CN113485009A - Super surface imaging device - Google Patents

Abstract

The present application provides a metasurface imaging device. The metasurface imaging device includes a diaphragm, at least one metasurface mirror and an imaging sensor, wherein the diaphragm is used to limit the incident light beam; at least one metasurface mirror is aligned with the diaphragm and has a plurality of phase compensation structures , so as to deflect the light beam limited by the diaphragm to perform phase compensation; the imaging sensor converts the phase-compensated light into an electrical signal proportional to the signal of the light. The metasurface lens has a plurality of phase compensation structures, and the equivalent focal length of the phase compensation structures gradually increases in a direction away from the center of the metasurface lens. The phase compensation of the phase compensation structure provided by the present application can be changed according to the change of the chief ray angle, so that the superlens can have a certain field of view.

Description

A metasurface imaging device

Divisional Application Statement

This application is a divisional application of the Chinese invention patent application with the invention title "A Metasurface Imaging Device" and the application number 202010331976.2 submitted on April 24, 2020.

technical field

The present application relates to the field of optical devices, and more particularly, to a metasurface imaging device.

Background technique

In the existing imaging field, lenses used for imaging, transmission, etc. are all made of transparent materials such as resin, plastic, and glass. Since such lenses need to introduce optical path difference through the gradual change in thickness, so that the light can be focused or divergent, it generally needs to have a larger size. In March 2015, Capasso et al. published a paper on metasurfaces in Science, Vol. 347, Issue No. 6228, which triggered the worldwide research on metasurface lenses.

The difference between the metasurface lens and the traditional lens is that the metasurface lens adopts the shape-dependent Pancharatnam-Berry phase difference introduced by the micro-nano-scale structure, so that the phase of the scattered incident light can be arbitrarily modulated to replace the traditional lens. The optical path difference on which the lens depends. Thus, metasurface lenses can form substantially planar optics that are easier to integrate and can be greatly reduced in size relative to conventional lenses. Because the metasurface lens relies in principle on diffractive optics rather than geometric optics, the inherent aberrations of conventional lenses such as spherical aberration can be avoided by design, but on the contrary, new types of aberrations specific to diffractive optics will be generated .

The use of metasurface imaging in the current prior art is limited to the case of paraxial imaging, that is, the use of a microscope lens to study the imaging of thin rays parallel to the optical axis in the central field of view. In practical application scenarios, the lens must image all incident light rays within a certain field of view on the sensor at the image surface, and cannot be limited to the paraxial situation. This requires that the design of application-oriented metasurface lenses must be considered. So that multiple field of view angles can be properly imaged.

SUMMARY OF THE INVENTION

An aspect of the present application provides a metasurface imaging device. The metasurface imaging device may include a diaphragm, at least one metasurface mirror and an imaging sensor, wherein the diaphragm is used to confine the incident light beam; at least one metasurface mirror is aligned with the diaphragm and has a plurality of phase compensations The structure is used to deflect the light beam limited by the diaphragm for phase compensation. The imaging sensor converts the phase-compensated light into an electrical signal proportional to the light signal. Wherein, the phase compensation produced by each of the plurality of phase compensation structures varies with the distance from the center of the diaphragm.

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

In one embodiment, the phase compensation varies with a decaying periodicity from the center of the metasurface mirror along the radial direction of the metasurface mirror.

In one embodiment, the rotation angle formed by each of the plurality of phase compensation structures on the metasurface mirror with respect to any radial direction of the metasurface mirror varies with distance from the metasurface mirror changes with the distance from the center.

In one embodiment, the rotation angle of each of the plurality of phase compensation structures exhibits a decaying periodic change from the center of the metasurface mirror along a radial direction of the metasurface mirror.

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

In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from the refractive index of the material forming the substrate.

In one embodiment, the index of refraction of the inorganic dielectric material is greater than the index of refraction of the material forming the transparent substrate.

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

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.

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

In one embodiment, the distance between the metasurface mirror and the imaging sensor is smaller than the distance between the metasurface mirror and the diaphragm.

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

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

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

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

Another aspect of the present application provides such a metasurface imaging device, comprising: a diaphragm for confining an incident light beam; at least one metasurface mirror, aligned with the diaphragm and having a plurality of phase compensations The structure is used for deflecting the light beam limited by the diaphragm to perform phase compensation; and the imaging sensor is used for converting the phase-compensated light into an electrical signal proportional to the signal of the light. Wherein, each of the metasurface lenses includes: a first part, the first part is located in the center of the metasurface lens, and includes a first plurality of phase compensation structures; and a second part, the second part surrounds the first part A part comprising a second plurality of phase compensation structures, wherein the light beams subjected to the 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 the non-overlapping first interferometric constructive position and the second interferometric constructive position.

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

In one embodiment, in the first portion, the phase shift changes introduced by the first plurality of phase compensation structures are symmetrical in directions close to and away from the center of the metasurface mirror.

In one embodiment, in the second portion, the phase shift variation introduced by the second plurality of phase compensation structures is asymmetric in directions near and far from the center of the metasurface mirror.

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

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.

In one embodiment, the index of refraction of the inorganic dielectric material is greater than the index of refraction of the material forming the transparent substrate.

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

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.

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

In one embodiment, the distance between the metasurface mirror and the imaging sensor is smaller than the distance between the metasurface mirror and the diaphragm.

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

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

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

Another aspect of the present application provides such a metasurface imaging device, comprising: a diaphragm for confining an incident light beam; at least one metasurface mirror, aligned with the diaphragm and having a plurality of phase compensations a structure for deflecting the light beam limited by the diaphragm to perform phase compensation; and an imaging sensor for converting the phase-compensated light into an electrical signal proportional to the signal of the light; The metasurface lens has a plurality of phase compensation structures, and the equivalent focal length of the phase compensation structures gradually increases in the direction away from the center of the metasurface lens.

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

In one embodiment, the phase compensation varies with a decaying periodicity from the center of the metasurface mirror along the radial direction of the metasurface mirror.

In one embodiment, the rotation angle formed by each of the plurality of phase compensation structures on the metasurface mirror with respect to any radial direction of the metasurface mirror varies with distance from the metasurface mirror changes with the distance from the center.

In one embodiment, the rotation angle of each of the plurality of phase compensation structures exhibits a decaying periodic change from the center of the metasurface mirror along a radial direction of the metasurface mirror.

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

In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from the refractive index of the material forming the substrate.

In one embodiment, the index of refraction of the inorganic dielectric material is greater than the index of refraction of the material forming the transparent substrate.

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

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.

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

In one embodiment, the distance between the metasurface mirror and the imaging sensor is smaller than the distance between the metasurface mirror and the diaphragm.

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

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

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

Another aspect of the present application provides such a metasurface imaging device, comprising: a diaphragm for confining an incident light beam; at least one metasurface mirror, aligned with the diaphragm and having a plurality of phase compensations a structure for deflecting the light beam limited by the diaphragm to perform phase compensation; 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 regions, each phase compensation region includes a plurality of phase compensation structures, and the phase compensation structure of at least one of the plurality of phase compensation regions is close to and away from the metasurface The phase shift variation introduced in the direction of the center of the lens is asymmetrical. In one embodiment, the center of the aperture is aligned with the center of the metasurface lens in the direction of the optical axis.

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

In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from the refractive index of the material forming the substrate.

In one embodiment, the index of refraction of the inorganic dielectric material is greater than the index of refraction of the material forming the transparent substrate.

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

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.

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

In one embodiment, the distance between the metasurface mirror and the imaging sensor is smaller than the distance between the metasurface mirror and the diaphragm.

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

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

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

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

The phase compensation of the phase compensation structure in the prior art varies only 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 be changed according to the change of the chief ray angle, instead of not compensating the incident angle of the chief ray and only meeting the requirements of paraxial imaging, so that the superlens can have a certain field of view angle, so that it can be matched with CMOS sensors that contain more than one pixel on the image surface in actual use. In addition, an advantage of the present application is that it can be integrated closer to the CMOS in a space-saving manner.

Description of drawings

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:

FIG. 1 shows a metasurface imaging device according to an embodiment of the present application;

FIG. 2 shows a phase compensation structure according to an embodiment of the present application;

Fig. 3 shows the phase compensation principle diagram of the phase compensation structure according to the embodiment of the present application;

Figure 4 shows the imaging of a beam with zero CRA by a lens according to an embodiment of the present application;

FIG. 5 illustrates the imaging of a light beam with a non-zero CRA by a lens according to an embodiment of the present application;

FIG. 6 shows that a lens according to an embodiment of the present application is divided into a plurality of concentric regions;

7 shows a graph of the rotation angle φ of the phase compensation structure fins at a distance Δr from a reference position in each region according to an embodiment of the present application;

FIG. 8 shows a graph of the rotation angle φ of a 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;

9 shows a graph of the rotation angle φ of the phase compensation structure fins at a distance Δr relative to a reference position in each region according to another embodiment of the present application;

FIG. 10 shows a graph of the variation of the rotation angle φ of a cuboid fin according to another embodiment of the present application as a function of the distance r from the center to the edge of the metasurface;

11 shows a graph of the rotation angle φ of the phase compensation structural fins at a distance Δr relative to a reference position in each region according to yet another embodiment of the present application;

FIG. 12 is 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 metasurface according to yet another embodiment of the present application.

13 shows a graph of the rotation angle φ of the phase compensation structure fins at a distance Δr relative to a reference position in each region according to yet another embodiment of the present application;

FIG. 14 is a graph showing the variation of the rotation angle φ of the cuboid fins with the distance r from the center to the edge of the metasurface according to yet another embodiment of the present application.

Detailed ways

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative 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.

It should be noted that in this specification, the expressions first, second, etc. are only used to distinguish one feature from another feature and do not imply any limitation on the feature. Accordingly, the first dielectric material discussed below may also be referred to as a second dielectric material without departing from the teachings of the present application.

In the drawings, the thickness, size and shape of components may be slightly exaggerated for convenience of explanation. In particular, the spherical or aspherical shapes shown in the figures are shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The drawings are examples only and are not drawn strictly to scale.

Throughout the specification, when an element such as a layer, region or substrate is described as being "on", "connected to" or "coupled to" another element, the element can be directly on the other element ", directly "connected to" or "coupled" directly 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 intervening element between the element and the other element. other components.

Spatially relative terms such as "above," "above," "below," and "lower" may be used in this application for descriptive convenience to describe an object as shown in the accompanying drawings. The relationship of one element to another element. In addition to encompassing the orientations depicted in the figures, these spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is turned over, elements described as "above" or "above" another element would then be oriented "below" or relative to the other element The element is "lower". Thus, depending on the spatial orientation of the device, the wording "above" covers both "above" and "below" orientations. The device may also be oriented in other ways (eg, rotated 90 degrees or at other orientations) and the spatially relative terms used in this application should be interpreted accordingly.

It will also be understood that the terms "comprising", "comprising", "having", "comprising" and/or "comprising" when used in this specification mean that the stated features, elements and/or components are present , but does not exclude the presence of one or more other features, elements, components and/or combinations thereof. Furthermore, when an expression such as "at least one of" appears after a list of listed features, it modifies all of the features in the list and not only individual elements of the list. Furthermore, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application." Additionally, the word "exemplary" is intended to refer to an example or illustration.

As used herein, the words "approximately," "approximately," and similar words are used as words of approximation, not of degree, and are intended to describe measurements or values that one of ordinary skill in the art would recognize. Inherent bias in calculated values.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill 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 meanings consistent with their meanings in the context of the related art and not in idealized or overly formalized meanings , unless expressly so limited herein.

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other if there is no conflict. In addition, unless clearly defined or contradicted by the context, the specific steps included in the methods described in the present application are not necessarily limited to the described order, but may be performed in any order or in parallel.

The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

FIG. 1 shows a metasurface imaging device 100 according to an embodiment of the present application. Referring to FIG. 1 , there is shown a simplified diagram of imaging an object 110 on the optical axis, the distances and scales in the diagram are for illustration only. As shown in the figure, the metasurface imaging device 100 includes a diaphragm 120 , at least one metasurface lens 130 and a sensor 140 , wherein the diaphragm 120 , the at least one metasurface lens 130 and the sensor 140 are in sequence along the optical axis of the metasurface imaging device 100 set up.

The diaphragm 120 confines the light beam, that is, restricts the light incident on the imaging device 100, so as to constrain the size of the incident light beam. The center O ₁ of the diaphragm 120 is substantially aligned with the center O ₂ of the metasurface lens 130 in the optical axis direction. At least one metasurface mirror 130 is aligned with the diaphragm 120 and has a plurality of phase compensation structures 220 (see FIG. 2 and FIG. 3 ) to deflect the light beam limited by the diaphragm 120 so as to perform phase compensation on the light beam . The phase compensation produced by each of the plurality of phase compensation structures 220 varies as a function of its distance from the center of the stop 120 . The imaging sensor 140 receives light and converts the light signal into an electrical signal proportional to the light signal, that is, converts the phase-compensated light into an electrical signal proportional to the light signal from the object.

In an exemplary embodiment, each metasurface lens 130 may include: a first portion located in a central region of the metasurface lens, the first portion containing the first plurality of phase compensation structures; and a second portion (ie, an intermediate portion) surrounding the first portion (the portion between the central region and the edge of the metasurface lens 130), the second portion includes a second plurality of phase compensation structures, wherein the first plurality of phase compensation structures and the second plurality of phase compensation structures are described. The phase-compensated light beams are incident on the imaging sensor at non-overlapping first and second interferometric constructive locations, respectively.

In the case of dividing the surface of the metasurface lens into a first portion and a second portion located in the central region, the phase compensating structures introduced by the first plurality of phase compensation structures in the first portion in directions close to and away from the center of the metasurface lens The shift variation is symmetric; the phase shift variation introduced by the second plurality of phase compensation structures of the second portion is asymmetric in directions close to and away from the center of the metasurface mirror.

Alternatively, the equivalent focal lengths of the above-mentioned plurality of phase compensation structures of the meta-surface lens 130 gradually increase in the direction away from the center of the meta-surface lens 130 .

Alternatively, the metasurface lens 130 has a plurality of phase compensation regions, each phase compensation region includes a plurality of phase compensation structures, and wherein, in at least one phase compensation region of the plurality of phase compensation regions, the phase compensation structure is close to the phase compensation region. and the phase shift variation introduced in the direction away from the center of the metasurface mirror is asymmetric.

Since the light rays emitted from different positions on the object 110 pass through the diaphragm 120 at different angles with the optical axis defined by O ₁ -O ₂ , for the convenience of description, the light passing through the center O ₁ of the diaphragm 120 will be used in this paper. The angle formed by the ray and the optical axis is defined as the principal ray angle CRA. A series of rays from object 110 centered at a particular chief ray angle (rays 121, 122, 123 and 131, 132, 133 as shown in FIG. 1) will be introduced into a The Pancharatnam-Berry (PB) phase difference is related to the shape of the phase compensation structure and produces an interfering constructive location at a particular location on the sensor 140 to form the image point of the image 150 .

FIG. 2 and FIG. 3 respectively show schematic structures of the phase compensation structure 220 according to an embodiment of the present application. As shown, the metasurface mirror 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 for forming the substrate 210 may be an inorganic material such as conductive glass ITO, aluminum oxide, zinc oxide, magnesium fluoride, silicon dioxide, or an organic transparent material such as resin. The dielectric material forming the phase compensation structure 220 may be an inorganic dielectric material, mainly including zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, At least one material among inorganic dielectric materials such as gallium arsenide, but may also include organic materials such as PMMA. The refractive index of the material forming the phase compensation structure 220 is different from that of the material forming the substrate 210 , and generally, the material forming the phase compensation structure 220 is required to have a higher refractive index. The dimensions of a single phase compensation structure 220 are 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 operating wavelength. 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 dimensions of the phase compensation structures 220 are several orders of magnitude smaller than the substrate 210, it can still be considered that the metasurface lens 130 is a planar optic, ie, the metasurface mirror 130 is approximately flat.

According to the embodiment of the present application, the distance between the meta-surface mirror 130 and the imaging sensor 140 is smaller than the distance between the meta-surface mirror and the diaphragm 120 , thereby saving space and integrating closer to the CMOS. .

The phase compensation structure 220 can be a cuboid fin. As shown in FIG. 2 , the length of each cuboid fin can be defined as L, the width as W, and the height as H. H may be in the range of 200-800 nm according to the kind of material, L may be in the range of 30-500 nm according to the kind of material, and W may be in the range of 30-500 nm according to the kind of material, so that as much as possible on the metasurface lens 130 A phase compensation structure 220 is arranged. It should be understood by those skilled in the art that such cuboid fins can be similar to a half-wave plate to adjust the phase of the circularly polarized incident light, so that the incident left-handed or right-handed circularly polarized light with the rotation angle α of the rotating fin respectively exits as Right- or left-handed polarized light rotated by 2α or -2α, as shown in Figure 3. As a result, the rotation angles of the cuboid fins are different to introduce different PB phase differences at different positions, and the light rays at the designed focus point with the above PB phase differences can 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, then under the limited condition of paraxial imaging, the design of the rotation angle α of the phase compensation structure should satisfy:

Among them, λ is the wavelength, r is the distance between each cuboid fin and the center of the metasurface mirror 130 , and k is an integer and can preferably be 0.

的相位补偿即可。Those skilled in the art will also know that each single phase compensation structure is not limited to cuboid fins, but can adopt solid micro-nano structures such as cuboid, cylinder, hemisphere, or further have cuboid, cylinder, hemisphere on it. The hollow or partially hollow micro-nano structure of the body is used to achieve further fine-tuning of the phase, so as to achieve further effects such as eliminating chromatic aberration and polarization sensitivity. In particular, it should be noted that the phase compensation structure can be composed of a combination of the above-mentioned solid or hollow micro-nano structures of different sizes to form a single phase compensation unit, and the combination of multiple phase compensation units can be used to eliminate chromatic aberration and polarization sensitivity. wait for further effects. That is, the sizes, spacings and rotation angles of the phase compensation structures 220 on the metasurface mirror 130 may vary, and are not limited to the cases in FIGS. 2 to 3 that are consistent with each other. If such a complex phase compensation structure is used, it is difficult to calculate the required size, spacing and rotation angle of the phase compensation structure 220 in analytical form, and numerical simulation methods such as FDTD (Finite Difference Time Domain), finite element FEM, etc. analysis, just satisfy

phase compensation.

For broadband (or multi-wavelength) imaging situations, λ in the above formula will vary. At this time, a plurality of phase compensation structures 220 with different wavelengths can be simply combined with each other in different spatial positions, for example, a plurality of phase compensation structures 220 representing wavelengths can be used as a group to achieve a certain balance of focusing effects of different wavelengths, or Multiple phase compensation structures representing wavelengths are formed as different spatial parts of the metasurface lens. It is also possible to further add a chromatic aberration compensation structure whose phase shift changes with wavelength on the basis of the phase compensation structure designed according to a certain participating wavelength, such as the resonance mode within the nanostructure such as the fin structure or the combined resonance between the nanostructures. The mode causes the provided phase shift to vary with wavelength. Since it is difficult to analytically calculate which nanostructures or combinations can provide such a wavelength-dependent phase shift, computer simulations are generally used in the prior art to be exhaustive. After selecting the possible structure, the structure that provides the most matching phase shift curve is selected.

In practical situations, since the pixels at various positions on the sensor 140 can be used for imaging, not just a small area near the optical axis for imaging, this requires that different incident light rays are simultaneously imaged at the location of the sensor 140 different positions of the plane, and cannot be limited to the special case of paraxial incidence in the above analysis. As shown in FIG. 1 , the CRAs of the light beams 121 , 122 , and 123 shown by the dotted lines are 0, which conforms to the above-mentioned situation of paraxial imaging. However, the CRA of the beams 131, 132 and 133 shown by the solid lines is not zero, and the imaging position required for the beams of the CRA is also different from the imaging positions of the paraxial beams 121, 122 and 123. In this case, The phase compensation that needs to be met will also change. As shown in Figure 5, since the lens needs to image an external scene with a distance far greater than the focal length in most cases, the incident beamlet can be regarded as parallel light equivalently, and the required phase compensation becomes:

in,

where λ is the wavelength,

f is the distance between the sensor 140 and the metasurface lens 130 (ie, the focal length),

f' is the distance traveled by the principal ray from the metasurface lens 130 to the sensor 140,

Δr is the distance from the phase compensation structure to the intersection of the chief ray and the metasurface mirror 130,

θ=arccos(f/f').

的1/2，其中，对于左旋入射光，则旋转的角度为

的正1/2，对于右旋偏振光，则旋转的角度为

的负1/2。对于不同圆偏振，旋转方向是相反的。仅在CRA＝0的情况下上式等价于傍轴情形，而对在0-90°之间的CRA则与傍轴情况下所需的相位补偿的差别将不断增大。It can be seen that the phase compensation is related to both f' and CRA, ie will vary according to the distance from the center of the stop 120. Through the selection of f', the metasurface imaging device can be adapted to sensors of different sizes. If a fin-shaped phase compensation structure is used, the angle of rotation of the fin should be in the above formula

1/2 of , where, for left-handed incident light, the angle of rotation is

positive 1/2 of , for right-handed polarized light, the angle of rotation is

minus 1/2 of . For different circular polarizations, the rotation directions are opposite. The above equation is equivalent to the paraxial case only in the case of CRA = 0, and the difference in phase compensation required from the paraxial case will continue to increase for CRA between 0-90°.

In a simplified implementation, the focal point can be located where the extension line of the chief ray intersects the image plane where the sensor is located:

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

In order to meet the requirements of the above formula, the metasurface lens 130 may be divided into multiple regions, and the multiple regions may not overlap with each other, each of which is designed according to a CRA within a certain range. It is also possible to partially overlap each other such that the response to CRA changes continuously in the radial direction of the lens.

As shown in FIG. 6 , the metasurface lens 130 can be divided into multiple concentric regions according to CRA, and each region is designed according to different CRAs in the above formula. The shape of each region is not limited to the above-mentioned ring shape, but can be divided according to the shape of the meta-surface lens 130 itself, such as a rectangle, a polygon, an irregular shape, and the like. The metasurface lens 130 can also be divided into multiple grids according to regions 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 region can be determined according to the actual micromachining capability.

Example 1

In one example, assuming that the CRA is 30° at maximum and the wavelength is 500 nm, 6 concentric annular regions are arranged in total, and the width of each region (for example, r ₁ , r ₂ , r ₃ , r ₄ and r ₅ ) and the diaphragm radius are both 20 microns, the distance between the diaphragm and the metasurface mirror is 200 microns, and f is 50 microns, then the phase compensation structure fins at the distance Δr relative to the corresponding reference position in each area The rotation angle φ is shown in Table 1 and Fig. 7 accordingly.

Specifically, in this example, for the region of CRA=0°, the reference position is the center O ₂ of the metasurface lens 130 ; for the region of CRA=5°, the reference position is the region of CRA=5° and CRA=0° For the area with CRA=10°, the reference position is the junction of the area with CRA=10° and the area with CRA=5°; for the area with CRA=15°, the reference position is the area with CRA=15° The junction of the area with the area with CRA=10°; for the area with CRA=20°, the reference position is the junction of the area with CRA=20° and the area with CRA=15°; for the area with 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°.

Table 1 Rotation angle φ of phase compensation structural fins in each region relative to the center distance Δr

One notable 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 variation of φ in the positive direction (that is, in the direction away from the center of the meta-surface mirror 130 ) begins to be greater than the amount of change in φ in the negative direction (that is, in the direction close to the center of the meta-surface mirror 130 ), and the positive direction and the The difference in the amount of change in the negative direction also tends to increase as the CRA increases.

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

Table 2 Rotation angle φ of cuboid fins as a function of r

Example 2

In another example, the maximum CRA is 30° and the wavelength is 700 nanometers, and 6 concentric annular regions are arranged in total. The width of each region and the radius of the aperture are both 20 microns, and the distance between the aperture and the metasurface mirror is 200 μm, 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 region is shown in Table 3 and FIG. 9 accordingly. In this embodiment, the reference position is defined similarly to Embodiment 1.

Table 3 Rotation angle φ of phase compensation structural fins in each region relative to the center distance Δr

If the distance r from the center to the edge of the metasurface is the criterion, the corresponding rotation angle of the cuboid fins can be extracted from the above table and listed together as shown in Table 4 and Figure 10.

Table 4 Rotation angle φ of cuboid fins as a function of r

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 twenty one 0 56 -109.28 91 -109.022 126 0 twenty two -2.54636 57 -80.7595 92 -143.17 127 -1.68469 twenty three -10.2001 58 -56.406 93 -182.154 128 -6.79694 twenty four -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

Example 3

In another example, the maximum CRA is 30° and the wavelength is 500 nanometers, and 6 concentric annular regions are arranged in total. The width of each region and the radius of the aperture are both 20 microns, and the distance between the aperture and the metasurface mirror is 200 μm, f is 60 μm, 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 shown in Table 5 and FIG. 11 accordingly. In this embodiment, the reference position is defined similarly to Embodiment 1.

Table 5 Rotation angle φ of phase compensation structure fins at distance Δr from center in each region

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 -297.945 -298.853 -292.926 -280.288 -261.449 -237.298 -209.068 9 -241.648 -242.038 -236.89 -226.339 -210.831 -191.112 -168.19 8 -191.154 -191.187 -186.846 -178.266 -165.824 -150.126 -131.978 7 -146.503 -146.317 -142.785 -136.033 -126.367 -114.264 -100.347 6 -107.731 -107.438 -104.693 -99.6001 -92.399 -83.4492 -73.2107 5 -74.8702 -74.5583 -72.5473 -68.9212 -63.8542 -57.6016 -50.4845 4 -47.9468 -47.6777 -46.3246 -43.9479 -40.6643 -36.6403 -32.0824 3 -26.9831 -26.7927 -25.9949 -24.6273 -22.7582 -20.4832 -17.9185 2 -11.9967 -11.8947 -11.524 -10.9029 -10.0628 -9.04702 -7.9071 1 -2.99979 -2.96998 -2.87334 -2.71481 -2.50258 -2.24755 -1.96264 0 0 0 0 0 0 0 0 -1 -2.99979 -2.96139 -2.85701 -2.69228 -2.47591 -2.21904 -1.93452 -2 -11.9967 -11.8261 -11.3934 -10.7227 -9.8496 -8.819 -7.68216 -3 -26.9831 -26.5614 -25.5546 -24.0198 -22.0391 -19.7141 -17.1596 -4 -47.9468 -47.1301 -45.2824 -42.5097 -38.9611 -34.8184 -30.2843 -5 -74.8702 -73.4908 -70.5152 -66.1164 -60.5318 -54.0463 -46.9746 -6 -107.731 -105.598 -101.188 -94.762 -86.6663 -77.3124 -67.15 -7 -146.503 -143.401 -137.234 -128.367 -117.279 -104.532 -90.7307 -8 -191.154 -186.848 -178.583 -166.85 -152.285 -135.62 -117.638 -9 -241.648 -235.881 -225.161 -210.13 -191.599 -170.493 -147.796 -10 -297.945 -290.44 -276.894 -258.122 -235.133 -209.067 -181.126

If the distance r from the center to the edge of the metasurface is the criterion, the required rotation angle of the cuboid fins can be extracted from the above table and listed together as shown in Table 6 and Figure 12.

Table 6 Rotation angle φ of cuboid fins as a function of r

Example 4

In another example, the maximum CRA is 36° and the wavelength is 500 nanometers, and 6 concentric annular regions are arranged in total. The width of each region and the radius of the aperture are both 20 microns, and the distance between the aperture and the metasurface mirror is 200 μm, 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 region should be as shown in Table 7 and Figure 13. In this embodiment, the reference position is defined similarly to Embodiment 1.

Table 7 Rotation angle φ of phase compensation structural fins at distance Δr from center in each region

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

If the distance r from the center to the edge of the metasurface is the criterion, the required rotation angle of the cuboid fins can be extracted from the above table and listed together as shown in Table 8 and Figure 14.

Table 8 Rotation angle φ of cuboid fins as a function of r

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 twenty one 0 56 -145.214 91 -141.335 126 0 twenty two -3.54819 57 -107.395 92 -185.832 127 -1.92445 twenty three -14.2182 58 -75.0665 93 -236.731 128 -7.77139 twenty four -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

The description of the present application is presented for the purpose of illustration and description, and is not intended to be exhaustive or to limit the application to the form disclosed. Many modifications and variations will be apparent to those skilled in the art. For example, one of ordinary skill in the art can use other semiconductor processes to fabricate metalens under the teachings of this disclosure. The embodiment was chosen and described in order to better explain the principles of the application and the practical application, and to enable others skilled in the art to understand the application for various embodiments with various modifications as are suited to the particular use.

Claims (10)

1. A super-surface imaging apparatus, the super-surface imaging apparatus comprising:

the diaphragm is used for limiting the incident light beam;

at least one super-surface lens aligned with the diaphragm and having a plurality of phase compensation structures to deflect the light beam limited by the diaphragm for phase compensation thereof; and

an imaging sensor that converts the phase-compensated light into an electrical signal proportional to a signal of the light;

wherein the super-surface lens has a plurality of phase compensation structures, and the equivalent focal length of the phase compensation structures gradually increases in a direction away from the center of the super-surface lens.

2. The super surface imaging device of claim 1, wherein a center of the stop is aligned with a center of the super surface mirror in an optical axis direction.

3. The super surface imaging device as claimed in claim 2, wherein the phase compensation varies with a decaying periodicity from the center of the super surface lens in a radial direction of the super surface lens.

4. The super surface imaging device of any one of claims 1 to 3, wherein the super surface mirror further comprises a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

5. The super surface imaging device according to claim 4, wherein the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from a refractive index of a material forming the transparent substrate.

6. The super surface imaging apparatus according to claim 5, wherein the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

7. The super surface imaging device of claim 5, wherein the inorganic dielectric material comprises at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, gallium arsenide.

8. The super surface imaging device according to claim 5, wherein the material forming the transparent substrate is an inorganic material comprising one of conductive glass ITO, alumina, zinc oxide, magnesium fluoride, silicon dioxide.

9. The super surface imaging device according to claim 5, wherein a material forming the transparent substrate is a resin-based organic transparent material.

10. The super surface imaging device as claimed in claim 5, wherein the distance of the super surface mirror from the imaging sensor is less than the distance of the super surface mirror from the diaphragm.

Images