WO2023045415A1

WO2023045415A1 - Spectral measurement device and method

Info

Publication number: WO2023045415A1
Application number: PCT/CN2022/098310
Authority: WO
Inventors: 郝成龙; 谭凤泽; 朱健
Original assignee: 深圳迈塔兰斯科技有限公司
Priority date: 2021-09-23
Filing date: 2022-06-13
Publication date: 2023-03-30
Also published as: CN113834568A

Abstract

Provided in the present application is a spectral measurement device and method, which belong to the field of spectral measurement. The device comprises: a metalens dispersion system, a microscopic system, a detector, and a computer processing system, wherein an optical axis of the metalens dispersion system is parallel to incident light; an optical axis of the microscopic system is perpendicular to the optical axis of the metalens dispersion system; an object-side focus of the microscopic system is located on the optical axis of the metalens dispersion system; and the microscopic system, the detector and the computer processing system are connected in sequence, and the detector is located in an image-side plane focal plane of the microscopic system. In the spectral measurement device, the metalens dispersion system and the microscopic system are of an L-type layout, which breaks through the limitations of a large-angle dispersion system on the size of the detector and improves the precision of a spectrometer.

Description

Spectral measurement device and method

technical field

The present application relates to the technical field of spectroscopic analysis, in particular, to a spectroscopic measurement device and method.

Background technique

The spectral measurement device is a scientific instrument that decomposes complex light into spectral lines. It is composed of a prism or a diffraction grating. The spectral measurement device can measure the light reflected by the surface of an object.

Spectrum measuring devices in the related art include grating-based spectroscopic measuring devices, narrow-band filter array-based spectroscopic measuring devices, and off-axis metasurface-based spectroscopic measuring devices.

In the related art, grating-based spectral measurement devices and spectral measurement devices based on narrow-band filter arrays cannot be measured off-axis; while off-axis metasurface-based spectral measurement devices use metasurfaces to focus light of different wavelengths to different heights of the image plane Or use the multi-reflection cavity metasurface for multiple reflection splitting. The phase change of the off-axis focusing metasurface adopted in this design is large, and the design, processing and assembly of the metasurface are difficult. Therefore, it is urgent to solve the difficulty of reducing the design, processing and assembly of off-axis detection.

Contents of the invention

In order to solve the existing technical problems, the embodiment of the present application provides a spectral measurement device to solve the problem of difficulty in the design, processing and assembly of off-axis detection in the related art. The technical solution provided by the embodiment of the present application is as follows :

An embodiment of the present application provides a spectral measurement device, including a metalens dispersion system, a microscopic system, a detector and a computer processing system;

Wherein, the optical axis of the metalens dispersion system is parallel to the incident light; the optical axis of the microscopic system is perpendicular to the optical axis of the metalens dispersion system; the object focus of the microscopic system is located in the metalens dispersion system on the optical axis; the microscopic system, the detector and the computer processing system are sequentially connected, and the detector is located on the image square focal plane of the microscopic system;

The metalens dispersion system is used to focus light of different wavelengths on different positions on the optical axis of the metalens dispersion system to form corresponding focal points;

The microscopic system is used to magnify and image the focus of the light of different wavelengths;

the detector is used to measure the light intensity of the focus of the different wavelengths of light;

The computer processing system is configured to process information obtained from measurements of the detectors.

Optionally, the metalens dispersion system includes at least one transmission type metalens.

Optionally, the focal length of the metalens dispersion system is the distance from the focus of light of different wavelengths to the back surface of the metalens dispersion system.

Optionally, the focal length of the metalens dispersion system has a one-to-one mapping relationship with the wavelength of the incident light.

Optionally, the diameter of the field of view of the microscopic system is greater than or equal to the depth of focus of the metalens dispersion system.

Optionally, the diameter of the field of view of the microscopic system is smaller than the focal depth of the metalens dispersion system.

Optionally, the working bands of the metalens dispersion system include visible light bands, near-infrared bands, mid-far infrared bands and terahertz bands.

Optionally, the operating wavebands of the microscope system include visible light, near-infrared, mid-to-far infrared and terahertz.

Optionally, the superstructural units of the metalens dispersion system are arranged in an array.

Optionally, the superstructure units of the metalens dispersion system include regular hexagons, squares and/or sectors, and nanostructures are respectively provided at the center and/or vertices of each superstructure unit.

Optionally, the nanostructures are filled with air or with a material transparent to the target waveband.

Optionally, the nanostructures include polarization dependent nanostructures and/or polarization independent nanostructures.

Optionally, the nanostructures include all-dielectric nanostructures or plasmonic nanostructures

Optionally, the material of the all-dielectric nanostructure includes titanium oxide, silicon nitride, fused silica, aluminum oxide, gallium nitride, gallium phosphide and hydrogenated amorphous silicon.

Optionally, the detector comprises a charge-coupled device or a complementary metal-oxide-semiconductor.

The embodiment of the present application also provides a spectral measurement method, which is applied to any of the above-mentioned spectral measurement devices, and the method includes:

Step S1, injecting the light to be measured in parallel into the metalens dispersion system, so that the lights of different wavelength bands in the light to be measured are focused on different positions on the optical axis of the metalens dispersion system;

Step S2, using the microscopic system to magnify and image focal points at different positions on the optical axis of the metalens dispersion system;

Step S3, acquiring the light intensity distribution of the focal point through the detector;

In step S4, the spectral information of the light to be detected is obtained through processing by the computer processing system.

The beneficial effects obtained by the technical solutions provided in the embodiments of the present application at least include:

The spectrum measurement device and method provided in the embodiments of the present application focus incident light of different wavelengths on different positions on the optical axis of the metalens dispersion system through the metalens dispersion system; The focus of different positions on the optical axis of the metalens dispersion system is used to obtain the light intensity information of the focus through the detector, and the light intensity information obtained by the detector is processed by the computer processing system to obtain the spectral information of the incident light. Spectral off-axis measurement of the incident beam axis. The spectroscopic measuring device utilizes an L-shaped layout of a hyperlens dispersion system and a microscopic system, which breaks through the limitation of the large-angle dispersion system on the size of the detector and improves the accuracy of the spectrometer. The spectrum measurement device provided by the embodiment of the present application has a simple structure, which reduces the difficulty of designing, processing and assembling the spectrum off-axis measurement device.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiment of the present application or the background art, the following will describe the drawings that need to be used in the embodiment of the present application or the background art.

Fig. 1 shows a kind of optional structural schematic diagram of a kind of spectrum measurement device provided by the embodiment of the application;

Fig. 2 shows a schematic diagram of an optional measurement method of a spectral measurement device provided in the embodiment of the present application;

Fig. 3 shows a schematic diagram of an optional measurement method of another spectral measurement device provided in the embodiment of the present application;

Fig. 4A shows a schematic diagram of a superstructure unit in the spectral measurement device provided by the embodiment of the present application;

Fig. 4B shows a schematic diagram of another superstructure unit in the spectral measurement device provided by the embodiment of the present application;

Fig. 4C shows a schematic diagram of another superstructure unit in the spectral measurement device provided by the embodiment of the present application;

FIG. 5A shows a schematic diagram of a polarization-independent structure of a nanostructure in the spectral measurement device provided by the embodiment of the present application;

FIG. 5B shows another polarization-independent structural schematic diagram of the nanostructure in the spectral measurement device provided by the embodiment of the present application;

FIG. 5C shows a schematic diagram of a polarization-related structure of a nanostructure in the spectral measurement device provided by the embodiment of the present application;

FIG. 5D shows a schematic diagram of a polarization-independent structure of a nanostructure in the spectral measurement device provided by the embodiment of the present application;

Fig. 6 shows the relationship between the diameter and light transmittance of the nanostructure of the spectroscopic measurement device provided by the embodiment of the present application;

Figure 7 shows the relationship between the diameter and phase of the nanostructure of the spectroscopic measurement device provided by the embodiment of the present application;

FIG. 8 shows the relationship between the focal length of the metalens and the working wavelength of the spectroscopic measurement device provided by the embodiment of the present application.

The reference signs in the figure indicate respectively:

1-Metalens dispersion system; 2-Microscopic system; 3-Detector; 4-Computer processing system;

101-substrate; 102-nanometer structure; 103-filling material; 110-superstructure unit;

1021-nanometer ellipse; 1022-nanometer fin; 1023-nanometer cylinder; 1024-nanometer square column;

201 - Microscope objective lens.

Detailed ways

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with aspects of the present application as recited in the appended claims.

The terminology used in this application is for the purpose of describing particular embodiments only, and is not intended to limit the application. As used in this application and the appended claims, the singular forms "a", "the", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be A mechanical connection can also be an electrical connection: it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the embodiments of the present application in specific situations.

It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, the information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of the present application, first information may also be called second information, and similarly, second information may also be called first information. Depending on the context, the word "if" as used herein may be interpreted as "at" or "when" or "in response to a determination." If there is no conflict, the features in the following embodiments and implementations can be combined with each other.

Traditional spectrometers mainly use gratings and prisms as dispersion systems. The metasurface of the metalens can be designed to achieve large-angle dispersion that is difficult to achieve with prisms and gratings. A large-angle dispersion system can improve the accuracy of the spectrometer, but when the dispersion deflection angle increases, the size of the detector and the size of the spectrometer also need to be greatly increased. Therefore, the size and detector size of traditional spectrometers cannot be adapted to large-angle dispersion systems. The embodiment of the present application provides a spectral measurement device, which uses a microscopic system together with a large-angle dispersion system to form an L-shaped layout, and realizes the use of a large-angle dispersion system to increase spectral measurement without increasing the size of the detector. accuracy of the device.

An embodiment of the present application provides a spectral measurement device, as shown in FIG. 1 , the spectral measurement device includes a metalens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Wherein, the optical axis of the metalens dispersion system 1 is parallel to the incident light; the optical axis of the microsystem 2 is located in the center of the focal area of the metalens dispersion system 1, and the optical axis of the microsystem 2 is perpendicular to the metalens dispersion system 1 The optical axis of the optical axis; the object space focus of the microscopic system 2 is located on the optical axis of the metalens dispersion system 1; the microscopic system 2, the detector 3 and the computer processing system 4 are connected in sequence.

The metalens dispersion system 1 is used to focus light of different wavelengths on different positions on the optical axis of the metalens dispersion system 1 to form corresponding focal points; the microscopic system 2 is used to magnify and image the focal points of lights of different wavelengths; the detector 3 is used to measure the light intensity of the focal point of light of different wavelengths; the computer processing system 4 is used to process the information obtained from the measurement of the detector 3 .

A metalens is a typical application of a metasurface. The metasurface is a layer of subwavelength artificial nanostructure film. The metasurface includes a substrate 101 and a superstructure unit 110 located on the surface of the substrate. The apex and/or center of the superstructure unit 110 is provided with a nanostructure 102 . Incident light can be modulated according to the superstructure units on the metasurface. The metalens dispersion system 1 utilizes a transmission-type metalens with large dispersion to modulate incident light to achieve a dispersion effect. The superlens modulates the incident light through the superstructural unit 110 on the superlens.

Specifically, as shown in Figure 1, the implementation of a spectral measurement device provided in the embodiment of the present application is as follows:

The spectrum measuring device includes a metalens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Wherein, the optical axis of the metalens dispersion system 1 is parallel to the incident light; the optical axis of the microsystem 2 is located in the center of the focal area of the metalens dispersion system 1, and the optical axis of the microsystem 2 is perpendicular to the metalens dispersion system 1 the optical axis of the microsystem 2; the object focus of the microsystem 2 is located on the optical axis of the metalens dispersion system 1; the microsystem 2, the detector 3 and the computer processing system 4 are connected in sequence, and the detector 3 is located square focal plane.

As shown in FIG. 1 , taking the optical axis of the metalens dispersion system 1 as the z axis, the metalens dispersion system 1 is located on the x-y plane. After the light to be measured is parallelized, it enters the superlens dispersion system 1 in the form of parallel light, and the optical axis of the superlens dispersion system 1 is parallel to the incident light. Lights of different wavelengths in the incident parallel light are focused to different positions on the z-axis by the metalens dispersion system 1 . The distance from the focal point corresponding to the light of different wavelengths to the back surface of the metalens dispersion system 1 is called the focal length (FL, Focal Length), and the range formed by all focal lengths is called the focal depth of the metalens dispersion system 1. The focal length of incident light of different wavelengths has a one-to-one mapping relationship with the wavelength. For example, the focal length of incident light of different wavelengths is proportional to the wavelength; or, the focal length of incident light of different wavelengths is inversely proportional to the wavelength or other one-to-one mapping relationship.

The depth of focus of the metalens dispersion system 1 satisfies: ΔFL=Max(FL(λ))-Min(FL(λ)), wherein, the focal length at which the incident light with a wavelength of λ is focused by the metalens dispersion system 1 is FL(λ) , ΔFL is the depth of focus of the metalens dispersion system 1.

The optical axis of the microsystem 2 is parallel to the x-axis, and the microsystem 2 magnifies the focal points corresponding to the incident light of different wavelengths on the z-axis to the focal plane of the image side of the microsystem 2 . The detector 3 located on the focal plane of the image side of the microscope system 2 acquires the light intensity distribution of the focal point. The computer processing system 4 reads and processes the spectral data obtained by the detector 3 .

Exemplarily, as shown in Figure 2, when the diameter of the field of view of the microsystem 2 is greater than or equal to the focal depth of the metalens dispersion system 1, the center of the field of view of the microsystem 2 and the focal point of the superlens dispersion system 1 form The centers of the areas coincide, and the microscope system 2 can directly image the entire focal area on the detector 3 . Exemplarily, as shown in FIG. 3 , when the diameter of the field of view of the microsystem 2 is smaller than the focal depth of the metalens dispersion system 1 , the microsystem 2 needs to scan from the minimum focal length to the maximum focal length to obtain imaging of the entire focal area.

In an optional implementation manner, as shown in FIG. 1 , the metalens dispersion system 1 includes at least one transmission type metalens. The transmissive metalens applies a converging spherical wave to parallel light, then for the reference wavelength λ _c , the radial phase distribution of the metalens with focal length f _c is given by formula (1):

where r is the radial position of the metalens. After the radial phase corresponding to the reference wavelength is determined, the nanostructure at the radial position r is determined, and the focal length f(λ) of the dispersion metalens at different wavelengths can be deduced from the phase response of the nanostructure corresponding to different wavelengths.

Exemplarily, an embodiment of the present application provides a spectroscopic measurement device, which includes a hyperlens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Wherein, the metalens dispersion system 1 comprises at least one transmission type metalens, the optical axis of at least one transmission type metalens is parallel to the incident light; And the optical axis of the microsystem 2 is perpendicular to the optical axis of at least one transmission type hyperlens; the object space focus of the microsystem 2 is located on the optical axis of at least one transmission type hyperlens; the microsystem 2, the detector 3 and the computer The processing systems 4 are connected in sequence.

At least one transmission-type metalens is used to focus light of different wavelengths on different positions on the optical axis of at least one transmission-type metalens to form corresponding focal points and realize dispersion on the same optical axis; the microscope system 2 is used to focus light of different wavelengths Focus magnification imaging of the light of the light; the detector 3 is used to measure the light intensity distribution of the focus of light of different wavelengths; the computer processing system 4 is used to process the information obtained from the measurement of the detector.

Taking the optical axis of the at least one transmission-type metalens as the z-axis, the at least one transmission-type metalens is located on the x-y plane. After the light to be measured is parallelized, it enters at least one transmission-type superlens in the form of parallel light, and the optical axis of the at least one transmission-type superlens is parallel to the incident light. Lights of different wavelengths in the incident light are focused to different positions on the z-axis by at least one transmissive metalens. The distance from the focal point corresponding to light of different wavelengths to the rear surface of at least one transmission-type metalens is called the focal length (FL, Focal Length), and the range formed by all focal lengths is called the focal depth of at least one transmission-type metalens. The focal length of incident light of different wavelengths has a one-to-one mapping relationship with the wavelength. For example, the focal length of incident light of different wavelengths is proportional to the wavelength; or, the focal length of incident light of different wavelengths is inversely proportional to the wavelength or other one-to-one mapping relationship.

The depth of focus of at least one transmission-type metalens satisfies: ΔFL=Max(FL(λ))-Min(FL(λ)), wherein, the incident light with a wavelength of λ is focused by at least one transmission-type metalens with a focal length of FL( λ), ΔFL is the depth of focus of at least one transmissive metalens.

Exemplarily, the metalens dispersion system 1 includes two or more metalens, or the metalens dispersion system 1 includes two or more metasurfaces. The cascading of multiple metasurfaces can superimpose the dispersion characteristics of multiple metasurfaces and enhance the dispersion rate of the metalens dispersion system, that is, to separate the light of different wavelengths further.

In an optional implementation manner, as shown in FIGS. 4A to 4C , the superstructure units 110 of the metalens dispersion system 1 are arranged in an array, and the center position and/or apex position of each superstructure unit 110 are respectively Nanostructures 102 are provided. Exemplarily, the superstructure unit 110 includes one or more of a square, a regular hexagon, or a sector.

Exemplarily, an embodiment of the present application provides a spectroscopic measurement device, including a metalens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Wherein, the metasurface structures 110 of the metalens dispersion system 1 are arranged in a regular hexagonal array, and the center and/or apex of each regular hexagon are respectively provided with nanostructures 102 .

The optical axis of the metalens dispersion system 1 is parallel to the incident light; the optical axis of the microscopic system 2 is located in the center of the focal area of the metalens dispersion system 1, and the optical axis of the microscopic system 2 is perpendicular to the light of the metalens dispersion system 1 axis; the object focus of the microsystem 2 is located on the optical axis of the metalens dispersion system 1; the microsystem 2, the detector 3 and the computer processing system 4 are sequentially connected.

The metalens dispersion system 1 is used to focus light of different wavelengths on different positions on the optical axis of the metalens dispersion system 1 to form corresponding focal points; the microscopic system 2 is used to magnify and image the focal points of lights of different wavelengths; the detector 3 is used to measure the light intensity of the focal point of light of different wavelengths; the computer processing system 4 is used to process the information obtained from the measurement of the detector.

In an optional embodiment, the metasurface nanostructure 102 of the metalens dispersion system 1 includes an all-dielectric nanostructure or a plasmonic nanostructure, which can directly regulate the phase, amplitude and polarization of light.

The working waveband of the metasurface includes one or more of visible light, near-infrared, mid-far infrared and terahertz wavebands. The space between the nanostructures 102 of the metasurface can be filled with air or other materials transparent to the target wavelength band. It should be noted that when the target wavelength band is visible light, the absolute value of the difference between the refractive index of the filling material 103 and the refractive index of the nanostructure 102 must be greater than or equal to 0.5.

Exemplarily, the nanostructure 102 can be a polarization-dependent structure. As shown in FIG. 5A and FIG. 5B, the nanostructure can be a structure such as a nano-elliptical column 1021 and a nano-fin 1022. Such structures impose a geometric phase on incident light; The structure 102 can also be a polarization-independent structure. As shown in FIG. 5C and FIG. 5D , the nanostructure 102 can be a structure such as a nano-cylinder 1023 and a nano-square column 1024. Such structures impose a propagation phase on the incident light. When the polarization state of the light to be measured is unknown before measurement, preferably, the nanostructure 102 adopts a polarization-independent shape.

Exemplarily, the spectrum measurement device provided in the embodiment of the present application includes a metalens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Wherein, the superstructure units 110 of the metalens dispersion system 1 are arranged in an array of regular hexagons, and the center and/or apex of each regular hexagon are respectively provided with nanostructures 102 . Wherein, the nanostructure 102 is a polarization-dependent structure, and the material is a visible light transparent material. The absolute value of the difference between the refractive index of the filling material 103 between the nanostructures 102 and the refractive index of the nanostructures 102 is greater than or equal to 0.5.

The metalens dispersion system 1 is used to focus light of different wavelengths on different positions on the optical axis of the metalens dispersion system 1 to form corresponding focal points; the microscopic system 2 is used to magnify and image the focal points of lights of different wavelengths; the detector 3 for measuring the light intensity of the focal point of light of different wavelengths; a computer processing system 4 for processing the information obtained from the measurements of the detector.

In an optional embodiment, the detector 3 includes a charge coupled device (CCD, Charge Coupled Device), a complementary metal oxide semiconductor (CMOS, Complementary Metal Oxide Semiconductor), a vanadium oxide detector, an amorphous silicon detector, Indium Gallium Arsenide Detector (InGaAs, Indium Gallium Arsenide Detector), Lead Sulfide Detector (PbS, Lead Sulfide Detector) and Lead Selenide Detector (PbSe, Lead Selenide Detector). For example, CCD and CMOS can be used for detection in the visible light band; vanadium oxide detectors, amorphous silicon detectors, indium gallium arsenide detectors, lead sulfide detectors and lead selenide detectors can be used for infrared band detection.

Exemplarily, the implementation of the spectral measuring device provided in the embodiment of the present application is as follows:

An embodiment of the present application provides a spectroscopic measurement device, which includes a metalens dispersion system 1 , a microscopic system 2 , a detector 3 and a computer processing system 4 .

Among them, the metalens dispersion system 1 includes a mid-infrared band metalens; the working band of the microscope system 2 is in the mid-infrared band; the detection band of the detector 3 is in the mid-infrared band.

The materials of the substrate 101 and the nanostructure 102 of the mid-infrared band superlens are both crystalline silicon, and the superstructure units 110 of the mid-infrared band superlens are regular hexagons arranged in an array, and the center and apex positions of each regular hexagon are equal to A cylindrical nanostructure 102 is provided. The height of the nanostructure is 6 μm, the diameter is 900 nm to 2.3 μm, and the distance between the centers of two adjacent nanostructures 102 is 3 μm.

Exemplarily, as shown in FIG. 6, the relationship between the diameter and light transmittance of the above-mentioned nanostructure 102 at a wavelength of 3 μm-5 μm; as shown in FIG. 7, the relationship between the diameter and phase of the above-mentioned nanostructure 102 at a wavelength of 3 μm-5 μm time relationship. When the diameter of the above-mentioned mid-infrared metalens is 2 mm, the focal length is 3.3 mm when the wavelength is 4 μm.

Optionally, when the wavelength is 3 μm-5 μm, the relationship between the focal length of the metalens and the working wavelength is shown in FIG. 8 . It can be seen from FIG. 8 that the minimum focal length and maximum focal length of the above-mentioned mid-infrared metalens are 2.95 mm and 3.67 mm, respectively. Therefore, the depth of focus is 0.72mm.

Preferably, the objective lens of the microscope system 2 is a reflective objective lens with a magnification of 10x, a numerical aperture of 0.2, a working distance of 16 mm, a focal length of 19.9 mm, and a field of view of 1 mm. The resolution of the microscope objective lens is 10 μm at the operating wavelength of 4 μm. The resolution 144 of the spectrometer can be obtained according to the range of the incident spectrum, the focal depth of the hyperlens, and the resolution of the microscope system 2 . The calculation process of spectrometer resolution is as follows:

Since the focal depth is 720 μm, and the average resolution of the microscopic objective lens (the resolution of the central wavelength of 4 μm) is 10 μm, the entire focal depth is divided into 720/10=72 parts. Since the entire spectral range is 5 μm-3 μm=2 μm, the resolvable spectral width at 4 μm is 2 μm/72=0.0278 μm. According to the spectrometer resolution definition R=λ/Δλ, the spectrometer resolution R=4/0.0278=144 can be obtained. Preferably, the detector 3 is a mid-infrared uncooled detector, and the pixel size of the detector 3 is 12 μm. The smallest resolvable object on the focal plane of the microscope objective lens is 100 μm after ten times magnification, which is larger than the pixel size of the detector 3 . Therefore, the detector 3 can obtain spectral information of the focal point, such as light intensity.

The spectral information of the incident light can be obtained by performing processing such as noise reduction on the light intensity information obtained by the detector 3 by the computer processing system 4 .

Therefore, the spectral measurement device provided by the embodiment of the present application focuses incident light of different wavelengths on different positions on the optical axis of the metalens dispersion system through the metalens dispersion system, which improves the transmittance of incident light and reduces the signal-to-noise ratio Amplify the focus points at different positions on the optical axis of the metalens dispersion system through a microscopic system perpendicular to the optical axis of the metalens dispersion system, so as to realize the acquisition of the light intensity information of the focus point through the detector, and the light obtained by the detector through the computer processing system The strong information is processed to obtain the spectral information of the incident light, and the off-axis measurement of the spectrum is realized. The spectroscopic measuring device utilizes an L-shaped layout of a hyperlens dispersion system and a microscopic system, which breaks through the limitation of the large-angle dispersion system on the size of the detector and improves the accuracy of the spectrometer. The spectrum measurement device provided by the embodiment of the present application has a simple structure, which reduces the difficulty of designing, processing and assembling the spectrum off-axis measurement device.

The embodiment of the present application also provides a spectral measurement method, which is applied to the above-mentioned spectral measurement device, and the method includes:

Step S1, injecting the light to be measured in parallel into the metalens dispersion system 1, so that the lights of different wavelength bands in the light to be measured are focused on different positions on the optical axis of the metalens dispersion system 1;

Step S2, through the microscope system 2, the focal points of different positions on the optical axis of the metalens dispersion system 1 are enlarged and imaged;

Step S3, acquiring the light intensity distribution of the focal point through the detector 3;

In step S4, the spectral information of the light to be detected is obtained through processing by the computer processing system 4 .

Specifically, an optional implementation of the spectral measurement method provided in the embodiments of the present application is as follows:

The light to be detected enters the superlens dispersion system 1 in the form of parallel light after being parallelized, and the optical axis of the superlens dispersion system 1 is parallel to the optical path of the incident parallel light. Lights of different wavelengths in the incident parallel light are focused onto the optical axis of the metalens dispersion system 1 by the metalens dispersion system 1 , and different focal points are formed at different positions on the optical axis of the metalens dispersion system 1 . The distance from the focal point corresponding to light of different wavelengths to the back surface of the metalens dispersion system 1 is called the focal length, and the range formed by all the focal lengths is called the focal depth of the metalens dispersion system 1 . The focal length of incident light of different wavelengths has a one-to-one mapping relationship with the wavelength.

The optical axis of the microscopic system 2 is perpendicular to the optical axis of the metalens dispersion system 1 , so that the focal points corresponding to the incident lights of different wavelengths are on the focal point of the object space of the microscopic system 2 . Microsystem 2 magnifies the focal point to image on the image-space focal plane of the microsystem. The detector 3 located on the focal plane of the image side of the microscope system 2 obtains the light intensity distribution of each focal point. The computer processing system 4 reads and processes the light intensity of each focal point obtained by the detector 3 to obtain the spectrum of the light to be detected.

Exemplarily, when the light to be detected is mid-infrared light, the implementation of the spectral measurement device and method provided in the embodiments of the present application is as follows:

Among them, the metalens dispersion system 1 includes a mid-infrared band metalens; the diameter of the mid-infrared band metalens is 2 mm, and its focal length is 3.3 mm when the incident wavelength is 4 μm; the minimum focal length and maximum focal length of the mid-infrared band metalens are respectively 2.95mm and 3.67mm, the depth of focus is 0.72mm. The optical axis of the microscopic system 2 is perpendicular to the optical axis of the metalens in the mid-infrared band, and the working band of the microscopic system 2 is in the mid-infrared band; the detector 3 is a CCD detector whose detection band is in the mid-infrared band; the detector 3 is a non- Cooled detector with a pixel size of 12 μm.

The substrate 101 and the nanostructure 102 of the mid-infrared band superlens are made of crystalline silicon, and the superstructure units 110 of the mid-infrared band superlens are arranged in an array of regular hexagons, and the center and apex positions of each regular hexagon are set. There are cylindrical nanostructures 102 . The height of the nanostructure 102 is 6 μm, the diameter is 900 nm, and the distance between the centers of two adjacent nanostructures 102 is 3 μm.

The objective lens of microscope system 2 is a reflective objective lens with a magnification of 10x, a numerical aperture of 0.2, a working distance of 16mm, a focal length of 19.9mm, and a field of view of 1mm. The resolution of the microscope objective lens is 10 μm at the operating wavelength of 4 μm. The resolution 144 of the spectrometer can be obtained according to the incident spectral range, the focal depth of the hyperlens, and the resolution of the microscopic system (refer to the above for the calculation process).

The mid-infrared light to be detected is parallelized and injected into the mid-infrared band metalens in the form of parallel light, so that the optical path of the incident mid-infrared light is parallel to the optical axis of the mid-infrared band metalens. Incident mid-infrared light of different wavelengths forms corresponding focal points at different positions on the optical axis of the mid-infrared band metalens. The focal length of the incident mid-infrared light of different wavelengths has a one-to-one mapping relationship with the wavelength.

The microscopic system 2 magnifies the focal points at different positions on the optical axis of the metalens in the mid-infrared band, so that different focal points are imaged on the detector 3 . The computer processing system 4 reads the light intensity information of each focal point obtained by the detector 3 to obtain the spectral information of the mid-infrared light to be detected.

In summary, the spectral measurement device and method provided by the embodiments of the present application focus incident light of different wavelengths on different positions on the optical axis of the superlens dispersion system through the superlens dispersion system, thereby improving the transmittance of the incident light and The signal-to-noise ratio is reduced; through the microscopic system perpendicular to the optical axis of the metalens dispersion system, the focal points at different positions on the optical axis of the metalens dispersion system are amplified, so that the light intensity information of the focus point can be obtained through the detector, and the computer processing system is used to control the The light intensity information obtained by the detector is processed to obtain the spectral information of the incident light, and the off-axis measurement of the spectrum is realized. The spectrum measurement device provided by the embodiment of the present application has a simple structure, which reduces the difficulty of designing, processing and assembling the spectrum off-axis measurement device.

The above is only the specific implementation of the embodiment of the present application, but the scope of protection of the embodiment of the present application is not limited thereto. Any person familiar with the technical field can easily Any changes or substitutions that come to mind should be covered within the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application should be determined by the protection scope of the claims.

Claims

A spectral measurement device, characterized in that it comprises a metalens dispersion system (1), a microscopic system (2), a detector (3) and a computer processing system (4);

Wherein, the optical axis of the superlens dispersion system (1) is parallel to the incident light; the optical axis of the microscopic system (2) is perpendicular to the optical axis of the superlens dispersion system (1); the microscopic system The object focus of (2) is located on the optical axis of the metalens dispersion system (1); the microscopic system (2), the detector (3) are sequentially connected with the computer processing system (4), And the detector (3) is located on the image square focal plane of the microscopic system (2);

The metalens dispersion system (1) is used to focus light of different wavelengths on different positions on the optical axis of the metalens dispersion system (1), forming corresponding focal points;

The microscopic system (2) is used to magnify and image the focus of the light of different wavelengths;

The detector (3) is used to measure the light intensity of the focal point of the light of different wavelengths;

The computer processing system (4) is used for processing the information measured by the detector (3).
The spectroscopic measurement device according to claim 1, characterized in that the metalens dispersion system (1) comprises at least one transmission type metalens.
The spectral measuring device according to claim 2, characterized in that, the focal length of the metalens dispersion system (1) is the distance from the focal point of light of different wavelengths to the rear surface of the metalens dispersion system (1).
The spectral measurement device according to claim 3, characterized in that the focal length of the metalens dispersion system (1) and the wavelength of incident light are in a one-to-one mapping relationship.
The spectroscopic measurement device according to claim 4, characterized in that the diameter of the field of view of the microscopic system (2) is greater than or equal to the focal depth of the metalens dispersion system (1).
The spectroscopic measurement device according to claim 4, characterized in that, the diameter of the field of view of the microscopic system (2) is smaller than the focal depth of the metalens dispersion system (1).
A spectroscopic measurement device according to any one of claims 1-6, characterized in that the working bands of the metalens dispersion system (1) include visible light bands, near-infrared bands, mid-to-far infrared bands and terahertz bands.
A spectroscopic measuring device according to any one of claims 1-6, characterized in that, the working wavebands of the microscopic system (2) include visible light wavebands, near-infrared wavebands, mid-to-far infrared wavebands and terahertz wavebands.
The spectral measurement device according to claim 7, characterized in that, the superstructure units (110) of the metalens dispersion system (1) are arranged in an array.
A kind of spectrum measurement device as claimed in claim 7, it is characterized in that, described superstructure unit (110) comprises regular hexagon, square and/or sector, the central position of each described superstructure unit (110) and/or apex positions are respectively provided with nanostructures (102).
The spectroscopic measurement device according to claim 10, characterized in that the space between the nanostructures (102) is filled with air or with a material transparent to the target wavelength band.
The spectroscopic measurement device according to claim 11, characterized in that, the shape of the nanostructure (102) includes a polarization-dependent shape and/or a polarization-independent shape.
A spectroscopic measurement device according to any one of claims 10-12, characterized in that the nanostructure (102) comprises an all-dielectric nanostructure or a plasmonic nanostructure.
A spectroscopic measurement device according to any one of claims 13, wherein the material of the all-dielectric nanostructure comprises titanium oxide, silicon nitride, fused silica, aluminum oxide, gallium nitride, gallium phosphide and hydrogenated amorphous silicon.
A spectroscopic measurement device according to claim 1, characterized in that the detector (3) includes a charge coupled device, complementary metal oxide semiconductor, vanadium oxide, amorphous silicon, InGaAs, PbS, PbSe detector.
A spectral measurement method, applied to the spectral measurement device according to any one of claims 1-15, said method comprising:

Step S1, injecting the light to be measured in parallel into the superlens dispersion system (1), so that the light of different wavelength bands in the light to be measured is focused on different positions on the optical axis of the superlens dispersion system (1);

Step S2, through the microscopic system (2), the focal points of different positions on the optical axis of the metalens dispersion system (1) are enlarged and imaged;

Step S3, acquiring the light intensity distribution of the focal point through the detector (3);

Step S4, obtaining the spectral information of the light to be detected through processing by the computer processing system (4).