Metasurface-based folded lens system and camera

Abstract

The present invention relates to the technical field of optical devices, and provides a folding lens system and a camera based on a super surface. The folding lens system includes a first substrate layer, a first electrode layer, a liquid crystal super surface integrated layer, and a second electrode layer; the liquid crystal super surface integrated layer includes a resonance type super surface layer and a liquid crystal layer; the incident light is emitted after multiple reflections between the first substrate layer and the resonance type super surface layer; in this process, by applying voltage to the first electrode layer and the second electrode layer, the steering of the liquid crystal molecules around the nano column reflected in the resonance type super surface layer is controlled to match the phase change of 0 to 2π around the resonance peak of the resonance type super surface layer, and the resonance of the nano column reflected in the liquid crystal super surface integrated layer and the surrounding liquid crystal molecules is adjusted to achieve phase regulation. The present invention uses the liquid crystal super surface integrated layer on the optical waveguide to form a folding lens system, which reduces the thickness of the lens; and realizes fine regulation of the phase of the incident light to achieve higher precision requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a folded lens system and a camera based on a metasurface. Background Art

[0002] Ultra-thin cameras are essential in state-of-the-art consumer electronics such as smartphones or augmented / virtual reality devices. However, reducing the thickness of cameras is challenging, mainly due to the thick lens system. The current lens system consists of stacked refractive lenses, which are fundamentally limited in how thin it can be due to the gaps between the lenses and the large volume of each lens. In addition, the structural indicators cannot be changed after manufacturing, which leads to the inherent limitations of traditional optical platforms.

[0003] Liquid crystal control can be used in the lens module to achieve dynamic optical adjustment function, which is achieved by applying voltage to change the arrangement of liquid crystal molecules. The accuracy of electric field control will be affected by the arrangement of the electrode layer. However, the electrode layer in the current liquid crystal control is limited by the manufacturing process and driving circuit, and cannot meet higher-precision liquid crystal control. Summary of the invention

[0004] The present invention provides a folded lens system and a camera based on a metasurface, so as to solve the technical problems in the prior art that the miniaturization of the lens module is difficult and the precision control cannot meet higher requirements.

[0005] The invention provides a folding lens system based on a metasurface, comprising: a first substrate layer; a first electrode layer, arranged on the first substrate layer; a liquid crystal metasurface integrated layer, arranged on the first electrode layer, the liquid crystal metasurface integrated layer comprising a resonance type metasurface layer and a liquid crystal layer; a second electrode layer, arranged on the liquid crystal metasurface integrated layer; wherein the first substrate layer and the first electrode layer are made of light-transmitting material; after incident light is incident on the first substrate layer, it is emitted after being reflected multiple times between the first substrate layer and the resonance type metasurface layer; in the process of multiple reflections, by applying voltage to the first electrode layer and the second electrode layer, the steering of liquid crystal molecules around nanocolumns reflecting in the resonance type metasurface layer is controlled to coordinate the phase change of the resonance type metasurface layer from 0 to 2π around the resonance peak, and the resonance of the nanocolumns reflecting in the liquid crystal metasurface integrated layer and the surrounding liquid crystal molecules is adjusted to achieve phase regulation of the incident light.

[0006] According to a folding lens system based on a metasurface provided by the present invention, the nanocolumns in the resonant metasurface layer are dielectric nanocolumns, which are used to support the resonance of electric dipoles and magnetic dipoles with spectral overlap; the material of the dielectric nanocolumns is at least one of titanium oxide, silicon nitride and silicon carbide; the cross-sectional shape of the dielectric nanocolumns is square, circular or cross-shaped; the resonant metasurface layer includes a plurality of metasurface units for effective reflection; each metasurface unit performs phase adjustment and reflection on light once.

[0007] A metasurface-based folding lens system provided according to the present invention also includes: a second substrate layer, arranged on the second electrode layer.

[0008] According to a metasurface-based folding lens system provided by the present invention, the second substrate layer and the second electrode layer are made of light-transmitting materials; during multiple reflections, the light passes through the first electrode layer, the second electrode layer, the first substrate layer, and the second substrate layer at least once.

[0009] According to a metasurface-based folding lens system provided by the present invention, the liquid crystal metasurface integration layer is configured to be transmissive or reflective.

[0010] According to a folding lens system based on a metasurface provided by the present invention, the resonant metasurface layer includes a first metasurface unit, a second metasurface unit and a third metasurface unit; the first metasurface unit, the second metasurface unit and the third metasurface unit are arranged between the liquid crystal layer and the first electrode layer; after the incident light is incident on the first substrate layer, it passes through the first electrode layer to reach the first metasurface unit; the first metasurface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, the first substrate layer reflects the first reflected light to the second metasurface unit, the second metasurface unit performs a second phase adjustment on the second reflected light and reflects it to the first substrate layer, the first substrate layer reflects the third reflected light to the third metasurface unit; the third metasurface unit performs a third phase adjustment on the fourth reflected light and emits it through the first electrode layer and the first substrate layer.

[0011] According to a metasurface-based folding lens system provided by the present invention, the metasurface unit includes a first metasurface unit, a second metasurface unit and a third metasurface unit; the first metasurface unit and the second metasurface unit are arranged between the liquid crystal layer and the first electrode layer, and the third metasurface unit is arranged between the liquid crystal layer and the second electrode layer.

[0012] According to a metasurface-based folding lens system provided by the present invention, after the incident light is incident on the first substrate layer, it passes through the first electrode layer to reach the first metasurface unit; the first metasurface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, the first substrate layer reflects the light reflected for the first time to the second metasurface unit, the second metasurface unit performs a second phase adjustment on the light reflected for the second time and reflects it to the first substrate layer, the first substrate layer sequentially passes the light reflected for the third time through the first electrode layer, the liquid crystal layer and the second electrode layer and then is incident on the second substrate layer; the second substrate layer reflects the second incident light to the third metasurface unit; the third metasurface unit performs a third phase adjustment on the light reflected for the fourth time and then emits it through the second electrode layer and the second substrate layer.

[0013] According to a folding lens system based on a metasurface provided by the present invention, after an incident light is incident on a first substrate layer, it passes through a first electrode layer to reach a first metasurface unit; the first metasurface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, and the first substrate layer causes the light reflected for the first time to pass through the first electrode layer, the liquid crystal layer, and the second electrode layer in sequence and then be incident on the second substrate layer; the second substrate layer reflects the light incident for the second time to the third metasurface unit; the third metasurface unit performs a third phase adjustment on the light reflected for the second time and reflects it to the second substrate layer; the second substrate layer causes the light reflected for the third time to pass through the second electrode layer, the liquid crystal layer, and the first electrode layer in sequence and then be incident on the first substrate layer; the first substrate layer reflects the light incident for the third time to the second metasurface unit, and the second metasurface unit performs a second phase adjustment on the light reflected for the fourth time and then emits through the first electrode layer and the first substrate layer, or reflects to the first substrate layer.

[0014] The present invention also provides a camera, comprising the above-mentioned metasurface-based folding lens system.

[0015] The present invention provides a folding lens system and a camera based on a metasurface. The folding lens system based on a metasurface comprises: a first substrate layer; a first electrode layer, which is arranged on the first substrate layer; a liquid crystal metasurface integrated layer, which is arranged on the first electrode layer, and the liquid crystal metasurface integrated layer comprises a resonance-type metasurface layer and a liquid crystal layer; a second electrode layer, which is arranged on the liquid crystal metasurface integrated layer; wherein the first substrate layer and the first electrode layer are made of light-transmitting material; after incident light is incident on the first substrate layer, it is emitted after multiple reflections between the first substrate layer and the resonance-type metasurface layer; during the multiple reflections, by applying voltages to the first electrode layer and the second electrode layer, the steering of liquid crystal molecules around nanocolumns reflecting in the resonance-type metasurface layer is controlled to coordinate the phase change of the resonance-type metasurface layer from 0 to 2π around the resonance peak, and the resonance of the nanocolumns reflecting in the liquid crystal metasurface integrated layer and the surrounding liquid crystal molecules is adjusted to achieve phase regulation of the incident light. Through the above method, the present invention utilizes the liquid crystal metasurface integrated layer on the optical waveguide to form a folded lens system, thereby reducing the thickness of the lens; and the liquid crystal metasurface integrated layer includes a resonant metasurface layer and a liquid crystal layer, both of which can achieve resonance control under the control of voltage, thereby achieving fine control of the phase of the incident light to achieve higher precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is one of the structural schematic diagrams of the folding lens system based on the metasurface provided in an embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of the structure of the super surface unit provided in an embodiment of the present invention.

[0019] Figure 3 This is a diagram of the electric field distribution generated by three liquid crystal molecular directions and nanocolumns at the working wavelength provided by an embodiment of the present invention.

[0020] Figure 4 It is a schematic diagram of the amplitude of the transmitted light in the nanocolumn provided by an embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of the phase shift of the transmitted light in the nanocolumn provided by an embodiment of the present invention.

[0022] Figure 6 This is the second structural schematic diagram of the metasurface-based folding lens system provided in an embodiment of the present invention.

[0023] Figure 7 This is the third structural schematic diagram of the metasurface-based folding lens system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0027] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0028] The present invention provides a folded lens system based on a metasurface, which uses a lens system of a metasurface folded optical element to overcome the thickness problem of a camera lens.

[0029] See also Figure 1 , Figure 1 FIG. 1 is one of the structural schematic diagrams of a folding lens system based on a metasurface provided in an embodiment of the present invention. In this embodiment, the folding lens system based on a metasurface may include a first substrate layer 110 , a first electrode layer 120 , a liquid crystal metasurface integration layer 130 , and a second electrode layer 140 .

[0030] Among them, the first electrode layer 120 is arranged on the first substrate layer 110; the liquid crystal supersurface integration layer 130 is arranged on the first electrode layer 120, and the liquid crystal supersurface integration layer 130 includes a resonance type supersurface layer 131 and a liquid crystal layer 132; the second electrode layer 140 is arranged on the liquid crystal supersurface integration layer 130.

[0031] Specifically, the first substrate layer 110 and the first electrode layer 120 are made of light-transmitting materials; the material of the first substrate layer 110 may be glass, and the material of the first electrode layer 120 may be indium tin oxide (ITO), which is a transparent conductive oxide material.

[0032] After the incident light enters the first substrate layer 110, it is emitted after multiple reflections between the first substrate layer 110 and the resonant supersurface layer 131; in the process of multiple reflections, by applying voltage to the first electrode layer 120 and the second electrode layer 140, the steering of the liquid crystal molecules around the nanocolumns reflecting in the resonant supersurface layer 131 is controlled to coordinate the phase change of the resonant supersurface layer 131 from 0 to 2π around the resonance peak, and adjust the resonance of the nanocolumns reflecting in the liquid crystal supersurface integrated layer 130 and the surrounding liquid crystal molecules to achieve phase control of the incident light.

[0033] In this embodiment, the metasurface is horizontally arranged on the first substrate layer 110 and directs light along the multi-folded paths inside the first substrate layer 110, which can provide quasi-diffraction-limited imaging quality and provide technical support for compact cameras using folded nano-optical devices.

[0034] Specifically, the resonant metasurface layer 131 is provided with periodically arranged microscopic structural units, namely nanopillars. The resonant metasurface layer relies on the local resonance effect. The local resonance effect can significantly enhance the interaction between electromagnetic waves and metasurface materials, thereby achieving more precise and efficient manipulation of electromagnetic waves.

[0035] In the resonant metasurface layer 131, each nanocolumn has its specific resonant frequency. The nanocolumn can exhibit a resonance phenomenon at a specific frequency or frequency range through a specific geometric shape, size and material properties. This resonance can be a plasma resonance, a resonant cavity effect, a Fabry-Perot resonance or other types of electromagnetic resonance. By adjusting the geometric parameters (such as size, shape and arrangement) of the resonant nanocolumn, the phase of the light can be adjusted.

[0036] In this embodiment, the liquid crystal layer is applied to the folding lens for phase control, and in order to increase the control accuracy of the liquid crystal molecules, the liquid crystal layer and the resonant metasurface layer are integrated together as a liquid crystal metasurface integrated layer to realize a metasurface folding lens with arbitrary phase regulation. Changing the direction of the liquid crystal molecules around the nanocolumns will change the local environment and resonance of the liquid crystal metasurface integrated layer. In this case, the main phase accumulation occurs inside the nanocolumns rather than in the liquid crystal layer, thereby decoupling the phase control from the liquid crystal layer, and multiple metasurfaces can be precisely regulated at the same time. Under the regulation of various specific phases, functions such as large field of view, achromatism, aberration elimination, and multi-focus can be achieved.

[0037] It should also be noted that due to the limitations of the manufacturing process and the driving circuit, in some applications where the light beam needs to be phase modulated, the accuracy of liquid crystal control is usually in the order of tens of microns (e.g., 20-30 microns), and there are certain limitations in phase control. However, if the liquid crystal metasurface integrated layer provided in this embodiment is used, since the metasurface can achieve nanometer-level phase control, fine control can be achieved between 0 and 2π phase changes around the resonance peak, which makes the phase control more precise.

[0038] Therefore, the working mechanism of the embodiment of the present application is to integrate the liquid crystal layer with the super surface layer to obtain a liquid crystal super surface integrated layer. This integrated structure allows the liquid crystal to work under the influence of the local environment and resonance of the super surface. By applying voltage to the independent electrode layers on both sides, the direction of the liquid crystal molecules can be adjusted. Under the action of voltage, the liquid crystal molecules and nanocolumns will resonate, thereby affecting the phase of the light. The liquid crystal super surface integrated layer can achieve fine control of the phase of light between hundreds of nanometers (for example, 100-200 nanometers), which has higher precision and better performance than the related liquid crystal phase modulation.

[0039] In some embodiments, the nanocolumns in the resonant metasurface layer are dielectric nanocolumns, which are used to support spectrally overlapping electric dipole and magnetic dipole resonances; the material of the dielectric nanocolumns is at least one of titanium oxide, silicon nitride and silicon carbide; the cross-sectional shape of the dielectric nanocolumns is square, circular or cross-shaped; the resonant metasurface layer includes multiple metasurface units for effective reflection; each metasurface unit performs phase adjustment and reflection on light once.

[0040] See also Figure 2 , Figure 2 It is a schematic diagram of the structure of the super surface unit provided in an embodiment of the present invention.

[0041] Exemplarily, dielectric nanopillars support spectrally overlapping electric and magnetic dipole resonances, can provide a full range of phase shifts from 0 to 2π around the resonance peak, and suppress backscattering when the induced dipole moments have the same amplitude and phase, resulting in a transmission efficiency close to unity. In order to achieve high efficiency in the visible spectrum, nanopillars made of titanium oxide or silicon nitride, silicon carbide can also be designed, whose absorption is negligible and whose refractive index is high enough to obtain resonance in a liquid crystal environment. Therefore, this embodiment embeds the metasurface layer into the liquid crystal layer and connects it between the two layers of electrodes and the substrate.

[0042] In some embodiments, the metasurface-based folded lens system may further include a second substrate layer 150 , which may be disposed on the second electrode layer 140 .

[0043] Optionally, the second substrate layer 150 and the second electrode layer 140 are made of light-transmitting materials; the material of the second substrate layer 150 may be glass, and the material of the second electrode layer 140 may be indium tin oxide.

[0044] In some embodiments, during the multiple reflections, the light passes through the first electrode layer 120 , the second electrode layer 140 , the first substrate layer 110 , and the second substrate layer 150 at least once.

[0045] In some embodiments, the liquid crystal metasurface integration layer is configured to be transmissive or reflective.

[0046] In the transmissive liquid crystal metasurface integrated layer, light can pass through the liquid crystal layer. The liquid crystal molecules change their arrangement direction according to the applied voltage signal, and cooperate with the resonant metasurface layer to control the transmittance and phase of light.

[0047] See also Figure 3 , Figure 3 This is a diagram of the electric field distribution generated by three liquid crystal molecular directions and nanocolumns at the working wavelength provided by an embodiment of the present invention.

[0048] Where E represents the total electric field, Ex represents the electric field in the x direction, and k represents the magnetic field. The first substrate layer and the second substrate layer are glass, and liquid crystal molecules (LC) are filled between the first substrate layer and the second substrate layer. At the working wavelength (for example, 665nm), it can be seen that the wavefront of the incident plane wave during propagation in the LC layer remains almost similar, indicating that the accumulated phase difference is very small. In contrast, when interacting with the nanopillars, the wavefront of the transmitted light undergoes significantly different phase delays, forming three adjacent phases. Therefore, the light transmitted through a system composed of such periodic repetitions of units will be deflected in a direction perpendicular to the tilted wavefront, as shown by the dotted line.

[0049] The incident light is usually incident into the optical waveguide, and mainly relies on the optical waveguide to transmit forward, and the metasurface and liquid crystal layer realize phase control. For example, the period of the nanocolumn is 200-500nm, so the unit cell is sub-diffraction, and the height of the nanocolumn is 100nm-500nm. This embodiment can be realized in high transmittance, 2π phase coverage, and a wide wavelength range of 650nm to 675nm.

[0050] For example, this embodiment also provides a simulation experiment of a nanorod with a height of 215 nm. Figure 4-Figure 5 , Figure 4 is a schematic diagram of the amplitude of the transmitted light in the nanocolumn provided by an embodiment of the present invention, Figure 5 It is a schematic diagram of the phase shift of the transmitted light in the nanocolumn provided by an embodiment of the present invention.

[0051] In the reflective liquid crystal metasurface integrated layer, a reflective layer is also provided. For example, a scattering reflector can be provided behind the liquid crystal layer (internal reflective type) or a reflector can be provided outside (external reflective type). The reflector is used to reflect the light, and then the phase of the light is changed through the modulation of the liquid crystal molecules and the resonant metasurface layer.

[0052] In some embodiments, a metasurface-based folded lens system may include n reflective metasurface units.

[0053] set up Indicates the first i reflective metasurface units in the band The equivalent focal length under represents the distance between the i-th and i+1-th reflective metasurface units, the recursive formula is:

[0054] ;

[0055] Initial , is the focal length of the first reflective metasurface unit. By continuously iterating the above formula, we can finally get the focal length of n reflective metasurface units in the band Equivalent focal length .

[0056] In some embodiments, a phase formula that accounts for the reflection phase variation may be used.

[0057] The generalized Snell's law in different media can be expressed as:

[0058] ;

[0059] in, is the refractive index of the incident medium, is the refractive index of the medium where the reflective metasurface unit is located, is the angle of incidence, is the reflection angle, is the wavelength of light in a vacuum, is the phase distribution of the reflective metasurface unit, are the coordinates along the reflective metasurface unit.

[0060] After integration, the phase formula can be obtained: :

[0061] ;

[0062] Where C is the integration constant.

[0063] When light is incident from one medium to another and is reflected, an additional reflection phase is introduced. The phase generated by the metasurface unit itself Reflection Phase The sum is:

[0064] .

[0065] Among them, for s-polarized light (the electric field vector is perpendicular to the incident plane), we have:

[0066] .

[0067] Among them, for p-polarized light (the electric field vector is parallel to the incident plane), we have:

[0068] .

[0069] In some embodiments, the resonant metasurface layer includes a first metasurface unit, a second metasurface unit, and a third metasurface unit.

[0070] Please continue reading Figure 1 The first supersurface unit, the second supersurface unit and the third supersurface unit are arranged between the liquid crystal layer 132 and the first electrode layer 120; after the incident light enters the first substrate layer 110, it passes through the first electrode layer 120 and reaches the first supersurface unit.

[0071] The first super-surface unit performs a first phase adjustment on the light and reflects it to the first substrate layer 110. The first substrate layer 110 reflects the light reflected for the first time to the second super-surface unit. The second super-surface unit performs a second phase adjustment on the light reflected for the second time and reflects it to the first substrate layer 110. The first substrate layer 110 reflects the light reflected for the third time to the third super-surface unit. The third super-surface unit performs a third phase adjustment on the light reflected for the fourth time and then emits it through the first electrode layer 120 and the first substrate layer 110.

[0072] It is understandable that other optical devices or coatings may be provided in the first substrate layer and the second substrate layer to assist in transmission, reflection and other processing, such as a reflective film, an anti-reflection film, etc., which will not be elaborated herein.

[0073] In some embodiments, the first supersurface unit and the second supersurface unit may be disposed between the liquid crystal layer and the first electrode layer, and the third supersurface unit may be disposed between the liquid crystal layer and the second electrode layer.

[0074] See also Figure 6 , Figure 6 This is the second structural schematic diagram of the metasurface-based folding lens system provided in an embodiment of the present invention.

[0075] After the incident light enters the first substrate layer 110, it passes through the first electrode layer 120 to reach the first super-surface unit; the first super-surface unit performs a first phase adjustment on the light and reflects it to the first substrate layer 110, the first substrate layer 110 reflects the light reflected for the first time to the second super-surface unit, the second super-surface unit performs a second phase adjustment on the light reflected for the second time and reflects it to the first substrate layer 110, the first substrate layer 110 reflects the light reflected for the third time through the first electrode layer 120, the liquid crystal layer 132 and the second electrode layer 140 in sequence and then enters the second substrate layer 150; the second substrate layer 150 reflects the second incident light to the third super-surface unit; the third super-surface unit performs a third phase adjustment on the light reflected for the fourth time and then emits it through the second electrode layer 140 and the second substrate layer 150.

[0076] It should be noted that other reflection or incident processing may be inserted into the above-mentioned optical path propagation, and those skilled in the art may make specific settings according to actual conditions, which will not be elaborated herein.

[0077] See also Figure 7 , Figure 7 This is the third structural schematic diagram of the metasurface-based folding lens system provided in an embodiment of the present invention.

[0078] After the incident light enters the first substrate layer 110, it passes through the first electrode layer 120 to reach the first metasurface unit; the first metasurface unit performs a first phase adjustment on the light and reflects it to the first substrate layer 110, and the first substrate layer 110 makes the light reflected for the first time pass through the first electrode layer 120, the liquid crystal layer 132 and the second electrode layer 140 in sequence and then enter the second substrate layer 150; the second substrate layer 150 reflects the light reflected for the second time to the third metasurface unit; the third metasurface unit performs a third phase adjustment on the light reflected for the second time and reflects it to the second substrate layer 150; the second substrate layer 150 makes the light reflected for the third time pass through the second electrode layer 140, the liquid crystal layer 132 and the first electrode layer 120 in sequence and then enter the first substrate layer 110; the first substrate layer 110 reflects the light reflected for the third time to the second metasurface unit, and the second metasurface unit performs a second phase adjustment on the light reflected for the fourth time, and then it exits through the first electrode layer 120 and the first substrate layer 110, or is reflected to the first substrate layer 110. Figure 7 As shown, the second metasurface unit performs a second phase adjustment on the fourth reflected light, reflects it to the first substrate layer 110, and then emits it from the first substrate layer 110 after passing through the first electrode layer 120, the liquid crystal layer 132, the second electrode layer 140 and the second substrate layer 150 in sequence.

[0079] The present invention also provides a camera, comprising the above-mentioned metasurface-based folding lens system.

[0080] In summary, the present invention provides a folding lens system and camera based on a metasurface, and the folding lens system based on a metasurface includes: a first substrate layer; a first electrode layer, arranged on the first substrate layer; a liquid crystal metasurface integrated layer, arranged on the first electrode layer, and the liquid crystal metasurface integrated layer includes a resonant metasurface layer and a liquid crystal layer; a second electrode layer, arranged on the liquid crystal metasurface integrated layer; wherein the first substrate layer and the first electrode layer are made of light-transmitting material; after the incident light is incident on the first substrate layer, it is emitted after multiple reflections between the first substrate layer and the resonant metasurface layer; in the process of multiple reflections, by applying voltage to the first electrode layer and the second electrode layer, the steering of the liquid crystal molecules around the nanocolumns reflecting in the resonant metasurface layer is controlled to coordinate the phase change of the resonant metasurface layer from 0 to 2π around the resonance peak, and the resonance of the nanocolumns reflecting in the liquid crystal metasurface integrated layer and the surrounding liquid crystal molecules is adjusted to achieve phase regulation of the incident light. Through the above method, the present invention utilizes the liquid crystal metasurface integrated layer on the optical waveguide to form a folded lens system, thereby reducing the thickness of the lens; and the liquid crystal metasurface integrated layer includes a resonant metasurface layer and a liquid crystal layer, both of which can achieve resonance control under the control of voltage, thereby achieving fine control of the phase of the incident light to achieve higher precision requirements.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A folded lens system based on a metasurface, characterized in that: include: a first substrate layer; A first electrode layer, disposed on the first substrate layer; A liquid crystal supersurface integrated layer, arranged on the first electrode layer, wherein the liquid crystal supersurface integrated layer comprises a resonance type supersurface layer and a liquid crystal layer; A second electrode layer is arranged on the liquid crystal supersurface integrated layer; Among them, the first substrate layer and the first electrode layer are made of light-transmitting materials; after the incident light enters the first substrate layer, it is emitted after multiple reflections between the first substrate layer and the resonant supersurface layer; in the process of multiple reflections, by applying voltage to the first electrode layer and the second electrode layer, the turning of the liquid crystal molecules around the nanocolumns reflecting in the resonant supersurface layer is controlled to cooperate with the phase change of the resonant supersurface layer from 0 to 2π around the resonance peak, and the resonance of the nanocolumns reflecting in the liquid crystal supersurface integrated layer and the surrounding liquid crystal molecules is adjusted to achieve phase regulation of the incident light.

2. The folded lens system based on a metasurface according to claim 1, characterized in that: The nanocolumns in the resonant metasurface layer are dielectric nanocolumns, and the dielectric nanocolumns are used to support the resonance of electric dipoles and magnetic dipoles with spectral overlap; The material of the dielectric nanocolumn is at least one of titanium oxide, silicon nitride and silicon carbide; the cross-sectional shape of the dielectric nanocolumn is square, circular or cross-shaped; The resonant metasurface layer includes a plurality of metasurface units for effective reflection; each metasurface unit performs phase adjustment and reflection on light once.

3. The folded lens system based on a metasurface according to claim 2, characterized in that: Also includes: The second substrate layer is arranged on the second electrode layer.

4. The folded lens system based on a metasurface according to claim 3, characterized in that: The second substrate layer and the second electrode layer are made of light-transmitting materials; during the multiple reflection process, the light passes through the first electrode layer, the second electrode layer, the first substrate layer and the second substrate layer at least once.

5. The folded lens system based on a metasurface according to any one of claims 1 to 4, characterized in that: The liquid crystal supersurface integration layer is configured as a transmission type or a reflection type.

6. The folded lens system based on a metasurface according to claim 2, characterized in that: The resonance type super surface layer includes a first super surface unit, a second super surface unit and a third super surface unit; the first super surface unit, the second super surface unit and the third super surface unit are arranged between the liquid crystal layer and the first electrode layer; After the incident light enters the first substrate layer, it passes through the first electrode layer and reaches the first super-surface unit; the first super-surface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, the first substrate layer reflects the first reflected light to the second super-surface unit, the second super-surface unit performs a second phase adjustment on the second reflected light and reflects it to the first substrate layer, the first substrate layer reflects the third reflected light to the third super-surface unit; the third super-surface unit performs a third phase adjustment on the fourth reflected light and emits it through the first electrode layer and the first substrate layer.

7. The folded lens system based on a metasurface according to claim 4, characterized in that: The super surface unit includes a first super surface unit, a second super surface unit and a third super surface unit; the first super surface unit and the second super surface unit are arranged between the liquid crystal layer and the first electrode layer, and the third super surface unit is arranged between the liquid crystal layer and the second electrode layer.

8. The metasurface-based folded lens system according to claim 7, characterized in that: After the incident light enters the first substrate layer, it passes through the first electrode layer and reaches the first super-surface unit; the first super-surface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, the first substrate layer reflects the light reflected for the first time to the second super-surface unit, the second super-surface unit performs a second phase adjustment on the light reflected for the second time and reflects it to the first substrate layer, and the first substrate layer sequentially passes the light reflected for the third time through the first electrode layer, the liquid crystal layer and the second electrode layer and then enters the second substrate layer; The second substrate layer reflects the second incident light to the third super surface unit; the third super surface unit performs a third phase adjustment on the fourth reflected light and then emits it through the second electrode layer and the second substrate layer.

9. The folded lens system based on a metasurface according to claim 7, characterized in that: After the incident light enters the first substrate layer, it passes through the first electrode layer and reaches the first supersurface unit; the first supersurface unit performs a first phase adjustment on the light and reflects it to the first substrate layer, and the first substrate layer sequentially passes the first reflected light through the first electrode layer, the liquid crystal layer and the second electrode layer and then enters the second substrate layer; The second substrate layer reflects the second incident light to the third metasurface unit; the third metasurface unit performs a third phase adjustment on the second reflected light and reflects it to the second substrate layer; The second substrate layer allows the light reflected for the third time to pass through the second electrode layer, the liquid crystal layer and the first electrode layer in sequence and then enter the first substrate layer; The first substrate layer reflects the third incident light to the second super surface unit, and the second super surface unit performs a second phase adjustment on the fourth reflected light, and then emits it through the first electrode layer and the first substrate layer, or reflects it to the first substrate layer.

10. A camera, characterized in that: Comprising a metasurface-based folded lens system as described in any one of claims 1 to 9.

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