CN115166958A

CN115166958A - Miniaturized tomography system

Info

Publication number: CN115166958A
Application number: CN202210832333.5A
Authority: CN
Inventors: 郝成龙; 谭凤泽; 朱瑞; 朱健
Original assignee: Shenzhen Metalenx Technology Co Ltd
Current assignee: Shenzhen Metalenx Technology Co Ltd
Priority date: 2022-07-15
Filing date: 2022-07-15
Publication date: 2022-10-11
Anticipated expiration: 2042-07-15
Also published as: CN115166958B

Abstract

The present disclosure provides a miniaturized tomographic imaging system. Comprises an illumination arm and a observation arm; the illumination arm comprises at least one superlens and a coherent light source; the observation arm comprises an observation objective lens and a detector; the super lens comprises a substrate, and a structural unit and a nano structure on the surface of the substrate; at least one superlens for forming the illumination light from the coherent light source into a plurality of focal points along an optical axis of the superlens; the observation objective lens is used for receiving light rays reflected by a sample to be detected at a plurality of focuses and imaging on the detector, an illumination light path of the illumination arm is separated from an observation light path of the observation arm, and the observation objective lens is perpendicular to the optical axis of the super lens. In the system, two beams of coherent light interfere through the super lens or pass through the multi-focus super lens to form a plurality of focuses, and the layered illumination of the sample to be measured is realized through the plurality of focuses; meanwhile, the receiving observation objective lens is arranged in the direction vertical to the optical axis of the super lens, so that single multilayer tomography is realized, and the problem of scanning in the z direction in tomography is solved.

Description

Miniaturized tomography system

Technical Field

The application relates to the field of microscopic equipment, in particular to a miniaturized tomography system.

Background

Compared with other types of tomography, optical tomography (optical tomography) has the advantages of small interference degree on tissues, high resolution level, capability of imaging in vitro or living body in real time and the like. The optical projection tomography reconstructs a two-dimensional image of a certain fault through an algorithm according to the data of the projection of the fault at different angles, and then all the faults are gathered and superposed to obtain an integral three-dimensional structure. The resolution reaches the micron order, and the imaging depth reaches the millimeter order.

In the optical tomography microscopic scheme in the prior art, optical layering is mostly realized in a confocal microscope mode, so that three-dimensional image reconstruction is realized according to layered images, but the axial resolution of the scheme is limited, and imaging with sub-wavelength resolution in the z-axis direction cannot be realized.

In the prior art, a 4pi microscope consisting of two microscope objectives forms a super-resolution focus in the optical axis direction by utilizing the interference of coherent light in the optical axis direction, so that high-resolution imaging in the z-axis direction can be realized. However, the focus of the traditional 4pi microscope is single, and moving scanning in three directions of x-y-z is still required to realize three-dimensional imaging, so that the imaging time is long.

Disclosure of Invention

In view of the shortcomings of the prior art, the present application provides, in a first aspect, a compact tomography system comprising an illumination arm and a viewing arm;

wherein the illumination arm comprises at least one superlens and a coherent light source; the observation arm comprises an observation objective lens and a detector;

the at least one superlens comprises a substrate and a structural unit on the surface of the substrate, and the vertexes and/or the centers of the structural units are provided with nano structures;

wherein the at least one superlens is to form illumination light from the coherent light source into a plurality of focal points along an optical axis of the superlens;

the observation objective lens is used for receiving the light rays reflected by the samples to be detected from the plurality of focuses and imaging on the detector so as to simultaneously obtain multilayer image information of the samples to be detected,

wherein the optical path of the illumination arm is different from the optical path of the viewing arm.

Optionally, a beam splitter for proportionally splitting the illumination light from the coherent light source into a first light ray and a second light ray; and the at least one superlens comprises a first superlens and a second superlens, the first superlens and the second superlens are oppositely arranged, and the first superlens and the second superlens are in a confocal point and are arranged in a coaxial axis;

the first superlens is configured to modulate a first light ray, and the second superlens is configured to modulate a second light ray such that the modulated first light ray and the modulated second light ray interfere to form a plurality of focal points along an optical axis.

Optionally, the beam splitter is a half-reflecting half-mirror or a cubic prism.

Optionally, the beam splitter has a splitting ratio of 50.

Optionally, the illumination arm further comprises a spatial filter disposed in an optical path upstream of the at least one superlens, the spatial filter configured to modulate coherent light from the coherent light source into an annular light beam.

Optionally, within the illumination arm, the following beams are incident to the at least one superlens: the light beam has a convergence angle of 10 degrees or less after being modulated by the at least one superlens.

Optionally, the at least one superlens is capable of having the light field intensity distribution at the plurality of focal points satisfy:

where h (z) is the intensity of light along the z-axis, Q is approximated by a sinc function, λ is the wavelength of the illuminating light, α is the angle of convergence, and n is the refractive index around the plurality of focal points.

where h (z) is the light intensity along the z-axis, λ is the illumination light wavelength, α is the convergence angle, and n is the refractive index around the plurality of focal points.

Optionally, the coherent light source provides illumination light having a coherence length greater than 10 times a depth of focus of the plurality of focal points.

Optionally, the superlens is a multifocal superlens, and the geometric parameter and/or phase arrangement of the structural unit and the nanostructure of the multifocal superlens is configured as follows: the coherent light from the coherent light source is received and converged, and the converged coherent light forms a plurality of focal points along a straight line.

Optionally, the nanostructures of the multifocal super lens are annularly arranged, where the arrangement structures of the nanostructures of different ring surfaces are different, and the focal lengths of the different ring surfaces are different, so that the converged coherent light can form a plurality of focuses along the optical axis, where the radius of each ring surface satisfies:

wherein k is the number of the circular rings from inside to outside, n is the total number of different areas and the number of focuses of the superlens, and R is the radius of the superlens.

Optionally, the observation objective comprises a collecting superlens, the collecting superlens being arranged parallel to the multifocal superlens optical axis.

Optionally, based on the geometric parameters and/or phase arrangement of the structural unit and the nanostructure, the collecting superlens and the multifocal superlens are configured identically, and the collecting superlens and the multifocal superlens are symmetrically disposed, and the straight line where the plurality of focuses are located is located on the central axis of symmetry.

Optionally, the collecting superlens and the multifocal superlens are formed in different regions of the same substrate.

Optionally, the viewing objective is arranged perpendicular to the superlens optical axis.

Optionally, the optical system comprises a sample stage, which is arranged at the plurality of focal points, is used for placing a sample to be measured, and is at least capable of moving in a plane perpendicular to the optical axis.

Optionally, the optical system further comprises a beam expander disposed downstream of the coherent light source in the optical path.

Optionally, the coherent light source is capable of providing coherent light in the visible or near infrared band.

Optionally, the imaging field of view of the viewing objective is larger than the depth of the plurality of focal points.

Optionally, the observation objective is a monochromatic aberration correction superlens; the conjugate distance of the observation objective is infinity.

The technical scheme has the advantages and effects that at least:

a plurality of focuses along the optical axis direction can be formed to realize layered illumination of a sample to be tested; meanwhile, an observation objective lens is arranged in the direction perpendicular to the optical axis of the superlens, namely a Theta structure is adopted, so that single multilayer tomography is realized, and the scanning speed is obviously improved.

Furthermore, the annular light beams are utilized to form layered illuminating light with a plurality of focuses along the optical axis direction, so that the problem of scanning in the z direction in tomography is solved;

and the super lens has the advantages of small volume, light weight, simple structure and easy mass production, and can form a small-sized tomography system.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present application;

FIG. 2 is a schematic structural diagram of another embodiment of the present application;

FIG. 3 is a schematic diagram showing the relationship between the field of view of the objective lens and the depth of focus of the superlens;

FIG. 4 is a schematic diagram of an embodiment of an annular beam path;

FIG. 5 is a schematic diagram of the light path of the very thin light beam in the embodiment;

FIG. 6 is a schematic view of a superlens structure unit;

FIG. 7 is a schematic view of a superlens nanostructure;

fig. 8 is a schematic structural diagram of another embodiment of the present application.

Reference numerals:

1 Superlens 11 first Superlens

12 second super lens 13 multifocal super lens

14-collecting superlens 2 observation objective lens

3 detector 4 coherent light source

5 Beam splitter 6 Beam expander

7 spatial filter 8 tube lens

9 plane mirror 10 sample stage

Detailed Description

The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This disclosure 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.

For reference directions such as the "z-axis" described in the embodiments, the reference coordinate systems shown in fig. 1 and 2 are taken as references.

Aiming at the defects in the prior art, the embodiment of the application aims to realize single multilayer tomography and solve the scanning problem in the direction of the z axis in the tomography by enabling the illuminating light to form a plurality of focuses along the optical axis and matching with the observation objective lens arranged in the direction vertical to the optical axis based on the Theta-type structure.

In view of the above, the embodiments of the present application first provide a miniaturized tomography system, which may include at least one superlens, as well as a sample stage, a light source, an observation objective, and a detector.

The super lens comprises a substrate and a structural unit on the surface of the substrate, wherein a nano structure is arranged at the vertex and/or the center of the structural unit; the at least one superlens is used for forming a plurality of focal points along an optical axis by the illumination light from the light source;

the sample stage is arranged at one of the plurality of focuses, is used for placing a sample to be tested, and can move at least in a plane perpendicular to the optical axis, and preferably can also move along the direction of the optical axis, so that an object with a very large thickness can be scanned;

the observation objective lens is used for receiving the plurality of focuses and the light reflected by the sample to be detected, and imaging is carried out on the detector so as to obtain layered image information of the sample to be detected.

The embodiment forms the layered illumination light with a plurality of focuses along the optical axis direction, and solves the problem of scanning in the z direction in tomography; meanwhile, the scheme inherits the advantages of small volume, light weight, simple structure and easy mass production of the superlens, and can form a small-sized analytic imaging system.

In the embodiments of the present application and various alternative embodiments, the superlens described includes the following features:

a superlens is a kind of supersurface. The super surface is a layer of sub-wavelength artificial nano-structure film, and incident light can be modulated according to super surface structure units on the super surface. The super-surface structure unit comprises a full-dielectric or plasma nano antenna, and the phase, amplitude, polarization and other characteristics of light can be directly adjusted and controlled. The super lens comprises a substrate and a structural unit on the surface of the substrate, wherein a nano structure is arranged at the vertex and/or the center of the structural unit;

the structural units are in a close-packed pattern, the structural units can be regular hexagons, and at least one nano structure is arranged at each vertex and the center of each regular hexagon. Or the structural unit is a square, and at least one nano structure is arranged at each vertex and the center of the square. Ideally, the structural units should be hexagonally-arranged and centrally-arranged nanostructures or quadrate-arranged and centrally-arranged nanostructures, and it should be understood that the actual product may have the loss of nanostructures at the edge of the superlens due to the limitation of the superlens shape, so that the actual product does not satisfy the complete hexagon/quadrate. Specifically, as shown in fig. 6, the structural units are formed by regularly arranging nanostructures, and a plurality of structural units are arranged in an array to form a super-surface structure.

One embodiment, as shown in the left part of fig. 6, includes a central nanostructure surrounded by 6 peripheral nanostructures at equal distances, and the peripheral nanostructures are uniformly distributed on the circumference to form a regular hexagon, which can also be understood as a regular triangle formed by a plurality of nanostructures combined with each other.

One embodiment, shown in the middle portion of fig. 6, includes a central nanostructure surrounded by 4 peripheral nanostructures spaced equally apart from the central nanostructure to form a square.

The form of the structural units and their close packing/array may also be a circular array of sectors, as shown in the right part of fig. 6, including two arc-shaped sides, or a sector of one arc-shaped side, as shown in the lower left corner region in the right part of fig. 6. And the intersection points of all sides of the fan shape and the center are provided with a nano structure.

The nano-structure can be a polarization-dependent structure, such as a nano-fin, a nano-elliptic cylinder and the like, and the structure exerts a geometric phase on incident light; the nanostructures may also be polarization-independent structures, such as nanocylinders and nanosquares, which impart a propagation phase to incident light. The form of the nanostructures is shown in fig. 7.

The nanostructures may be filled with air or other material that is transparent or translucent in the operating band. According to embodiments of the present disclosure, the absolute value of the difference between the refractive index of the filled material and the refractive index of the nanostructures should be greater than or equal to 0.5.

Illustratively, the phase of the superlens in an embodiment may satisfy one of the following equations:

wherein r is the distance from the center of the superlens to the center of any of the nanostructures; lambda is the wavelength of operation and,

and x and y are the coordinates of the mirror surface of the super lens, and f is the focal length of the super lens.

According to the embodiments of the present application, an example in which two beams of coherent light interfere to form a plurality of focal points by two superlenses is provided as follows.

As shown in fig. 1, it includes a coherent light source 4 (the coherent wavelength is λ), a superlens (11 and 12 in this embodiment each represent a superlens), a beam splitter 5, a sample stage 10, an observation objective 2, and a detector 3.

In the present embodiment, the coherent light provided by the coherent light source 4 is divided into two beams propagating along two different directions by the beam splitter 5, and the two beams are transmitted to the two superlenses respectively.

As shown in fig. 1, the beam splitter 5 is disposed downstream of the coherent light source 4 and upstream of the two superlenses in the propagation light path of the illumination arm, and may be combined with a plane mirror 9 and other devices to transmit the split first light and second light to the corresponding superlenses, respectively.

Illustratively, the beam splitter may be a half-reflecting and half-transmitting mirror or a cubic prism or the like.

It will be appreciated that the beam splitter 5 may split the coherent light into two beams in a certain proportion, in a preferred embodiment 50.

In this embodiment, the superlenses are two superlenses operating at coherent wavelengths. The optical lens specifically comprises a first super lens 11 and a second super lens 12 which are oppositely arranged and arranged in a confocal and coaxial way; the first superlens 11 is configured to receive and converge a first light, and the second superlens 12 is configured to receive and converge a second light, the first light and the second light being coherent light provided by a coherent light source.

The first light ray and the second light ray pass through the super lens and are focused at a common focus of the two super lenses respectively, so that interference is generated, and a plurality of focuses along the optical axis are formed.

The light intensity field distribution around the focus thereof satisfies formula 1:

where h (z) is the intensity of light along the z-axis, where Q can be approximated by a sinc function, λ is the illumination light wavelength, α can be given by FIG. 4, and n is the refractive index around the focal point. When α approaches 0, equation 1 approximates equation 2:

equation 2 gives an array of points along the z-axis with a period of λ/n.

In this embodiment, the sample stage 10 is arranged at the common focal point of the first and

second superlenses

11, 12, and this sample stage is movable at least in the x-y plane, based on the reference direction in fig. 1, to thereby effect scanning. However, the present application is not limited thereto, and when the dimension of the sample to be measured in the z-axis direction is too large to exceed the plurality of focal depths, the sample stage 10 may be moved in the z-axis direction.

The observation objective 2 observes the sample illuminated by the plurality of focal points, imaged onto the detector 3 by the tube lens 8, and can image a plurality of layers in the z-direction at a time. The observation objective 2 is arranged here perpendicular to the optical axis of the superlens.

In a preferred embodiment, as shown in fig. 3, the imaging field of view of the observation objective 2 has a depth of focus greater than 4pi focus. The beneficial effects that can be realized thereby are: the detector is capable of imaging focal planes simultaneously, imaging multiple slices in the z-direction at a time. Based on this, the detector 3 can separately image a plurality of focal spots to different positions.

In a preferred embodiment, optics such as tube lens 8, filters (not shown) may also be provided in the viewing arm for use with the viewing objective and detector.

In a preferred embodiment, the associated light source may emit coherent light in the visible and near infrared bands, wherein the coherence length of the first and second light rays is greater than 10 times the focal depth of the focal point. The effect of this is to allow the first light and the second light to interfere correctly at a predetermined position. If the coherence length is exceeded, interference cannot occur and the z-axis multifocal, super-resolution effect required by the present application is lost.

According to an embodiment of the present application, an embodiment is provided that forms layered illumination light of a plurality of focal points in an optical axis direction with a ring-shaped light beam to solve a problem of scanning in a z direction in tomography.

The coherent light input into the superlens forms a ring in a cross section perpendicular to the optical axis, that is, the coherent light input into the superlens is a hollow ring beam. As shown in fig. 5, when two coherent ring beams converge to the common focus point of the optical axis, a plurality of light focus points with the same intensity, equal spacing and equal resolution can be formed in the optical axis direction, and the reflected light of each focus point is received and imaged by a detector, thereby realizing tomography of a plurality of layers along the optical axis.

To form an annular beam, the system may comprise a spatial filter 7, as shown in fig. 1, arranged upstream of the superlens in the optical path of the illumination arm.

In an embodiment, each superlens is capable of satisfying a light field intensity distribution at the plurality of focal points:

where h (z) is the light intensity along the z-axis, λ is the illumination light wavelength, α is the convergence angle, and n is the refractive index around the plurality of focal points. Meanwhile, as noted in fig. 5, the value θ in the above equation is the convergence angle of the annular beam as a whole. According to an embodiment of the present application, an embodiment is provided in which layered illumination light of a plurality of focal points in the optical axis direction is formed using an extremely thin light beam to solve the problem of scanning in the z direction in tomography.

In the embodiment of the present application, as shown in fig. 4, the extremely fine light beam means a light beam having a convergence angle 2 α of 10 ° or less.

The first superlens and the second superlens are capable of converging the extremely fine light beams at a common focus point along an optical axis. And a plurality of focal points are formed by interference between the respective extremely fine light beams.

In the above embodiment, the first superlens 11 and the second superlens 12 are preferably spherical aberration correction superlenses having the same aperture, numerical aperture, and focal length.

In a preferred embodiment, the observation objective 2 may comprise a superlens, which is used to achieve the function of collecting optical information of the sample instead of conventional optics. The superlens is configured as a monochromatic aberration-corrected superlens, and is configured as an infinity conjugate lens.

It is to be understood that the infinity conjugate lens (viewing objective), as well as the tube lens described in the above embodiments, can form: the light scattered from the sample is parallel light beams after passing through the observation objective lens, and the tube lens is arranged between the observation objective lens and the ocular lens to form an intermediate image, so that the configuration of the optical system is more flexible, the magnification is not changed even if the distance between the observation objective lens and the tube lens is changed, the distance is not limited, and the expansion of imaging modules such as fluorescence and the like, an optical filter and the like in the optical system is facilitated.

According to the embodiment of the present application, the sample stage 10 is movable in two directions perpendicular to the optical axis, thereby achieving scanning. Illustratively, the sample stage 10 may be driven stepwise by a high precision translation stage. However, the present application is not limited thereto, and the sample stage 10 may be configured to be movable in the optical axis direction in order to accommodate a sample to be measured having a large size.

According to an embodiment of the present application, as shown in fig. 1, the system may further include a beam expander 6 for diffusing light emitted from the coherent light source (e.g., laser) to a desired aperture Di, wherein the beam expander 6 may be, for example, an inverted telescope.

According to the embodiment of the present application, the arrangement of the entire system is as shown in fig. 1, with the common optical axis of the two superlenses as the z-axis, and the observation objective lens 2, the tube lens 8, and the detector 3 are arranged in this order in the x-axis direction perpendicular to the z-axis. The sample stage is arranged at the focus of the z-axis and the x-axis. And the optical axes of the observation objective 2, tube lens 8 and detector 3 are shown to be coincident or parallel to the x-axis. The first and

second superlenses

11 and 12 are arranged symmetrically with respect to the x-axis, and the spatial filter 7 and the plane mirror 9, which are respectively located upstream of the first and

second superlenses

11 and 12, are arranged symmetrically with respect to the x-axis.

According to an embodiment of the application, a system is provided with an illumination arm and a viewing arm. The illumination arm is used for forming a plurality of focuses for illuminating the sample, and the observation arm is used for collecting light signals which are reflected by the plurality of focuses and carry sample layering information. Wherein the illumination arm is provided with the superlens, the spatial filter 7, the plane mirror 9, the beam splitter 5, the beam expander 6 and the coherent light source 4 as described in the above embodiments, and may further include other optical devices for forming an optical path. The first superlens 11 and the second superlens 12 are provided in the illumination arm. The viewing arm is provided with a viewing objective 2, a tube lens 8 and a detector 3 as described in the above embodiments.

Optionally, when the system has nonlinear imaging light wavelength λ ₁ The viewing arm optical system needs to be at a nonlinear optical wavelength λ (e.g., two-photon excitation imaging, second harmonic imaging, single photon excitation imaging, etc.) ₁ Is greater than 90%, and wherein the filter is capable of filtering the wavelength λ of the illumination light.

In the above embodiment, the coherent light source provides coherent light in the visible or near infrared band, and the coherence length is greater than 10 times the focal depth of the 4pi focal point. The coherent light source may be a laser source.

According to embodiments of the present application, an example of arranging the illumination and observation optical paths in a theta configuration is provided as follows.

It is understood that the prior art observation light and the illumination light adopt the same optical path, and then an artifact is generated due to a side lobe effect, and therefore, the prior art aims to suppress the side lobe to reduce the artifact. This embodiment overcomes the inertial thinking in the prior art, in the present invention, the observation optical path and the illumination optical path are separated by the microscopic tomographic imaging system of Theta structure, and by generating multi-focus simultaneously, the side lobe can be directly utilized, preferably, the energy distribution of the side lobe can be the same as the main lobe in the case of using the ring beam to be incident into the superlens, thereby generating a uniformly distributed tomographic. It is preferable to make the modulated light waves have the same amplitude, i.e. the side lobes and the main lobe are close to each other, which is more convenient for observation.

In this embodiment, as shown in fig. 1, the illumination path of the illumination arm is separated from the observation path of the observation arm, and the observation objective 2 is disposed perpendicularly to the superlens optical axis.

It should be understood that the optical axis of the observation arm is parallel to the x-axis in fig. 1 for clarity of description, but the application is not limited thereto, and the optical axis of the observation arm may be parallel to the y-axis, for example, and so on.

According to embodiments of the present application, another example of arranging the illumination and viewing optical paths in a theta configuration is provided as follows.

As shown in fig. 2, the illumination path of the illumination arm is separated from the observation path of the observation arm, and the observation objective 2 is arranged perpendicularly to the superlens optical axis.

It should be understood that the optical axis of the observation arm is parallel to the x-axis in fig. 2 for clarity of description, but the application is not limited thereto, and the optical axis of the observation arm may be parallel to the y-axis, for example.

According to embodiments of the present application, an example is provided in which multiple focal points are directly formed by a single superlens.

As shown in fig. 2, such a system comprises a coherent light source 4, a superlens 1, an optional sample stage (not shown) located at the intersection of the superlens optical axis and the observation objective optical axis, an observation objective 2 and a detector 3;

the super lens 1 is a multi-focus super lens 13 and comprises a substrate and a structural unit arranged on the surface of the substrate, and a nano structure is arranged at the top point and/or the center of the structural unit; the multi-axial focus superlens is used for receiving and converging the illumination light, and the multi-axial focus superlens is configured to: forming the converged illumination light into a plurality of equally large focal points along an optical axis;

the sample stage is arranged perpendicular to the optical axis, can enable at least one focus to be formed on the sample, and can move at least in a plane perpendicular to the optical axis;

the observation objective lens 2 is used for receiving the light rays reflected by the samples to be detected at the multiple focuses, and imaging is carried out on the light rays by the detector 3 so as to obtain layered image information of the samples to be detected.

In a preferred embodiment, as shown in fig. 2, further comprising: the coherent light source 4 is capable of providing coherent light in the visible or near infrared band.

In a preferred embodiment, as shown in fig. 2, further comprising: and the beam expander 6 is arranged at the downstream of the optical path of the coherent light source 4 and is used for diffusing the light emitted by the coherent light source to a required aperture.

In a preferred embodiment, the total depth of focus formed by the multifocal superlens is DOF, which is larger than the imaging field of view of the observation objective 2.

In order to realize the multifocal super lens, the structural unit and the nanostructure of the surface of the multifocal super lens are divided into a plurality of ring surfaces, the arrangement structure of the nanostructure of different ring surfaces is different, and different focuses exist. Preferably, the annuli have the same area, so as to provide similar luminous flux, with the focus brightness being as uniform as possible.

Wherein the radius of each torus satisfies:

wherein k is the number of the rings from inside to outside, n is the total number of different areas and the number of focuses of the super lens, and R is the radius of the super lens.

According to the implementation mode of the application, in a preferred embodiment, the multifocal superlens can also be realized by an adjustable superlens.

The embodiment aims to form the focuses at different positions at different time nodes by continuously adjusting the phase of the superlens, so that tomography of multiple focuses is realized.

It will be appreciated that the optical performance of a superlens is largely determined by two factors: 1 the geometry and dimensions of the structural units; 2 dielectric constant of the material. It can be seen that if the above two factors can be changed, the superlens can be adjusted. Thus, the dielectric constant of the material can be changed to realize the regulation or reconstruction of the optical performance of the device. Illustratively, the phase change material can be applied to the superlens, and the phase change material can change the crystal lattice inside the substance under the action of external excitation (such as heat, laser, external voltage and the like), so that the dielectric constant can be greatly changed, and the adjustability of the superlens is realized. For example, a flexible material may be applied to the superlens, and a stretching force may be applied to the flexible material, so that the geometric shape and size of the structural unit may be changed, and the superlens may be adjusted.

The tunable superlens used in the embodiments includes, by way of example and not limitation, a thermally-controlled tunable superlens, an optically-controlled tunable superlens, or an electrically-controlled tunable superlens. For example, the substrate of the superlens is made of a stretchable material, the nanostructure of the superlens is fixed on the substrate after being processed, and the substrate is stretched or compressed by an external mechanical device to change the spacing of the nanostructure on the superlens, thereby changing the period of light passing through the superlens and further changing the phase of the light.

According to an embodiment of the present application, another example of forming multiple focuses and collecting by a superlens is provided as follows.

The observation objective in this embodiment specifically includes a collecting superlens 14, and the collecting superlens 14 is disposed in parallel with the optical axis of the multifocal superlens 13.

Specifically, as shown in fig. 8, the light rays (illumination light) emitted from the light source 4 are collimated, input to the multifocal super lens 13, and a plurality of focal points along the axis (dotted line in the figure) are formed by the multifocal super lens 13. It should be noted that, in order to clearly show the optical path of the present embodiment, the object to be measured has been hidden in fig. 8.

Meanwhile, a collecting superlens 14 is arranged to receive the reflected light beams of the plurality of focal points on the object to be measured, modulate the reflected light beams into collimated light beams, and input the collimated light beams to the detector 3.

In a preferred embodiment, the collecting super lens 14 and the multifocal super lens 13 are configured identically based on the principle that the optical path is reversible, and the collecting super lens 14 and the multifocal super lens 13 have the same geometric parameters and/or phase arrangement of the structural units and the nanostructures exemplarily. And exemplarily, the collecting super lens 14 is arranged symmetrically to the multi-focus super lens 13, and a straight line where the plurality of focuses are located is located on the central axis of symmetry (a dotted line in the figure).

Based on the above embodiment, the present embodiment can at least realize three-dimensional high-resolution imaging in a relatively large depth range, and effectively avoid the limitation caused by diffraction.

In a preferred embodiment, the collecting superlens 14 and the multifocal superlens 13 are formed in different regions of the same substrate. Specifically, the illumination light incidence and collection paths are separated by two superlenses (two super-surface regions of the same substrate). And a one-to-one or "bijective" relationship is created between the illumination light incident and the focal point of the collection path, effectively eliminating the out-of-focus signal.

According to an embodiment of the present application, a superlens-based tomography method is provided as follows.

The method comprises the following steps:

providing coherent light in an optical path of an illumination arm;

modulating the coherent light through at least one superlens to form a plurality of focuses along an optical axis, and enabling the plurality of focuses to irradiate a sample to be detected;

moving the sample to be detected in a plane vertical to the optical axis, and scanning the sample to be detected;

and in the light path of the observation arm different from that of the illumination arm, the observation objective lens is used for simultaneously receiving the reflected light rays of the samples to be detected at the plurality of focuses and imaging the reflected light rays at the detector so as to obtain the layered image information of the samples to be detected.

In a preferred embodiment, two coherent light beams are provided and are caused to interfere to form the plurality of focal points by two confocal, co-axial superlenses.

In a preferred embodiment, the two coherent light beams are both hollow annular light beams.

In a preferred embodiment, the two beams of coherent light each comprise a very thin beam of light. As in the other embodiments, the above-described very thin light beam means a light beam having a convergence angle 2 α of 10 ° or less.

Examples of the invention

Example 1

A tomography system based on a 4pi superlens is provided, wherein the system parameters are shown in table 1. The x-y resolution of the chromatography is 500nm, the axial resolution is 400nm, the resolution of the system is high, and the imaging speed is high.

TABLE 1

Parameter(s)	Numerical value
		Working wavelength of lighting arm (nm)	532
Convergent angle (°) of superlens	2
		Observation lens operating wavelength (nm)	532
Numerical aperture of observation lens	0.5

Example 2

A tomography system based on multifocal superlenses is provided wherein the system parameters are shown in table 2. The x-y resolution of the chromatography is 550nm, the axial resolution is 500nm, the resolution of the system is high, and the imaging speed is high.

TABLE 2

The above description is only a specific implementation of the embodiments of the present invention, but the scope of the embodiments of the present invention 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 of the present invention, and all such changes or substitutions should be covered by the scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention shall be subject to the protection scope of the claims.

Claims

1. A miniaturized tomography system comprising an illumination arm and a viewing arm;

the at least one superlens comprises a substrate and a structural unit on the surface of the substrate, and the apex and/or the center of the structural unit is provided with a nano structure;

wherein the at least one superlens is to form the illumination light from the coherent light source into a plurality of focal points along an optical axis of the superlens;

2. The miniaturized tomography system of claim 1 further comprising a beam splitter for proportionally splitting the illumination light from the coherent light source into first and second light rays; and the at least one superlens comprises a first superlens and a second superlens, the first superlens and the second superlens are oppositely arranged, and the first superlens and the second superlens are in a confocal point and are arranged in a coaxial axis;

the first superlens is configured to modulate a first light ray, and the second superlens is configured to modulate a second light ray, so that the modulated first light ray and the modulated second light ray interfere with each other to form a plurality of focal points along an optical axis.

3. The miniaturized tomography system of claim 2, wherein the beam splitter is a half-mirror or a cube prism.

4. The miniaturized tomography system of claim 2, wherein the beam splitter has a splitting ratio of 50.

5. The miniaturized tomography system of claim 2, wherein the illumination arm further comprises a spatial filter disposed in the optical path upstream of the at least one superlens, the spatial filter configured to modulate coherent light from the coherent light source into an annular light beam.

6. The miniaturized tomography system of claim 2, wherein within the illumination arm, the following beams are incident to the at least one superlens: the light beam has a convergence angle of 10 degrees or less after being modulated by the at least one superlens.

7. The miniaturized tomography system of claim 5 or 6, wherein the at least one superlens is capable of having the light field intensity distribution at the plurality of focal points satisfy:

8. The miniaturized tomographic imaging system of claim 6, wherein the at least one superlens is capable of having the light field intensity distribution at the plurality of focal points satisfy:

9. The miniaturized tomographic imaging system of claim 5, wherein the at least one superlens is capable of having the light field intensity distribution at the plurality of focal points satisfy:

10. The miniaturized tomography system of claim 2, wherein the coherent light source provides illumination light having a coherence length greater than 10 times a depth of focus of the plurality of focal points.

11. The miniaturized tomographic imaging system of claim 1, wherein the superlens is a multifocal superlens, and the geometric parametric and/or phase arrangement of the structural units and the nanostructures of the multifocal superlens is configured as: the coherent light from the coherent light source is received and converged, and the converged coherent light forms a plurality of focal points along a straight line.

12. The miniaturized tomography system of claim 11, wherein the nanostructures of the multifocal superlens are arranged in a ring, wherein the nanostructures of different ring surfaces are arranged differently, and wherein the focal lengths of different ring surfaces are different, such that the focused coherent light forms multiple focal points along the optical axis, wherein the radius of each ring surface satisfies:

13. The miniaturized tomography system of claim 11, wherein the viewing objective comprises a collection superlens disposed parallel to the multifocal superlens optical axis.

14. The miniaturized tomography system of claim 13, wherein the collecting superlens is configured identically to the multifocal superlens based on geometric parameters and/or phase arrangements of structural units and nanostructures, and the collecting superlens and the multifocal superlens are symmetrically disposed, and the straight line of the plurality of foci is located on the central axis of symmetry.

15. The miniaturized tomography system of claim 14, wherein the collection superlens and the multifocal superlens are formed in different regions of the same substrate.

16. The miniaturized tomography system of any one of claims 1 to 6 or 9 to 12, wherein the viewing objective is disposed perpendicular to the superlens optical axis.

17. The miniaturized tomography system of any one of claims 1 to 6 or 9 to 15, comprising a sample stage disposed at the plurality of focal points for placing a sample to be measured and movable at least in a plane perpendicular to the optical axis.

18. The miniaturized tomography system of any of claims 2-6 or 9-15, further comprising a beam expander disposed in the optical path downstream of the coherent light source.

19. The miniaturized tomography system of any of claims 1 to 6 or 9 to 15 wherein the coherent light source is capable of providing coherent light in the visible or near infrared band.

20. The miniaturized tomography system of claim 16 wherein the field of view of the viewing objective is greater than the depth of the plurality of focal points.

21. The miniaturized tomographic imaging system of claim 20, wherein the observation objective is a monochromatic aberration-correcting superlens; the conjugate distance of the observation objective is infinity.