layer 30 with two metal reflection layers to achieve a filtering effect. On the one hand, by utilizing the excellent stray light suppression effect of the metal reflection layer, its optical performance is more uniform and stable, so that the filtering system 100 improves the signal-to-noise ratio; on the other hand, by utilizing the structure of multiple elementary units 311 of the subwavelength structure of the metasurface layer 30, the filtering wavelength is finely adjusted to allow light of a specific frequency to pass through, obtaining a very precise spectral channel; on the third hand, by covering the multiple elementary units 311 with a single metal reflection layer, while simplifying the structure and manufacturing process, the processing error between layers in the system can be reduced, and the reliability of the filtering system 100 is improved.

[0067] It should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0068] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A filtering system, characterized in that, It includes a first metal reflection layer, a second metal reflection layer and a metasurface layer. Both the first metal reflection layer and the second metal reflection layer are set as sub-wavelength thin film structures. The metasurface layer is disposed between the first metal reflection layer and the second metal reflection layer. The metasurface layer includes an element layer, and the element layer includes a plurality of elements with sub-wavelength structures. The sizes and arrangement manners of the plurality of elements are determined according to the target waveband. Both the first metal reflection layer and the second metal reflection layer are set as single-piece continuous structures and cover the plurality of elements.

2. The filtering system according to claim 1, wherein The filtering system includes multiple groups of narrowband filtering partitions. Each group of narrowband filtering partitions corresponds to a different narrowband waveband, and the parameters of the plurality of elements in each narrowband filtering partition are determined according to the narrowband waveband corresponding to each group of narrowband filtering partitions.

3. The filtering system according to claim 1 or 2, characterized in that, The filtering system includes multiple groups of broadband filtering partitions. Each group of broadband filtering partitions corresponds to a different broadband waveband. Each group of broadband filtering partitions corresponds to a group of the first metal reflection layer and the second metal reflection layer. The distances between the first metal reflection layer and the second metal reflection layer in different broadband filtering partitions are different. The parameters of the first metal reflection layer, the second metal reflection layer and the plurality of elements in each broadband filtering partition are determined according to the broadband waveband corresponding to each group of broadband filtering partitions.

4. The filtering system according to claim 3, characterized in that, One of the first metal reflection layer and the second metal reflection layer is shared by the multiple groups of broadband filtering partitions, and the other of the first metal reflection layer and the second metal reflection layer includes multiple sub-reflection layers with different heights. Each group of broadband filtering partitions corresponds to its respective sub-reflection layer.

5. The filtering system according to claim 3, wherein Both the first metal reflection layer and the second metal reflection layer are set as multiple pieces. Each group of broadband filtering partitions respectively corresponds to one of the first metal reflection layer and one of the second metal reflection layer.

6. The filtering system according to claim 1, wherein The metasurface layer further includes a filling layer, and the filling layer at least partially fills between the plurality of elements.

7. The filtering system according to claim 6, wherein The filtering system further includes a buffer layer, and the buffer layer is disposed between the metasurface layer and the first metal reflection layer. and / or The buffer layer is disposed between the metasurface layer and the second metal reflection layer.

8. The filtering system according to claim 1, wherein Each of the elements is composed of multiple materials, and in the direction from the first metal reflection layer to the second metal reflection layer, each material of the element is arranged in sequence.

9. An imaging system, characterized in that, The imaging system further includes the filtering system according to any one of claims 1 to 8, and an image sensor layer. The first metal reflection layer is located on the light incident side of the filtering system, the second metal reflection layer is located on the light exiting side of the filtering system, and the image sensor layer is disposed on one side of the filtering system close to the second metal reflection layer.

10. The imaging system according to claim 9, wherein The imaging system further includes a protective layer and a substrate. The protective layer is disposed between the image sensor layer and the second metal reflection layer, and the substrate is disposed on one side of the image sensor layer away from the filtering system.

Images