CN217639715U - Optical system, superlens therein, imaging device comprising same and electronic equipment - Google Patents
Optical system, superlens therein, imaging device comprising same and electronic equipment Download PDFInfo
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- CN217639715U CN217639715U CN202221011048.9U CN202221011048U CN217639715U CN 217639715 U CN217639715 U CN 217639715U CN 202221011048 U CN202221011048 U CN 202221011048U CN 217639715 U CN217639715 U CN 217639715U
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Abstract
The embodiment of the application provides an optical system, a super lens therein, an imaging device comprising the super lens and electronic equipment, and belongs to the technical field of optical imaging. The optical system comprises a first lens, a second lens and a third lens which are arranged in sequence from an object side to an image sideA mirror and a fourth lens; any one of the first lens, the second lens, the third lens and the fourth lens is a super lens, and the rest are refractive lenses; the surface of the object side and the surface of the image side of the refraction lens in the optical system comprise at least one aspheric surface, and the aspheric surface comprises an inflection point; the optical system satisfies: f/EDP<3；25°≤HFOV≤65°；0.3≤f N The/f is less than or equal to 5.5; wherein f is the focal length of the optical system; EPD is the entrance pupil diameter of the optical system; f. of N The focal length of the first refractive lens from the object side to the image side in the optical system; the HFOV is half of the maximum field angle of the optical system. The optical system employs the superlens to promote miniaturization and weight reduction of the optical system.
Description
Technical Field
The present application relates to the field of optical imaging technology, and more particularly, to an optical system, a superlens included in the optical system, and an imaging device and an electronic apparatus including the superlens.
Background
With the development of scientific technology, electronic devices are increasingly pursuing miniaturization and lightweight.
However, the imaging device in the electronic apparatus, particularly the optical system in the imaging device, is bulky and heavy, which hinders the miniaturization and weight saving of the electronic apparatus.
Therefore, a miniaturized optical system is required.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem that the miniaturization of the projection system in the prior art is limited by the number of lenses and the volume of the lens, the embodiment of the application provides an optical system, a super lens therein, and an imaging device and an electronic device comprising the super lens.
In a first aspect, embodiments of the present application provide an optical system including a first lens, a second lens, a third lens, and a fourth lens arranged in this order from an object side to an image side;
any one of the first lens, the second lens, the third lens and the fourth lens is a super lens, and the rest are refractive lenses;
the surface of the object side and the surface of the image side of the refraction lens in the optical system comprise at least one aspheric surface, and the aspheric surface comprises an inflection point;
the optical system satisfies:
f/EDP<3；
25°≤HFOV≤65°；
0.3≤f N /f≤5.5；
wherein f is the focal length of the optical system; EPD is the entrance pupil diameter of the optical system; f. of N The focal length of the first refractive lens from the object side to the image side in the optical system; the HFOV is half of the maximum field angle of the optical system.
Optionally, the first refractive lens from the object side to the image side in the optical system has positive optical power.
Optionally, the optical system further comprises a diaphragm;
the diaphragm is disposed between any two adjacent lenses among the first lens, the second lens, the third lens, and the fourth lens.
Optionally, the first refractive lens in the optical system satisfies:
R No /f N ≥0.23；
wherein R is No The radius of curvature of the object side surface which is refracted and transmitted by the first sheet in the optical system; f. of N Is the focal length of the first piece of refractive lens.
Optionally, the optical system further satisfies:
(V N +V N+2 )/2-V N+1 >20；
wherein, V N The Abbe number of a first refractive lens in the optical system; v N+1 The Abbe number of a second refraction lens in the optical system; v N+2 The abbe number of the third refractive lens in the optical system.
Optionally, the optical system further satisfies:
1.2<TTL/ImgH<2.8；
wherein, TTL is the total system length of the optical system; imgH is the maximum imaging height of the optical system.
Optionally, the optical system further satisfies:
1.54≤n N ≤1.6；
1.5≤n N+1 ≤1.6；
wherein n is N The refractive index of a first refraction lens in the optical system; n is N+1 The refractive index of the second piece of refractive lens in the optical system.
Optionally, the optical system further satisfies:
|f ML |/f>10；
wherein f is ML Is the focal length of the superlens; f is the focal length of the optical system.
Optionally, the thickness of the superlens is greater than or equal to 0.05mm and less than or equal to 2mm.
Optionally, the first lens is a superlens; the object side surface of the second lens is a convex surface and has positive focal power; the object side surface of the third lens is a concave surface; the object side surface of the fourth lens is a convex surface.
Optionally, the thickness of the first lens is greater than or equal to 0.05mm and less than or equal to 1mm.
Optionally, the second lens is a superlens; the object side surface of the first lens is a convex surface and has positive focal power; the object side surface of the third lens is a concave surface; the object side surface of the fourth lens is a convex surface.
Optionally, the third lens is a superlens; the object side surface of the first lens is a convex surface and has positive focal power; the object side surface of the second lens is a concave surface; the object side surface of the fourth lens is a convex surface.
Optionally, the fourth lens is a superlens; the object side surface of the first lens is a convex surface and has positive focal power; the object side surface of the second lens is a concave surface; the object side surface of the third lens is a convex surface.
In a second aspect, embodiments of the present application further provide an imaging apparatus, where the imaging apparatus includes the optical system provided in any of the above embodiments; and a photosensitive element disposed on the image plane of the optical system.
In a third aspect, an embodiment of the present application further provides an electronic device, which includes the imaging apparatus provided in the foregoing embodiment.
In a fourth aspect, embodiments of the present application further provide a superlens, which is suitable for use in the optical system provided in any of the above embodiments, the superlens includes a substrate layer and at least one nanostructure layer;
the at least one nanostructure layer is disposed on one side of the substrate layer;
each of the at least one nanostructure layer includes periodically arranged nanostructures.
Optionally, the superlens comprises at least two nanostructure layers;
the nanostructures in adjacent ones of the at least two nanostructure layers are coaxially arranged.
Optionally, the nanostructures are periodically arranged in the form of superstructure units;
the superstructure unit is a close-packed graph, and the nano structure is arranged at the vertex and/or the center of the close-packed graph.
Optionally, the phase of the superlens at least satisfies:
wherein r is the distance from the center of the superlens to the center of any nanostructure; λ is the operating wavelength of the superlens,
for any phase associated with the operating wavelength, (x, y) are coordinates on the superlens, f ML Is the focal length of the superlens, a i And b i Are real number coefficients.
Optionally, the wide-spectrum phase of the superstructure unit and the operating wavelength of the superlens further satisfy:
wherein r is the coordinate of the superlens along the radial direction; r is a radical of hydrogen 0 Is any point on the superlens; λ is the operating wavelength.
Optionally, the range of equivalent refractive indices of the superlens is less than 2;
the equivalent refractive index range is the maximum refractive index of the superlens minus the minimum refractive index of the superlens.
Optionally, the nanostructures have an alignment period greater than or equal to 0.3 λ c And is less than or equal to 2λ c ；
Wherein λ is c Is the center wavelength of the superlens operating band.
Optionally, the height of the nanostructures is greater than or equal to 0.3 λ c And is less than or equal to 5 lambda c ；
Wherein λ is c Is the center wavelength of the working waveband of the superlens.
Optionally, the shape of the nanostructure is a polarization-independent structure.
Optionally, a filling material is further filled between the nanostructures of the same nanostructure layer;
and the extinction coefficient of the filling material to the working wave band of the super lens is less than 0.01.
Optionally, the filler material is different from the material of the nanostructures; and the number of the first and second electrodes,
the filler material is different from the material of the base layer.
Optionally, the filler material comprises any one or combination of air, fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon.
Optionally, the superlens further comprises an antireflection film;
the antireflection film is arranged on one side, away from the at least one nanostructure layer, of the substrate layer; or,
the antireflection film is arranged on one side of the at least one nanostructure layer, which is adjacent to air.
In a fifth aspect, an embodiment of the present application further provides a method for processing a superlens, where the method is applied to the superlens provided in any of the above embodiments, and the method includes:
step S1, arranging a layer of structural layer material on the substrate layer;
s2, coating photoresist on the structural layer material, and exposing a reference structure;
s3, etching the nano structure on the structural layer material according to the reference structure to form a nano structural layer;
s4, arranging the filling material between the nano structures;
and S5, finishing the surface of the filling material to ensure that the surface of the filling material is superposed with the surface of the nano structure.
Optionally, the method comprises:
and S6, repeating the steps S1 to S5 until all the nanostructure layers are completed.
The optical system provided by the embodiment of the application is combined by one super lens and the other three refractive lenses, and the optical system meets f/EDP<3；25°≤HFOV≤65°；0.3≤f N The/f is less than or equal to 5.5; therefore, the total length of the optical system is reduced on the premise of ensuring the imaging effect, and the miniaturization and the light weight of the optical system are promoted.
The super lens provided by the embodiment of the application has the advantages that the depth-to-width ratio of a single nano structure is increased through at least one nano structure layer, the design freedom degree of the super lens is improved, and the design of the super lens structure on the optical performance of the super lens is broken through.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.
Fig. 1 is a schematic diagram illustrating an alternative structure of an optical system provided in an embodiment of the present application;
FIG. 2 is a schematic diagram illustrating an alternative configuration of an optical system provided by an embodiment of the present application;
FIG. 3 is a schematic diagram illustrating an alternative configuration of an optical system provided by an embodiment of the present application;
FIG. 4 is a schematic diagram illustrating an alternative configuration of an optical system provided by an embodiment of the present application;
FIG. 5 is a phase diagram illustrating a superlens in an alternative optical system provided by embodiments of the present application;
FIG. 6 is a diagram illustrating an equivalent refractive index of an alternative superlens of an optical system provided by an embodiment of the present application;
FIG. 7 illustrates an astigmatism diagram of an alternative optical system provided by embodiments of the present application;
FIG. 8 illustrates a field curvature diagram of an alternative optical system provided by embodiments of the present application;
FIG. 9 is a diagram illustrating a modulation transfer function of an alternative optical system provided by embodiments of the present application;
FIG. 10 is a phase diagram illustrating a superlens in yet another alternative optical system provided by an embodiment of the present application;
FIG. 11 is a graph showing an equivalent refractive index of a superlens of yet another alternative optical system provided by an embodiment of the present application;
FIG. 12 shows astigmatism diagrams of yet another alternative optical system provided by embodiments of the present application;
FIG. 13 illustrates a field curvature diagram of yet another alternative optical system provided by embodiments of the present application;
FIG. 14 illustrates a modulation transfer function of yet another alternative optical system provided by an embodiment of the present application;
FIG. 15 is a phase diagram illustrating a superlens in yet another alternative optical system provided by an embodiment of the present application;
FIG. 16 is a graph showing an equivalent refractive index of a superlens of yet another alternative optical system provided by an embodiment of the present application;
fig. 17 shows an astigmatism diagram of yet another alternative optical system provided by an embodiment of the present application;
FIG. 18 illustrates a field curvature diagram of yet another alternative optical system provided by an embodiment of the present application;
FIG. 19 illustrates a modulation transfer function of yet another alternative optical system provided by embodiments of the present application;
FIG. 20 is a phase diagram illustrating a superlens of yet another alternative optical system provided by an embodiment of the present application;
FIG. 21 is a graph showing the equivalent refractive index of a superlens of yet another alternative optical system provided by an embodiment of the present application;
FIG. 22 shows an astigmatism diagram for yet another alternative optical system provided by an embodiment of the present application;
FIG. 23 is a field curvature diagram of yet another alternative optical system provided by an embodiment of the present application;
FIG. 24 is a graph showing the modulation transfer function of yet another alternative optical system provided by an embodiment of the present application;
FIG. 25 is a schematic diagram illustrating an alternative superlens structure provided by an embodiment of the present application;
FIG. 26 is a schematic diagram illustrating a structure of yet another alternative superlens provided by an embodiment of the present application;
FIG. 27 illustrates an alternative perspective view of nanostructures in a superlens provided by embodiments of the present application;
FIG. 28 illustrates yet another alternative perspective view of nanostructures in a superlens provided by an embodiment of the present application;
FIG. 29 is a schematic diagram illustrating an alternative arrangement of nanostructures in a superlens provided by an embodiment of the present application;
FIG. 30 is a schematic diagram illustrating yet another alternative arrangement of nanostructures in a superlens provided by an embodiment of the present application;
FIG. 31 is a schematic diagram illustrating yet another alternative arrangement of nanostructures in a superlens provided by an embodiment of the present application;
FIG. 32 illustrates an alternative perspective view of a superlens provided by an embodiment of the present application;
FIGS. 33a-d show an alternative structural schematic of a nanostructure provided by an embodiment of the present application;
FIGS. 34a-d show schematic structural diagrams of yet another alternative nanostructure provided by embodiments of the present application;
FIGS. 35a-d show schematic structural diagrams of yet another alternative nanostructure provided by embodiments of the present application;
FIGS. 36a-d show schematic structural diagrams of yet another alternative nanostructure provided by embodiments of the present application;
FIG. 37 is a schematic diagram illustrating an alternative configuration of a superlens provided by an embodiment of the present application;
FIG. 38 is a graph showing the matching of the phase of the superlens to the ideal phase in example 1 provided by the present application;
FIG. 39 is a graph showing the phase matching of the superlens with the ideal phase in example 2 provided by the present application;
FIG. 40 is a graph showing the phase matching of the superlens with the ideal phase in example 3 provided by the present application;
FIG. 41 is a graph showing the matching of the phase of the superlens to the ideal phase in example 4 provided by the present application;
FIG. 42 is a schematic flow chart diagram illustrating an alternative method of processing a superlens provided by an embodiment of the present application;
FIG. 43 is a schematic flow chart diagram illustrating an alternative method for processing a superlens provided by an embodiment of the present application;
FIG. 44 is a schematic flow chart diagram illustrating yet another alternative method of fabricating a superlens provided by an embodiment of the present application;
FIG. 45 illustrates an alternative phase diagram for a superlens provided by embodiments of the present application;
FIG. 46 illustrates an alternative transmittance graph for a superlens provided by embodiments of the present application;
FIG. 47 illustrates an alternative phase diagram for a superlens provided by embodiments of the present application;
FIG. 48 illustrates an alternative transmittance graph for a superlens provided by embodiments of the present application.
The reference numerals in the drawings denote:
10-a first lens; 20-a second lens; 30-a third lens; 40-a fourth lens; 50-a diaphragm; 60-infrared filter plate;
11-a base layer; 12-a nanostructure layer; 13-antireflection coating; 12 a-a nanostructured material;
121-superstructure unit; 1201-nanostructures; 1202-filling material.
Detailed Description
The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like parts throughout. Also, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity of illustration.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly dictates otherwise. For example, "a component" means the same as "at least one component" unless the context clearly dictates otherwise. "at least one of" should not be construed as limited to the quantity "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is the same as a meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "comprises" indicates a property, a quantity, a step, an operation, a component, a part, or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts, or combinations thereof.
Embodiments are described herein with reference to cross-sectional views that are idealized embodiments. Thus, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, regions shown or described as flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.
Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.
With the development of scientific technology, electronic devices are increasingly pursuing miniaturization and lightweight. On one hand, the optical system using the traditional plastic lens is difficult to break through on the thickness and the large-curvature surface due to the limitation of the injection molding process, so that the optical system with the four-piece lens structure is difficult to break through on the thickness of each lens, the interval of each lens and the total length of the system; on the other hand, the plastic lenses can be made of more than ten materials, so that the freedom of system aberration correction is limited. Although the problems of chromatic aberration and the like are solved to a certain extent by the glass-resin mixed lens at present, the miniaturization and the light weight of an optical system are still greatly hindered by an injection molding process. Today, great efforts are made to reduce the total length of an optical system by every 1mm. For example, in the related art, an optical system having a four-piece structure has a total length of 3.53mm or more, and it is difficult to make the thickness of the entire system 2.5mm or less due to process limitations.
The present embodiment provides an optical system including, as illustrated in fig. 1 to 4, a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40, which are arranged in order from an object side to an image side.
Specifically, in this optical system, any one of the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 is a superlens, and the remaining three lenses are refractive lenses. At least one of an object-side surface and an image-side surface of each refractive lens in the optical system includes an aspheric surface, and the aspheric surface includes an inflection point. And, the optical system satisfies:
f/EDP<3； (1)
25°≤HFOV≤65°； (2)
0.3≤f N /f≤5.5； (3)
wherein f is the focal length of the optical system; EPD is the Entrance Pupil Diameter (Entrance Pupil Diameter) of the optical system; f. of N The focal length of the first refractive lens from the object side to the image side in the optical system; the HFOV is half the maximum field angle of the optical system. N denotes the order of the first refractive lens in the optical system in the entire optical system from the object side to the image side. For example, when the first lens 10 is a first refractive lens in the optical system, the focal length of the first refractive lens is f 1 (ii) a When the second lens 20 is the first refractive lens in the optical system, the focal length of the first refractive lens is f 2 。
In an alternative implementation, the optical system provided in the embodiment of the present application further includes a diaphragm 50. The position of the diaphragm 50 in the optical system affects the aperture of the optical system. In general, the closer the position of the diaphragm 50 is to the object side, the smaller the aperture of the optical system, and vice versa. Optionally, a diaphragm 50 is arranged between the first lens 10 and the second lens 20. Illustratively, the stop 50 is an aperture Stop (STO).
According to an embodiment of the present application, referring to fig. 1 to 4, an optical system provided in an embodiment of the present application further includes an infrared filter 60 (IR filter). The infrared filter 60 functions to shield visible light for improving a night vision function of the optical system.
In some embodiments of the present application, the thickness of the superlens in the optical system is greater than or equal to 0.05mm and less than or equal to 2mm. According to an embodiment of the application, the optical system further satisfies:
|f ML |/f>10； (4)
wherein f is ML Is the focal length of the superlens; f is the focal length of the optical system provided by the embodiment of the application.
In an alternative embodiment, the first refractive lens in the optical system from the object side to the image side has positive optical power. Illustratively, the object-side surface of the first refractive lens is a convex surface.
According to an embodiment of the present application, optionally, the first refractive lens in the optical system satisfies:
R No /f N ≥0.23； (5)
in the formula (5), R No The radius of curvature of the object side surface refracted and transmitted by the first sheet in the optical system; f. of N Is the focal length of the first refractive lens in the optical system. N denotes the order of the first refractive lens in the optical system in the entire optical system from the object side to the image side.
In some optional embodiments of the present application, referring to fig. 1 to 4, the optical system provided in the embodiments of the present application further satisfies:
(V N +V N+2 )/2-V N+1 >20； (6)
wherein, V N The Abbe number of a first refractive lens in the optical system; v N+1 The Abbe number of a second refraction lens in the optical system; v N+2 The abbe number of the third refractive lens in the optical system. N denotes the order of the first refractive lens in the optical system in the entire optical system from the object side to the image side. For example, when the first lens 10 is a superlens in the optical system and the second lens 20 is a first refractive lens, the abbe number of the first refractive lens is V 1 The abbe number of the second refractive lens is V 3 The third refractive lens has an Abbe number V 4 。
According to an embodiment of the application, optionally, the optical system further satisfies:
1.2<TTL/ImgH<2.8； (7)
wherein, TTL is a total system length of the optical system provided in the embodiments of the present application; imgH is the maximum imaging height of the optical system.
According to an embodiment of the application, optionally, the optical system further satisfies:
1.54≤n N ≤1.6； (8)
1.5≤n N+1 ≤1.6； (9)
wherein n is N The refractive index of a first refractive lens in the optical system; n is a radical of an alkyl radical N+1 The refractive index of the second piece of refractive lens in the optical system.
According to an embodiment of the present application, the aspheric surface in the implementation of the present application is shown in formula (10):
wherein z is a surface vector parallel to the optical axis of the refractive lens, c is the curvature of the central point of the refractive lens, k is a conic constant, and A-J correspond to high-order coefficients respectively.
Optionally, in an optical system provided in this embodiment of the present application, an equivalent refractive index range of the superlens is smaller than 2. The equivalent refractive index range is the maximum refractive index of the superlens minus its minimum refractive index.
Example 1
Referring to fig. 1, an exemplary embodiment of the present application provides an optical system. Fig. 1 shows an optical system including a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40, which are arranged in order from an object side to an image side. The first lens 10 is a super lens, and the second lens 20, the third lens 30, and the fourth lens 40 are refractive lenses. The object-side surface of the second lens element 20 is convex and has positive optical power; the object-side surface of the third lens element 30 is concave; the object-side surface of the fourth lens element 40 is convex. At least one of an object-side surface and an image-side surface of each of the second lens 20, the third lens 30, and the fourth lens 40 includes an aspheric surface, and the aspheric surface includes an inflection point. And, the optical system satisfies:
f/EDP<3； (1)
25°≤HFOV≤65°； (2)
0.3≤f 2 /f≤5.5； (3-1)
wherein f is the focal length of the optical system; EPD is the Entrance Pupil Diameter (Entrance Pupil Diameter) of the optical system; f. of 2 Is the focal length of the second lens 20 in the optical system(ii) a The HFOV is half the maximum field angle of the optical system.
The system parameters of the optical system provided in example 1 of the present application are shown in table 1-1. The parameters of the respective lens surfaces in the optical system are shown in tables 1-2, and the aspherical coefficients in the respective refractive lenses are shown in tables 1-3. Referring to fig. 5, fig. 5 shows the phase diagrams of the superlens (i.e. the first lens 10) in the optical system at three selectable operating wavelengths (486.13 nm, 587.25nm, 656.27 nm), respectively. Referring to fig. 6, fig. 6 shows an equivalent refractive index diagram of a superlens in the optical system. As can be seen from fig. 6, the equivalent refractive index of the superlens in the optical system is less than 2.
Optionally, the thickness of the superlens (i.e. the first lens 10) in the optical system is greater than or equal to 0.05mm and less than or equal to 1mm. Optionally, the optical system further satisfies:
R 2o /f 2 ≥0.35； (5-1)
in the formula (5-1), R 2o The radius of curvature of the object side surface refracted and transmitted by the first sheet in the optical system; f. of 2 The focal length of the first refractive lens in the optical system.
According to an embodiment of the application, the optical system further satisfies:
(V 2 +V 4 )/2-V 3 >20； (6-1)
wherein, V 2 The abbe number of the first refractive lens (i.e., the second lens 20) in the optical system; v 3 The abbe number of the second refractive lens (i.e., the third lens 30) in the optical system; v 4 The abbe number of the third refractive lens (i.e., the fourth lens 40) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.54≤n 2 ≤1.6； (8-1)
1.5≤n 3 ≤1.6； (9-1)
wherein n is 2 The refractive index of the first refractive lens (i.e., the second lens 20) in the optical system; n is a radical of an alkyl radical 3 The refractive index of the second piece of refractive lens (i.e., the third lens 30) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.2<TTL/ImgH<2.8； (7)
wherein, TTL is a total system length of the optical system provided in the embodiments of the present application; imgH is the maximum imaging height of the optical system.
Fig. 7 shows astigmatism diagrams of the optical system according to an embodiment of the present application. As can be seen from fig. 7, the meridional astigmatism of the optical system is less than 0.1, and the sagittal astigmatism is less than 0.05. The field curvature (i.e., distortion) of the optical system is shown in fig. 8. As can be seen from fig. 8, the distortion of the optical system is less than 5% in the full field of view. Fig. 9 shows the modulation transfer function of the optical system, which is close to the diffraction limit at each field of view according to fig. 9. In summary, the optical system has good imaging effect and excellent control of astigmatism and field curvature.
TABLE 1-1
| Parameter item | Numerical value |
| Working wave band (WL) | VIS(400-700nm) |
| Equivalent Focal Length (EFL) | 1.59mm |
| Viewing angle (2 omega) | 60° |
| F number | 2.4 |
| Total length of system | 2.3mm |
Tables 1 to 2
| Surface numbering | Surface type | Radius (mm) | Thickness (mm) | Material |
| L 1o | Spherical surface | Unlimited in size | 0.1 | 45800.676000 |
| L 1i | Super surface | Unlimited in size | 0.1 | |
| L 2o | Aspherical surface | 0.82 | 0.45 | 543000.568000 |
| L 2i | Aspherical surface | -24.02 | 0.1 | |
| STO | Spherical surface | Unlimited in size | 0.1 | |
| L 3o | Aspherical surface | -1.82 | 0.3 | 583000.320000 |
| L 3i | Aspherical surface | -26.23 | 0.1007 | |
| L 4o | Aspherical surface | 0.85 | 0.3364 | 530000.560000 |
| L 4i | Aspherical surface | 0.81 | 0.1 | |
| IR filter o | Spherical surface | Unlimited in size | 0.4 | 517000.642000 |
| IR filter i | Spherical surface | Infinite number of elements | 0.21 | |
| Image plane | Spherical surface | Infinite number of |
0 |
Tables 1 to 3
In the surface numbers of tables 1 to 2 and tables 1 to 3, L denotes a lens, the number denotes the order of the lens from the object side to the image side in the optical system provided in the embodiment of the present application, o denotes an object side surface, and i denotes an image side surface. For example, L 1o Denotes an object side surface, L, of the first lens 10 1i The image side surface of the first lens 10 is shown, and so on for the remaining lens surfaces.
Example 2
As shown in fig. 2, embodiment 2 provides an alternative optical system. The optical system is configured as shown in fig. 2, and includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40 disposed in this order from the object side to the image side. The second lens 20 is a superlens, and the first lens 10, the third lens 30, and the fourth lens 40 are refractive lenses. The object side surface of the first lens element 10 is a convex surface and has positive optical power; the object-side surface of the third lens element 30 is concave; the object-side surface of the fourth lens element 40 is convex. At least one of an object-side surface and an image-side surface of each of the first lens 10, the third lens 30, and the fourth lens 40 includes an aspheric surface, and the aspheric surface includes an inflection point. And, the optical system satisfies:
f/EDP<3； (1)
25°≤HFOV≤65°； (2)
0.55≤f 1 /f≤5.2 (3-2)
wherein f is the focal length of the optical system; EPD is the Entrance Pupil Diameter (Entrance Pupil Diameter) of the optical system; f. of 1 The focal length of the first lens 10 in the optical system; the HFOV is half the maximum field angle of the optical system.
The system parameters of the optical system provided in example 2 of the present application are shown in table 2-1. The parameters of the respective lens surfaces in the optical system are shown in tables 2-2, and the aspherical coefficients in the respective refractive lenses are shown in tables 2-3. Referring to fig. 10, fig. 10 shows the phase diagrams of the superlens (i.e., the second lens 20) in the optical system at three selectable operating wavelengths (486.13 nm, 587.25nm, 656.27 nm), respectively. Referring to fig. 11, fig. 11 shows an equivalent refractive index diagram of a superlens in the optical system. As can be seen from fig. 11, the equivalent refractive index of the superlens in the optical system is less than 2.
Optionally, the thickness of the superlens (i.e., the second lens 20) in the optical system is greater than or equal to 0.05mm and less than or equal to 2mm. Optionally, the optical system further satisfies:
R 1o /f 1 ≥0.4； (5-2)
in the formula (5-2), R 1o The radius of curvature of the object side surface refracted and transmitted by the first sheet in the optical system; f. of 1 The focal length of the first refractive lens in the optical system.
According to an embodiment of the application, the optical system further satisfies:
(V 1 +V 4 )/2-V 3 >20； (6-2)
wherein, V 2 The abbe number of the first refractive lens (i.e., the first lens 10) in the optical system; v 3 The abbe number of the second refractive lens (i.e., the third lens 30) in the optical system; v 4 The abbe number of the third refractive lens (i.e., the fourth lens 40) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.54≤n 1 ≤1.6； (8-2)
1.5≤n 3 ≤1.6； (9-2)
wherein n is 2 The refractive index of the first refractive lens (i.e. the first lens 10) in the optical system; n is 3 The refractive index of the second refractive lens (i.e., the third lens 30) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.2<TTL/ImgH<2.8； (7)
wherein, TTL is a total system length of the optical system provided in the embodiments of the present application; imgH is the maximum imaging height of the optical system.
Fig. 12 shows astigmatism diagrams of the optical system according to an embodiment of the present application. As can be seen from fig. 12, the meridional astigmatism of the optical system is less than 0.1, and the sagittal astigmatism is less than 0.1. The curvature of field (i.e., distortion) of the optical system is shown in fig. 13. As can be seen from fig. 13, the distortion of the optical system is less than 10% in the full field of view. Fig. 14 shows the modulation transfer function of the optical system, which is close to the diffraction limit for each field of view according to fig. 14. In summary, the optical system has good imaging effect and excellent control of astigmatism and field curvature.
TABLE 2-1
| Item of parameter | Numerical value |
| Working wave band (WL) | VIS(400-700nm) |
| Equivalent Focal Length (EFL) | 1.59mm |
| Viewing angle (2 omega) | 70° |
| F number | 2.4 |
| Total length of system | 2.2mm |
Tables 2 to 2
| Surface numbering | Surface type | Radius (mm) | Thickness (mm) | Material |
| L 1o | Aspherical surface | 1.023 | 0.41 | 543000.568000 |
| L 1i | Aspherical surface | -6.153 | 0.05 | |
| STO | Spherical surface | Unlimited in size | 0.07 | |
| L 2o | Super surface | Unlimited in size | 0.1 | 45800.676000 |
| L 2i | Spherical surface | Infinite number of elements | 0.0542 | |
| L 3o | Aspherical surface | -9.153 | 0.3021 | 583000.320000 |
| L 3i | Aspherical surface | 101.15 | 0.168 | |
| L 4o | Aspherical surface | 1.1568 | 0.363 | 530000.560000 |
| L 4i | Aspherical surface | 0.6515 | 0.0732 | |
| IR filtero | Spherical surface | Unlimited in size | 0.4 | 517000.642000 |
| IR filteri | Spherical surface | Infinite number of elements | 0.21 | |
| Image plane | Spherical surface | Infinite number of |
0 |
Tables 2 to 3
In the surface numbers of tables 2 to 2 and 2 to 3, L denotes a lens, the number denotes an order of the lens from an object side to an image side in the optical system provided in the embodiment of the present application, o denotes an object side surface, and i denotes an image side surface. For example, L 1o Denotes an object side surface, L, of the first lens 10 1i The image side surface of the first lens 10 is shown, and so on for the remaining lens surfaces.
Example 3
As shown in fig. 3, embodiment 3 provides an alternative optical system. Structure of the optical system referring to fig. 3, the system includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40, which are disposed in order from an object side to an image side. The third lens 30 is a superlens, and the first lens 10, the second lens 20, and the fourth lens 40 are refractive lenses. The object side surface of the first lens element 10 is a convex surface and has positive optical power; the object-side surface of the second lens element 20 is concave; the object-side surface of the fourth lens element 40 is convex. At least one of an object-side surface and an image-side surface of each of the first lens 10, the second lens 20, and the fourth lens 40 includes an aspheric surface, and the aspheric surface includes an inflection point. And, the optical system satisfies:
f/EDP<3； (1)
25°≤HFOV≤65°； (2)
0.5≤f 1 /f≤5 (3-3)
wherein f is the focal length of the optical system; EPD is the Entrance Pupil Diameter (Entrance Pupil Diameter) of the optical system; f. of 1 The focal length of the first lens 10 in the optical system; the HFOV is half the maximum field angle of the optical system.
The system parameters of the optical system provided in example 3 of the present application are shown in table 3-1. The parameters of the respective lens surfaces in the optical system are shown in Table 3-2, and the aspherical coefficients in the respective refractive lenses are shown in Table 3-3. Referring to fig. 15, fig. 15 shows the phase diagrams of the superlens (i.e., the third lens 30) in the optical system at three selectable operating wavelengths (486.13 nm, 587.25nm, 656.27 nm), respectively. Referring to fig. 16, fig. 16 shows an equivalent refractive index diagram of a superlens in the optical system. As can be seen from fig. 16, the equivalent refractive index of the superlens in the optical system is less than 2.
Optionally, the thickness of the superlens (i.e., the third lens 30) in the optical system is greater than or equal to 0.05mm and less than or equal to 2mm. Optionally, the optical system further satisfies:
R 1o /f 1 ≥0.23； (5-3)
in the formula (5-1), R 1o The radius of curvature of the object-side surface of the first refractive lens (i.e., the first lens 10) in the optical system; f. of 1 Is the focal length of the first refractive lens (i.e., first lens 10) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
(V 1 +V 4 )/2-V 2 >20； (6-3)
wherein, V 2 The abbe number of the first refractive lens (i.e., the first lens 10) in the optical system; v 2 The abbe number of the second refractive lens (i.e., second lens 20) in the optical system; v 4 The abbe number of the third refractive lens (i.e., the fourth lens 40) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.54≤n 1 ≤1.6； (8-3)
1.5≤n 2 ≤1.6； (9-3)
wherein n is 2 The refractive index of the first refractive lens (i.e. the first lens 10) in the optical system; n is a radical of an alkyl radical 2 The refractive index of the second sheet of refractive lens (i.e., second lens 20) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.2<TTL/ImgH<2.8； (7)
wherein, TTL is a total system length of the optical system provided in the embodiments of the present application; imgH is the maximum imaging height of the optical system.
Fig. 17 shows an astigmatism diagram of the optical system according to an embodiment of the present application. As can be seen from fig. 17, the meridional astigmatism of the optical system is less than 0.1, and the sagittal astigmatism is less than 0.1. The curvature of field (i.e., distortion) of the optical system is shown in fig. 18. As can be seen from fig. 18, the distortion of the optical system at 0.7 field of view is less than 5%. Fig. 19 shows the modulation transfer function of the optical system, which is close to the diffraction limit at each field of view according to fig. 19. In summary, the optical system has good imaging effect and excellent control of astigmatism and field curvature.
TABLE 3-1
| Item of parameter | Numerical value |
| Working wave band (WL) | VIS(400-700nm) |
| Equivalent Focal Length (EFL) | 1.59mm |
| Viewing angle (2 omega) | 65° |
| F number | 2.4 |
| Total length of system | 2.3mm |
TABLE 3-2
Tables 3 to 3
| Surface numbering | L 1o | L 1i | L 2i | L 4o | L 4i |
| K | -2.341857 | -4.90E+02 | 1491.586 | 19.672446 | -12660.07 |
| A | 0.6516439 | 2.7574252 | 2.6579999 | -0.245929 | 2.4311091 |
| B | 0.7510671 | 5.9129416 | -27.73932 | 1.5379281 | -11.05537 |
| C | 7.5478715 | -36.84544 | 877.59197 | -111.3454 | 17.173914 |
| D | -58.93335 | 1507.2242 | -11203.42 | 5.87E+01 | -6.266085 |
| E | 281.62081 | -4392.26 | 6.04E+04 | 5.58E+03 | -1.21E+01 |
| F | -429.8374 | 2.27E-01 | -1.35E-04 | -2.41E+04 | 5.15E+00 |
| G | 0.00E+00 | 0.00E+00 | 0.00E+00 | 0.00E+00 | 0.00E+00 |
In the surface numbers of table 3-2 and table 3-3, L denotes a lens, the number denotes an order of the lens from an object side to an image side in the optical system provided in the embodiment of the present application, o denotes an object side surface, and i denotes an image side surface. For example, L 1o Denotes an object side surface, L, of the first lens 10 1i The image side surface of the first lens 10 is shown, and so on for the remaining lens surfaces.
Example 4
As shown in fig. 4, embodiment 4 provides an alternative optical system. Structure of the optical system referring to fig. 4, the system includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40, which are disposed in order from an object side to an image side. The fourth lens 40 is a super lens, and the first lens 10, the second lens 20, and the third lens 30 are refractive lenses. The object side surface of the first lens element 10 is a convex surface and has positive optical power; the object side surface of the second lens 20 is a concave surface; the object-side surface of the third lens element 30 is convex. At least one of an object side surface and an image side surface of each of the first lens 10, the second lens 20, and the third lens 30 includes an aspheric surface, and the aspheric surface includes an inflection point. And, the optical system satisfies:
f/EDP<3； (1)
25°≤HFOV≤65°； (2)
0.5≤f 1 /f≤3.2 (3-4)
wherein f is the focal length of the optical system; EPD is the Entrance Pupil Diameter (Entrance Pupil Diameter) of the optical system; f. of 1 The focal length of the first lens 10 in the optical system; the HFOV is half the maximum field angle of the optical system.
The system parameters of the optical system provided in example 4 of the present application are shown in table 4-1. The parameters of the respective lens surfaces in the optical system are shown in Table 4-2, and the aspherical coefficients in the respective refractive lenses are shown in Table 4-3. Referring to fig. 20, fig. 20 shows the phase diagrams of the superlens (i.e., the fourth lens 40) in the optical system at three selectable operating wavelengths (486.13 nm, 587.25nm, 656.27 nm), respectively. Referring to fig. 21, fig. 21 shows an equivalent refractive index diagram of a superlens in the optical system. As can be seen from fig. 21, the equivalent refractive index of the superlens in the optical system is less than 2.
Optionally, the thickness of the superlens (i.e., the third lens 30) in the optical system is greater than or equal to 0.05mm and less than or equal to 2mm. Optionally, the optical system further satisfies:
R 1o /f 1 ≥0.55； (5-4)
in the formula (5-1), R 1o The radius of curvature of the object-side surface of the first refractive lens (i.e., the first lens 10) in the optical system; f. of 1 Is the focal length of the first refractive lens (i.e., first lens 10) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
(V 1 +V 3 )/2-V 2 >20； (6-4)
wherein, V 2 The abbe number of the first refractive lens (i.e., the first lens 10) in the optical system; v 2 Is the first in the optical systemAbbe numbers of the two refractive lenses (i.e., second lens 20); v 3 The abbe number of the third refractive lens (i.e., the third lens 30) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.54≤n 1 ≤1.6； (8-4)
1.5≤n 2 ≤1.6； (9-4)
wherein n is 2 The refractive index of the first refractive lens (i.e. the first lens 10) in the optical system; n is a radical of an alkyl radical 2 The refractive index of the second piece of refractive lens (i.e., second lens 20) in the optical system.
According to an embodiment of the application, the optical system further satisfies:
1.2<TTL/ImgH<2.8； (7)
wherein, TTL is a total system length of the optical system provided in the embodiments of the present application; imgH is the maximum imaging height of the optical system.
Fig. 22 shows an astigmatism diagram of the optical system according to an embodiment of the present application. As can be seen from fig. 22, the meridional astigmatism of the optical system is less than 0.1, and the sagittal astigmatism is less than 0.1. The field curvature (i.e., distortion) of the optical system is shown in fig. 23. As can be seen from fig. 23, the distortion of the optical system at 0.7 field of view is less than 5%. Fig. 24 shows the modulation transfer function of the optical system, which is close to the diffraction limit at each field of view according to the illustration in fig. 24. In summary, the optical system has good imaging effect and excellent control of astigmatism and field curvature.
TABLE 4-1
| Parameter item | Numerical value |
| Working wave band (WL) | VIS(400-700nm) |
| Equivalent Focal Length (EFL) | 1.59mm |
| Viewing angle (2 omega) | 60° |
| F number | 2.4 |
| Total length of system | 2.2mm |
TABLE 4-2
Tables 4 to 3
In the surface numbers of tables 4-2 and 4-3, L denotes a lens, the number denotes the order of the lens from the object side to the image side in the optical system provided in the embodiment of the present application, o denotes an object side surface, and i denotes an image side surface. For example, L 1o Denotes an object side surface, L, of the first lens 10 1i The image side surface of the first lens 10 is shown, and so on for the remaining lens surfaces.
The phase matching degree of the superlens provided in embodiments 1 to 4 described above with respect to the ideal phase is shown in fig. 42 to 45, respectively.
The embodiment of the application also provides an imaging device, which comprises the optical system provided by any one of the embodiments; and a photosensitive element disposed on the image plane of the optical system.
The embodiment of the application also provides electronic equipment which comprises the imaging device provided by the embodiment.
Next, a superlens provided by an embodiment of the present application will be described with reference to fig. 25 to 37.
In particular, a superlens is a specific application of a supersurface that modulates phase, amplitude, and polarization of incident light by periodically arranged sub-wavelength-sized nanostructures. According to an embodiment of the present application, as shown in fig. 25 and 26, the superlens provided by any of the above embodiments includes a substrate layer 11 and at least one nanostructure layer 12. Wherein, at least one layer of nanostructure layer 12 times is arranged on one side of the substrate layer 11; each of the at least one nanostructure layer 12 comprises periodically arranged nanostructures 1201. Fig. 27 and 28 are perspective views illustrating a nanostructure 1201 in a nanostructure layer 12 of any one of the layers of a superlens employed in an optical system provided by an embodiment of the present application. Optionally, the filling material 1202 may be filled between the nanostructures on the superlens, and the filling material 1202 may include air or other material transparent or translucent in the working wavelength band. According to embodiments of the present application, the absolute value of the difference between the refractive index of the filled material and the refractive index of the nanostructure should be greater than or equal to 0.5. When the superlens provided by the embodiment of the present application has at least two nanostructure layers 12, the filling material in the nanostructure layer 12 farthest from the substrate layer 11 may be air. Alternatively, as shown in fig. 29 to 31, the nanostructures 1201 in any of the nanostructure layers 12 are periodically arranged in the form of superstructure units 121. The superstructure unit 121 is a close-packable pattern having a nanostructure 1201 disposed at the apex and/or center of the pattern. In the embodiments of the present application, the close-packable patterns refer to one or more patterns that can fill the entire plane without gaps and without overlapping.
As shown in fig. 29, according to an embodiment of the present application, the superstructure units may be arranged in a fan shape. As shown in fig. 30, according to embodiments of the present application, superstructure units may be arranged in an array of regular hexagons. Furthermore, as shown in fig. 31, according to embodiments of the present application, the superstructure units may be arranged in a square array. Those skilled in the art will recognize that the superstructure units included in the micro-structural layer may also include other forms of array arrangements, and all such variations are within the scope of the present application.
Optionally, the wide-spectrum phase of the superstructure unit 121 and the operating band of the superlens provided in the embodiment of the present application further satisfy:
wherein r is the coordinate of the superlens along the radial direction; r is 0 At any point on said superlens; λ is the operating wavelength.
The nanostructures 1201 provided by embodiments of the present application may be polarization independent structures that impart a propagation phase to incident light. The nanostructures 1201 may be positive or negative structures according to embodiments of the present application. For example, the shape of the nanostructures 1201 includes a cylinder, a hollow cylinder, a square prism, a hollow square prism, and the like. Illustratively, fig. 32 provides a perspective view of a three-layered nanostructure layer 12 in a superlens provided by an embodiment of the present application.
Alternatively, as shown in fig. 26, the superlens provided by the embodiment of the present application includes at least two layers of nanostructures 12. Wherein the nanostructures in adjacent nanostructure layers of the at least two layers of nanostructures 12 are coaxially aligned. The coaxial arrangement means that the arrangement periods of the nanostructures in the two adjacent nanostructure layers 12 are the same; or the axes of the nanostructures at the same position in two adjacent nanostructure layers coincide, as shown in fig. 26 or fig. 32. Fig. 32 shows a perspective view of a three-layer nanostructure layer. According to the embodiment of the present application, the shapes, sizes or materials of the nanostructures 12 in the adjacent nanostructure layers 12 may be the same or different.
Exemplarily, fig. 33a to 33d show a cylinder, a hollow cylinder, a square column and a hollow square column with a packing material, respectively. In fig. 33, a nanostructure 1021 is provided at the center of a positive quadrilateral superstructure unit 121. In some embodiments of the present application, fig. 34 a-34 d illustrate a cylinder, a hollow cylinder, a square column, and a hollow square column, respectively, with a filler material. In fig. 34, the nanostructure 1021 is arranged at the center of the positive quadrilateral superstructure unit 121.
Fig. 35a to 35d show a cylinder, a hollow cylinder, a square column, and a hollow square column, respectively, without a packing material, according to an embodiment of the present application. In fig. 35, nanostructures 1021 are arranged in the center of regular hexagonal superstructure unit 121. Alternatively, fig. 36a to 36d show negative nanostructures without a filler material, such as square hole pillars, circular hole pillars, square ring pillars, and circular ring pillars, respectively. In fig. 36, nanostructure 1021 is a negative structure disposed in the center of a regular hexagonal superstructure cell 121.
According to the embodiment of the present application, the arrangement period of the nanostructures 1201 in any one of the nanostructure layers 12 is greater than or equal to 0.3 λ c And is less than or equal to 2 lambda c . Optionally, the height of the nanostructures 1201 in any one of the nanostructure layers 12 is greater than or equal to 0.3 λ c And is less than or equal to 5 lambda c 。λ c The center wavelength of the operating band of the superlens provided by the present application.
According to an embodiment of the present application, the base layer 11 is made of a material having an extinction coefficient to the operating band of less than 0.1. For example, the material of the base layer 11 includes fused silica, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon. As another example, when the operating wavelength band of the superlens is the visible wavelength band, the material of the substrate layer 11 includes fused silica, quartz glass, crown glass, flint glass, sapphire, and alkali glass. The material of the nano-structure 1201 may be the same as or different from that of the base layer 11. Alternatively, the material of the filling material 1202 may be the same as or different from the material of the base layer 11.
It is understood that the material of the filler material 1202 may be the same as or different from the material of the nanostructures 1201. Optionally, the material of the filling material 1202 is a high-transmittance material in the working band, and the extinction coefficient thereof is less than 0.01. Illustratively, the material of the fill material 1202 includes fused quartz, quartz glass, crown glass, flint glass, sapphire, crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon.
Optionally, the superlens provided by the embodiment of the present application has an equivalent refractive index range smaller than 2. The equivalent refractive index range is the maximum refractive index of the superlens minus its minimum refractive index. According to the implementation mode of the application, the phase of the superlens provided by the embodiment of the application also satisfies the formula (11-1) to the formula (11-8):
wherein r is the distance from the center of the superlens to the center of any nanostructure; λ is the operating wavelength of the superlens,
for any phase associated with the operating wavelength, (x, y) are coordinates on the superlens, f ML Is the focal length of the superlens, a i And b i Are real number coefficients. In the formulas (11-1) to (11-3), (11-7) and (11-8), a 1 Or b 1 Less than zero. In the formulae (11-4) to (11-6), a 2 Or b 2 Less than zero. The phase of the superlens may be expressed in higher order polynomials, including odd and even polynomials. In order not to destroy the rotational symmetry of the phase of the superlens, the phase corresponding to the even-order polynomial can be optimized, which greatly reduces the degree of freedom of the design of the superlens. In the above formulas (11-1) to (11-8), compared with the other formulas, the formulas (11-4) to (11-6) can optimize the phase satisfying the odd polynomial without destroying the rotational symmetry of the superlens phase, thereby greatly improving the degree of freedom of optimization of the superlens.
In an alternative implementation, as shown in fig. 37, the superlens provided in the example of the present application further includes an antireflection film 13. The antireflection film 13 is arranged on the side of the substrate layer 11 far away from the at least one nanostructure layer 12; alternatively, the antireflection film 13 is disposed on a side of the at least one nanostructure layer 12 adjacent to air. The antireflection film 13 plays a role in antireflection and reflection reduction of incident radiation.
According to an embodiment of the present application, the phase of the superlens provided in any of the above embodiments is matched with the broadband phase as shown in equation 12:
in equation 12, λ max =700nm, λ min =400nm,
and
respectively, a theoretical target phase and a phase in the actual database. Fig. 38 to 41 show the matching degree of the phase of the superlens with the ideal phase in embodiments 1 to 4 provided by the present application.
The embodiment of the application also provides a processing method of the super lens, which is suitable for the super lens provided by any embodiment. As shown in fig. 42 and 43, the method includes at least steps S1 to S5.
Step S1, a layer of structural layer material 12a is disposed on the base layer 11.
Step S2, a photoresist 14 is coated on the structural layer material 12a, and the reference structure 1401 is exposed.
In step S3, a nanostructure 1201 is etched on the structural layer material 12a according to the reference structure 1401 to form the nanostructure layer 12.
Step S4, a filling material 1202 is disposed between the nanostructures 1201.
Step S5, the surface of the filling material 1202 is trimmed to make the surface of the filling material 1202 coincide with the surface of the nanostructure 1201.
Optionally, as shown in fig. 42 and fig. 44, the method provided in the embodiment of the present application further includes:
and S6, repeating the steps S1 to S5 until the setting of all the nanostructure layers is completed.
Example 5
The embodiment of the application provides an optional superlens, and the parameters of the superlens are shown in a table 5-1. The phase and transmittance of the superlens are shown in fig. 45 and 46, respectively.
The wide-spectrum phase response and the wavelength of any superstructure unit in the embodiment 5 meet the following conditions:
TABLE 5-1
Example 6
The embodiments of the present application provide an alternative superlens, the parameters of which are shown in table 6-1. The phase and transmittance of the superlens are shown in fig. 47 and 48, respectively. The wide-spectrum phase response and the wavelength of any superstructure unit in the embodiment 6 meet the following conditions:
TABLE 6-1
It should be noted that the superlens provided by the embodiments of the present application can be processed by a semiconductor process, and has the advantages of light weight, thin thickness, simple structure and process, low cost, high consistency of mass production, and the like.
In summary, the optical system provided by the embodiments of the present application is combined by a superlens and the other three refractive lenses, and the optical system satisfies f/EDP<3；25°≤HFOV≤65°；0.3≤f N F is less than or equal to 5.5; thereby realizing thatThe total length of the optical system is reduced on the premise of ensuring the imaging effect, and the miniaturization and the light weight of the optical system are promoted.
According to the super lens provided by the embodiment of the application, the depth-to-width ratio of a single nano structure is increased through at least one layer of nano structure layer, the design freedom degree of the super lens is improved, and the design of the super lens structure on the optical performance of the super lens is broken through.
The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments disclosed in the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.
Claims (28)
1. An optical system characterized by comprising a first lens (10), a second lens (20), a third lens (30), and a fourth lens (40) disposed in this order from an object side to an image side;
wherein any one of the first lens (10), the second lens (20), the third lens (30) and the fourth lens (40) is a super lens, and the rest are refractive lenses;
at least one of an object side surface and an image side surface of each refractive lens in the optical system includes an aspheric surface including an inflection point;
the optical system satisfies:
f/EDP<3；
25°≤HFOV≤65°；
0.3≤f N /f≤5.5；
wherein f is the focal length of the optical system; EPD is the entrance pupil diameter of the optical system; f. of N The focal length of the first refractive lens from the object side to the image side in the optical system; the HFOV is half of the maximum field angle of the optical system.
2. The optical system of claim 1, wherein a first refractive lens from the object side to the image side in the optical system has positive optical power.
3. The optical system according to claim 1, characterized in that it further comprises a diaphragm (50);
the diaphragm (50) is disposed between any two adjacent lenses of the first lens (10), the second lens (20), the third lens (30), and the fourth lens (40).
4. The optical system of claim 1, wherein the first refractive lens in the optical system satisfies:
R No /f N ≥0.23；
wherein R is No The radius of curvature of the object side surface of the first piece of refractive power in the optical system; f. of N Is the focal length of the first refractive lens.
5. The optical system of claim 1, wherein the optical system further satisfies:
(V N +V N+2 )/2-V N+1 >20；
wherein, V N The Abbe number of a first refractive lens in the optical system; v N+1 The Abbe number of a second refraction lens in the optical system; v N+2 The abbe number of the third refractive lens in the optical system.
6. The optical system of claim 1, wherein the optical system further satisfies:
1.2<TTL/ImgH<2.8；
wherein, TTL is the total system length of the optical system; imgH is the maximum imaging height of the optical system.
7. The optical system of claim 1, wherein the optical system further satisfies:
1.54≤n N ≤1.6；
1.5≤n N+1 ≤1.6；
wherein n is N The refractive index of a first refractive lens in the optical system; n is N+1 The refractive index of the second piece of refractive lens in the optical system.
8. The optical system of claim 1, wherein the optical system further satisfies:
|f ML |/f>10；
wherein f is ML Is the focal length of the superlens; f is the focal length of the optical system.
9. The optical system of claim 1, wherein the superlens has a thickness greater than or equal to 0.05mm and less than or equal to 2mm.
10. An optical system according to any one of claims 1 to 9, characterized in that the first lens (10) is a superlens; the object side surface of the second lens (20) is a convex surface and has positive focal power; the object side surface of the third lens (30) is a concave surface; the object side surface of the fourth lens (40) is convex.
11. The optical system according to claim 10, characterized in that the thickness of the first lens (10) is greater than or equal to 0.05mm and less than or equal to 1mm.
12. The optical system according to any of claims 1 to 9, wherein the second lens (20) is a superlens; the object side surface of the first lens (10) is a convex surface and has positive focal power; the object side surface of the third lens (30) is a concave surface; the object side surface of the fourth lens (40) is a convex surface.
13. The optical system according to any of claims 1 to 9, wherein the third lens (30) is a superlens; the object side surface of the first lens (10) is a convex surface and has positive focal power; the object side surface of the second lens (20) is a concave surface; the object side surface of the fourth lens (40) is a convex surface.
14. The optical system according to any of claims 1 to 9, wherein the fourth lens (40) is a superlens; the object side surface of the first lens (10) is a convex surface and has positive focal power; the object side surface of the second lens (20) is a concave surface; the object side surface of the third lens (30) is convex.
15. An imaging apparatus, characterized in that the imaging apparatus comprises an optical system according to any one of claims 1 to 14; and a photosensitive element disposed on the image plane of the optical system.
16. An electronic device characterized in that it comprises the imaging apparatus according to claim 15.
17. A superlens adapted for use in an optical system according to any one of claims 1 to 14, the superlens comprising a substrate layer (11) and at least one nanostructure layer (12);
wherein the at least one nanostructure layer (12) is arranged on one side of the substrate layer (11);
each of the at least one nanostructure layer (12) comprises periodically arranged nanostructures (1201).
18. A superlens according to claim 17, wherein the superlens comprises at least two nanostructure layers (12);
the nanostructures (1201) in adjacent ones of the at least two nanostructure layers (12) are coaxially arranged.
19. The superlens of claim 17, wherein the nanostructures (1201) are arranged periodically in the form of superstructure units (121);
the superstructure unit (121) is a close-packable pattern, the nanostructures (1201) being disposed at vertices and/or central locations of the close-packable pattern.
20. A superlens as claimed in any one of claims 17 to 19, wherein the phase of the superlens is such that at least:
wherein r is the distance from the center of the superlens to the center of any nanostructure; λ is the operating wavelength of the superlens,
for any phase associated with the operating wavelength, (x, y) are coordinates on the superlens, f ML Is the focal length of the superlens, a i And b i Are real number coefficients.
21. The superlens of claim 19, wherein the wide-spectrum phase of the superstructure unit (121) and the operating wavelength of the superlens further satisfy:
wherein r is the coordinate of the superlens along the radial direction; r is 0 At any point on said superlens; λ is the operating wavelength.
22. A superlens according to any of claims 17-19, wherein said superlens has an equivalent refractive index in the range of less than 2;
the equivalent refractive index range is the maximum refractive index of the superlens minus the minimum refractive index of the superlens.
23. A superlens according to any of claims 17-19, wherein the nanostructures (1201) have an arrangement period of greater than or equal to 0.3 λ c And is less than or equal to 2 lambda c ；
Wherein λ is c Is the center wavelength of the working waveband of the superlens.
24. The superlens of any of claims 17-19, wherein the height of the nanostructures (1201) is greater than or equal to 0.3 λ c And is less than or equal toEqual to 5 λ c ；
Wherein λ is c Is the center wavelength of the superlens operating band.
25. A superlens according to any of claims 17-19, wherein the nanostructures (1201) are shaped as polarization-independent structures.
26. A superlens according to any of claims 17-19, wherein filling material (1202) is further filled between the nanostructures of the same nanostructure layer;
the fill material (1202) has an extinction coefficient of less than 0.01 for the superlens operating band.
27. The superlens of claim 26, wherein the fill material (1202) is different from a material of the nanostructures (1201); and the number of the first and second electrodes,
the filler material (1202) is different from the material of the base layer (11).
28. A superlens according to any of claims 17-19, wherein the superlens further comprises an antireflection film (13);
the antireflection film (13) is arranged on one side of the substrate layer (11) far away from the at least one nanostructure layer (12); or,
the antireflection film (13) is arranged on one side, adjacent to air, of the at least one nanostructure layer (12).
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| CN202221011048.9U CN217639715U (en) | 2022-04-28 | 2022-04-28 | Optical system, superlens therein, imaging device comprising same and electronic equipment |
| PCT/CN2023/090245 WO2023207892A1 (en) | 2022-04-28 | 2023-04-24 | Optical system and imaging device comprising same, and electronic device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
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2022
- 2022-04-28 CN CN202221011048.9U patent/CN217639715U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
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