Method and apparatus for measuring lateral spatial resolution of confocal raman microscopy

Abstract

The application provides a method and device for measuring lateral spatial resolution of a confocal Raman microscope, and relates to the field of optical measurement and microscopic spectroscopy technology. The method comprises the following steps: positioning a region of a straight edge on a single-layer graphene sample by using a confocal Raman microscope, wherein the single-layer graphene sample is prepared on a silicon oxide substrate; determining a straight scanning path and a scanning step in a direction perpendicular to the straight edge from a bare region of the substrate to a sample region in the region of the straight edge which has been positioned by using the confocal Raman microscope; determining a plurality of scanning points on the straight scanning path based on the scanning step in the process of moving the single-layer graphene sample, and collecting Raman spectrum signals of the scanning points; and measuring the lateral spatial resolution of the confocal Raman microscope based on the Raman spectrum of each scanning point. By using the method provided in the application, the accuracy of the lateral spatial resolution of the confocal Raman microscope can be improved.

Description

Technical Field

[0001] This application relates to the fields of optical measurement and microspectroscopy, and in particular to a method and apparatus for determining the lateral spatial resolution of a confocal Raman microscope. Background Technology

[0002] A confocal Raman microscope is a precision instrument that combines confocal microscopy with Raman spectroscopy analysis, combining high spatial resolution with high spectral resolution to achieve accurate characterization of the microstructure of materials.

[0003] The lateral spatial resolution of a confocal Raman microscope is one of its core performance indicators. It is primarily determined by the laser wavelength (λ), the numerical aperture (NA) of the objective lens, and the size of the confocal pinhole. Theoretically, the lateral resolution can be estimated using the Rayleigh criterion: 0.61 * λ / NA. However, the actual lateral spatial resolution is often affected by various factors such as pinhole alignment, aberrations, and laser beam quality, thus requiring experimental determination.

[0004] Current techniques primarily employ the knife-edge method for determining the lateral spatial resolution of confocal Raman microscopy. This involves high-density line scanning along the steep edges of metal nanostructures, acquiring a curve showing the signal intensity transitioning from the exposed substrate area to the sample-covered area to derive the lateral spatial resolution. However, the traditional knife-edge method utilizes metal or semiconductor knife edges with inherent edge angles and thicknesses, introducing geometric aberrations and positioning errors in confocal Raman measurements, thus affecting the accuracy of lateral spatial resolution measurements. Particularly at steep edges, abnormal signal enhancement or distortion often occurs due to enhanced electromagnetic fields and scattered light interference, significantly distorting the intensity distribution curve. This causes the fitted spot size and spatial resolution to deviate from the true value, resulting in low accuracy of the measured lateral spatial resolution. Summary of the Invention

[0005] This application provides a method and apparatus for measuring the lateral spatial resolution of a confocal Raman microscope, which can effectively improve the accuracy of the measured lateral spatial resolution.

[0006] This application provides a method for determining the lateral spatial resolution of a confocal Raman microscope, including:

[0007] The region of a straight edge was located on a monolayer graphene sample prepared on a silicon oxide substrate using a confocal Raman microscope.

[0008] Using the confocal Raman microscope, within the area of ​​the already located straight edge, a straight scanning path and scanning step size are determined from the substrate exposed area to the sample area along a direction perpendicular to the straight edge; wherein, the substrate exposed area is the area of ​​the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area of ​​the silicon oxide substrate covered by the monolayer graphene.

[0009] During the movement of the monolayer graphene sample, multiple scanning points are determined on the straight scanning path based on the scanning step size, and Raman spectral signals of each scanning point are acquired.

[0010] The lateral spatial resolution of the confocal Raman microscope is determined based on the Raman spectral signals at each scanning point.

[0011] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the determination of the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point includes:

[0012] The D-mode characteristics in the Raman spectral signals of each scanning point are fitted to obtain the D-mode characteristic distribution curve of the D-mode peak area as a function of the scanning path;

[0013] The lateral spatial resolution of the confocal Raman microscope is determined by measuring the full width at half maximum (FWHM) of the characteristic distribution curve of the D-mode.

[0014] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, data fitting analysis is performed on the Raman spectra of each scanning point to determine the lateral spatial resolution of the confocal Raman microscope, including:

[0015] The G-mode features in the Raman spectral signals of each scanning point are fitted to obtain the distribution curve of the G-mode feature as the G-mode peak area changes with the scanning path;

[0016] The lateral spatial resolution of the confocal Raman microscope is determined by measuring the distance between the peak area of ​​the G-mode changing from 12% to 88% in the characteristic distribution curve of the G-mode.

[0017] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the acquisition of Raman spectral signals at each scanning point includes:

[0018] The focusing state of the confocal Raman microscope when the G-mode peak area is maximized is determined by scanning along the z-axis of the monolayer graphene sample using the confocal Raman microscope.

[0019] In the focused state, Raman spectral signals of each scanning point are acquired.

[0020] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the acquisition of Raman spectral signals at each scanning point includes:

[0021] Raman spectral signals at each scanning point are acquired when the incident laser is configured to fill the entrance pupil of the confocal Raman microscope.

[0022] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the intensity of the D-mode feature within the region of the edge of the positioning line should be at least 1 / 20 of the intensity of the G-mode feature.

[0023] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the length of the straight scanning path is greater than A times the expected value of the lateral spatial resolution.

[0024] According to the method for determining the lateral spatial resolution of a confocal Raman microscope provided in this application, the scanning step size is less than B times the expected value of the lateral spatial resolution, wherein B is less than 1.

[0025] According to the method for measuring the lateral spatial resolution of a confocal Raman microscope provided in this application, the numerical aperture of the confocal Raman microscope is in the range of 0.25 to 0.90.

[0026] This application also provides a device for measuring the lateral spatial resolution of a confocal Raman microscope, comprising:

[0027] A positioning unit is used to locate the region of a straight edge on a monolayer graphene sample using a confocal Raman microscope, wherein the monolayer graphene sample is prepared on a silicon oxide substrate.

[0028] The determining unit is used to determine a straight scanning path and scanning step size from the substrate exposed area to the sample area in the region of the already located straight edge, along a direction perpendicular to the straight edge, using the confocal Raman microscope; wherein, the substrate exposed area is the area of ​​the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area of ​​the silicon oxide substrate covered by the monolayer graphene.

[0029] The determining unit is also used to determine multiple scanning points on the straight scanning path based on the scanning step size during the movement of the monolayer graphene sample.

[0030] The acquisition unit is used to acquire the Raman spectral signals at each scanning point;

[0031] The measurement unit is also used to measure the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point.

[0032] This application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining the lateral spatial resolution of a confocal Raman microscope as described in any of the preceding claims.

[0033] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the lateral spatial resolution of a confocal Raman microscope as described in any of the preceding claims.

[0034] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method for determining the lateral spatial resolution of a confocal Raman microscope as described in any of the preceding claims.

[0035] The method and apparatus for determining the lateral spatial resolution of a confocal Raman microscope provided in this application involve locating the region of a straight edge on a monolayer graphene sample, which is prepared on a silicon oxide substrate, using a confocal Raman microscope. Within the region of the located straight edge, a straight scanning path and scanning step size are determined along a direction perpendicular to the straight edge, from the exposed area of ​​the substrate to the sample area. The exposed area of ​​the substrate is the region of the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the region of the silicon oxide substrate covered by the monolayer graphene. During the movement of the monolayer graphene sample, multiple scanning points are determined along the straight scanning path based on the scanning step size, and Raman spectral signals are acquired at each scanning point. The lateral spatial resolution of the confocal Raman microscope is then determined based on the Raman spectral signals at each scanning point. By utilizing the atomically sharp, straight edges of a single-layer graphene sample and the Raman spectral signals at each scanning point to determine the lateral spatial resolution of a confocal Raman microscope, the problem of abnormal signal enhancement or distortion caused by electromagnetic field enhancement and scattered light interference at the edges, as in the knife-edge method, is effectively avoided. This significantly improves the accuracy of the measured lateral spatial resolution of the confocal Raman microscope. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1This is a schematic flowchart illustrating a method for determining the lateral spatial resolution of a confocal Raman microscope, as provided in an embodiment of this application.

[0038] Figure 2 An optical image of a monolayer graphene sample with a region having straight edges, provided for an embodiment of this application.

[0039] Figure 3 Raman spectrum of the straight edge region of a monolayer graphene sample provided in this application embodiment.

[0040] Figure 4 A peak area I of the G-mode provided in the embodiments of this application G and D-mode peak area I D The measured values ​​of the distribution curve, the fitted curve, and a schematic diagram of the lateral spatial resolution.

[0041] Figure 5 A peak area I of the G-mode provided in the embodiments of this application G and D-mode peak area I D Curves showing spatial distribution and schematic diagram of lateral spatial resolution.

[0042] Figure 6 The G-mode peak area I obtained by using microscope objectives with different NAs is provided in the embodiments of this application. G and D-mode peak area I D The measured values ​​and fitted curves of the distribution curve.

[0043] Figure 7 This is a schematic diagram of a device for measuring the lateral spatial resolution of a confocal Raman microscope, provided in an embodiment of this application.

[0044] Figure 8 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0047] The technical solution provided in this application can be applied to the determination of lateral spatial resolution in confocal Raman microscopy. Lateral spatial resolution refers to the minimum distance that can reliably distinguish two adjacent points within a plane on the sample surface or within a plane perpendicular to the imaging optical axis. Therefore, high lateral spatial resolution is crucial for accurately characterizing the compositional distribution, defect states, stress fields, and phase transition behavior of micro / nanoscale materials, determining the fidelity and reliability of Raman spectroscopy imaging.

[0048] Given that the current method uses the knife-edge method to determine lateral spatial resolution, the metal or semiconductor knife-edge itself has a certain edge tilt angle and thickness, which introduces geometric aberrations and positioning errors, resulting in low accuracy of the measured lateral spatial resolution. Especially at steep edges, abnormal signal enhancement or distortion often occurs due to effects such as enhanced electromagnetic fields and scattered light interference at the edge, significantly distorting the intensity distribution curve. This causes the fitted spot size and spatial resolution to deviate from the true value, thus resulting in low accuracy of the lateral spatial resolution.

[0049] To effectively improve the accuracy of lateral spatial resolution, this application provides a method for measuring the lateral spatial resolution of a confocal Raman microscope. The following specific embodiments will describe in detail the method for measuring the lateral spatial resolution of a confocal Raman microscope provided by this application. It is understood that these specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0050] Figure 1 A schematic flowchart illustrating a method for determining the lateral spatial resolution of a confocal Raman microscope, as provided in this application embodiment, is shown below. Figure 1 As shown, the method for determining the lateral spatial resolution of this confocal Raman microscope may include:

[0051] S101. Using a confocal Raman microscope, locate the region of the straight edge on the monolayer graphene sample, which is prepared on a silicon oxide substrate.

[0052] For example, the length of the straight edge should be at least 10 times the diameter of the laser spot focused by the confocal Raman microscope; the specific value can be set according to actual needs. For example, see [link to example]. Figure 2 As shown, Figure 2 An optical image of a monolayer graphene sample with a region having a straight edge is provided for an embodiment of this application. Typically, the straight edge of a monolayer graphene sample is clearly visible under a confocal Raman microscope. One side of the straight edge is the area covered by the monolayer graphene sample, and the other side is the exposed area of ​​the bare substrate.

[0053] For example, within the area where the straight line edge is located, the intensity of the D-mode feature should be at least 1 / 20th of the intensity of the G-mode feature. For instance, the intensity of the D-mode feature can be 1 / 20th of the intensity of the G-mode feature, and this can be set according to actual needs.

[0054] For example, when using a confocal Raman microscope to find monolayer graphene samples with straight edges on a silicon oxide substrate, the region containing monolayer graphene with steep edges and appropriate size should be selected as the region with straight edges. The specific settings can be made according to actual needs.

[0055] For example, a pre-prepared monolayer graphene sample can be obtained directly, or a monolayer graphene sample can be prepared on a silicon oxide substrate using a preparation device, etc. The specific settings can be made according to actual needs.

[0056] For example, when preparing a monolayer graphene sample on a silicon oxide substrate using a preparation device, any one of the following methods can be used: micromechanical exfoliation, dry transfer, wet transfer, or chemical vapor deposition. The specific method can be set according to actual needs.

[0057] Among them, the micromechanical exfoliation method only requires adhesive tape and highly oriented pyrolytic graphite, with extremely low equipment requirements, making it very suitable for rapid and low-cost sample preparation in the laboratory.

[0058] The dry transfer method uses techniques such as electrochemical bubbling or thermal release tape to directly peel and transfer graphene from a metal substrate without using corrosive chemical reagents to etch the metal catalyst.

[0059] The chemical reagents used in wet transfer technology include, for example, polymethyl methacrylate (PMMA), which are common chemical reagents.

[0060] Chemical vapor deposition, although involving equipment, can be used to prepare samples on large scale and in batches on inexpensive metal foils, such as copper foil, with extremely low amortized costs per sample.

[0061] Taking the micromechanical exfoliation method as an example, when preparing a monolayer graphene sample on a silicon oxide substrate using a fabrication device, firstly, highly oriented pyrolytic graphite can be repeatedly peeled off with adhesive tape, imprinting the tape with attached graphite flakes onto the surface of the silicon oxide substrate. Then, the tape is peeled off, yielding a thin layer of graphene on the substrate. Secondly, a confocal Raman microscope is used for rapid screening to locate candidate regions with suitable thickness and steep, clean edges, i.e., the regions with the aforementioned straight edges. To ensure that the graphene sample is a monolayer graphene sample, Raman spectroscopy is used to accurately characterize the candidate regions. Specifically, according to the national standard GB / T 40069-2021, when excited by a 633nm laser, if the 2D mode of the candidate region exhibits a symmetrical single Lorentz peak line shape, the candidate region can be determined to be a monolayer graphene. For example, see [link to relevant documentation]. Figure 3 As shown, Figure 3 The image shows the Raman spectrum of the straight edge region of a monolayer graphene sample provided in this embodiment of the application. Through the above steps, a verified monolayer graphene sample that meets the measurement requirements is prepared. Unlike the standard substances of the traditional knife-edge method, which are consumables, the monolayer graphene or silicon dioxide samples used in this application are chemically stable, not easily damaged or oxidized, and can be used repeatedly for a long time under normal use and storage conditions, further reducing the average cost of a single measurement.

[0062] S102. Using a confocal Raman microscope, within the area of ​​the already located straight edge, determine the straight scanning path and scanning step size from the substrate exposed area to the sample area along a direction perpendicular to the straight edge.

[0063] The exposed substrate area refers to the region of the silicon oxide substrate that is not covered by a single layer of graphene, while the sample area refers to the region of the silicon oxide substrate that is covered by a single layer of graphene.

[0064] For example, the numerical aperture (NA) of a confocal Raman microscope is in the range of 0.25 to 0.90, which can be set according to actual needs.

[0065] For example, the length of the straight-line scan path is greater than A times the expected value of the lateral spatial resolution. For example, the value of A can be 4, 4.1, or other values, and can be set according to actual needs.

[0066] For example, the scan step size is less than B times the expected value of the lateral spatial resolution, where B is less than 1. For example, the value of B can be 1 / 3, 1 / 4, or other values, and can be set according to actual needs.

[0067] S103. During the movement of the monolayer graphene sample, multiple scanning points are determined on the straight scanning path based on the scanning step size, and the Raman spectral signals of each scanning point are collected.

[0068] The scanning step size is the physical distance between adjacent scanning points, which directly affects the spatial resolution of the measurement.

[0069] Using a confocal Raman microscope, a linear scanning path and scanning step size can be determined first within the area of ​​the pre-defined straight edge, along a direction perpendicular to the straight edge, from the exposed substrate area to the sample area. By precisely controlling the movement of the monolayer graphene sample on the sample stage, multiple scanning points are determined on the linear scanning path based on the scanning step size during the movement of the monolayer graphene sample, and the Raman spectral signals of each scanning point are acquired.

[0070] S104. Based on the Raman spectral signals at each scanning point, determine the lateral spatial resolution of the confocal Raman microscope.

[0071] As can be seen from the embodiments of this application, when determining the lateral spatial resolution of the confocal Raman microscope, the confocal Raman microscope is used to locate the region of the straight edge on the monolayer graphene sample, which is prepared on a silicon oxide substrate. Using the confocal Raman microscope, within the region of the located straight edge, a straight scanning path and scanning step size are determined from the substrate exposed area to the sample area along a direction perpendicular to the straight edge. The substrate exposed area is the region of the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the region of the silicon oxide substrate covered by the monolayer graphene. During the movement of the monolayer graphene sample, multiple scanning points are determined along the straight scanning path based on the scanning step size, and the Raman spectral signal of each scanning point is acquired. Based on the Raman spectral signal of each scanning point, the lateral spatial resolution of the confocal Raman microscope is determined. By utilizing the atomically sharp, straight edges of a single-layer graphene sample and the Raman spectral signals at each scanning point to determine the lateral spatial resolution of a confocal Raman microscope, the problem of abnormal signal enhancement or distortion caused by electromagnetic field enhancement and scattered light interference at the edges, as in the knife-edge method, is effectively avoided. This significantly improves the accuracy of the measured lateral spatial resolution of the confocal Raman microscope.

[0072] Based on the above Figure 1 In the illustrated embodiment, for example, in S103 above, when acquiring Raman spectral signals at each scanning point, the incident laser is configured to fill the incident pupil of the confocal Raman microscope, and the confocal Raman microscope is scanned along the z-axis to determine the focusing state of the confocal Raman microscope when the G-mode peak area is the largest. In the focusing state, the Raman spectral signals at each scanning point are acquired.

[0073] Based on any of the above embodiments, for example, in S104 above, when determining the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point, at least two of the following possible implementation methods may be included:

[0074] In one possible implementation, the lateral spatial resolution of a confocal Raman microscope can be determined based on the D-mode characteristics of the Raman spectral signals at each scanning point, specifically including:

[0075] First, the D-mode characteristics in the Raman spectral signals of each scanning point are fitted to obtain the D-mode characteristic distribution curve of the D-mode peak area as a function of the scanning path; then, the full width at half maximum (FWHM) of the D-mode characteristic distribution curve is used to determine the lateral spatial resolution of the confocal Raman microscope.

[0076] For example, in the embodiments of this application, when fitting the D-mode features in the Raman spectral signals of each scanning point, for each scanning point, the D-mode features in the Raman spectral signals of the scanning point can first be fitted using double Lorentz peaks, and the sum of the areas of the two Lorentz peaks can be used to obtain the D-mode peak area corresponding to the scanning point. For example, see [link to relevant documentation]. Figure 4 As shown, Figure 4 A peak area I of the G-mode provided in the embodiments of this application G and D-mode peak area I D The measured values ​​of the distribution curve, the fitted curve, and a schematic diagram of the lateral spatial resolution are shown. The peak area of ​​the D-mode varies with the distance x between the center and edge of the laser spot (i.e., x=0 represents the edge). The peak area of ​​the D-mode corresponding to the scanning point is then fitted to obtain the characteristic distribution curve of the D-mode with varying peak area as a function of the scanning path. This allows the determination of the lateral spatial resolution of the confocal Raman microscope using the full width at half maximum (FWHM) and full width at half maximum (FWHM) of the D-mode characteristic distribution curve. For example, see [example provided]. Figure 5 As shown, Figure 5 A peak area I of the G-mode provided in the embodiments of this application G and D-mode peak area I D The curves showing the spatial distribution and the schematic diagram of the lateral spatial resolution effectively avoid the signal amplification or distortion problems caused by electromagnetic field enhancement and scattered light interference at the edge when using the knife-edge method, thereby effectively improving the accuracy of the measured lateral spatial resolution of the confocal Raman microscope.

[0077] In another possible implementation, the lateral spatial resolution of the confocal Raman microscope can be determined based on the G-mode characteristics in the Raman spectral signals at each scanning point, specifically including:

[0078] First, the G-mode characteristics in the Raman spectral signals of each scanning point are fitted to obtain the G-mode characteristic distribution curve of the G-mode peak area changing with the scanning path; then, the distance between the G-mode peak area changing from 12% to 88% in the G-mode characteristic distribution curve is used to determine the lateral spatial resolution of the confocal Raman microscope.

[0079] For example, in this embodiment of the application, when fitting the G-mode features in the Raman spectral signals of each scanning point, for each scanning point, the G-mode peak area corresponding to the scanning point can be obtained by first fitting the G-mode features in the Raman spectral signals of the scanning point with a single Lorentz peak. This yields a G-mode feature distribution curve showing the peak area changing with the scanning path. The G-mode peak area changes with the distance x between the center and edge of the laser spot (x=0 represents the edge). The distance between 12% and 88% of the G-mode peak area is determined as the lateral spatial resolution of the confocal Raman microscope.

[0080] It should be noted that, in the embodiments of this application, when the D-mode features are weak, the lateral spatial resolution of the confocal Raman microscope can be mainly determined based on the G-mode features, and the specific settings can be made according to actual needs.

[0081] For example, the numerical aperture of the confocal Raman microscope is selected as 0.90, the incident laser emission wavelength is 532 nm, the incident laser power is less than 1 mW to avoid thermal effects, and the confocal pinhole diameter is selected as 80 µm. The incident laser is configured to fill the entrance pupil of the confocal Raman microscope. The confocal Raman microscope is scanned along the z-axis to determine the focusing state of the confocal Raman microscope when the G-mode peak area is maximized. Under this configuration, the expected lateral spatial resolution is 0.4 µm, and the scanning step size is less than 1 / 3 of the expected lateral spatial resolution, for example, a scanning step size of 0.1 µm. Raman spectral signals at each scanning point are acquired along a direction perpendicular to the edge of the straight line from the substrate exposed area to the sample area, and the D-mode characteristic distribution curve of the D-mode peak area changing with the scanning path, or the G-mode characteristic distribution curve of the G-mode peak area changing with the scanning path, is fitted. The obtained mode characteristic distribution curve has a lower plateau and an upper plateau. In each plateau region, the intensity of the D-mode feature and the intensity of the G-mode feature are approximately constant.

[0082] Based on the above description, the influence of the system parameters of the confocal Raman microscope on the lateral spatial resolution of the confocal Raman microscope will be verified below.

[0083] In one scenario, keeping the laser wavelength and power constant, confocal Raman microscopes with numerical apertures NA = 0.25, 0.55, 0.75, and 0.90 were used. Under the same confocal pinhole size, for example, 80 µm, the D-mode and G-mode characteristic distribution curves were fitted, respectively. For example, see [link to relevant documentation]. Figure 6 As shown, Figure 6 The G-mode peak area I obtained by using microscope objectives with different NAs is provided in the embodiments of this application. G and D-mode peak area I D The measured values ​​and fitted curves of the distribution curves are used to determine the lateral spatial resolution of the confocal Raman microscope based on the full width at half maximum (FWHM) of the D-mode characteristic distribution curve. The lateral spatial resolution is also determined by comparing the distance between the peak area of ​​the G-mode and the peak area of ​​the G-mode characteristic distribution curve (from 12% to 88%). See Table 1 below for more details.

[0084] Table 1

[0085] NA 0.25 0.55 0.75 0.90 Lateral spatial resolution based on full width at half maximum (FWHM) measurement using D-mode characteristic distribution curves 1.35 0.74 0.44 0.35 Lateral spatial resolution determined based on the change of the characteristic distribution curve of the G-mode from 12% to 88%. 1.38 0.78 0.42 0.37

[0086] As can be seen from Table 1, different numerical apertures (NA) affect the lateral spatial resolution of confocal Raman microscopy. However, under the same numerical aperture, the lateral spatial resolution measured by the full width at half maximum (FWHM) based on the D-mode characteristic distribution curve is basically consistent with the lateral spatial resolution measured by the G-mode characteristic distribution curve from 12% to 88%.

[0087] In another scenario, keeping the laser wavelength and power constant, a confocal Raman microscope with a numerical aperture (NA) of 0.90 was used. The confocal pinhole diameters were set to 10 µm, 20 µm, 40 µm, 80 µm, 120 µm, and 160 µm, respectively. D-mode and G-mode characteristic distribution curves were fitted, and the lateral spatial resolution of the confocal Raman microscope, measured based on the full width at half maximum (FWHM) of the D-mode characteristic distribution curve, was compared with the distance between the G-mode peak area (from 12% to 88%) in the G-mode characteristic distribution curve. The results are shown in Table 2 below.

[0088] Table 2

[0089] Confocal pinhole diameter (µm) 10 20 40 80 120 160 Lateral spatial resolution based on full width at half maximum (FWHM) measurement using D-mode characteristic distribution curves 0.29 0.27 0.34 0.35 0.36 0.36 Lateral spatial resolution determined based on the change of the characteristic distribution curve of the G-mode from 12% to 88%. 0.29 0.28 0.33 0.37 0.38 0.38

[0090] As can be seen from Table 1, different confocal pinhole diameters affect the lateral spatial resolution of the confocal Raman microscope. However, for the same confocal pinhole diameter, the lateral spatial resolution measured by the full width at half maximum (FWHM) based on the D-mode characteristic distribution curve is basically consistent with the lateral spatial resolution measured by the G-mode characteristic distribution curve from 12% to 88%.

[0091] It is easy to see from Tables 1 and 2 above that, especially when the D-mode characteristic signal is weak, the lateral spatial resolution of the confocal Raman microscope can be determined based on the G-mode characteristic signal.

[0092] Tables 1 and 2 above quantify the effects of different numerical apertures (NA) and confocal pinhole sizes on the lateral spatial resolution of confocal Raman microscopy. This provides direct and reliable data support for optimizing the measurement conditions of lateral spatial resolution and evaluating the status of confocal Raman microscopy. The data processing is simpler, the signal is easier to acquire, and the anti-interference ability is stronger, which can significantly improve the measurement efficiency of lateral spatial resolution and the repeatability of the results.

[0093] The apparatus for measuring the lateral spatial resolution of a confocal Raman microscope provided in this application is described below. The apparatus for measuring the lateral spatial resolution of a confocal Raman microscope described below can be referred to in correspondence with the method for measuring the lateral spatial resolution of a confocal Raman microscope described above.

[0094] Figure 7 A schematic diagram of a device for measuring the lateral spatial resolution of a confocal Raman microscope provided in this application embodiment is shown below. For example, please refer to... Figure 7 As shown, the device 70 for measuring the lateral spatial resolution of the confocal Raman microscope may include:

[0095] The positioning unit 701 is used to locate the region of a straight edge on a monolayer graphene sample using a confocal Raman microscope, wherein the monolayer graphene sample is prepared on a silicon oxide substrate.

[0096] The determining unit 702 is used to determine a straight scanning path and scanning step size in the region of the already located straight edge, along a direction perpendicular to the straight edge, from the substrate exposed area to the sample area; wherein, the substrate exposed area is the area of ​​the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area of ​​the silicon oxide substrate covered by the monolayer graphene.

[0097] The determining unit 702 is also used to determine multiple scanning points on the straight scanning path based on the scanning step size during the movement of the monolayer graphene sample.

[0098] Acquisition unit 703 is used to acquire Raman spectral signals at each scanning point;

[0099] The measurement unit 704 is also used to measure the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point.

[0100] For example, in an embodiment of this application, the measuring unit 704 is used to measure the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point, including:

[0101] The D-mode characteristics in the Raman spectral signals of each scanning point are fitted to obtain the D-mode characteristic distribution curve of the D-mode peak area as a function of the scanning path;

[0102] The lateral spatial resolution of the confocal Raman microscope is determined by measuring the full width at half maximum (FWHM) of the characteristic distribution curve of the D-mode.

[0103] For example, in an embodiment of this application, the measuring unit 704 is used to measure the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point, including:

[0104] The G-mode features in the Raman spectral signals of each scanning point are fitted to obtain the distribution curve of the G-mode feature as the G-mode peak area changes with the scanning path;

[0105] The lateral spatial resolution of the confocal Raman microscope is determined by measuring the distance between the peak area of ​​the G-mode and the peak area of ​​the G-mode in the characteristic distribution curve of the G-mode, which varies from 12% to 77%.

[0106] For example, in an embodiment of this application, the acquisition unit 703 is used to acquire Raman spectral signals at each scanning point, including:

[0107] The focusing state of the confocal Raman microscope when the G-mode peak area is maximized is determined by scanning along the z-axis of the monolayer graphene sample using the confocal Raman microscope.

[0108] In the focused state, Raman spectral signals of each scanning point are acquired.

[0109] For example, in an embodiment of this application, the acquisition unit 703 is used to acquire Raman spectral signals at each scanning point, including:

[0110] Raman spectral signals at each scanning point are acquired when the incident laser is configured to fill the entrance pupil of the confocal Raman microscope.

[0111] For example, in an embodiment of this application, the intensity of the D-mode feature within the area of ​​the edge of the positioning line should be at least 1 / 20 of the intensity of the G-mode feature.

[0112] For example, in an embodiment of this application, the length of the straight-line scanning path is greater than A times the expected value of the lateral spatial resolution.

[0113] For example, in an embodiment of this application, the scanning step size is less than B times the expected value of the lateral spatial resolution, wherein B is less than 1.

[0114] For example, in an embodiment of this application, the numerical aperture of the confocal Raman microscope is in the range of 0.25 to 0.90.

[0115] The device 70 for measuring the lateral spatial resolution of a confocal Raman microscope provided in this application embodiment can execute the technical solution of the method for measuring the lateral spatial resolution of a confocal Raman microscope in any of the above embodiments. Its implementation principle and beneficial effects are similar to those of the method for measuring the lateral spatial resolution of a confocal Raman microscope. Please refer to the implementation principle and beneficial effects of the method for measuring the lateral spatial resolution of a confocal Raman microscope, which will not be repeated here.

[0116] Figure 8 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of this application, such as... Figure 8 As shown, the electronic device may include: a processor 810, a communications interface 820, a memory 830, and a communications bus 840, wherein the processor 810, the communications interface 820, and the memory 830 communicate with each other through the communications bus 840. The processor 810 can call logic instructions in the memory 830 to execute a method for determining the lateral spatial resolution of a confocal Raman microscope. This method includes: locating a region with a straight edge on a monolayer graphene sample prepared on a silicon oxide substrate using a confocal Raman microscope; determining a straight scanning path and scanning step size within the located straight edge region, along a direction perpendicular to the straight edge, from a substrate exposed area to a sample area using the confocal Raman microscope; wherein the substrate exposed area is the region of the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the region of the silicon oxide substrate covered by the monolayer graphene; during the movement of the monolayer graphene sample, determining multiple scanning points along the straight scanning path based on the scanning step size, and acquiring Raman spectral signals at each scanning point; and determining the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals at each scanning point.

[0117] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] On the other hand, this application also provides a computer program product, which includes a computer program that can be stored on a computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the method for determining the lateral spatial resolution of a confocal Raman microscope provided by the above methods. The method includes: locating a region of a straight edge on a monolayer graphene sample using a confocal Raman microscope, wherein the monolayer graphene sample is prepared on a silicon oxide substrate; determining a straight scanning path and scanning step size in the region of the located straight edge, along a direction perpendicular to the straight edge, from the substrate exposed area to the sample area using the confocal Raman microscope; wherein the substrate exposed area is the area of ​​the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area of ​​the silicon oxide substrate covered by the monolayer graphene; determining multiple scanning points on the straight scanning path based on the scanning step size during the movement of the monolayer graphene sample, and acquiring the Raman spectral signal of each scanning point; and determining the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signal of each scanning point.

[0119] In another aspect, this application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, performs a method for determining the lateral spatial resolution of a confocal Raman microscope provided by the methods described above. This method includes: locating a region of a straight edge on a monolayer graphene sample using a confocal Raman microscope, the monolayer graphene sample being prepared on a silicon oxide substrate; using the confocal Raman microscope, within the region of the located straight edge, determining a straight scanning path and scanning step size along a direction perpendicular to the straight edge, from a substrate exposed area to a sample area; wherein the substrate exposed area is a region in the silicon oxide substrate not covered by the monolayer graphene, and the sample area is a region in the silicon oxide substrate covered by the monolayer graphene; during the movement of the monolayer graphene sample, determining multiple scanning points on the straight scanning path based on the scanning step size, and acquiring Raman spectral signals at each scanning point; and determining the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals at each scanning point.

[0120] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0121] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for determining the lateral spatial resolution of a confocal Raman microscope, characterized in that, include: The region of a straight edge was located on a monolayer graphene sample prepared on a silicon oxide substrate using a confocal Raman microscope. Using the confocal Raman microscope, within the area of ​​the already located straight edge, a straight scanning path and scanning step size are determined from the substrate exposed area to the sample area along a direction perpendicular to the straight edge; wherein, the substrate exposed area is the area on the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area on the silicon oxide substrate covered by the monolayer graphene. During the movement of the monolayer graphene sample, multiple scanning points are determined on the straight scanning path based on the scanning step size, and Raman spectral signals of each scanning point are acquired. The lateral spatial resolution of the confocal Raman microscope is determined based on the Raman spectral signals at each scanning point.

2. The method according to claim 1, characterized in that, The determination of the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point includes: The D-mode characteristics in the Raman spectral signals of each scanning point are fitted to obtain the D-mode characteristic distribution curve of the D-mode peak area as a function of the scanning path; The lateral spatial resolution of the confocal Raman microscope is determined by measuring the full width at half maximum (FWHM) of the characteristic distribution curve of the D-mode.

3. The method according to claim 1, characterized in that, The determination of the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point includes: The G-mode features in the Raman spectral signals of each scanning point are fitted to obtain the distribution curve of the G-mode feature as the G-mode peak area changes with the scanning path; The lateral spatial resolution of the confocal Raman microscope is determined by measuring the distance between the peak area of ​​the G-mode changing from 12% to 88% in the characteristic distribution curve of the G-mode.

4. The method according to claim 3, characterized in that, The acquisition of Raman spectral signals at each scanning point includes: The focusing state of the confocal Raman microscope when the G-mode peak area is maximized is determined by scanning along the z-axis of the monolayer graphene sample using the confocal Raman microscope. In the focused state, Raman spectral signals of each scanning point are acquired.

5. The method according to claim 3, characterized in that, The acquisition of Raman spectral signals at each scanning point includes: Raman spectral signals at each scanning point are acquired when the incident laser is configured to fill the entrance pupil of the confocal Raman microscope.

6. The method according to any one of claims 1-5, characterized in that, Within the area of ​​the edge of the positioning straight line, the intensity of the D-mode feature should be at least 1 / 20 of the intensity of the G-mode feature.

7. The method according to any one of claims 1-5, characterized in that, The length of the linear scanning path is greater than A times the expected value of the lateral spatial resolution.

8. The method according to any one of claims 1-5, characterized in that, The scanning step size is less than B times the expected value of the lateral spatial resolution, where B is less than 1.

9. The method according to any one of claims 1-5, characterized in that, The numerical aperture of the confocal Raman microscope is in the range of 0.25 to 0.

90.

10. A device for measuring the lateral spatial resolution of a confocal Raman microscope, characterized in that, include: A positioning unit is used to locate the region of a straight edge on a monolayer graphene sample using a confocal Raman microscope, wherein the monolayer graphene sample is prepared on a silicon oxide substrate. The determining unit is used to determine a straight scanning path and scanning step size from the substrate exposed area to the sample area in the region of the already located straight edge, along a direction perpendicular to the straight edge, using the confocal Raman microscope; wherein, the substrate exposed area is the area on the silicon oxide substrate not covered by the monolayer graphene, and the sample area is the area on the silicon oxide substrate covered by the monolayer graphene. The determining unit is also used to determine multiple scanning points on the straight scanning path based on the scanning step size during the movement of the monolayer graphene sample. The acquisition unit is used to acquire the Raman spectral signals at each scanning point; The measurement unit is used to measure the lateral spatial resolution of the confocal Raman microscope based on the Raman spectral signals of each scanning point.

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