WO2020019601A1 - 超构表面主镜、辅镜，及其制备方法和光学系统 - Google Patents

超构表面主镜、辅镜，及其制备方法和光学系统 Download PDF

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Publication number
WO2020019601A1
WO2020019601A1 PCT/CN2018/116927 CN2018116927W WO2020019601A1 WO 2020019601 A1 WO2020019601 A1 WO 2020019601A1 CN 2018116927 W CN2018116927 W CN 2018116927W WO 2020019601 A1 WO2020019601 A1 WO 2020019601A1
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Prior art keywords
mirror
metamorphic
metasurface
auxiliary
main mirror
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PCT/CN2018/116927
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English (en)
French (fr)
Inventor
李贵新
刘萱
邓俊鸿
李敬辉
程鑫
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Southern University of Science and Technology
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Southern University of Science and Technology
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Priority to KR1020217005316A priority Critical patent/KR20210043590A/ko
Priority to US17/278,865 priority patent/US20220050225A1/en
Priority to JP2021528343A priority patent/JP2022507847A/ja
Publication of WO2020019601A1 publication Critical patent/WO2020019601A1/zh
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0808—Mirrors having a single reflecting layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
    • G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
    • G02B5/0858—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising a single metallic layer with one or more dielectric layers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
    • G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
    • G02B5/0875—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising two or more metallic layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/16—Coating processes; Apparatus therefor
    • G03F7/162—Coating on a rotating support, e.g. using a whirler or a spinner
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2037—Exposure with X-ray radiation or corpuscular radiation, through a mask with a pattern opaque to that radiation
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
    • G02B23/02—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors
    • G02B23/06—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors having a focussing action, e.g. parabolic mirror

Definitions

  • the present disclosure relates to the technical field of metasurfaces, for example, to a metasurface main mirror, a secondary mirror, a primary mirror, a method for preparing a secondary mirror, and an optical system.
  • Refractive lenses occupy an irreplaceable position in focusing and imaging systems.
  • Reflective lenses made up of multiple mirrors also have essential applications in microscopes, telescopes, cameras, and infrared imaging equipment. In order to observe and photograph objects more conveniently, objects and images are often required to be located on both sides of the lens, respectively.
  • effective phase tuning and wavefront shaping depend on the continuous geometric curvature of the element surface. To obtain a high-quality lens, manufacturing processes such as harsh grinding and polishing are required. Therefore, it is inevitable that the lenses in the related art will be bulky and expensive to prepare, making it difficult to achieve miniaturization, integration, and low-cost mass production.
  • the related technology provides an effective solution for this, that is, using a metastructured surface, which is an interface composed of subwavelength metastructured surface functional units with spatial variation.
  • a metastructured surface which is an interface composed of subwavelength metastructured surface functional units with spatial variation.
  • metasurfaced functional units By carefully designing metasurfaced functional units, Can effectively control the polarization, amplitude and phase of electromagnetic waves on the sub-wavelength scale.
  • the two-dimensional properties of the metamorphic surface enable the metamorphic surface to realize electromagnetic functional elements that are more compact, lighter, and less lossy.
  • the fabrication process of the superstructured surface is compatible with the complementary metal oxide semiconductor technology in the related technology, and it is easier to integrate into the optoelectronic technology.
  • Planar elements based on metastructured surfaces have a wide range of applications, such as holographic imaging, polarization conversion, spin-orbit angular momentum that generates light, and abnormal reflection / refraction.
  • the most attractive and promising examples are planar lenses, which can be used as a single lens, can also form a lens group, or even combine into other more complex optical systems.
  • Metasurface lenses make refractive optical components thin, compact, and easy to integrate, and they can play a more important role in ultra-small optical devices with more advanced functions.
  • planar transmissive lenses based on refractive metamorphic surfaces have rarely been involved.
  • reflective metamorphic surfaces a single reflective element cannot form an effective transmissive lens.
  • a plane transmission lens based on a reflective metasurface is as important as a plane transmission lens based on a refractive metasurface, and in telescopes and a large number of infrared systems, the reflective transmission focusing system Design is irreplaceable.
  • the present disclosure proposes a superstructured surface main mirror, auxiliary mirror, main mirror, auxiliary mirror preparation method, and optical system, which can realize the design of a reflective superstructured surface for a transmissive lens, and solve the reflective objective lens process preparation in the related technology. Harsh, heavy, bulky and difficult to miniaturize and integrate problems, which is conducive to low-volume production in large quantities.
  • An embodiment provides a method for preparing a metamorphic surface primary mirror, comprising: providing a transparent substrate; and forming a pattern of a functional unit of a metamorphic surface of the primary mirror on the transparent substrate to satisfy the phase distribution of the primary mirror to The incident light reflected by the metasurface auxiliary mirror to the metasurface main mirror is reflected and focused.
  • An embodiment provides a metamorphic surface primary mirror prepared by using the above method for preparing a metamorphic surface primary mirror, wherein the metamorphic surface primary mirror includes: a transparent substrate; and the transparent substrate is located on the transparent substrate.
  • the primary mirror metamorphic surface functional unit pattern, the primary mirror metamorphic surface functional unit pattern is set to satisfy the phase distribution of the primary mirror to perform incident light reflected by the metamorphic surface auxiliary mirror to the metamorphic surface primary mirror Reflection focus.
  • An embodiment provides a method for preparing a superstructured surface auxiliary mirror, including: providing a transparent substrate; and forming a pattern of the functional unit of the superstructured surface of the auxiliary mirror that satisfies the phase distribution of the auxiliary mirror on the transparent substrate, so that The incident light incident on the metasurface auxiliary mirror is reflected on the metasurface primary mirror, and is reflected and focused by the metasurface primary mirror.
  • An embodiment provides a metamorphic surface auxiliary mirror, which is prepared by using the above method for preparing a metamorphic surface auxiliary mirror, and includes: a transparent substrate; and a functional unit pattern of a superstructure surface on the transparent substrate.
  • the auxiliary mirror metamorphic surface functional unit pattern is set to satisfy the auxiliary mirror phase distribution, so as to reflect the incident light incident on the metamorphic surface auxiliary mirror to the metamorphic surface main mirror and pass through the metamorphic surface master Mirror for reflective focusing.
  • An embodiment provides an optical system including the above-mentioned metasurface primary mirror and the above-mentioned metasurface auxiliary mirror.
  • FIG. 1 is a side view of a reflective objective lens in the related art
  • FIG. 2 is a schematic diagram of a planar metasurface reflector reflecting incident light according to an embodiment
  • FIG. 3 is a schematic structural diagram of a metastructured surface functional unit according to an embodiment
  • FIG. 4 is a side view of a planar reflective metasurface objective provided by an embodiment
  • FIG. 5 is a top view of a superstructured surface primary mirror provided by an embodiment
  • FIG. 6 is a top view of a metasurface auxiliary mirror provided by an embodiment
  • FIG. 7 is a schematic flowchart of a method for preparing a superstructured surface primary mirror according to an embodiment
  • FIG. 8 is a schematic flowchart of another method for preparing a superstructured surface primary mirror according to an embodiment
  • 9 to 13 are side views of the metamorphic surface primary mirror corresponding to the multiple processes of the method for preparing the metamorphic surface primary mirror of FIG. 8;
  • FIG. 14 is a schematic flowchart of a method for manufacturing a superstructured surface auxiliary lens according to an embodiment
  • 15 is a schematic flowchart of another method for manufacturing a superstructured surface auxiliary lens according to an embodiment
  • FIGS. 16-21 are side views of the metasurface auxiliary mirror corresponding to the multiple processes of the method for manufacturing the metasurface auxiliary mirror of FIG. 15.
  • FIG. 1 is a side view of a reflective objective lens in the related art.
  • the reflective objective lens includes a curved main lens 10 and a curved auxiliary lens 20.
  • the reflective objective lens is usually a Schwarzschild reflective objective lens, that is, the curved main lens 10 and the curved auxiliary lens 20 are co-spherical.
  • Spherical mirror, curved auxiliary mirror 20 is aligned with the opening in curved main mirror 10
  • incident light 100 is incident on the reflecting surface of curved auxiliary mirror 20 through the opening in curved main mirror 10
  • incident light 100 passes through curved auxiliary mirror After reflecting at 20, it reaches the reflecting surface of the curved main mirror 10 in two parts, and finally reflects and focuses to point A through the curved main mirror 10.
  • this reflective objective requires continuous geometric curvature changes on the reflecting surfaces of the curved main mirror 10 and curved auxiliary mirror 20 to achieve the ideal phase tuning and wavefront shaping. Therefore, to obtain high-quality reflective focusing, harsh Preparation processes such as grinding and polishing make the reflective objective lenses in the related art large in size, heavy in weight, and expensive to prepare, making it difficult to achieve miniaturization, integration, and low-cost mass production.
  • the present embodiment realizes the design of a plane transmission type metamorphic surface lens by using a flat reflective metamorphic surface, so that the reflective lens has the advantages of lightness, compactness and easy integration, and the preparation process of the metamorphic surface is also It greatly reduces the difficulty of preparing curved reflective objective lenses in the related art, and is conducive to the realization of large-scale and low-cost production and assembly of reflective objective lenses.
  • FIG. 2 is a schematic diagram of a planar metamorphic surface reflector provided in this embodiment to reflect incident light
  • FIG. 3 is a schematic structural diagram of a metamorphic surface functional unit provided in this embodiment.
  • the metasurface mirror 30 is designed according to the generalized reflection law.
  • the generalized reflection law can be understood as that the wave vector component of the reflected light along the direction of the reflection interface is equal to the wave vector of the incident light along the direction of the reflection interface.
  • the metamorphic surface reflector 30 has a gradient phase metamorphic surface.
  • the reflected light of the gradient phase metamorphic surface is deflected relative to the reflected light of the horizontal specular surface, which is caused by the extra phase gradient introduced by the metamorphic surface.
  • the metasurface reflector includes a plurality of metasurface functional units 31, and each metasurface functional unit 31 includes at least an anisotropic sub-wavelength structure 311.
  • each metasurface functional unit 31 includes at least an anisotropic sub-wavelength structure 311.
  • the deflection angle of the reflected light can be caused by different angles, and the deflection angle of the reflected light can be adjusted by setting the azimuth angle of the sub-wavelength structure 311.
  • the superstructured surface functional unit 31 may be a laminated structure of the reflective metal layer 313, the dielectric layer 312, and the sub-wavelength structure 311, or may be a single-layer structure of the sub-wavelength structure 311.
  • the sub-wavelength structure 311 may be It is a metal sub-wavelength structure or a medium sub-wavelength structure, and the sub-wavelength structure 311 may be a rod shape or an ellipse shape to achieve a higher conversion efficiency of circularly polarized light.
  • FIG. 4 is a side view of the planar reflective metamorphic surface lens provided in this embodiment.
  • the planar reflective metamorphic surface lens includes a metamorphic surface main mirror 1 and a metamorphic lens that are oppositely disposed.
  • the surface auxiliary mirror 2 has a predetermined distance between the metasurface main mirror 1 and the metasurface auxiliary mirror 2.
  • the metasurface main mirror 1 includes a ring-shaped main mirror metasurface functional structure 11 And the circular light transmitting hole 12 surrounded by the main mirror metasurface functional structure 11, the main mirror metasurface functional structure 11 includes a plurality of main mirror metasurface functional units (not shown in FIG. 5, refer to FIG. 3) Structure of the metamorphic surface functional unit), the main mirror metasurface functional unit includes a main mirror subwavelength structure 111, and the main mirror subwavelength structure 111 is arranged on the main mirror metasurface functional structure 11 at a specific azimuth angle;
  • the metamorphic surface auxiliary mirror 2 includes a disc-shaped metamorphic surface functional structure 21, and the metamorphic surface functional structure 21 includes a plurality of metamorphic surface functional units (not shown in FIG. 6, which can be referred to FIG.
  • auxiliary mirrors Sub-wavelength structure 211 auxiliary mirror Sub-wavelength structure 211 is arranged on the auxiliary mirror metamorphic surface functional structure 21 at a specific azimuth angle.
  • the metamorphic surface functional structure 21 and the metamorphic surface of the auxiliary surface secondary mirror 2 The light transmission holes 12 of the primary mirror 1 are aligned so that the incident light 100 passes through the light transmission holes 12 and is incident on the auxiliary mirror superstructure surface functional structure 21.
  • the incident light 100 reaching the auxiliary mirror superstructure surface functional structure 21 is due to the auxiliary mirror.
  • the additional phase gradient introduced by the sub-wavelength structure 211 reflects in a specific direction and reaches the main mirror superstructure surface functional structure 11.
  • the additional phase gradient introduced by the main mirror sub-wavelength structure 111 causes the main mirror 1 to be reflected by the superstructure surface.
  • the reflected light is focused at point B. Therefore, in this embodiment, the combination of the metamorphic surface main mirror 1 and the metamorphic surface auxiliary mirror 2 can be used to implement the design of a planar reflective metamorphic surface lens.
  • This embodiment provides a method for preparing a metamorphic surface primary mirror, a metamorphic surface main mirror, a metamorphic surface auxiliary mirror, and a metamorphic surface auxiliary mirror, respectively.
  • FIG. 7 is a schematic flowchart of a method for preparing a superstructured surface primary mirror provided in this embodiment. As shown in FIG. 7, the method for preparing the metasurface primary mirror includes:
  • step 110 a transparent substrate is provided.
  • a transparent substrate in a corresponding working wavelength band is selected according to a material of the functional unit pattern of the primary mirror metasurface on the transparent substrate, so as to adapt to incident light in different working wavelength bands.
  • step 120 a main mirror metamorphic surface functional unit pattern that satisfies the phase distribution of the main mirror is formed on the transparent substrate, so as to reflect and focus the incident light reflected on the main mirror via the metasurface auxiliary mirror.
  • the phase distribution of the main mirror can be determined according to the setting parameters in combination with ray optics and the generalized law of reflection.
  • the setting parameters include the focal length of the system, the diameter of the metasurface master mirror and the metasurface auxiliary mirror, and the metasurface master mirror. , The distance between the metasurface auxiliary mirrors, the operating wavelength of the system, and the mapping relationship between the position where the incident light reaches the metasurface auxiliary mirror and the position where the metasurface auxiliary mirror reflects the incident light to the main surface.
  • the optical path of the incident light after entering the system can be determined according to the above-mentioned setting parameters, and combined with ray optics and the generalized reflection law, the additional phase gradients that need to be introduced at multiple positions of the primary mirror of the superstructured surface can be determined, thereby determining Phase distribution of the main mirror of the main mirror on the metasurface.
  • the phase distribution of the main mirror can also be determined according to the geometry of the curved main mirror in the curved reflective objective lens.
  • the curved reflective objective includes a curved main mirror and a curved auxiliary mirror.
  • the curved main mirror is set to reflect the curved auxiliary mirror to The incident light on the curved main mirror is reflected and focused.
  • the set curved reflection objective lens can be any existing curved reflection objective lens or a curved reflection objective lens set according to requirements.
  • the phase-tuning effect of the curved main lens on the light in the set curved reflection objective lens can be adjusted. , Determine the phase of the corresponding position on the main mirror of the metamorphic surface in this embodiment, thereby determining the phase distribution of the main mirror of the main mirror of the metamorphic surface.
  • the curved reflective objective lens may be a Schwarzschild reflective objective lens
  • the superstructured surface primary lens may be determined according to the direction angle of the reflected light at multiple positions on the curved main mirror that is normally incident on the curved main mirror, and combined with the generalized law of reflection The phase distribution needed to be introduced.
  • a metamorphic surface primary mirror that matches a metamorphic surface auxiliary mirror in an optical system can be prepared, thereby achieving
  • the design of a plane transflective lens based on a reflective metastructured surface solves the problems of harsh preparation, heavy weight, large volume, difficulty in miniaturization, and integration of reflective objective lenses in related technologies.
  • a flat reflective superstructured surface is used to replace the curved mirror in the related art, which has the advantages of lightness, compactness and ease of integration, and the preparation process of the superstructured surface greatly reduces the curved reflective objective lens in the related technology.
  • the difficulty of preparation is conducive to the large-scale and low-cost production of reflective lenses.
  • forming a primary mirror metasurface functional unit pattern on a transparent substrate that satisfies the phase distribution of the primary mirror includes:
  • a main mirror metamorphic surface functional structure is formed on a set annular region above a transparent substrate, wherein the main mirror metamorphic surface functional structure includes a plurality of main mirror metamorphic surface functional units, and the main mirror metamorphic surface functional unit includes a main mirror. Sub-wavelength structure. The phase introduced by the main-wavelength sub-wavelength structure satisfies the phase distribution of the main mirror. The incident light passes through the light-transmissive holes to reach the metasurface auxiliary mirror. .
  • the main mirror metamorphic surface functional unit includes a laminated structure of a reflective metal layer, a dielectric layer, and a metal sub-wavelength structure; or, the main mirror metamorphic surface functional unit includes a reflective metal layer and a metal main mirror subwavelength structure.
  • a laminated structure of the main mirror meta-surface function unit including a reflective metal layer and a dielectric sub-wavelength sub-wavelength structure of the main mirror; the main mirror sub-wavelength structure has at least one of a rod shape and an oval shape.
  • forming a primary mirror metasurface functional structure on a set annular region above a transparent substrate includes:
  • the electron beam evaporation process or the thermal evaporation process is used to sequentially deposit and stack the reflective metal layer and the dielectric layer on the transparent substrate; and the electronic layer or the photoresist is spin-coated on the dielectric layer.
  • Electron beam exposure or photomask exposure process is used to pattern the portion of the electronic glue or photoresist in the set annular area, so that the patterned electronic glue or photoresist meets the phase distribution of the main mirror; the electron beam evaporation process is used
  • the metal layer is deposited on the surface of the dielectric layer and the patterned electronic adhesive or photoresist by a thermal evaporation process, and the patterned electronic adhesive or photoresist is removed to retain the metal layer on the surface of the dielectric layer and form a main layer.
  • FIG. 8 is a schematic flowchart of another method for preparing a superstructured surface primary mirror provided in this embodiment. As shown in FIG. 8, the method for preparing the metasurface primary mirror includes:
  • step 210 a transparent substrate is provided.
  • step 220 an electron beam evaporation process or a thermal evaporation process is used to sequentially vapor-deposit the stacked reflective metal layer and the dielectric layer on the transparent substrate.
  • the reflective metal layer 112 may be first deposited on the transparent substrate 200 by using an electron beam evaporation process, and then the dielectric layer 113 may be deposited on the reflective metal layer 112 by using a thermal evaporation process.
  • the material of the reflective metal layer 112 and the dielectric layer 113 can be selected according to the working wavelength band of the optical system.
  • the material of the reflective metal layer 112 can be a metal material such as gold, silver, or aluminum, and the dielectric layer 113
  • the material of the material can be silicon dioxide or titanium dioxide; in the infrared band, the material of the reflective metal layer 112 can be gold, silver, aluminum, silicon dioxide or titanium dioxide, and the material of the dielectric layer 113 can be CaF2, MgF2, Ge, or polytetrafluoride A medium such as ethylene; in the microwave band, the material of the reflective metal layer 112 may be a metal material such as gold, silver, or aluminum, and the material of the dielectric layer 113 may be a transparent ceramic.
  • step 230 an electronic glue or a photoresist is spin-coated on the dielectric layer.
  • step 240 electron beam or photomask exposure is used to pattern the electronic glue or photoresist located in the set annular area, so that the patterned electronic glue or photoresist can satisfy the phase distribution of the main mirror.
  • a photoresist 114 is spin-coated on the dielectric layer 113, and the photoresist 114 located in a set annular region is patterned by using an electron beam exposure or a mask exposure process (all patterns can also be patterned) (Only the photoresist after patterning in the set annular region satisfies the phase distribution of the main mirror), so that the photoresist after patterning satisfies the phase distribution of the main mirror.
  • the ring-shaped region is a region surrounding the light-transmissive hole, and the inner aperture size of the ring-shaped region can be designed according to the set size of the metasurface auxiliary mirror.
  • electron beam lithography should be used to pattern the electronic glue
  • ultraviolet lithography should be used to pattern the photoresist.
  • the size of the subsequent sub-wavelength structure of the main mirror will be different, and the lithography process used in this step will also be different.
  • the visible light band electron beam lithography is mostly used; in the infrared band, Optional UV lithography.
  • the microwave band printed circuit board technology can be used.
  • a metal layer is vapor-deposited on the surface of the dielectric layer and the surface of the patterned electronic adhesive or photoresist using an electron beam evaporation process or a thermal evaporation process.
  • step 260 the patterned electronic glue or photoresist is removed, and the metal layer on the surface of the dielectric layer is retained to form a pattern of the sub-wavelength structure of the main mirror.
  • an electron beam evaporation process may be used to vapor-deposit a metal layer 115 on the surface of the dielectric layer 113 and the surface of the remaining photoresist 114 (photoresist after patterning), wherein the remaining photoresist
  • the opening 114 defines the shape, size, and azimuth of the main mirror sub-wavelength structure formed on the surface of the dielectric layer 113.
  • the remaining photoresist 114 is removed by using a corresponding degreasing solution, and then the metal layer 115 formed on the surface of the remaining photoresist 114 is peeled off at the same time, and the metal layer on the surface of the dielectric layer 113 is retained to form the main mirror sub.
  • Wavelength structure 111 is used to vapor-deposit a metal layer 115 on the surface of the dielectric layer 113 and the surface of the remaining photoresist 114 (photoresist after patterning), wherein the remaining photoresist
  • the opening 114 defines the shape, size, and azimut
  • a focused ion beam etching process, a reactive ion beam etching process, an inductively coupled plasma etching process, an ion thinning process, a photolithography process, or a laser process are used to remove the reflective metal layer surrounded by the set annular region and The dielectric layer forms a flat circular light transmitting hole.
  • any one of a focused ion beam etching process, a reactive ion beam etching process, an inductively coupled plasma etching process, an ion thinning process, a photolithography process, or a laser process may be used for removal.
  • the reflective metal layer 112 and the dielectric layer 113 in the areas corresponding to the light-transmitting holes to be formed form circular flat light-transmitting holes 12 and form a ring-shaped main mirror superstructured surface functional structure, thereby completing the preparation of the superstructured surface main mirror.
  • using a photolithography process to pattern the electronic adhesive or photoresist located in the set annular region further includes:
  • an electron beam exposure or photomask exposure process is used to pattern the portion of the electronic or photoresist in a set annular region.
  • This embodiment provides a superstructured surface primary mirror, which can be prepared by using the method for preparing a superstructured surface primary mirror provided in any of the embodiments.
  • the metamorphic surface main mirror includes: a transparent substrate; a metamorphic surface functional unit pattern of the main mirror on the transparent substrate; the metamorphic surface functional unit pattern of the main mirror satisfies the phase distribution of the main mirror, so that The incident light reflected on the metasurface primary mirror is reflected and focused.
  • the main mirror metamorphic surface functional unit pattern includes a main mirror metamorphic surface functional structure 11 located in a set annular region, and the main mirror metamorphic surface functional structure 11 includes a plurality of main mirrors.
  • Metamorphic surface functional unit, the main mirror The metamorphic surface functional unit includes an anisotropic main mirror subwavelength structure 111, and the phase introduced by the main mirror subwavelength structure 111 satisfies the phase distribution of the main mirror; the metamorphic surface main mirror also includes a circular main The light transmission hole 12 surrounded by the mirror metasurface surface functional structure 11 passes incident light through the light transmission hole 12 to the metasurface auxiliary mirror.
  • the main mirror meta-surface functional unit includes a laminated structure of a reflective metal layer 112, a dielectric layer 113, and a metal sub-wavelength structure 111; or, the main mirror meta-surface functional unit includes a reflective metal layer and a metal main mirror.
  • the primary mirror of a metastructured surface designed based on the principle of Bailey's geometric phase has different azimuth angles of the main mirror sub-wavelength structures corresponding to different phases, that is, the main mirror sub-wavelength structures at different positions are set according to the required phase distribution. Azimuth angle to achieve reflection focusing of the main mirror of the metasurface.
  • the sub-wavelength structure of the main mirror is at least one of a rod shape and an ellipse shape, so as to achieve higher conversion efficiency of circularly polarized light.
  • the functional unit of the main surface of the main mirror includes a laminated structure of the reflective metal layer 112, the dielectric layer 113, and the metal sub-wavelength structure 111
  • the materials of the reflective metal layer 112 and the metal sub-wavelength structure 111 are gold
  • the material of 113 is silicon dioxide
  • the metal sub-wavelength structure 111 is rod-shaped, the conversion efficiency of circularly polarized light can be as high as 80% in the near-infrared band.
  • the preparation method of the superstructured surface main mirror provided in this embodiment and the preparation method of the superstructured surface main mirror provided in this embodiment have the same functions and beneficial effects.
  • the preparation method for preparing the superstructured surface primary mirror of this embodiment will not be repeated here.
  • FIG. 14 is a schematic flowchart of a method for preparing a superstructured surface auxiliary lens provided in this embodiment. As shown in FIG. 14, the method for preparing the superstructured surface auxiliary lens includes:
  • step 310 a transparent substrate is provided.
  • a transparent substrate in a corresponding working band is selected to adapt to incident light in different working bands.
  • step 320 a secondary mirror metasurface functional unit pattern that satisfies the phase distribution of the secondary mirror is formed on the transparent substrate to reflect the incident light incident on the secondary mirror to the primary mirror of the secondary surface, The main mirror of the surface is focused by reflection.
  • the phase distribution of the auxiliary mirror can be determined according to the set parameters in combination with ray optics and the generalized law of reflection.
  • the set parameters include the focal length of the system, the diameter of the metasurface primary mirror and the metasurface primary mirror, and the metasurface primary The mapping relationship between the distance between the mirror and the metasurface auxiliary mirror, the working wavelength of the optical system, and the position where the incident light reaches the metasurface auxiliary mirror and the position of the metasurface auxiliary mirror reflecting the incident light to the position on the metasurface main mirror;
  • the optical path of the incident light after entering the system is determined, and combined with the ray optics and the generalized reflection law, the additional phase gradients that need to be introduced at multiple positions of the meta-surface auxiliary mirror are determined, thereby determining the entire Phase distribution of auxiliary mirrors for metasurface auxiliary mirrors.
  • the phase distribution of the auxiliary mirror can also be determined according to the geometry of the curved auxiliary mirror in the set curved reflective objective lens.
  • the curved reflective objective lens includes a curved main mirror and a curved auxiliary mirror.
  • the curved auxiliary mirror is used to reflect incident light to the curved main lens. On the mirror, focus is reflected by a curved main mirror.
  • the phase tuning effect of the curved auxiliary lens on the light in the set curved reflective objective lens is used to determine the phase of the corresponding position on the superstructured surface auxiliary lens in this embodiment, thereby determining the auxiliary lens of the entire superstructured surface auxiliary lens. Phase distribution.
  • the curved reflective objective lens may be a Schwarzschild reflective objective lens, and the direction angle of the reflected light at multiple positions where the parallel light is normally incident on the curved auxiliary lens is combined with the generalized law of reflection to determine the metasurface auxiliary lens.
  • a superstructured surface auxiliary mirror that matches the main mirror of a superstructured surface in an optical system (including a planar reflective superstructured surface lens) can be prepared, thereby achieving
  • the design of the planar transmissive lens with a reflective metamorphic surface solves the problems in the related art that the preparation of reflective objective lenses is harsh, heavy, bulky, and difficult to miniaturize and integrate.
  • a planar reflective metamorphic surface lens is used instead of the curved mirror in the related art.
  • the planar reflective metamorphic surface lens has the advantages of lightness, compactness and ease of integration, and the preparation process of the metamorphic surface is greatly reduced.
  • the curved surface of the related art objective lens in the related art is difficult to prepare, which is conducive to the large-scale and low-cost production of reflective lenses.
  • forming the auxiliary mirror metasurface functional unit pattern on the transparent substrate to satisfy the auxiliary mirror phase distribution includes:
  • the auxiliary mirror metamorphic surface functional structure is formed on a set circular area above the transparent substrate, wherein the auxiliary mirror metamorphic surface functional structure includes a plurality of auxiliary mirror metamorphic surface functional units, and the auxiliary mirror metamorphic surface functional unit includes auxiliary The sub-wavelength structure of the mirror, the phase introduced by the sub-wavelength structure of the auxiliary mirror satisfies the phase distribution of the auxiliary mirror.
  • the circular area is set to be aligned with the light transmission hole of the main mirror of the metasurface, so that the incident light passes through the light aperture to reach the metastructure surface.
  • Auxiliary mirror is set to be aligned with the light transmission hole of the main mirror of the metasurface, so that the incident light passes through the light aperture to reach the metastructure surface.
  • the auxiliary mirror metamorphic surface functional unit includes a laminated structure of a reflective metal layer, a dielectric layer, and a metal sub-wavelength structure; or, the auxiliary mirror metamorphic surface functional unit includes a reflective metal layer and a metal main mirror subwavelength structure.
  • the functional unit of the secondary surface of the auxiliary mirror includes a laminated structure of a reflective metal layer and a sub-wavelength structure of the main mirror of the medium; the sub-wavelength structure of the auxiliary mirror is at least one of a rod shape and an oval shape.
  • forming a secondary mirror metasurface functional structure on a set circular area above the transparent substrate includes:
  • a photoresist is spin-coated on a transparent substrate, and a portion of the photoresist located in a set circular area is removed; an electron beam evaporation process or a thermal evaporation process is sequentially performed on the transparent substrate surface and the remaining photoresist surface.
  • FIG. 15 is a schematic flowchart of another method for manufacturing a superstructured surface auxiliary lens provided in this embodiment. As shown in FIG. 15, the method for preparing the metasurface primary mirror includes:
  • step 410 a transparent substrate is provided.
  • step 420 a photoresist is spin-coated on the transparent substrate, and the photoresist located in a set circular area is removed.
  • a photoresist 212 is spin-coated on the transparent substrate 200, the photoresist 212 is exposed by using a mask having the same opening as the set circular area, and developed in a developing solution. The portion where the photoresist 212 is located in the set circular area is removed. The circular area is set to correspond to the light transmission hole of the primary mirror of the metasurface.
  • step 430 an electron beam evaporation process or a thermal evaporation process is used to sequentially deposit a stacked reflective metal layer and a dielectric layer on the surface of the transparent substrate and the remaining photoresist, and remove the remaining photoresist.
  • a reflective metal layer 213 may be first deposited on the surface of the transparent substrate 200 and the remaining photoresist 212 by an electron beam evaporation process, and then a thermal evaporation process may be used to vaporize the reflective metal layer 213. Side of the dielectric layer 214.
  • the material of the reflective metal layer 213 and the dielectric layer 214 can be selected according to the operating band of the system. For example, in the visible near-infrared band, the material of the reflective metal layer 213 can be a metal material such as gold, silver, or aluminum.
  • the material may be silicon dioxide or titanium dioxide; in the infrared band, the material of the reflective metal layer 213 may be gold, silver, aluminum, silicon dioxide or titanium dioxide, and the material of the dielectric layer 214 may be CaF2, MgF2, Ge, or polytetrafluoroethylene In the microwave band, the material of the reflective metal layer 213 may be a metal material such as gold, silver, or aluminum, and the material of the dielectric layer 214 may be a transparent ceramic. Referring to FIG. 18, the remaining photoresist 212 is removed by using a corresponding de-gluing solution, and a stacked structure of a reflective metal layer 213 and a dielectric layer 214 is formed in a set circular area.
  • step 440 an electronic glue or a photoresist is spin-coated on the dielectric layer and the transparent substrate.
  • step 450 based on the Berry geometric phase principle, an electron beam or photoresist exposure process is used to pattern the electronic glue or photoresist on the dielectric layer, so that the patterned electronic glue or photoresist meets the auxiliary requirements.
  • Mirror phase distribution based on the Berry geometric phase principle, an electron beam or photoresist exposure process is used to pattern the electronic glue or photoresist on the dielectric layer, so that the patterned electronic glue or photoresist meets the auxiliary requirements.
  • a photoresist 215 is spin-coated on the dielectric layer 214 and the exposed transparent substrate 200. Based on the principle of the Perry geometric phase, the photoresist 215 is located in a set circular area by a photolithography process. Partially patterning is performed so that the patterned photoresist 215 satisfies the auxiliary mirror phase distribution.
  • the electronic glue should be patterned by electron beam lithography, and the photoresist should be patterned by ultraviolet lithography.
  • the size of the sub-wavelength structure of the auxiliary mirror to be formed subsequently will be different, and the lithography process used in this step will also be different.
  • the visible light band electron beam lithography is mostly used; in the infrared band, Optional UV lithography.
  • the microwave band printed circuit board technology can be used.
  • a metal layer is vapor-deposited on the surface of the dielectric layer and the surface of the patterned electronic adhesive or photoresist by using an electron beam evaporation process or a thermal evaporation process.
  • step 470 the patterned electronic glue or photoresist is removed, and the metal layer on the surface of the dielectric layer is retained to form a pattern of the auxiliary mirror sub-wavelength structure.
  • an electron beam evaporation process may be used to vapor-deposit a metal layer 216 on the surface of the dielectric layer 214 and the surface of the remaining photoresist 215 (photoresist after patterning).
  • the opening of the sealant 215 defines the shape, size, and azimuth of the sub-mirror sub-wavelength structure formed on the surface of the dielectric layer 214.
  • the corresponding photoresist 215 is used to remove the remaining photoresist 215, and the metal layer 216 formed on the surface of the remaining photoresist 114 is peeled off at the same time, and the metal layer on the surface of the dielectric layer 113 is retained, thereby forming an auxiliary mirror
  • the wavelength structure 211 completes the preparation of the meta-surface auxiliary mirror.
  • using a photolithography process to pattern the electronic adhesive or photoresist on the dielectric layer further includes:
  • a photolithography process is used to pattern the electronic or photoresist on the dielectric layer.
  • the geometric size of the sub-wavelength structure of the auxiliary mirror to be formed can be adjusted to achieve high optical reflection efficiency in the required working band, thereby improving the utilization of incident light and reducing the loss of incident light. For focusing and imaging systems, it can improve imaging the quality of.
  • This embodiment also provides a metamorphic surface auxiliary lens, which can be prepared by using the method for preparing a metamorphic surface auxiliary lens provided by any of the embodiments.
  • the metasurface auxiliary mirror includes a transparent substrate, and the transparent substrate includes a subsurface metasurface functional unit pattern on the transparent substrate.
  • the subsurface metasurface functional unit pattern satisfies a phase distribution of the submirror, and
  • the incident light of the meta-surface auxiliary mirror is reflected on the meta-surface main mirror, and is reflected and focused by the meta-surface main mirror.
  • the auxiliary mirror metamorphic surface functional unit pattern includes an auxiliary mirror metamorphic surface functional structure 21 located in a set circular area, and the auxiliary mirror metamorphic surface functional structure 21 includes a plurality of auxiliary mirrors.
  • Metamorphic surface functional unit, auxiliary mirror Metamorphic surface functional unit includes anisotropic auxiliary mirror subwavelength structure 211, the phase introduced by auxiliary mirror subwavelength structure 211 satisfies the phase distribution of auxiliary mirror; disc-shaped auxiliary mirror superstructure surface function
  • the structure 21 is aligned with the circular light transmitting hole of the main mirror of the metamorphic surface, and the incident light passes through the light transmitting hole and reaches the functional structure of the superstructure surface of the auxiliary mirror.
  • the auxiliary mirror metamorphic surface functional unit includes a laminated structure of the reflective metal layer 213, the dielectric layer 214, and the metallic sub-wavelength structure 211; or the auxiliary mirror metamorphic surface functional unit includes a reflective metal layer 213, a metallic sublayer, and the like. Single-layer structure of wavelength structure or medium sub-wavelength structure.
  • the azimuth of the auxiliary mirror subwavelength structure corresponding to different phases is different, that is, the auxiliary mirror subwavelength structures at different positions are set according to the required phase distribution Azimuth angle to reflect incident light to the corresponding position of the primary mirror on the metasurface.
  • the sub-mirror sub-wavelength structure is at least one of a rod shape and an ellipse shape, so as to achieve a high circularly polarized light conversion efficiency.
  • the preparation method of the superstructured surface main mirror provided in this embodiment and the preparation method of the superstructured surface main mirror provided in this embodiment have the same functions and beneficial effects.
  • the preparation method for preparing the superstructured surface primary mirror of this embodiment will not be repeated here.
  • this embodiment also provides an optical system, including a superstructured surface main mirror provided in any one of the foregoing embodiments and a superstructured surface auxiliary mirror provided in any one of the foregoing embodiments.
  • the metasurface primary mirror and the metasurface secondary mirror are oppositely disposed, and there is a set distance between the metasurface primary mirror and the metasurface secondary mirror, so that the incident light incident on the metasurface auxiliary mirror is reflected to the metasurface. Reflective focusing on the main mirror of the structured surface and by the main mirror of the superstructured surface.
  • the optical system may be a planar transmission focusing and imaging system based on a reflective metasurface, including a microscope, a telescope, a camera, an infrared imaging device, and the like.
  • the matlab software is used to simulate light passing through the optical path of the system, the wavelength ⁇ of the incident light is changed, and the focal length change ⁇ f of the system is observed.
  • the optical system composed of the metasurface primary mirror and the metasurface secondary mirror of this embodiment has a greatly reduced dispersion.
  • the primary mirror, secondary mirror, primary mirror, secondary mirror preparation method and optical system provided in this embodiment form a primary mirror metasurface functional unit that satisfies the phase distribution of the primary mirror on a transparent substrate of the primary mirror Pattern on the transparent substrate of the meta-surface auxiliary mirror to form the auxiliary mirror meta-surface functional unit pattern that satisfies the phase distribution of the auxiliary mirror, so that after the incident light is reflected by the meta-surface auxiliary mirror onto the meta-surface main mirror, The main surface of the mirror is focused by reflection. Therefore, through the combined design of the main mirror and the auxiliary mirror of the superstructured surface, the design of the plane transmission lens based on the reflective superstructured surface is achieved, and the reflection in the related technology is solved.
  • Type objective lens has the problems of harsh preparation, heavy weight, large volume, and difficulty in miniaturization and integration.
  • a flat reflective superstructured surface is used to replace the curved mirror in the related art, which has the advantages of lightness, compactness and ease of integration, and the preparation process of the superstructured surface also greatly reduces the curved reflective objective lens in the related technology.
  • the preparation is difficult, which is conducive to the large-scale and low-cost production of reflective objectives.

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Abstract

一种超构表面主镜（1）、辅镜（2）及主镜（1）、辅镜（2）制备方法和光学系统，超构表面主镜（1）采用超构表面主镜（1）的制备方法制备，包括：透明衬底（200），透明衬底（200）包括位于透明衬底（200）之上的主镜（1）超构表面图案，主镜（1）超构表面设置为图案满足主镜（1）相位分布，以对经超构表面辅镜（2）反射到超构表面主镜（1）上的入射光进行反射聚焦。

Description

超构表面主镜、辅镜，及其制备方法和光学系统
本申请要求申请日为2018年07月23日、申请号为201810814042.7、名称为“超构表面主镜、辅镜及主镜、辅镜制备方法和光学系统”的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本公开涉及超构表面技术领域，例如涉及一种超构表面主镜、辅镜及主镜、辅镜制备方法和光学系统。
背景技术
折射式透镜在聚焦与成像系统中占有不可替代的地位，多个反射镜构成的反射式透镜在显微镜、望远镜、相机和红外成像设备中亦有着必不可少的应用。为了更便利地观察和拍摄物体，往往要求物体与图像分别位于透镜的两侧。对于相关技术中的透镜而言，无论是反射型，折射型还是混合型，有效的相位调谐和波前整形都依赖于元件表面连续的几何曲率。要想获得高质量的透镜，需要苛刻地研磨抛光等制备工艺，因此，不可避免地导致相关技术中的透镜笨重且制备成本高昂，难以实现小型化、集成化和低成本地批量生产。
相关技术中为此提供了一种有效的解决方案，即使用超构表面，超构表面是由具有空间变化的亚波长超构表面功能单元构成的界面，通过精心地设计超构表面功能单元，可以在亚波长尺度下实现对电磁波的偏振、振幅和相位的有效调控。超构表面的二维属性使该超构表面能实现体积更紧凑，质量更轻，损耗更低的电磁功能元件。且超构表面的制备工艺与相关技术中的互补金属氧化物半导体技术兼容，更容易集成到光电技术中。基于超构表面设计的平面元件具有广泛的应用，例如实现全息成像、偏振转换、产生光的自旋轨道角动量和异常反射/折射等。在基于超构表面的精密光学元件中，最有吸引力和应用前景的例子要数平面透镜，它既可以作为单个透镜，也能构成透镜组，甚至组合成其它更复杂的光学系统。超构表面透镜使折射光学元件变得轻薄紧凑易于集成，可以在具有更先进功能的超小型光学设备中发挥更重要的作用。随着超构表面透镜的蓬勃发展趋势，几乎所有的注意力都集中在基于折射式超构表面的平面透射式透镜上，而基于反射式超构表面的平面透射式透镜却少有涉及。尽管反 射型超构表面存在，但单个反射元件并不能形成有效的透射式透镜。对许多光学设备来说，基于反射式超构表面的平面透射式透镜与基于折射式超构表面的平面透射式透镜同等重要，而且在望远镜和大量红外系统中，反射型的透射式聚焦系统的设计是无法替代的。
发明内容
本公开提出一种超构表面主镜、辅镜及主镜、辅镜制备方法和光学系统，可以实现反射式超构表面用于透射式透镜的设计，解决相关技术中的反射型物镜工艺制备苛刻、质量重、体积大和难以小型化以及集成化的问题，利于大批量低成本地生产。
一实施例提供了一种超构表面主镜的制备方法，包括：提供透明衬底；及在所述透明衬底之上形成满足主镜相位分布的主镜超构表面功能单元图案，以对经超构表面辅镜反射到所述超构表面主镜上的入射光进行反射聚焦。
一实施例提供了一种超构表面主镜，采用上述的超构表面主镜的制备方法制备，其中，所述超构表面主镜包括：透明衬底；及位于所述透明衬底之上的主镜超构表面功能单元图案，所述主镜超构表面功能单元图案设置为满足主镜相位分布，以对经超构表面辅镜反射到所述超构表面主镜上的入射光进行反射聚焦。
一实施例提供了一种超构表面辅镜的制备方法，包括：提供透明衬底；及在所述透明衬底之上形成满足辅镜相位分布的辅镜超构表面功能单元图案，以将入射到所述超构表面辅镜的入射光反射到超构表面主镜上，并经所述超构表面主镜进行反射聚焦。
一实施例提供了一种超构表面辅镜，采用上述的超构表面辅镜的制备方法制备，包括：透明衬底；及位于所述透明衬底之上的辅镜超构表面功能单元图案，所述辅镜超构表面功能单元图案设置为满足辅镜相位分布，以将入射到所述超构表面辅镜的入射光反射到超构表面主镜上，并经所述超构表面主镜进行反射聚焦。
一实施例提供了一种光学系统，包括上述的超构表面主镜和上述超构表面辅镜。
附图说明
图1是相关技术中的反射式物镜的侧视图；
图2是一实施例提供的平面的超构表面反射镜反射入射光的示意图；
图3是一实施例提供的超构表面功能单元的结构示意图；
图4是一实施例提供的平面反射式超构表面物镜的侧视图；
图5是一实施例提供的超构表面主镜的俯视图；
图6是一实施例提供的超构表面辅镜的俯视图；
图7是一实施例提供的超构表面主镜的制备方法的流程示意图；
图8是一实施例提供的另一种超构表面主镜的制备方法的流程示意图；
图9-图13是图8的超构表面主镜的制备方法的多个流程对应的超构表面主镜的侧视图；
图14是一实施例提供的超构表面辅镜的制备方法的流程示意图；
图15是一实施例提供的另一种超构表面辅镜的制备方法的流程示意图；
图16-图21是图15的超构表面辅镜的制备方法的多个流程对应的超构表面辅镜的侧视图。
具体实施方式
图1是相关技术中的反射式物镜的侧视图。如图1所示，该反射式物镜包括曲面主镜10和曲面辅镜20，该反射式物镜通常为史瓦兹德反射式物镜，即曲面主镜10和曲面辅镜20是共球心的球面反射镜，曲面辅镜20与曲面主镜10上的开孔相对准，入射光100经曲面主镜10上的开孔入射至曲面辅镜20的反射面上，入射光100经曲面辅镜20反射后，分两部分分别到达曲面主镜10的反射面，最后经曲面主镜10反射聚焦至A点。然而，该反射式物镜需要通过曲面主镜10和曲面辅镜20反射面连续的几何曲率变化来实现理想的相位调谐和波前整形，因此，要想获得高质量的反射式聚焦，需要苛刻的研磨和抛光等制备工艺，使得相关技术中的反射式物镜体积大、质量重且制备成本高昂，难以实现小型化、集成化和低成本的批量生产。
针对上述技术问题，本实施例利用平面的反射式超构表面实现了平面透射式超构表面透镜的设计，使得反射式透镜具有轻薄紧致和便于集成的优点，且超构表面的制备工艺也大大降低了相关技术中曲面的反射式物镜的制备难度，有利于实现反射式物镜大批量低成本地生产及装配。
图2是本实施例提供的平面的超构表面反射镜反射入射光的示意图；图3是本实施例提供的超构表面功能单元的结构示意图。如图2所示，超构表面反射镜30是根据广义的反射定律设计的，其中，广义的反射定律可理解为反射光沿反射界面方向的波矢分量等于入射光沿反射界面方向的波矢分量与反射面上引入的额外相位梯度的矢量和。示例性的，该超构表面反射镜30具有梯度相位超构表面，图2中虚线箭头表示水平镜面反射光，实线箭头表示该超构表面反射镜30实现的梯度相位超构表面反射光，显然，梯度相位超构表面反射光相对于水平镜面反射光反射光发生了偏转，这正是由于超构表面引入的额外相位梯度引起的。
在一实施例中，如图3所示，该超构表面反射镜包括多个超构表面功能单元31，每个超构表面功能单元31至少包括各向异性的亚波长结构311。由贝里几何相位原理，即圆偏振光与各向异性的亚波长结构相互作用，可以使入射圆偏振光的圆偏振态发生反转同时引入几何相位因子
Figure PCTCN2018116927-appb-000001
其中σ＝±1代表入射光的圆偏振态；
Figure PCTCN2018116927-appb-000002
是各向异性纳米结构在平面上的方位角，可以看出，通过简单改变各向异性的亚波长结构的方位角可实现对入射光相位从0-2π的连续调控，而入射光不同的相位可以引起反射光不同角度的偏转，进而可以通过设置亚波长结构311的方位角来调节反射光的偏转角度。在一实施例中，上述超构表面功能单元31可以为反射金属层313、介质层312和亚波长结构311的叠层结构，也可以为亚波长结构311的单层结构，亚波长结构311可以为金属亚波长结构或介质亚波长结构，亚波长结构311可以为棒状或椭圆状，以实现较高的圆偏振光转换效率。
基于上述超构表面反射镜的结构及原理，本实施例可通过设置超构表面反射镜的多个超构表面功能单元31的亚波长结构的方位角，使整个超构表面反射镜满足特定的相位分布，利用至少两个超构表面反射镜组合成平面反射式超构表面透镜。示例性的，图4是本实施例提供的平面反射式超构表面透镜的侧视图，如图4所示，该平面反射式超构表面透镜包括相对设置的超构表面主镜1和超构表面辅镜2，超构表面主镜1和超构表面辅镜2之间具有预设间距，同时结合图5和图6，超构表面主镜1包括环形的主镜超构表面功能结构11和主镜超构表面功能结构11所围绕的圆形的透光孔12，主镜超构表面功能结构11包括多个主镜超构表面功能单元(图5中未示出，可参考图3的超构表面功能单元的结构)，主镜超构表面功能单元包括主镜亚波长结构111，主镜亚波长结构111以特定的方位角排布于主镜超构表面功能结构11上；超构表面辅镜2包括圆盘状的辅镜超构表 面功能结构21，辅镜超构表面功能结构21包括多个辅镜超构表面功能单元(图6中未示出，可参考图3的超构表面功能单元的结构)，辅镜超构表面功能单元包括辅镜亚波长结构211，辅镜亚波长结构211以特定的方位角排布于辅镜超构表面功能结构21上，其中，超构表面辅镜2的辅镜超构表面功能结构21与超构表面主镜1的透光孔12相对准，以使入射光100透过透光孔12入射至辅镜超构表面功能结构21上，到达辅镜超构表面功能结构21的入射光100由于辅镜亚波长结构211引入的额外相位梯度而向特定的方向反射，并到达主镜超构表面功能结构11，再由主镜亚波长结构111引入的额外相位梯度使得经超构表面主镜1反射形成的反射光聚焦于B点。由此，本实施例可通过超构表面主镜1和超构表面辅镜2组合，实现平面反射式超构表面透镜的设计。
本实施例分别提供了超构表面主镜的制备方法、超构表面主镜、超构表面辅镜的制备方法和超构表面辅镜。
图7是本实施例提供的超构表面主镜的制备方法的流程示意图。如图7所示，该超构表面主镜的制备方法包括：
步骤110中，提供透明衬底。
示例性的，根据透明衬底之上的主镜超构表面功能单元图案的材料，选择相应工作波段内的透明衬底，以适应不同工作波段的入射光。
步骤120中，在透明衬底之上形成满足主镜相位分布的主镜超构表面功能单元图案，以对经超构表面辅镜反射到主镜上的入射光进行反射聚焦。
其中，主镜相位分布可根据设定参数结合射线光学及广义的反射定律确定，其中，设定参数包括系统的焦距、超构表面主镜和超构表面辅镜的口径、超构表面主镜、超构表面辅镜的间距、系统的工作波长，及入射光到达超构表面辅镜上的位置与超构表面辅镜反射入射光至超构表面主镜上的位置的映射关系。本实施例可根据上述设定参数，确定入射光进入系统后的光路，再结合射线光学及广义的反射定律，确定超构表面主镜的多个位置需要引入的额外相位梯度，由此可确定整个超构表面主镜的主镜相位分布。
主镜相位分布也可根据设定的曲面反射式物镜中曲面主镜的几何形状确定，其中，曲面反射式物镜包括曲面主镜和曲面辅镜，曲面主镜设置为将经曲面辅镜反射到曲面主镜上的入射光进行反射聚焦。设定的曲面反射式物镜可以为已有的任一曲面反射式物镜或根据需求设置的曲面反射式物镜，本实施例可根据设定的曲面反射式物镜中曲面主镜对光的相位调谐作用，确定本实施例的超构 表面主镜上对应位置的相位，从而确定整个超构表面主镜的主镜相位分布。示例性的，曲面反射式物镜可以为史瓦兹德反射式物镜，可以根据平行光正入射到曲面主镜上多个位置处反射光线的方向角，并结合广义的反射定律确定超构表面主镜上所需引入的相位分布。
本实施例通过上述反射式超构表面主镜的制备方法，可制备出与光学系统(包括平面反射式超构表面透镜)中的超构表面辅镜相匹配的超构表面主镜，从而实现了基于反射式超构表面的平面透射反射式透镜的设计，解决了相关技术中的反射型物镜工艺制备苛刻、质量重、体积大、难以小型化以及集成化的问题。本实施例利用平面反射式超构表面来替代相关技术中的曲面反射镜，具有轻薄紧致和便于集成的优点，且超构表面的制备工艺也大大降低了相关技术中的曲面的反射式物镜的制备难度，有利于实现反射式透镜大批量低成本地生产。
在一实施例中，在透明衬底之上形成满足主镜相位分布的主镜超构表面功能单元图案，包括：
在透明衬底之上的设定环形区域形成主镜超构表面功能结构，其中，主镜超构表面功能结构包括多个主镜超构表面功能单元，主镜超构表面功能单元包括主镜亚波长结构，主镜亚波长结构引入的相位满足主镜相位分布，入射光透过透光孔到达超构表面辅镜，环形的主镜超构表面功能结构所围绕的中间区域形成透光孔。在一实施例中，主镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构；或者，主镜超构表面功能单元包括反射金属层及金属主镜亚波长结构的叠层结构；或主镜超构表面功能单元包括反射金属层及介质主镜亚波长结构的叠层结构；主镜亚波长结构呈棒状和椭圆形中至少一种形状。
在一实施例中，在透明衬底之上的设定环形区域形成主镜超构表面功能结构，包括：
采用电子束蒸镀工艺或热蒸镀工艺在透明衬底之上依次蒸镀叠层的反射金属层和介质层；在介质层上旋涂电子胶或光刻胶，基于贝里几何相位原理，采用电子束曝光或光罩曝光工艺对电子胶或光刻胶位于设定环形区域的部分进行图案化，以使图案化的电子胶或光刻胶满足主镜相位分布；采用电子束蒸镀工艺或热蒸镀工艺在介质层表面和图案化之后的电子胶或光刻胶表面蒸镀金属层，并去除图案化之后的电子胶或光刻胶，以保留介质层表面的金属层，形成主镜 亚波长结构；及采用焦离子束刻蚀工艺、反应离子束刻蚀工艺、感应耦合等离子体刻蚀工艺、离子减薄工艺、光刻工艺或激光工艺去除设定环形区域所围绕的反射金属层和介质层，形成平整的圆形透光孔。
本实施例以主镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构为例进行说明。图8是本实施例提供的另一种超构表面主镜的制备方法的流程示意图。如图8所示，该超构表面主镜的制备方法包括：
步骤210中，提供透明衬底。
步骤220中，采用电子束蒸镀工艺或热蒸镀工艺在透明衬底之上依次蒸镀叠层的反射金属层和介质层。
示例性的，参考图9，可先采用电子束蒸镀工艺在透明衬底200之上蒸镀反射金属层112，再采用热蒸镀工艺在反射金属层112上蒸镀介质层113。其中，反射金属层112和介质层113的材料可根据光学系统的工作波段进行选择，例如，在可见近红外波段，反射金属层112的材料可以为金、银或铝等金属材料，介质层113的材料可以为二氧化硅或二氧化钛；在红外波段，反射金属层112的材料可以为金、银、铝、二氧化硅或二氧化钛，介质层113的材料可以为CaF2、MgF2、Ge或聚四氟乙烯等介质；在微波波段，反射金属层112的材料可以为金、银或铝等金属材料，介质层113的材料可以为透明陶瓷等。
步骤230中，在介质层上旋涂电子胶或光刻胶。
步骤240中，采用电子束曝光或光罩曝光工艺对位于设定环形区域的电子胶或光刻胶进行图案化，以使图案化之后的电子胶或光刻胶满足主镜相位分布。
示例性的，参考图10，在介质层113上旋涂光刻胶114，采用电子束曝光或光罩曝光工艺对位于设定环形区域的光刻胶114进行图案化(也可全部进行图案化，仅位于设定环形区域的图案化之后的光刻胶满足主镜相位分布)，以使图案化之后的光刻胶满足主镜相位分布。其中，设定环形区域是围绕透光孔的区域，环形区域的内孔径大小可根据设定的超构表面辅镜的大小进行设计。
本实施例中，应采用电子束光刻对电子胶进行图案化，应采用紫外光刻对光刻胶进行图案化。对于不同的工作波段，后续形成的主镜亚波长结构的尺寸会有所不同，进而该步骤采用的光刻工艺也会不同，例如，在可见光波段，多采用电子束光刻；在红外波段，可选择紫外光刻。另外，在微波波段，可采用印刷电路板技术。
步骤250中，采用电子束蒸镀工艺或热蒸镀工艺在介质层表面和图案化之后 的电子胶或光刻胶表面蒸镀金属层。
步骤260中，去除图案化之后的电子胶或光刻胶，保留介质层表面的金属层，以形成主镜亚波长结构的图案。
示例性的，参考图11，可采用电子束蒸镀工艺在介质层113表面和残留的光刻胶114(图案化之后的光刻胶)表面蒸镀金属层115，其中，残留的光刻胶114的开口限定出了形成于介质层113表面的主镜亚波长结构的形状、尺寸及方位角。参考图12，利用相应的去胶液去除残留的光刻胶114，进而同时剥离掉形成于残留的光刻胶114表面的金属层115，保留介质层113表面的金属层，从而形成主镜亚波长结构111。
步骤270中，采用聚焦离子束刻蚀工艺、反应离子束刻蚀工艺、感应耦合等离子体刻蚀工艺、离子减薄工艺、光刻工艺或激光工艺去除设定环形区域所围绕的反射金属层和介质层，形成平整的圆形透光孔。
示例性的，参考图13，可采用聚焦离子束刻蚀工艺、反应离子束刻蚀工艺、感应耦合等离子体刻蚀工艺、离子减薄工艺、光刻工艺或激光工艺中的任一种工艺去除待形成的透光孔所对应区域的反射金属层112和介质层113，形成圆形平整的透光孔12，同时形成环形的主镜超构表面功能结构，完成超构表面主镜的制备。
在一实施例中，采用光刻工艺对位于设定环形区域的电子胶或光刻胶进行图案化，还包括：
基于表面等离激元共振或者纳米结构散射理论，采用电子束曝光或光罩曝光工艺对电子胶或光刻胶位于设定环形区域的部分进行图案化。
通过调整后续形成的主镜亚波长结构的几何尺寸，在所需的工作波段实现高的光学反射效率，进而提高入射光的利用率，减少入射光的损失，对于聚焦与成像系统，可提高成像的质量。
本实施例提供了一种超构表面主镜，可采用任一实施例提供的超构表面主镜的制备方法制备。该超构表面主镜包括：透明衬底；位于透明衬底之上的主镜超构表面功能单元图案，主镜超构表面功能单元图案满足主镜相位分布，以对经超构表面辅镜反射到超构表面主镜上的入射光进行反射聚焦。
示例性的，可参考图5和图13，主镜超构表面功能单元图案包括位于设定环形区域内的主镜超构表面功能结构11，主镜超构表面功能结构11包括多个主镜超构表面功能单元，主镜超构表面功能单元包括各向异性的主镜亚波长结构111， 主镜亚波长结构111引入的相位满足主镜相位分布；超构表面主镜还包括环形的主镜超构表面功能结构11所围成的透光孔12，入射光透过透光孔12到达超构表面辅镜。
在一实施例中，主镜超构表面功能单元包括反射金属层112、介质层113和金属亚波长结构111的叠层结构；或者，主镜超构表面功能单元包括反射金属层、金属主镜亚波长结构或介质主镜亚波长结构的单层结构。
在一实施例中，基于贝里几何相位原理设计的超构表面主镜，不同相位对应的主镜亚波长结构的方位角不同，即根据所需相位分布设置不同位置处的主镜亚波长结构的方位角，以实现超构表面主镜对光的反射聚焦。
在一实施例中，主镜亚波长结构呈棒状和椭圆形中的至少一种，以实现较高的圆偏振光转换效率。示例性的，主镜超构表面功能单元包括反射金属层112、介质层113和金属亚波长结构111的叠层结构时，反射金属层112和金属亚波长结构111的材料均为金，介质层113的材料为二氧化硅，金属亚波长结构111呈棒状时，在近红外波段，圆偏振光转换效率可高达80％。
本实施例提供的超构表面主镜和本实施例提供的超构表面主镜的制备方法具备相同的功能和有益效果，未在本实施例的超构表面主镜中详尽描述的内容请参考本实施例的超构表面主镜的制备方法，此处不再赘述。
同时，本实施例还提供了一种超构表面辅镜的制备方法，图14是本实施例提供的超构表面辅镜的制备方法的流程示意图。如图14所示，该超构表面辅镜的制备方法包括：
步骤310中，提供透明衬底。
示例性的，根据透明衬底之上的辅镜超构表面功能单元图案的材料，选择相应工作波段内的透明衬底，以适应不同工作波段的入射光。
步骤320中，在透明衬底之上形成满足辅镜相位分布的辅镜超构表面功能单元图案，以将入射到超构表面辅镜的入射光反射到超构表面主镜上，并经超构表面主镜进行反射聚焦。
类似的，辅镜相位分布可根据设定参数结合射线光学及广义的反射定律确定，其中，设定参数包括系统的焦距、超构表面主镜和超构表面辅镜的口径、超构表面主镜和超构表面辅镜的间距、光学系统的工作波长，及入射光到达超构表面辅镜上的位置与超构表面辅镜反射入射光至超构表面主镜上的位置的映射关系；本实施例可根据上述设定参数，确定入射光进入系统后的光路，再结 合射线光学及广义的反射定律，确定超构表面辅镜多个位置需要引入的额外相位梯度，由此可确定整个超构表面辅镜的辅镜相位分布。
辅镜相位分布也可根据设定的曲面反射式物镜中曲面辅镜的几何形状确定，其中，曲面反射式物镜包括曲面主镜和曲面辅镜，曲面辅镜用于将入射光反射到曲面主镜上，以经曲面主镜进行反射聚焦。本实施例可根据设定的曲面反射式物镜中曲面辅镜对光的相位调谐作用，确定本实施例的超构表面辅镜上对应位置的相位，从而确定整个超构表面辅镜的辅镜相位分布。示例性的，曲面反射式物镜可以为史瓦兹德反射式物镜，可以根据平行光正入射到曲面辅镜上的多个位置处反射光线的方向角，并结合广义的反射定律确定超构表面辅镜上所需引入的相位分布。
本实施例通过上述超构表面辅镜的制备方法，可制备出与光学系统(包括平面反射式超构表面透镜)中的超构表面主镜相匹配的超构表面辅镜，从而实现了基于反射式超构表面的平面透射式透镜的设计，解决了相关技术中的反射型物镜工艺制备苛刻、质量重、体积大和难以小型化以及集成化的问题。本实施例利用平面反射式超构表面透镜来替代相关技术中的曲面反射镜，该平面反射式超构表面透镜具有轻薄紧致和便于集成的优点，且超构表面的制备工艺也大大降低了相关技术中的曲面的反射式物镜的制备难度，有利于实现反射式透镜大批量低成本地生产。
在一实施例中，在透明衬底之上形成满足辅镜相位分布的辅镜超构表面功能单元图案，包括：
在透明衬底之上的设定圆形区域形成辅镜超构表面功能结构，其中，辅镜超构表面功能结构包括多个辅镜超构表面功能单元，辅镜超构表面功能单元包括辅镜亚波长结构，辅镜亚波长结构引入的相位满足辅镜相位分布，设定圆形区域与超构表面主镜的透光孔相对准，以使入射光透过透光孔到达超构表面辅镜。在一实施例中，辅镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构；或者，辅镜超构表面功能单元包括反射金属层及金属主镜亚波长结构，或辅镜超构表面功能单元包括反射金属层及介质主镜亚波长结构的叠层结构；辅镜亚波长结构呈棒状和椭圆形中的至少一种。
在一实施例中，在透明衬底之上的设定圆形区域形成辅镜超构表面功能结构，包括：
在透明衬底之上旋涂光刻胶，并去除光刻胶位于设定圆形区域的部分；采 用电子束蒸镀工艺或热蒸镀工艺在透明衬底表面及残留的光刻胶表面依次蒸镀叠层的反射金属层和介质层，并去除残留的光刻胶；在介质层及暴露的透明衬底上旋涂电子胶或光刻胶，基于贝里几何相位原理，采用电子束曝光或光罩曝光工艺对位于介质层上的电子胶或光刻胶进行图案化，以使图案化之后的电子胶或光刻胶满足辅镜相位分布；采用电子束蒸镀工艺或热蒸镀工艺在介质层表面和残留的电子胶或光刻胶表面蒸镀金属层；去除图案化之后的电子胶或光刻胶，保留介质层表面的金属层，以形成辅镜亚波长结构的图案。
本实施例以辅镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构为例进行说明。图15是本实施例提供的另一种超构表面辅镜的制备方法的流程示意图。如图15所示，该超构表面主镜的制备方法包括：
步骤410中，提供透明衬底。
步骤420中，在透明衬底之上旋涂光刻胶，并去除位于设定圆形区域的光刻胶。
示例性的，参考图16，在透明衬底200之上旋涂光刻胶212，采用开口与设定圆形区域相同的掩膜板对光刻胶212进行曝光，并在显影液中显影，去除光刻胶212位于设定圆形区域的部分。其中，设定圆形区域与超构表面主镜的透光孔相对应。
步骤430中，采用电子束蒸镀工艺或热蒸镀工艺在透明衬底表面及残留的光刻胶表面依次蒸镀叠层的反射金属层和介质层，并去除残留的光刻胶。
示例性的，参考图17，可先采用电子束蒸镀工艺在透明衬底200表面及残留的光刻胶212表面蒸镀反射金属层213，再采用热蒸镀工艺在反射金属层213表面蒸镀介质层214。其中，反射金属层213和介质层214的材料可根据系统的工作波段进行选择，例如，在可见近红外波段，反射金属层213的材料可以为金、银或铝等金属材料，介质层214的材料可以为二氧化硅或二氧化钛；在红外波段，反射金属层213的材料可以为金、银、铝、二氧化硅或二氧化钛，介质层214的材料可以为CaF2、MgF2、Ge或聚四氟乙烯等介质；在微波波段，反射金属层213的材料可以为金、银或铝等金属材料，介质层214的材料可以为透明陶瓷等。参考图18，利用相应的去胶液去除残留的光刻胶212，在设定圆形区域内形成反射金属层213和介质层214的叠层结构。
步骤440中，在介质层及透明衬底上旋涂电子胶或光刻胶。
步骤450中，基于贝里几何相位原理，采用电子束曝光或光罩曝光工艺对位 于介质层上的电子胶或光刻胶进行图案化，以使图案化之后的电子胶或光刻胶满足辅镜相位分布。
示例性的，参考图19，在介质层214及暴露的透明衬底200上旋涂光刻胶215，基于贝里几何相位原理，采用光刻工艺对光刻胶215位于设定圆形区域的部分进行图案化，以使图案化之后的光刻胶215满足辅镜相位分布。
本实施例中，电子胶应采用电子束光刻进行图案化，光刻胶应采用紫外光刻进行图案化。对于不同的工作波段，后续形成的辅镜亚波长结构的尺寸会有所不同，进而该步骤采用的光刻工艺也会不同，例如，在可见光波段，多采用电子束光刻；在红外波段，可选择紫外光刻。另外，在微波波段，可采用印刷电路板技术。
步骤460中，采用电子束蒸镀工艺或热蒸镀工艺在介质层表面和图案化之后的电子胶或光刻胶表面蒸镀金属层。
步骤470中，去除图案化之后的电子胶或光刻胶，保留介质层表面的金属层，以形成辅镜亚波长结构的图案。
示例性的，参考图20，可采用电子束蒸镀工艺在介质层214表面和残留的光刻胶215(图案化之后的光刻胶)表面蒸镀金属层216，其中，图案化之后的光刻胶215的开口限定出了形成于介质层214表面的辅镜亚波长结构的形状、尺寸及方位角。参考图21，利用相应的去胶液去除残留的光刻胶215，进而同时剥离掉形成于残留的光刻胶114表面的金属层216，保留介质层113表面的金属层，从而形成辅镜亚波长结构211，完成超构表面辅镜的制备。
在一实施例中，采用光刻工艺对位于介质层上的电子胶或光刻胶进行图案化，还包括：
基于表面等离激元共振或者纳米结构散射理论，采用光刻工艺对位于介质层上的电子胶或光刻胶进行图案化。
可调整后续形成的辅镜亚波长结构的几何尺寸，在所需的工作波段实现高的光学反射效率，进而提高入射光的利用率，减少入射光的损失，对于聚焦与成像系统，可提高成像的质量。
本实施例还提供了一种超构表面辅镜，可采用任一实施例提供的超构表面辅镜的制备方法制备。该超构表面辅镜包括：透明衬底，透明衬底包括位于透明衬底之上的辅镜超构表面功能单元图案，辅镜超构表面功能单元图案满足辅镜相位分布，以将入射到超构表面辅镜的入射光反射到超构表面主镜上，并经 超构表面主镜进行反射聚焦。
示例性的，参考图6和图21，辅镜超构表面功能单元图案包括位于设定圆形区域内的辅镜超构表面功能结构21，辅镜超构表面功能结构21包括多个辅镜超构表面功能单元，辅镜超构表面功能单元包括各向异性的辅镜亚波长结构211，辅镜亚波长结构211引入的相位满足辅镜相位分布；圆盘状的辅镜超构表面功能结构21与超构表面主镜的圆形的透光孔相对准，入射光透过透光孔到达辅镜超构表面功能结构。
在一实施例中，辅镜超构表面功能单元包括反射金属层213、介质层214和金属亚波长结构211的叠层结构；或者，辅镜超构表面功能单元包括反射金属层213、金属亚波长结构或介质亚波长结构的单层结构。
在一实施例中，基于贝里几何相位原理设计的超构表面辅镜，不同相位对应的辅镜亚波长结构的方位角不同，即根据所需相位分布设置不同位置处的辅镜亚波长结构的方位角，以使入射光反射至超构表面主镜对应的位置。
在一实施例中，辅镜亚波长结构呈棒状和椭圆形中的至少一种，以实现较高的圆偏振光转换效率。
本实施例提供的超构表面主镜和本实施例提供的超构表面主镜的制备方法具备相同的功能和有益效果，未在本实施例的超构表面主镜中详尽描述的内容请参考本实施例的超构表面主镜的制备方法，此处不再赘述。
另外，本实施例还提供了一种光学系统，包括上述任一实施例提供的超构表面主镜和上述任一实施例提供的超构表面辅镜。其中，超构表面主镜和超构表面辅镜相对设置，且超构表面主镜和超构表面辅镜之间具有设定间距，以使入射到超构表面辅镜的入射光反射到超构表面主镜上，并经超构表面主镜进行反射聚焦。
在一实施例中，上述光学系统可以为基于反射式超构表面的平面透射式聚焦与成像系统，包括显微镜、望远镜、相机和红外成像设备等。
本实施例在完成光学系统的设计后，利用matlab软件模拟光线经过系统的光路，变化入射光的波长Δλ，观察系统的焦距变化Δf。利用Δf/Δλ的绝对值大小衡量系统的色散强弱，其中，正负反应系统是正色散还是负色散。经模拟验证，与相关技术中的史瓦兹德反射式物镜相比，由本实施例的超构表面主镜和超构表面辅镜组成的光学系统，该系统的色散大大降低。
本实施例提供的超构表面主镜、辅镜及主镜、辅镜制备方法和光学系统， 在超构表面主镜的透明衬底上形成满足主镜相位分布的主镜超构表面功能单元图案，在超构表面辅镜的透明衬底上形成满足辅镜相位分布的辅镜超构表面功能单元图案，使得入射光经超构表面辅镜反射到超构表面主镜上后，可由超构表面主镜进行反射聚焦，由此通过上述超构表面主镜和超构表面辅镜的组合设计，实现了基于反射式超构表面的平面透射式透镜的设计，解决了相关技术中的反射型物镜工艺制备苛刻、质量重、体积大和难以小型化以及集成化的问题。本实施例利用平面反射式超构表面来替代相关技术中的曲面反射镜，具有轻薄紧致和便于集成的优点，且超构表面的制备工艺也大大降低了相关技术中曲面的反射式物镜的制备难度，有利于实现反射式物镜大批量低成本地生产。

Claims (22)

  1. 一种超构表面主镜的制备方法，包括：
    提供透明衬底；及
    在所述透明衬底之上形成满足主镜相位分布的主镜超构表面功能单元图案，以对经超构表面辅镜反射到所述主镜上的入射光进行反射聚焦。
  2. 根据权利要求1所述的超构表面主镜的制备方法，其中，所述主镜相位分布根据设定参数结合射线光学及广义的反射定律确定，其中，所述设定参数包括系统的焦距、超构表面主镜和超构表面辅镜的口径、超构表面主镜和超构表面辅镜的间距、系统的工作波长，及入射光到达所述超构表面辅镜上的位置与所述超构表面辅镜反射所述入射光至所述超构表面主镜上的位置的映射关系；或者，
    所述主镜相位分布根据设定的曲面反射式物镜中曲面主镜的几何形状确定，其中，所述曲面反射式物镜包括曲面主镜和曲面辅镜，所述曲面主镜设置为将经所述曲面辅镜反射到所述曲面主镜上的入射光进行反射聚焦。
  3. 根据权利要求1所述的超构表面主镜的制备方法，其中，在所述透明衬底之上形成满足主镜相位分布的主镜超构表面功能单元图案，包括：
    在所述透明衬底之上的设定环形区域形成主镜超构表面功能结构，其中，所述主镜超构表面功能结构包括多个主镜超构表面功能单元，所述主镜超构表面功能单元包括主镜亚波长结构，所述主镜亚波长结构引入的相位满足所述主镜相位分布，环形的所述主镜超构表面功能结构所围绕的中间区域形成透光孔，所述入射光透过所述透光孔到达所述超构表面辅镜。
  4. 根据权利要求3所述的超构表面主镜的制备方法，其中，在所述透明衬底之上的设定环形区域形成主镜超构表面功能结构，包括：
    采用电子束蒸镀工艺或热蒸镀工艺在所述透明衬底之上依次蒸镀叠层的反射金属层和介质层；
    在所述介质层上旋涂电子胶或光刻胶；
    基于贝里几何相位原理，采用电子束曝光或光罩曝光工艺对位于所述设定环形区域的所述电子胶或所述光刻胶进行图案化，以使图案化之后的所述电子胶或所述光刻胶满足所述主镜相位分布；
    采用电子束蒸镀工艺或热蒸镀工艺在所述介质层表面和图案化之后的所述电子胶或所述光刻胶表面蒸镀金属层；
    去除图案化之后的所述电子胶或所述光刻胶，并保留所述介质层表面的金 属层，以形成所述主镜亚波长结构的图案；及
    采用聚焦离子束刻蚀工艺、反应离子束刻蚀工艺、感应耦合等离子体刻蚀工艺、离子减薄工艺、光刻工艺或激光工艺去除所述设定环形区域所围绕的反射金属层和介质层，形成平整的圆形所述透光孔。
  5. 根据权利要求4所述的超构表面主镜的制备方法，其中，采用电子束曝光或光罩曝光工艺对位于所述设定环形区域的所述电子胶或所述光刻胶进行图案化，包括：
    基于表面等离激元共振或者纳米结构散射理论，采用电子束曝光或光罩曝光工艺对位于所述设定环形区域的所述电子胶或所述光刻胶进行图案化。
  6. 一种超构表面主镜，采用如权利要求1-5任一项所述的超构表面主镜的制备方法制备，其中，所述超构表面主镜包括：
    透明衬底；及
    位于所述透明衬底之上的主镜超构表面功能单元图案，所述主镜超构表面功能单元图案设置为满足主镜相位分布，以对经超构表面辅镜反射到所述超构表面主镜上的入射光进行反射聚焦。
  7. 根据权利要求6所述的超构表面主镜，其中，所述主镜超构表面功能单元图案包括位于设定环形区域内的主镜超构表面功能结构，所述主镜超构表面功能结构包括多个主镜超构表面功能单元，所述主镜超构表面功能单元包括各向异性的主镜亚波长结构，所述主镜亚波长结构引入的相位满足所述主镜相位分布；
    所述超构表面主镜还包括透光孔，环形的所述主镜超构表面功能结构围绕所述透光孔设置，所述入射光透过所述透光孔到达所述超构表面辅镜。
  8. 根据权利要求7所述的超构表面主镜，其中，所述主镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构；或者，
    所述主镜超构表面功能单元包括反射金属层及金属主镜亚波长结构；或者
    所述主镜超构表面功能单元包括反射金属层及介质主镜亚波长结构的叠层结构。
  9. 根据权利要求7所述的超构表面主镜，其中，所述超构表面主镜的不同相位对应的所述主镜亚波长结构的方位角不同。
  10. 根据权利要求7所述的超构表面主镜，其中，所述主镜亚波长结构为各向异性结构，所述各向异性结构包括棒状和椭圆形中的至少一种。
  11. 一种超构表面辅镜的制备方法，包括：
    提供透明衬底；及
    在所述透明衬底之上形成满足辅镜相位分布的辅镜超构表面功能单元图案，以将入射到所述超构表面辅镜的入射光反射到超构表面主镜上，并经所述超构表面主镜进行反射聚焦。
  12. 根据权利要求11所述的超构表面辅镜的制备方法，其中，所述辅镜相位分布根据设定参数结合射线光学及广义的反射定律确定，其中，所述设定参数包括系统的焦距、超构表面主镜和超构表面辅镜的口径、超构表面主镜和超构表面辅镜的间距、系统的工作波长，及入射光到达所述超构表面辅镜上的位置与所述超构表面辅镜反射所述入射光至所述超构表面主镜上的位置的映射关系；或者，
    所述辅镜相位分布根据设定的曲面反射式物镜中曲面辅镜的几何形状确定，其中，所述曲面反射式物镜包括曲面主镜和曲面辅镜，所述曲面辅镜设置为将入射光反射到所述曲面主镜上，以经所述曲面主镜进行反射聚焦。
  13. 根据权利要求11所述的超构表面辅镜的制备方法，其中，在所述透明衬底之上形成满足辅镜相位分布的辅镜超构表面功能单元图案，包括：
    在所述透明衬底之上的设定圆形区域形成辅镜超构表面功能结构，其中，所述辅镜超构表面功能结构包括多个辅镜超构表面功能单元，所述辅镜超构表面功能单元包括辅镜亚波长结构，所述辅镜亚波长结构引入的相位满足所述辅镜相位分布，所述设定圆形区域设置为与所述超构表面主镜的透光孔相对准，以使入射光透过所述透光孔到达所述超构表面辅镜。
  14. 根据权利要求13所述的超构表面辅镜的制备方法，其中，在所述透明衬底之上的设定圆形区域形成辅镜超构表面功能结构，包括：
    在所述透明衬底之上旋涂光刻胶，并去除位于所述设定圆形区域的光刻胶；
    采用电子束蒸镀工艺或热蒸镀工艺在所述透明衬底表面及残留的光刻胶表面依次蒸镀叠层的反射金属层和介质层，并去除残留的光刻胶；
    在所述介质层及透明衬底上旋涂电子胶或光刻胶；
    基于贝里几何相位原理，采用电子束曝光或光罩曝光工艺对位于所述介质层上的电子胶或光刻胶进行图案化，以使图案化之后的所述电子胶或所述光刻胶满足所述辅镜相位分布；及
    采用电子束蒸镀工艺或热蒸镀工艺在所述介质层表面和图案化之后的电子 胶或光刻胶表面蒸镀金属层；
    去除图案化之后的电子胶或光刻胶，保留所述介质层表面的金属层，以形成所述辅镜亚波长结构的图案。
  15. 根据权利要求14所述的超构表面辅镜的制备方法，其中，采用电子束曝光或光罩曝光工艺对位于所述介质层上的电子胶或光刻胶进行图案化，还包括：
    基于表面等离激元共振或者纳米结构散射理论，采用电子束曝光或光罩曝光工艺对位于所述介质层上的电子胶或光刻胶进行图案化。
  16. 一种超构表面辅镜，采用如权利要求11-15任一项所述的超构表面辅镜的制备方法制备，所述超构表面辅镜包括：
    透明衬底；及
    位于所述透明衬底之上的辅镜超构表面功能单元图案，所述辅镜超构表面功能单元图案设置为满足辅镜相位分布，以将入射到所述超构表面辅镜的入射光反射到超构表面主镜上，并经所述超构表面主镜进行反射聚焦。
  17. 根据权利要求16所述的超构表面辅镜，其中，所述辅镜超构表面功能单元图案包括位于设定圆形区域内的辅镜超构表面功能结构，所述辅镜超构表面功能结构包括多个辅镜超构表面功能单元，所述辅镜超构表面功能单元包括辅镜亚波长结构，所述辅镜亚波长结构引入的相位满足所述辅镜相位分布；
    圆盘状的所述辅镜超构表面功能结构与所述超构表面主镜的圆形透光孔相对准，所述入射光透过所述透光孔到达所述辅镜超构表面功能结构。
  18. 根据权利要求17所述的超构表面辅镜，其中，所述辅镜超构表面功能单元包括反射金属层、介质层和金属亚波长结构的叠层结构；或者，
    所述辅镜超构表面功能单元包括反射金属层及金属亚波长结构；或
    所述辅镜超构表面功能单元包括反射金属层及介质亚波长结构的叠层结构。
  19. 根据权利要求17所述的超构表面辅镜，其中，所述超构表面辅镜的不同相位对应的所述辅镜亚波长结构的方位角不同。
  20. 根据权利要求17所述的超构表面辅镜，其中，所述辅镜亚波长结构为各向异性结构，所述各向异性结构包括棒状和椭圆形中至少一种。
  21. 一种光学系统，包括权利要求6-10任一项所述的超构表面主镜和权利要求16-20任一项所述的超构表面辅镜。
  22. 根据权利要求21所述的光学系统，其中，所述光学系统为基于反射式超构表面的平面透射式聚焦与成像系统。
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