A super surface imaging device

Abstract

The present application provides a metasurface imaging device. The metasurface imaging device includes an aperture, at least one metasurface lens, and an imaging sensor, wherein the aperture is used to limit an incident light beam; at least one metasurface lens is aligned with the aperture and has multiple phase compensation structures to deflect the light beam after being limited by the aperture to perform phase compensation on it; and the imaging sensor converts the light after the phase compensation into an electrical signal proportional to the signal of the light. The phase compensation generated by each of the multiple phase compensation structures changes with the change of the distance from the center of the aperture. The phase compensation of the phase compensation structure provided in the present application can change according to the change of the main light angle, so that the metalens can have a certain field of view angle.

Description

Technical Field

[0001] The present application relates to the field of optical devices, and more specifically, to a metasurface imaging device. Background Art

[0002] The existing lenses used for imaging and transmission in the field of photography are all made of transparent materials such as resin, plastic, and glass. Since such lenses need to introduce optical path difference through gradual changes in thickness to make the light produce focusing or divergence effects, they generally need to be larger in size. In March 2015, Capasso et al. published a paper on metasurfaces in Science magazine, volume 347, issue 6228, which triggered research on metasurface lenses around the world.

[0003] The difference between metasurface lenses and traditional lenses is that metasurface lenses use shape-dependent Pancharatnam-Berry phase differences introduced by micro-nanoscale structures so that the phase of the scattered incident light can be arbitrarily modulated to replace the optical path difference that traditional lenses rely on. Therefore, metasurface lenses can form substantially planar optical devices that are easier to integrate, and their size can be greatly reduced relative to traditional lenses. Since metasurface lenses rely on diffraction optics rather than geometric optics in principle, they can avoid inherent aberrations of traditional lenses such as spherical aberration from a design perspective, but on the contrary, new types of aberrations specific to diffraction optics will be generated.

[0004] The use of metasurface imaging in current existing technologies is limited to paraxial imaging, that is, using a microscope lens to study the imaging of thin rays parallel to the optical axis in the central field of view. In actual application scenarios, the lens must image all incident rays within a certain field of view angle on the sensor at the image plane, and cannot be limited to the paraxial situation. This requires that the design of the application-oriented metasurface lens must take into account the normal imaging of multiple field of view angles. Summary of the invention

[0005] One aspect of the present application provides a metasurface imaging device. The metasurface imaging device may include an aperture, at least one metasurface lens, and an imaging sensor, wherein the aperture is used to limit an incident light beam; at least one metasurface lens is aligned with the aperture and has a plurality of phase compensation structures to deflect the light beam limited by the aperture to perform phase compensation. The imaging sensor converts the light after the phase compensation into an electrical signal proportional to the signal of the light. The phase compensation generated by each of the plurality of phase compensation structures varies with the distance from the center of the aperture.

[0006] In one embodiment, the center of the aperture is aligned with the center of the metasurface lens in the optical axis direction.

[0007] In one embodiment, the phase compensation varies in a decaying periodic manner from the center of the metasurface lens along the radial direction of the metasurface lens.

[0008] In one embodiment, a rotation angle formed by each of the plurality of phase compensation structures located on the metasurface lens relative to any radial direction of the metasurface lens changes with a distance from the center of the metasurface lens.

[0009] In one embodiment, the rotation angle of each of the plurality of phase compensation structures varies in a decaying periodic manner from the center of the metasurface lens along the radial direction of the metasurface lens.

[0010] In one embodiment, the metasurface lens further includes a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

[0011] In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material, and the refractive index of the inorganic dielectric material is different from the refractive index of the material forming the substrate.

[0012] In one embodiment, the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

[0013] In one embodiment, the inorganic dielectric material includes at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, and gallium arsenide.

[0014] In one embodiment, the material forming the transparent substrate is an inorganic material, and the inorganic material includes one of conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, and silicon dioxide.

[0015] In one embodiment, the material forming the transparent substrate is a resin-based organic transparent material.

[0016] In one embodiment, the distance between the metasurface lens and the imaging sensor is smaller than the distance between the metasurface lens and the aperture.

[0017] In one embodiment, the phase compensation structure is formed as a cuboid fin.

[0018] In one embodiment, the phase compensation structure is a rectangular parallelepiped fin with a height of 200-800 nm and a length and width of 30-500 nm.

[0019] In one embodiment, the phase compensation structure is formed as a solid micro-nano structure of a cuboid, a column or a hemisphere.

[0020] In one embodiment, a hollow structure of a cuboid, a column or a hemisphere is further formed on the solid micro-nano structure.

[0021] Another aspect of the present application provides such a metasurface imaging device, which includes: an aperture for limiting an incident light beam; at least one metasurface lens, aligned with the aperture and having a plurality of phase compensation structures, to deflect the light beam after the aperture limitation to perform phase compensation on it; and an imaging sensor, which converts the light after the phase compensation into an electrical signal proportional to the signal of the light. Each of the metasurface lenses includes: a first part, which is located at the center of the metasurface lens and includes a first plurality of phase compensation structures; and a second part, which surrounds the first part and includes a second plurality of phase compensation structures, wherein the light beams that have undergone the phase compensation through the first plurality of phase compensation structures and the second plurality of phase compensation structures are respectively incident on the imaging sensor at non-overlapping first and second constructive interference positions.

[0022] In one embodiment, the center of the aperture is aligned with the center of the metasurface lens in the optical axis direction.

[0023] In one embodiment, in the first portion, the phase shift variations introduced by the first plurality of phase compensation structures in directions approaching and away from the center of the metasurface lens are symmetrical.

[0024] In one embodiment, in the second portion, the phase shift variations introduced by the second plurality of phase compensation structures in directions approaching and away from the center of the metasurface lens are asymmetric.

[0025] In one embodiment, the metasurface lens further includes a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

[0026] In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material, and the refractive index of the inorganic dielectric material is different from the refractive index of the material forming the transparent substrate.

[0027] In one embodiment, the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

[0028] In one embodiment, the inorganic dielectric material includes at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, and gallium arsenide.

[0029] In one embodiment, the material forming the transparent substrate is an inorganic material, and the inorganic material includes one of conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, and silicon dioxide.

[0030] In one embodiment, the material forming the transparent substrate is a resin-based organic transparent material.

[0031] In one embodiment, the distance between the metasurface lens and the imaging sensor is smaller than the distance between the metasurface lens and the aperture.

[0032] In one embodiment, the phase compensation structure is formed as a cuboid fin.

[0033] In one embodiment, the phase compensation structure is formed as a solid micro-nano structure of a cuboid, a column or a hemisphere.

[0034] In one embodiment, a hollow structure of a cuboid, a column or a hemisphere is further formed on the solid micro-nano structure.

[0035] Another aspect of the present application provides a metasurface imaging device, which includes: an aperture for limiting an incident light beam; at least one metasurface lens, aligned with the aperture and having a plurality of phase compensation structures, for deflecting the light beam after the aperture limitation to perform phase compensation thereon; and an imaging sensor, for converting the phase-compensated light into an electrical signal proportional to the signal of the light; wherein the metasurface lens has a plurality of phase compensation structures, and the equivalent focal length of the phase compensation structure gradually increases in a direction away from the center of the metasurface lens.

[0036] In one embodiment, the center of the aperture is aligned with the center of the metasurface lens in the optical axis direction.

[0037] In one embodiment, the phase compensation varies in a decaying periodic manner from the center of the metasurface lens along the radial direction of the metasurface lens.

[0038] In one embodiment, a rotation angle formed by each of the plurality of phase compensation structures located on the metasurface lens relative to any radial direction of the metasurface lens changes with a distance from the center of the metasurface lens.

[0039] In one embodiment, the rotation angle of each of the plurality of phase compensation structures varies in a decaying periodic manner from the center of the metasurface lens along the radial direction of the metasurface lens.

[0040] In one embodiment, the metasurface lens further includes a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

[0041] In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material, and the refractive index of the inorganic dielectric material is different from the refractive index of the material forming the substrate.

[0042] In one embodiment, the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

[0043] In one embodiment, the inorganic dielectric material includes at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, and gallium arsenide.

[0044] In one embodiment, the material forming the transparent substrate is an inorganic material, and the inorganic material includes one of conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, and silicon dioxide.

[0045] In one embodiment, the material forming the transparent substrate is a resin-based organic transparent material.

[0046] In one embodiment, the distance between the metasurface lens and the imaging sensor is smaller than the distance between the metasurface lens and the aperture.

[0047] In one embodiment, the phase compensation structure is formed as a cuboid fin.

[0048] In one embodiment, the phase compensation structure is formed as a solid micro-nano structure of a cuboid, a column or a hemisphere.

[0049] In one embodiment, a hollow structure of a cuboid, a column or a hemisphere is further formed on the solid micro-nano structure.

[0050] Another aspect of the present application provides such a metasurface imaging device, which includes: an aperture for limiting an incident light beam; at least one metasurface lens, aligned with the aperture and having a plurality of phase compensation structures, to deflect the light beam after the aperture limitation to perform phase compensation; and an imaging sensor, which converts the light after the phase compensation into an electrical signal proportional to the signal of the light; wherein the metasurface lens has a plurality of phase compensation regions, each phase compensation region includes a plurality of phase compensation structures, and the phase shift variation introduced by the phase compensation structure of at least one of the plurality of phase compensation regions in the direction close to and away from the center of the metasurface lens is asymmetric. In one embodiment, the center of the aperture is aligned with the center of the metasurface lens in the direction of the optical axis.

[0051] In one embodiment, the metasurface lens further includes a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

[0052] In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material, and the refractive index of the inorganic dielectric material is different from the refractive index of the material forming the substrate.

[0053] In one embodiment, the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

[0054] In one embodiment, the inorganic dielectric material includes at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, and gallium arsenide.

[0055] In one embodiment, the material forming the transparent substrate is an inorganic material, and the inorganic material includes one of conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, and silicon dioxide.

[0056] In one embodiment, the material forming the transparent substrate is a resin-based organic transparent material.

[0057] In one embodiment, the distance between the metasurface lens and the imaging sensor is smaller than the distance between the metasurface lens and the aperture.

[0058] In one embodiment, the phase compensation structure is formed as a cuboid fin.

[0059] In one embodiment, the phase compensation structure is a rectangular parallelepiped fin with a height of 200-800 nm and a length and width of 30-500 nm.

[0060] In one embodiment, the phase compensation structure is formed as a solid micro-nano structure of a cuboid, a column or a hemisphere.

[0061] In one embodiment, a hollow structure of a cuboid, a column or a hemisphere is further formed on the solid micro-nano structure.

[0062] The phase compensation of the phase compensation structure in the prior art only changes according to the distance r from the center of the lens. According to the present application, the phase compensation of the phase compensation structure can change according to the change of the main light angle, rather than not compensating for the incident angle of the main light and only meeting the requirements of paraxial imaging, so that the metalens can have a certain field of view, so that it can be matched with a CMOS sensor containing more than one pixel on the image plane in actual use. In addition, the advantage of the present application is that it can save space and be integrated closer to CMOS. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0064] Figure 1 A super-surface imaging device according to an embodiment of the present application is shown;

[0065] Figure 2 A phase compensation structure according to an embodiment of the present application is shown;

[0066] Figure 3 A phase compensation principle diagram of a phase compensation structure according to an embodiment of the present application is shown;

[0067] Figure 4 It shows that the lens according to the embodiment of the present application images the light beam with zero CRA;

[0068] Figure 5 It shows that the lens according to the embodiment of the present application images the light beam with non-zero CRA;

[0069] Figure 6 It is shown that the lens according to the embodiment of the present application is divided into a plurality of concentric areas;

[0070] Figure 7 A graph showing a rotation angle φ of a phase compensation structure fin at a distance Δr relative to a reference position in each region according to an embodiment of the present application;

[0071] Figure 8 A graph showing the change in the rotation angle φ of the cuboid fin according to an embodiment of the present application as a function of the distance r from the center to the edge of the metasurface;

[0072] Fig. 9A graph showing a rotation angle φ of a phase compensation structure fin at a distance Δr relative to a reference position in each region according to another embodiment of the present application;

[0073] Fig.10 A graph showing a change in the rotation angle φ of a rectangular parallelepiped fin according to another embodiment of the present application as a function of the distance r from the center to the edge of the super surface;

[0074] Fig.11 A graph showing a rotation angle φ of a phase compensation structure fin at a distance Δr relative to a reference position in each region according to yet another embodiment of the present application;

[0075] Fig.12 A graph showing the variation of the rotation angle φ of the cuboid fin according to yet another embodiment of the present application with the distance r from the center to the edge of the metasurface.

[0076] Fig.13 A graph showing a rotation angle φ of a phase compensation structure fin at a distance Δr relative to a reference position in each region according to yet another embodiment of the present application;

[0077] Fig.14 A graph showing the variation of the rotation angle φ of the cuboid fin with the distance r from the center to the edge of the super surface according to yet another embodiment of the present application. DETAILED DESCRIPTION

[0078] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0079] It should be noted that in this specification, the expressions of first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first dielectric material discussed below may also be referred to as the second dielectric material.

[0080] In the drawings, the thickness, size and shape of each component may be slightly exaggerated for ease of explanation. Specifically, the shapes of spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of spherical or aspherical surfaces are not limited to the shapes of spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0081] Throughout the specification, when an element such as a layer, a region, or a substrate is described as being “on,” “connected to,” or “coupled to” another element, the element may be directly “on,” “connected to,” or “coupled to” the other element, or one or more other elements may be present between the element and the other element. Conversely, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there may be no other elements between the element and the other element.

[0082] Spatially relative terms such as "above", "higher", "below", and "lower" may be used in this application for descriptive convenience to describe the relationship of one element relative to another element as shown in the accompanying drawings. In addition to covering the orientations depicted in the accompanying drawings, these spatially relative terms are intended to also cover different orientations of the device in use or operation. For example, if the device in the accompanying drawings is flipped, an element described as being "above" or "higher" relative to another element will be "below" or "lower" relative to the other element. Therefore, depending on the spatial orientation of the device, the term "above" covers both "above" and "below" orientations. The device may also be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatially relative terms used in this application should be interpreted accordingly.

[0083] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or parts, but do not exclude the presence of one or more other features, elements, parts and / or combinations thereof. In addition, when a statement such as "at least one of..." appears after a list of listed features, it modifies all the features in the list, rather than just the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". In addition, the word "exemplary" is intended to refer to an example or illustration.

[0084] As used herein, the words "substantially," "approximately," and similar words are used as words of approximation rather than degrees, and are intended to account for the inherent variations in measurements or calculations that one of ordinary skill in the art would recognize.

[0085] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having the same meaning as they have in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined in this article.

[0086] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments in this application can be combined with each other. In addition, unless explicitly limited or contradictory to the context, the specific steps included in the method recorded in this application are not necessarily limited to the recorded order, but can be performed in any order or in parallel.

[0087] The present application will be described in detail below with reference to the accompanying drawings and in combination with implementation modes.

[0088] Figure 1 FIG. 1 shows a super-surface imaging device 100 according to an embodiment of the present application. Figure 1 , which shows a simplified diagram of imaging an object 110 on an optical axis, wherein the distance and scale in the figure are for illustration only. As shown in the figure, the metasurface imaging device 100 includes an aperture 120, at least one metasurface lens 130, and a sensor 140, wherein the aperture 120, at least one metasurface lens 130, and the sensor 140 are sequentially arranged along the optical axis of the metasurface imaging device 100.

[0089] The aperture 120 limits the light beam, that is, it limits the light incident to the imaging device 100 to constrain the size of the incident light beam. The center O1 of the aperture 120 is roughly aligned with the center O2 of the metasurface lens 130 in the optical axis direction. At least one metasurface lens 130 is aligned with the aperture 120 and has a plurality of phase compensation structures 220 (see Figure 2 and Figure 3 ) to deflect the light beam after being limited by the aperture 120, so as to perform phase compensation on the light beam. The phase compensation generated by each of the multiple phase compensation structures 220 changes as its distance from the center of the aperture 120 changes. The imaging sensor 140 receives the light and converts the light signal into an electrical signal that is proportional to the light signal, that is, converts the light after phase compensation into an electrical signal that is proportional to the signal of the light from the object.

[0090] In an exemplary embodiment, each metasurface lens 130 may include: a first portion located in a central area of ​​the metasurface lens, the first portion including a first plurality of phase compensation structures; and a second portion surrounding the first portion (i.e., a portion between the central area and the edge of the metasurface lens 130), the second portion including a second plurality of phase compensation structures, wherein light beams subjected to phase compensation by the first plurality of phase compensation structures and the second plurality of phase compensation structures are respectively incident on the imaging sensor at non-overlapping first constructive interference positions and second constructive interference positions.

[0091] When the surface of the metasurface lens is divided into a first part and a second part located in the central area, the phase shift changes introduced by the first multiple phase compensation structures in the first part in the directions close to and away from the center of the metasurface lens are symmetrical; the phase shift changes introduced by the second multiple phase compensation structures in the second part in the directions close to and away from the center of the metasurface lens are asymmetric.

[0092] Alternatively, the equivalent focal lengths of the multiple phase compensation structures of the metasurface lens 130 gradually increase in a direction away from the center of the metasurface lens 130 .

[0093] Alternatively, the metasurface lens 130 has a plurality of phase compensation regions, each of which includes a plurality of phase compensation structures, and wherein, in at least one of the plurality of phase compensation regions, the phase shift variation introduced by the phase compensation structure in directions approaching and away from the center of the metasurface lens is asymmetric.

[0094] Since the angles formed by the light rays emitted from different positions on the object 110 and the optical axis defined by O1-O2 when passing through the aperture 120 are different, for the convenience of explanation, the angle formed by the light rays passing through the center O1 of the aperture 120 and the optical axis is defined as the chief ray angle CRA in this article. Figure 1 The light rays 121, 122, 123 and light rays 131, 132, 133) shown in the figure will introduce a Pancharatnam-Berry (PB) phase difference related to the shape of the phase compensation structure through the phase compensation structure on the metasurface lens 130, and generate a constructive interference position at a specific position on the sensor 140 to form an image point of the image 150.

[0095] Figure 2 and Figure 3The schematic structures of the phase compensation structure 220 according to the embodiments of the present application are shown respectively. As shown in the figure, the metasurface lens 130 may include a substrate 210 and a plurality of phase compensation structures 220 on the substrate. The phase compensation structure 220 is formed on the transparent substrate 210 by a dielectric material. The material forming the substrate 210 may be an inorganic material such as conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, silicon dioxide, etc., or may be an organic transparent material of a resin type. The dielectric material forming the phase compensation structure 220 may be an inorganic dielectric material, mainly including at least one material of inorganic dielectric materials such as zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, gallium arsenide, etc., but may also include organic materials such as PMMA. The refractive index of the material forming the phase compensation structure 220 is different from the refractive index of the material forming the substrate 210, and the refractive index of the material forming the phase compensation structure 220 is generally required to be higher. The scale of a single phase compensation structure 220 is similar to or smaller than the wavelength of light, and its maximum length or height may be, for example, in the range of 50 nm to 2000 nm, depending on the working band. In the metasurface lens 130, although a plurality of the above-mentioned phase compensation structures 220 are arranged on the transparent substrate 210, since the scale of the phase compensation structure 220 is several orders of magnitude smaller than that of the substrate 210, the metasurface lens 130 can still be considered to be a planar optical device, that is, the metasurface lens 130 is approximately flat.

[0096] According to the embodiment of the present application, the distance between the metasurface lens 130 and the imaging sensor 140 is smaller than the distance between the metasurface lens and the aperture 120, so that space can be saved and the CMOS can be integrated closer.

[0097] The phase compensation structure 220 may be a rectangular parallelepiped fin, such as Figure 2 As shown, the length of each rectangular fin can be defined as L, the width as W, and the height as H. H can be in the range of 200-800nm ​​according to the material type, L can be in the range of 30-500nm according to the material type, and W can be in the range of 30-500nm according to the material type, so as to arrange the phase compensation structure 220 on the metasurface lens 130 as much as possible. It should be understood by those skilled in the art that such a rectangular fin can adjust the phase of the incident circularly polarized light similar to a half-wave plate, so that the incident left-handed or right-handed circularly polarized light rotated by the rotating fin at an angle α is emitted as right-handed or left-handed polarized light rotated by 2α or -2α, respectively, as shown in FIG. Figure 3As shown. Thus, the rotation angles of the cuboid fins are different, and different PB phase differences are introduced at different positions, and the light at the designed focal point of the PB phase difference is constructively interfered to achieve the focusing effect. For example, the distance between the sensor 140 and the metasurface lens 130 can be defined as the focal length f. Under the limited condition of paraxial imaging, the rotation angle α of the phase compensation structure should be designed to meet the following requirements:

[0098]

[0099] Wherein, λ is the wavelength, r is the distance between each cuboid fin and the center of the metasurface lens 130, and k is an integer and can preferably be 0.

[0100] Those skilled in the art will also know that each single phase compensation structure is not limited to a rectangular fin, but may be a solid micro-nano structure such as a rectangular parallelepiped, a cylinder, a hemisphere, or a hollow or partially hollow micro-nano structure having a rectangular parallelepiped, a cylinder, a hemisphere, or a depression or hole thereon to achieve further fine-tuning of the phase, so as to achieve further effects such as eliminating chromatic aberration and polarization sensitivity. It should be particularly noted that the phase compensation structure may be composed of a combination of a plurality of the above-mentioned solid or hollow micro-nano structures of different sizes to form a single phase compensation unit, and a combination of a plurality of phase compensation units may be used to achieve further effects such as eliminating chromatic aberration and polarization sensitivity. In other words, the size, spacing, and rotation angle of the phase compensation structure 220 on the metasurface lens 130 may be different, and are not limited to being consistent with each other. Figures 2 to 3 If such a complex phase compensation structure is used, it is difficult to calculate the size, spacing, rotation angle, etc. of the required phase compensation structure 220 in an analytical form, and it is necessary to use numerical simulation methods such as FDTD (finite difference time domain) and finite element FEM for analysis. Phase compensation is sufficient.

[0101] For wide-band (or multi-wavelength) imaging, λ in the above formula will change. At this time, multiple phase compensation structures 220 of different wavelengths can be simply combined with each other in different spatial positions, for example, multiple phase compensation structures 220 representing wavelengths can be used as a group to make the focusing effects of different wavelengths have a certain balance, or multiple phase compensation structures representing wavelengths can be formed into different spatial parts of the metasurface lens. It is also possible to further add a chromatic aberration compensation structure in which the introduced phase shift varies with the wavelength on the basis of the phase compensation structure designed according to a certain participating wavelength, such as according to the resonance mode inside the nanostructure such as the fin structure or the combined resonance mode between the nanostructures so that the provided phase shift varies with the wavelength. Since it is difficult to calculate in analytical form which nanostructure or combination can provide such a phase shift that varies with the wavelength, the prior art generally selects the structure that can provide the most suitable phase shift curve after exhausting multiple possible structures by computer simulation.

[0102] In actual situations, since pixels at all positions on the sensor 140 can be used for imaging, rather than just a small area near the optical axis, it is required that different incident light rays are imaged at different positions on the plane where the sensor 140 is located, and cannot be limited to the special case of paraxial incidence in the above analysis. Figure 1 As shown in FIG. 1 , the CRA of the light beams 121, 122, and 123 shown by the dotted lines is 0, which is consistent with the above-mentioned paraxial imaging situation. However, the CRA of the light beams 131, 132, and 133 shown by the solid lines is not zero, and the imaging position required for the light beams with the CRA is also different from the imaging position of the paraxial light beams 121, 122, and 123. In this case, the phase compensation that needs to be satisfied will also change. Figure 5 As shown in the figure, since the lens in most cases needs to image the external scene at a distance much greater than the focal length, the incident thin beam can be regarded as parallel light, and the required phase compensation becomes:

[0103]

[0104] in,

[0105] Where λ is the wavelength,

[0106] f is the distance between the sensor 140 and the metasurface lens 130 (i.e., focal length),

[0107] f' is the distance that the principal light travels from the metasurface lens 130 to the sensor 140,

[0108] Δr is the distance between the phase compensation structure and the intersection of the principal light and the metasurface lens 130,

[0109] θ = arccos(f / f').

[0110] It can be seen that the phase compensation is related to both f' and CRA, that is, it will change according to the change of the distance from the center of the aperture 120. The selection of f' can make the metasurface imaging device adaptable to sensors of different sizes. If a fin-shaped phase compensation structure is used, the angle of rotation of the fin should be 1 / 2 of the incident light, where for left-handed incident light, the angle of rotation is For right-hand polarized light, the rotation angle is The negative 1 / 2 of . For different circular polarizations, the rotation direction is opposite. The above formula is equivalent to the paraxial case only when CRA = 0, while the difference in phase compensation required for CRA between 0-90° and the paraxial case will continue to increase.

[0111] In a simplified implementation, the focus point can be located at the position where the extension line of the principal ray intersects the image plane where the sensor is located:

[0112]

[0113] Here, f / cosCRA can be defined as an equivalent focal length, that is, in the radial direction of the metasurface lens 130, the equivalent focal length should gradually increase.

[0114] In order to meet the requirements of the above formula, the metasurface lens 130 can be divided into multiple regions, which may not overlap with each other and are each designed according to a CRA within a certain range. They may also partially overlap with each other so that the response to the CRA changes continuously in the radial direction of the lens.

[0115] like Figure 6 As shown, the metasurface lens 130 can be divided into multiple concentric areas according to CRA, and each area is designed according to the different CRAs in the above formula. The shape of each area is not limited to the above-mentioned ring, but can be divided according to the shape of the metasurface lens 130 itself, such as rectangle, polygon, irregular shape, etc. The metasurface lens 130 can also be divided into multiple grids according to the area in the coordinate system, and different phase compensation structures can be arranged in different grids according to the corresponding CRA and Δr and the above formula. The size or width of each concentric area can be determined according to the actual micromachining capability.

[0116] Example 1

[0117] In one example, assuming that the maximum CRA is 30° and the wavelength is 500 nanometers, a total of 6 concentric annular regions are arranged, and the width of each region (e.g., Figure 6The r1, r2, r3, r4 and r5 in the figure and the aperture radius are all 20 μm, the distance between the aperture and the metasurface lens is 200 μm, and f is 50 μm. Then, the rotation angle φ of the phase compensation structure fin at the distance Δr relative to the corresponding reference position in each area is correspondingly as shown in Tables 1 and Figure 7 shown.

[0118] Specifically, in this example, for the area of ​​CRA=0°, the reference position is the center O2 of the metasurface lens 130; for the area of ​​CRA=5°, the reference position is the junction of the area of ​​CRA=5° and the area of ​​CRA=0°; for the area of ​​CRA=10°, the reference position is the junction of the area of ​​CRA=10° and the area of ​​CRA=5°; for the area of ​​CRA=15°, the reference position is the junction of the area of ​​CRA=15° and the area of ​​CRA=10°; for the area of ​​CRA=20°, the reference position is the junction of the area of ​​CRA=20° and the area of ​​CRA=15°; for the area of ​​CRA=25°, the reference position is the junction of the area of ​​CRA=25° and the area of ​​CRA=20°; for the area of ​​CRA=30°, the reference position is the junction of the area of ​​CRA=30° and the area of ​​CRA=25°.

[0119] Table 1 Rotation angle φ of the phase compensation structure fin relative to the center distance Δr in each region

[0120]

[0121]

[0122] One significant difference is that, for the case of CRA=0°, the change of φ is symmetrical in the positive and negative directions; while for the case of CRA not equal to 0°, at the same distance from the reference position of each area, the change of φ in the positive direction (i.e., in the direction away from the center of the metasurface lens 130) begins to be greater than the change of φ in the negative direction (i.e., in the direction close to the center of the metasurface lens 130), and the difference in the change in the positive and negative directions also tends to increase as the CRA increases.

[0123] If the distance r from the center to the edge of the metasurface is taken as the standard, the corresponding rotation angle of the cuboid fin can be extracted from the above table and listed together as shown in Table 2 and Figure 8 shown.

[0124] Table 2 The variation of the rotation angle φ of the rectangular fin with r

[0125]

[0126]

[0127] Example 2

[0128] In another example, assuming that the maximum CRA is 30°, the wavelength is 700 nanometers, and a total of 6 concentric annular regions are arranged, the width of each region and the aperture radius are both 20 microns, the distance between the aperture and the metasurface lens is 200 microns, and f is 50 microns. Then, the rotation angle φ of the phase compensation structure fin at the distance Δr relative to the corresponding reference position in each region is correspondingly as shown in Tables 3 and Fig. 9 In this embodiment, the reference position is defined similarly to that in the first embodiment.

[0129] Table 3 Rotation angle φ of the phase compensation structure fin relative to the center distance Δr in each region

[0130] Example 1 CRA=0° CRA=5° CRA=10° CRA=15° CRA=20° CRA=25° CRA=30° Δr(μm) φ(°) φ(°) φ(°) φ(°) φ(°) φ(°) φ(°) 10 -254.622 -256.125 -251.784 -241.631 -226.031 -205.692 -181.638 9 -206.625 -207.492 -203.616 -195.06 -182.154 -165.5 -145.943 8 -163.531 -163.936 -160.591 -153.572 -143.17 -129.878 -114.376 7 -125.389 -125.482 -122.705 -117.138 -109.022 -98.7505 -86.8504 6 -92.2405 -92.1498 -89.9521 -85.723 -79.6531 -72.0418 -63.2802 5 -64.1258 -63.9514 -62.317 -59.2858 -54.9994 -49.6722 -43.5778 4 -41.0772 -40.8942 -39.7797 -37.7808 -34.9941 -31.5602 -27.6553 3 -23.1221 -22.9789 -22.3139 -21.1574 -19.5666 -17.6224 -15.4245 2 -10.2816 -10.2001 -9.8879 -9.36001 -8.64316 -7.77403 -6.79694 1 -2.57117 -2.54636 -2.4642 -2.32887 -2.14733 -1.92891 -1.68469 0 0 0 0 0 0 0 0 -1 -2.57117 -2.53753 -2.4474 -2.3057 -2.1199 -1.89958 -1.65576 -2 -10.2816 -10.1296 -9.75365 -9.17479 -8.42388 -7.53954 -6.5656 -3 -23.1221 -22.7412 -21.8614 -20.533 -18.8272 -16.8316 -14.644 -4 -41.0772 -40.3318 -38.7091 -36.3032 -33.2439 -29.6875 -25.8067 -5 -64.1258 -62.8558 -60.2311 -56.406 -51.5871 -46.0193 -39.9702 -6 -92.2405 -90.2626 -86.3583 -80.7595 -73.769 -65.7396 -57.0527 -7 -125.389 -122.497 -117.018 -109.28 -99.7016 -88.7615 -76.9736 -8 -163.531 -159.499 -152.135 -141.884 -129.297 -114.999 -99.6536 -9 -206.625 -201.204 -191.631 -178.483 -162.466 -144.367 -125.015 -10 -254.622 -247.546 -235.426 -218.992 -199.121 -176.782 -152.982

[0131] If the distance r from the center to the edge of the metasurface is taken as the standard, the corresponding rotation angle of the cuboid fin can be extracted from the above table and listed together as shown in Tables 4 and Fig.10 shown.

[0132] Table 4 The variation of the rotation angle φ of the rectangular fin with r

[0133] r(μm) φ(°) r(μm) φ(°) r(μm) φ(°) r(μm) φ(°) 0 0 35 -117.018 70 -117.138 105 0 1 -2.57117 36 -86.3583 71 -153.572 106 -1.92891 2 -10.2816 37 -60.2311 72 -195.06 107 -7.77403 3 -23.1221 38 -38.7091 73 -241.631 108 -17.6224 4 -41.0772 39 -21.8614 74 -199.121 109 -31.5602 5 -64.1258 40 -9.75365 75 -162.466 110 -49.6722 6 -92.2405 41 -2.4474 76 -129.297 111 -72.0418 7 -125.389 42 0 77 -99.7016 112 -98.7505 8 -163.531 43 -2.4642 78 -73.769 113 -129.878 9 -206.625 44 -9.8879 79 -51.5871 114 -165.5 10 -254.622 45 -22.3139 80 -33.2439 115 -205.692 11 -247.546 46 -39.7797 81 -18.8272 116 -152.982 12 -201.204 47 -62.317 82 -8.42388 117 -125.015 13 -159.499 48 -89.9521 83 -2.1199 118 -99.6536 14 -122.497 49 -122.705 84 0 119 -76.9736 15 -90.2626 50 -160.591 85 -2.14733 120 -57.0527 16 -62.8558 51 -203.616 86 -8.64316 121 -39.9702 17 -40.3318 52 -251.784 87 -19.5666 122 -25.8067 18 -22.7412 53 -218.992 88 -34.9941 123 -14.644 19 -10.1296 54 -178.483 89 -54.9994 124 -6.5656 20 -2.53753 55 -141.884 90 -79.6531 125 -1.65576 21 0 56 -109.28 91 -109.022 126 0 22 -2.54636 57 -80.7595 92 -143.17 127 -1.68469 23 -10.2001 58 -56.406 93 -182.154 128 -6.79694 24 -22.9789 59 -36.3032 94 -226.031 129 -15.4245 25 -40.8942 60 -20.533 95 -176.782 130 -27.6553 26 -63.9514 61 -9.17479 96 -144.367 131 -43.5778 27 -92.1498 62 -2.3057 97 -114.999 132 -63.2802 28 -125.482 63 0 98 -88.7615 133 -86.8504 29 -163.936 64 -2.32887 99 -65.7396 134 -114.376 30 -207.492 65 -9.36001 100 -46.0193 135 -145.943 31 -256.125 66 -21.1574 101 -29.6875 136 -181.638 32 -235.426 67 -37.7808 102 -16.8316 33 -191.631 68 -59.2858 103 -7.53954 34 -152.135 69 -85.723 104 -1.89958

[0134] Example 3

[0135] In another example, assuming that the maximum CRA is 30°, the wavelength is 500 nanometers, 6 concentric annular areas are arranged, the width of each area and the aperture radius are 20 microns, the distance between the aperture and the metasurface lens is 200 microns, and f is 60 microns. Then, the rotation angle φ of the phase compensation structure fin at the distance Δr relative to the corresponding reference position in each area is correspondingly as shown in Tables 5 and Fig.11 In this embodiment, the reference position is defined similarly to that in the first embodiment.

[0136] Table 5 Rotation angle φ of the phase compensation structure fin relative to the center distance Δr in each region

[0137]

[0138]

[0139] If the distance r from the center to the edge of the metasurface is taken as the standard, the required rotation angle of the cuboid fin can be extracted from the above table and listed together as shown in Tables 6 and Fig.12 shown.

[0140] Table 6 The variation of the rotation angle φ of the rectangular fin with r

[0141]

[0142]

[0143] Example 4

[0144] In another example, assuming that the maximum CRA is 36°, the wavelength is 500 nanometers, and a total of 6 concentric annular regions are arranged, the width of each region and the aperture radius are both 20 microns, the distance between the aperture and the metasurface lens is 200 microns, and f is 50 microns. Then, the rotation angle φ of the phase compensation structure fin at the distance Δr relative to the corresponding reference position in each region should be as shown in Tables 7 and Fig.13 In this embodiment, the reference position is defined similarly to that in the first embodiment.

[0145] Table 7 Rotation angle φ of the phase compensation structure fin relative to the center distance Δr in each region

[0146] Example 1 CRA=0° CRA=6° CRA=12° CRA=18° CRA=24° CRA=30° CRA=36° Δr(μm) φ(°) φ(°) φ(°) φ(°) φ(°) φ(°) φ(°) 10 -356.47 -358.019 -347.77 -326.042 -294.132 -254.294 -209.567 9 -289.276 -289.937 -281.04 -262.928 -236.731 -204.321 -168.163 8 -228.944 -228.994 -221.498 -206.793 -185.832 -160.126 -131.624 7 -175.544 -175.219 -169.125 -157.574 -141.335 -121.591 -99.8272 6 -129.137 -128.629 -123.895 -115.199 -103.138 -88.5923 -72.6514 5 -89.7761 -89.2367 -85.7723 -79.5933 -71.1319 -61.0089 -49.9761 4 -57.5081 -57.0431 -54.7147 -50.6733 -45.207 -38.7174 -31.6824 3 -32.3709 -32.0419 -30.6707 -28.3504 -25.2489 -21.5942 -17.6527 2 -14.3942 -14.2182 -13.5819 -12.5306 -11.1412 -9.51571 -7.77139 1 -3.59964 -3.54819 -3.38256 -3.11491 -2.76504 -2.35856 -1.92445 0 0 0 0 0 0 0 0 -1 -3.59964 -3.53347 -3.35516 -3.07851 -2.72425 -2.31806 -1.88819 -2 -14.3942 -14.1005 -13.3629 -12.2396 -10.815 -9.19183 -7.48136 -3 -32.3709 -31.6454 -29.9324 -27.3693 -24.149 -20.5017 -16.6741 -4 -57.5081 -56.105 -52.9678 -48.3512 -42.6026 -36.1293 -29.3633 -5 -89.7761 -87.4093 -82.3684 -75.0665 -66.0522 -55.9583 -45.4482 -6 -129.137 -125.481 -118.029 -107.395 -94.3747 -79.8738 -64.8304 -7 -175.544 -170.239 -159.841 -145.214 -127.448 -107.763 -87.4141 -8 -228.944 -221.592 -207.693 -188.402 -165.15 -139.515 -113.106 -9 -289.276 -279.448 -261.469 -236.835 -207.36 -175.021 -141.814 -10 -356.47 -343.706 -321.052 -290.39 -253.959 -214.175 -173.451

[0147] If the distance r from the center to the edge of the metasurface is taken as the standard, the required rotation angle of the cuboid fin can be extracted from the above table and listed together as shown in Table 8 and Fig.14 shown.

[0148] Table 8 The variation of the rotation angle φ of the rectangular fin with r

[0149] r(μm) φ(°) r(μm) φ(°) r(μm) φ(°) r(μm) φ(°) 0 0 35 -159.841 70 -157.574 105 0 1 -3.59964 36 -118.029 71 -206.793 106 -2.35856 2 -14.3942 37 -82.3684 72 -262.928 107 -9.51571 3 -32.3709 38 -52.9678 73 -326.042 108 -21.5942 4 -57.5081 39 -29.9324 74 -253.959 109 -38.7174 5 -89.7761 40 -13.3629 75 -207.36 110 -61.0089 6 -129.137 41 -3.35516 76 -165.15 111 -88.5923 7 -175.544 42 0 77 -127.448 112 -121.591 8 -228.944 43 -3.38256 78 -94.3747 113 -160.126 9 -289.276 44 -13.5819 79 -66.0522 114 -204.321 10 -356.47 45 -30.6707 80 -42.6026 115 -254.294 11 -343.706 46 -54.7147 81 -24.149 116 -173.451 12 -279.448 47 -85.7723 82 -10.815 117 -141.814 13 -221.592 48 -123.895 83 -2.72425 118 -113.106 14 -170.239 49 -169.125 84 0 119 -87.4141 15 -125.481 50 -221.498 85 -2.76504 120 -64.8304 16 -87.4093 51 -281.04 86 -11.1412 121 -45.4482 17 -56.105 52 -347.77 87 -25.2489 122 -29.3633 18 -31.6454 53 -290.39 88 -45.207 123 -16.6741 19 -14.1005 54 -236.835 89 -71.1319 124 -7.48136 20 -3.53347 55 -188.402 90 -103.138 125 -1.88819 21 0 56 -145.214 91 -141.335 126 0 22 -3.54819 57 -107.395 92 -185.832 127 -1.92445 23 -14.2182 58 -75.0665 93 -236.731 128 -7.77139 24 -32.0419 59 -48.3512 94 -294.132 129 -17.6527 25 -57.0431 60 -27.3693 95 -214.175 130 -31.6824 26 -89.2367 61 -12.2396 96 -175.021 131 -49.9761 27 -128.629 62 -3.07851 97 -139.515 132 -72.6514 28 -175.219 63 0 98 -107.763 133 -99.8272 29 -228.994 64 -3.11491 99 -79.8738 134 -131.624 30 -289.937 65 -12.5306 100 -55.9583 135 -168.163 31 -358.019 66 -28.3504 101 -36.1293 136 -209.567 32 -321.052 67 -50.6733 102 -20.5017 33 -261.469 68 -79.5933 103 -9.19183 34 -207.693 69 -115.199 104 -2.31806

[0150] The description of the present application is given for the purpose of illustration and description, and is not intended to be exhaustive or to limit the present application to the disclosed form. Many modifications and variations will be apparent to those skilled in the art. For example, those skilled in the art will be able to use other semiconductor processes to prepare metalenses under the guidance of the present disclosure. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present application, and to enable those skilled in the art to understand the present application and thereby design various embodiments with various modifications suitable for specific purposes.

Claims

1. A metasurface imaging device, characterized in that: The super surface imaging device comprises: Aperture, used to limit the incident light beam; at least one metasurface lens, aligned with the aperture and having a plurality of phase compensation structures, for deflecting the light beam restricted by the aperture to perform phase compensation thereon; and An imaging sensor converts the phase-compensated light into an electrical signal proportional to the light signal; The center of the aperture is aligned with the center of the metasurface lens in the optical axis direction and the phase compensation generated by each of the multiple phase compensation structures changes with the distance from the center of the aperture, and the phase compensation changes in a decaying periodic manner from the center of the metasurface lens along the radial direction of the metasurface lens.

2. The super-surface imaging device according to claim 1, characterized in that: The metasurface lens also includes a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

3. The super-surface imaging device according to claim 2, characterized in that: The dielectric material forming the phase compensation structure is an inorganic dielectric material, and the refractive index of the inorganic dielectric material is different from the refractive index of the material forming the transparent substrate.

4. The super-surface imaging device according to claim 3, characterized in that: The inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

5. The super-surface imaging device according to claim 3, characterized in that: The inorganic dielectric material includes at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, and gallium arsenide.

6. The super-surface imaging device according to claim 3, characterized in that: The material forming the transparent substrate is an inorganic material, and the inorganic material includes one of conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, and silicon dioxide.

7. The super-surface imaging device according to claim 3, characterized in that: The material forming the transparent substrate is a resin-based organic transparent material.

8. The super-surface imaging device according to claim 3, characterized in that: The distance between the metasurface lens and the imaging sensor is smaller than the distance between the metasurface lens and the aperture.

9. The super-surface imaging device according to claim 8, characterized in that: The phase compensation structure is formed as a rectangular parallelepiped fin.

10. The super-surface imaging device according to claim 9, characterized in that: The phase compensation structure is a rectangular parallelepiped fin with a height of 200-800nm ​​and a length and width of 30-500nm.

11. The super-surface imaging device according to claim 8, characterized in that: The phase compensation structure is formed as a solid micro-nano structure of a cuboid, a column or a hemisphere.

12. The super-surface imaging device according to claim 11, characterized in that: A hollow structure of a cuboid, a column or a hemisphere is further formed on the solid micro-nano structure.

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