Light field regulated laser-induced fluorescence spectrum rare earth element detection method and system

Abstract

The application discloses a light field regulation laser-induced fluorescence spectrum rare earth element detection method and system, and belongs to the technical field of spectral analysis and optical precision detection. The method adopts an ultrashort supercontinuum light source to cooperate with an acousto-optic tunable filter to realize rapid and accurate tuning of an excitation wavelength, and converts the excitation light into an angular or radial polarization vector light beam through a vortex wave plate, and then focuses the light beam through a high numerical aperture objective lens, so that a significant local enhancement of a longitudinal electric field or magnetic field component is formed in a focal point region, thereby selectively enhancing an electric dipole or magnetic dipole transition fluorescence signal of a rare earth ion, collecting the fluorescence signal, and analyzing the fluorescence signal through a spectrometer. The method has the advantages of high signal-to-noise ratio, strong specificity and flexible operation, and is suitable for trace detection and spatial distribution imaging of rare earth elements in geological, material and environmental samples.

Description

Technical Field

[0001] This invention belongs to the field of spectral analysis and optical precision detection technology, specifically relating to a laser-induced fluorescence spectroscopy method and system for detecting rare earth elements with light field modulation. Background Technology

[0002] Rare earth elements (REEs) play an irreplaceable role in modern high-tech industries and cutting-edge scientific research due to their unique optical, electrical, and magnetic properties. Accurate and rapid in-situ analysis of their content, types, and spatial distribution is a key technological requirement in fields such as mineral resource assessment, advanced materials research and development, and environmental monitoring.

[0003] Currently, precise quantitative analysis of rare earth elements in laboratories mainly relies on large-scale instrumental methods such as inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Although these methods are highly sensitive, they generally have inherent limitations such as complex sample pretreatment, destruction of the original sample state, and inability to perform in-situ and real-time analysis. While X-ray fluorescence spectrometry (XRF) and laser-induced breakdown spectroscopy (LIBS) can achieve a certain degree of in-situ analysis, their ability to resolve the complex and overlapping 4f-4f transition spectra of rare earth elements is limited, making it difficult to achieve highly specific identification.

[0004] Laser-induced fluorescence spectroscopy (LIF) is a highly sensitive optical detection method that enables non-contact and in-situ analysis, showing great potential in the field of elemental analysis. However, its application to rare earth element detection still faces a series of technical bottlenecks: First, traditional LIF systems mostly use lasers with fixed wavelengths, making it difficult to flexibly match the diverse characteristic absorption energy levels of different rare earth ions, thus limiting their multi-element detection capabilities; second, in the fluorescence signals of rare earth ions, the intensity of magnetic dipole (MD) transitions, which are crucial for structural analysis, is usually much weaker than that of electric dipole (ED) transitions, and their signals are easily submerged by noise, leading to the loss of important information; third, conventional LIF systems have large excitation spots and limited spatial resolution, making it difficult to combine with microscopic imaging techniques to achieve visualized in-situ analysis of the compositional distribution in micron- or even nanoscale regions of samples.

[0005] Therefore, developing a laser-induced fluorescence spectroscopy detection method and system that can achieve rapid tuning of excitation wavelength, effectively enhance weak transition signals, and possess high spatial resolution in-situ imaging capabilities is of great scientific significance and application value for promoting the development of rare earth element analysis technology towards higher sensitivity, stronger specificity, and better spatial resolution. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a laser-induced fluorescence spectroscopy method and system for detecting rare earth elements using light field modulation. It utilizes an acousto-optic tunable filter (AOTF) to achieve rapid and precise tuning of the excitation wavelength to match the excited state of the target rare earth element. A vortex waveplate converts the excitation light into an angularly or radially polarized vector beam. A high numerical aperture objective lens tightly focuses this vector beam, forming a localized enhancement field on the sample surface for longitudinal electric or magnetic field components. The electric field promotes electric dipole transitions of rare earth ions, and the magnetic field promotes magnetic dipole transitions. Simultaneously, a conjugate imaging optical path enables visualization and in-situ spectral acquisition of the sample's micro-regions. This method is particularly suitable for highly specific identification, high-sensitivity detection, and micro-region spatial distribution analysis of rare earth elements, and has significant application value in geological exploration, materials science, and environmental monitoring.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] Laser-induced fluorescence spectroscopy methods for rare earth element detection with light field modulation include:

[0009] Step 1: Construct an integrated optical detection system, which includes an excitation unit, a collection unit, and a correction unit. The excitation unit includes a wavelength selection module, a light field modulation module, and a high-resolution focusing module arranged sequentially along the optical axis.

[0010] Step 2: Using the wavelength selection module, select an excitation light of a specific wavelength from the supercontinuum source; using the light field modulation module, convert the excitation light into a vector beam of angularly polarized light or radially polarized light; using the high-resolution focusing module, focus the vector beam onto the sample surface.

[0011] Step 3: Using the calibration unit, observe the excitation spot image corresponding to the vector beam acting on the sample surface, and adjust the sample position so that the excitation spot image is precisely aligned with the test area of ​​the sample.

[0012] Step 4: Using the collection unit, collect the fluorescence signal generated by the sample under stimulation and acquire the spectrum or image;

[0013] Step 5: Based on the acquired spectral or image data, perform specific identification and quantitative analysis of rare earth elements.

[0014] Furthermore, the wavelength selection module includes a supercontinuum light source and an acousto-optic tunable filter. The output end of the supercontinuum light source is optically connected to the input end of the acousto-optic tunable filter. The acousto-optic tunable filter is used to achieve rapid, mechanical-free tuning of the excitation wavelength through electronic control of radio frequency signals to match the characteristic absorption energy level of the target rare earth element.

[0015] Furthermore, the light field modulation module includes a half-wave plate and a vortex wave plate. The output end of the half-wave plate is optically connected to the input end of the vortex wave plate. The half-wave plate is used to adjust the linear polarization direction of the excitation light, and the vortex wave plate is used to convert the linearly polarized light into angularly polarized light or radially polarized light. The fast axis direction of the vortex wave plate changes linearly with the azimuth angle of its location.

[0016] Furthermore, the high-resolution focusing module includes an objective lens with a numerical aperture (NA) ≥ 0.8 and a nano-displacement platform. The objective lens is positioned on the output optical path of the optical field control module, and the nano-displacement platform is used to support the sample and is positioned near the focal plane of the objective lens. It is used to focus the vector beam tightly onto the sample surface and form a local enhancement field of longitudinal electric or magnetic field in the focal region, thereby selectively enhancing the fluorescence signal of electric dipole transition or magnetic dipole transition of rare earth ions.

[0017] Furthermore, the correction unit includes a flip mirror, an imaging lens, and an area array camera. The flip mirror is disposed in the optical path of the collection unit and can switchably guide the light beam to the imaging lens. The output end of the imaging lens is optically connected to the input end of the area array camera to realize conjugate imaging of the sample surface and the excitation spot, and to monitor and accurately locate the area to be tested in real time.

[0018] Furthermore, the collecting unit includes a beam splitter, a filter, a focusing lens, and a spectrometer. The beam splitter is located at the intersection of the optical paths of the excitation unit and the collecting unit. The output end of the beam splitter is optically connected to the input end of the filter, the output end of the filter is optically connected to the input end of the focusing lens, and the output end of the focusing lens is optically connected to the input end of the spectrometer. The filter is a long-pass or band-pass filter used to filter out excitation light scattering and collect target fluorescence signals.

[0019] Furthermore, step 5 also includes: simultaneously identifying multiple rare earth elements by combining excitation wavelength scanning with polarization-resolved spectroscopy; and obtaining a two-dimensional spatial distribution image of rare earth elements on the sample surface by performing point-by-point scanning through a nano-displacement platform and reconstructing characteristic fluorescence intensity.

[0020] On the other hand, the present invention provides a laser-induced fluorescence spectroscopy rare earth element detection system with light field modulation, applied to the aforementioned method, specifically including:

[0021] The excitation unit, used to generate a wavelength-tunable and polarization-controllable tightly focused excitation light field and apply it to the sample, includes a wavelength selection module, a light field modulation module and a high-resolution focusing module optically connected in sequence along the optical axis;

[0022] The collection unit, which is optically connected to the excitation unit, is used to collect and analyze the fluorescence signal generated by the excited sample.

[0023] The calibration unit, which is optically switchably connected to the collection unit, is used to output precise sample spatial coordinates through imaging positioning and transmit them to the excitation unit to ensure the accuracy of the excitation action.

[0024] Thirdly, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors enable the aforementioned laser-induced fluorescence spectroscopy method for detecting rare earth elements with light field modulation.

[0025] Fourthly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned laser-induced fluorescence spectroscopy method for detecting rare earth elements with light field modulation.

[0026] The beneficial effects of this invention are as follows:

[0027] High excitation flexibility and strong multi-element adaptability: By adopting a combination of supercontinuum light source and acousto-optic tunable filter (AOTF), the excitation wavelength can be rapidly and accurately electronically tuned in a wide spectral range without changing the laser. It can flexibly match the optimal absorption wavelength of different rare earth ions, which significantly improves the system's adaptability and efficiency in detecting a variety of rare earth elements.

[0028] Significantly improved signal specificity and signal-to-noise ratio: A vector beam polarized angularly or radially is generated by a vortex waveplate and tightly focused using a high numerical aperture objective, creating localized enhancement of the longitudinal electric or magnetic field components in the diffraction-limited focal region. This enhancement field can selectively couple the electric or magnetic dipole moments of rare-earth ions, thereby efficiently enhancing the fluorescence signals of their ED or MD transitions, respectively. By comparing the spectral differences under the two polarization excitations, weak magnetic dipole transition signals that are difficult to detect using traditional methods can be effectively extracted, greatly improving the specificity of rare-earth elements, especially those with severely overlapping spectral lines.

[0029] High spatial resolution and in-situ analysis capabilities: The system integrates a camera-based conjugate imaging optical path, enabling visual positioning and real-time monitoring of sample micro-regions before spectral acquisition, ensuring precise alignment of the excitation spot with the target area. Combined with a nanoscale displacement stage, it can achieve localized excitation and compositional analysis in micron to nanoscale regions, obtaining spatial distribution images of rare earth elements, truly realizing high spatial resolution in-situ analysis.

[0030] The system is robust and easy to operate: the entire system has a high degree of optical path integration, and wavelength tuning and polarization switching are both electronically controlled, eliminating the need for complex mechanical adjustments. It has good stability and is easy to operate, providing a reliable technical means for laboratory research and field applications. Attached Figure Description

[0031] Figure 1 This is a flowchart of the laser-induced fluorescence spectroscopy method for detecting rare earth elements with light field modulation according to the present invention.

[0032] Figure 2 This is a schematic diagram of the optical path structure of the laser-induced fluorescence spectroscopy rare earth element detection system with light field modulation according to the present invention;

[0033] Figure 3 This is a schematic diagram for selecting the excitation wavelength, where (a) is the fluorescence intensity curve at the excitation wavelength and (b) is the fitted curve;

[0034] Figure 4 To detect Eu 3+ A schematic diagram of the effect of rare earth ions, where (a) is the fluorescence spectrum excited by radially polarized light, angularly polarized light and Gaussian light, (b) is the difference in fluorescence spectrum excited by radially polarized light and Gaussian light, and (c) is the difference in fluorescence spectrum excited by angularly polarized light and Gaussian light.

[0035] Figure 5 The diagram shows the growth rate of electric and magnetic dipole transition intensities in the fluorescence spectra of different samples under different excitation modes. (a) is excited by radially polarized light at 532 nm and 533.7 nm; (b) is excited by angularly polarized light at 532 nm and 533.7 nm; and (c) is excited by radially and angularly polarized light at 533.7 nm.

[0036] Figure label:

[0037] 1-Supercontinuum light source; 2-Acousto-optic tunable filter; 31-First convex lens; 32-Second convex lens; 33-Third convex lens; 34-Fourth convex lens; 4-Pinhole filter; 5-Aperture; 6-Half-wave plate; 7-Vortex wave plate; 8-Beam splitter; 9-Objective lens; 10-Sample; 11-Nanometer displacement stage; 12-Flip mirror; 13-Area array camera; 14-Filter; 15-Spectrometer; 16-Host computer. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] This invention provides a laser-induced fluorescence spectroscopy method and system for detecting rare earth elements using light field modulation. Its key feature is the use of a vortex waveplate to generate an angularly or radially polarized vector beam, which, after being tightly focused by a high numerical aperture objective lens, forms a localized enhancement field of longitudinal electric or magnetic fields at the diffraction-limited focal point. This field couples with the electric or magnetic dipole moments of rare earth ions, amplifying the fluorescence signal of the electric dipole (ED) or magnetic dipole (MD) transitions of the rare earth ions. Simultaneously, an integrated acousto-optic tunable filter (AOTF) enables rapid matching of the excitation wavelength, and a conjugate imaging optical path is used to achieve micro-area visualization and localization. This method not only meets the need for specific identification of rare earth elements in complex matrices but also achieves high-sensitivity detection of trace signals and in-situ analysis of micro-areas, thereby improving the accuracy of rare earth element detection and spatial information acquisition capabilities. Figures 1-2 As shown, the method specifically includes:

[0040] Step 1: Construct an integrated optical detection system. The system includes an excitation unit, a collection unit, and a correction unit. The excitation unit includes a wavelength selection module, a light field modulation module, and a high-resolution focusing module arranged sequentially along the optical axis.

[0041] The excitation unit is used to generate a wavelength-tunable, polarization-controllable, tightly focused excitation light field and apply it to the sample; the collection unit is used to collect and analyze the fluorescence signal generated by the excited sample; the calibration unit is used to output precise sample spatial coordinates through imaging positioning, and these coordinates are transmitted to the excitation unit as a key input to ensure the accuracy of the excitation action.

[0042] The excitation unit includes a wavelength selection module, a light field modulation module, and a high-resolution focusing module arranged sequentially along the optical axis.

[0043] Step 2: Using the wavelength selection module, select an excitation light of a specific wavelength from the supercontinuum light source; using the light field modulation module, convert the excitation light into a vector beam of angularly polarized light or radially polarized light; using the high-resolution focusing module, focus the vector beam onto the sample surface.

[0044] The wavelength selection module consists of a supercontinuum light source 1 and an acousto-optic tunable filter 2 (AOTF). The supercontinuum light source 1 is used to provide a broadband laser covering the ultraviolet to near-infrared band. The acousto-optic tunable filter 2 is based on the acousto-optic diffraction effect and achieves rapid, non-mechanical and electronic tuning of the output laser wavelength by applying radio frequency drive signals of different frequencies.

[0045] The optical field modulation module includes a half-wave plate 6 and a vortex wave plate 7; the half-wave plate 6 is used to adjust the linear polarization direction of the excitation light; the vortex wave plate 7 is used to convert the linearly polarized light into a vector beam with polarization states distributed axially symmetrically on the cross section, that is, angularly polarized light with a longitudinal magnetic field component or radially polarized light with a longitudinal electric field component.

[0046] The high-resolution focusing module includes a high numerical aperture (NA) objective lens 9 and a nanostage 11; the high numerical aperture objective lens 9 has a numerical aperture NA ≥ 0.8 and is used to tightly focus the vector beam, so that the vector beam produces significant local enhancement of the longitudinal field component in the focal region; the nanostage 11 is used to support the sample and realize its nanometer-level precision displacement and positioning in three-dimensional space.

[0047] According to vector diffraction theory, radially polarized light, after being tightly focused by the high numerical aperture objective lens, mainly exhibits a significant enhancement of the longitudinal electric field component at the focal point; angularly polarized light, after being tightly focused, mainly exhibits a significant enhancement of the longitudinal magnetic field component at the focal point. The enhancement intensity of the longitudinal field component is related to tight focusing; therefore, using a high NA (≥0.8) objective lens is a necessary condition for achieving effective local enhancement.

[0048] The principle of wavelength selection and optical field manipulation achieved by the excitation unit is as follows: First, using a supercontinuum light source 1 in conjunction with an acousto-optic tunable filter 2 (AOTF), the optimal excitation wavelength for the target rare earth element is rapidly and accurately selected over a wide spectral range by electronically controlling the radio frequency signal. Then, the obtained monochromatic excitation light is sequentially passed through a half-wave plate 6 and a vortex wave plate 7 to convert it into a vector beam with a spatially axially symmetric polarization distribution, i.e., angularly polarized light or radially polarized light. Finally, the vector beam is tightly focused onto the sample surface using a high numerical aperture (NA≥0.8) objective lens 9.

[0049] The beam is focused by the first convex lens 31 and reaches the pinhole filter 4 for spatial filtering. It is then converted into parallel light by the second convex lens 32. The beam diameter is adjusted by the aperture 5 to match the light transmission aperture of the optical element. The focusing is adjusted by the nano-displacement stage 11 so that the beam is tightly focused onto the sample 10 by the objective lens 9.

[0050] The selection of the excitation wavelength is based on the characteristic absorption energy level of the target rare earth ion and is achieved by controlling the AOTF driver through a host computer.

[0051] The vortex waveplate 7 is a continuous phase delay element, whose fast axis azimuth angle changes linearly with the azimuth coordinate φ, mathematically expressed as α(φ)=qφ+α0, where q is the topological charge and α0 is the initial phase; when q=±0.5, the vortex waveplate 7 can efficiently convert linearly polarized light into angularly polarized light or radially polarized light.

[0052] Step 3: Using the calibration unit, observe the excitation spot image corresponding to the vector beam acting on the sample surface, and adjust the sample position so that the excitation spot image is precisely aligned with the test area of ​​the sample.

[0053] Before excitation, a calibration unit is used to visualize and locate the micro-region of the sample. A portion of the light signal is guided into the imaging optical path, composed of a third convex lens 33 and an area array camera 13, via a flip mirror 12 that cuts into the optical path. The conjugate image of the excitation spot and the sample surface morphology is observed in real time on a display. Combined with a nano-displacement stage 11, the sample position is precisely adjusted so that the excitation spot is aligned with the micrometer-scale target region to be analyzed.

[0054] The fluorescence emitted by sample 10 upon excitation passes through objective lens 9, reaches beam splitter 8, and is reflected to flip mirror 12. Flip mirror 12 controls the beam transmission to area array camera 13 or spectrometer 15. A third convex lens 33 is placed in front of area array camera 13 to achieve conjugate imaging. Filter 14 is placed in front of spectrometer 15 to filter out laser light and other stray light reflected from the sample surface, allowing cleaner fluorescence to enter spectrometer 15. Area array camera 13 or spectrometer 15 can be controlled by host computer 16. The correction unit includes flip mirror 12, imaging lens, and area array camera 13 (such as a CCD or CMOS camera).

[0055] When the flip mirror 12 enters the optical path, reflected or scattered light from the sample surface is reflected to the third convex lens 33 of the imaging lens, forming a clear image on the area array camera 13 that is strictly conjugate to the focal plane of the objective lens, thereby achieving real-time monitoring of the excitation spot and precise positioning of the sample micro-area. When the camera presents a circular focused spot, the flip mirror 12 can be used to allow the light beam to enter the spectrometer 15 for further detection.

[0056] Step 4: Using the collection unit, collect the fluorescence signal generated by the sample under stimulation and perform spectral or image acquisition.

[0057] Excite and collect fluorescence signals. Remove the flip mirror 12 and excite the sample with the constructed enhanced light field. The generated fluorescence signal is separated by a beam splitter in the collection unit, and then filtered by a long-pass or band-pass filter to remove residual excitation light scattering. Finally, the complete fluorescence spectrum is obtained by the spectrometer 15, or a fluorescence image of a specific wavelength band is obtained by the CCD.

[0058] The collection unit includes a beam splitter 8, a filter 14, a fourth convex lens 34, and a spectrometer 15; the beam splitter 8 is a dichroic mirror designed to reflect fluorescence wavelengths.

[0059] The filter 14 is a long-pass or bandpass filter, and its cutoff wavelength or passband center wavelength is selected to ensure efficient filtering of excitation light and transmission of target fluorescence signal.

[0060] Step 5: Based on the acquired spectral or image data, perform specific identification and quantitative analysis of rare earth elements.

[0061] First, the positions of characteristic peaks in the fluorescence spectrum are extracted and matched with the standard spectral data of rare earth ions to achieve preliminary element identification.

[0062] For the initially identified ions, the intensity of their magnetic dipole transition peak under angularly polarized light excitation and the intensity of their electric dipole transition peak under radially polarized light excitation were analyzed.

[0063] For complex samples with unknown components, multi-element analysis can be performed by combining excitation wavelength scanning with polarization-resolved spectroscopy.

[0064] Step 6: Control the AOTF to scan within a preset wavelength range (e.g., 400-700 nm) at a certain step size to achieve simultaneous identification and differentiation of multiple rare earth elements. At each scanning wavelength point, fluorescence spectra under angular polarization and radial polarization excitation are collected to obtain a data matrix. By analyzing the variation of different fluorescence characteristic peak intensities with excitation wavelength and polarization state, simultaneous identification and differentiation of multiple rare earth elements can be achieved.

[0065] Step 7: Micro-area scanning imaging analysis to obtain spatial distribution information of rare earth elements.

[0066] After determining the analyte and its optimal excitation parameters, the AOTF wavelength and the polarization state of the vortex waveplate are fixed. The nanoscale displacement stage is controlled to move the sample for point-by-point or continuous scanning within the two-dimensional region of interest. At each scanning point, a complete spectrum is acquired using a spectrometer, or the fluorescence intensity of a specific characteristic spectral band is recorded using a bandpass filter in conjunction with a CCD. After scanning, a two-dimensional compositional concentration map of the target rare earth element within the scanning region is generated by spatially reconstructing the characteristic fluorescence intensities.

[0067] Based on the method and system described in this invention, the fluorescence spectrum of Eu2O3 was measured, such as... Figure 3 As shown in Figure (a), according to Eu 3+ The characteristic absorption energy level was used, and the excitation wavelength was set to 533.7 nm using an acousto-optic tunable filter (AOTF). For example... Figure 3 (b) shows the spectrum of the laser emitted by the laser, which was verified to be Gaussian light after Gaussian fitting. The flip mirror of the calibration unit was inserted, and the sample surface and excitation spot were observed through a camera. A nano-displacement stage was used to precisely align the excitation spot with the area to be measured. After removing the flip mirror, the fluorescence spectra of the sample were acquired sequentially in three polarization modes. The acquired spectral data were analyzed. Figure 4 As shown in Figure (a), Eu can be observed under excitation by conventional Gaussian linearly polarized light, radially polarized light, and angularly polarized light. 3+ Characteristic fluorescence peaks; such as Figure 4As shown in Figures (b) and (c), the fluorescence characteristic peak intensity is significantly enhanced to varying degrees under radially polarized light and angularly polarized light excitation compared to Gaussian linearly polarized light. Figure 5 The differences in the growth rate of ED and MD transition intensities under different excitation modes are further demonstrated. Figure 5 Figures (a) and (b) compare the intensity growth rates of characteristic fluorescence peaks under fixed excitation wavelengths (532 nm and 533.7 nm) when excited by radially polarized light and conventional Gaussian light, and angularly polarized light and conventional Gaussian light, respectively. This visually reflects the directional enhancement effect of radially polarized light on ED transitions and angularly polarized light on MD transitions. In this study, "532 nm and 533.7 nm" and "angularly polarized light and radially polarized light" are both considered as independent variables, while "610 nm and 590 nm" in the figure are considered as dependent variables (i.e., the peak wavelengths of the fluorescence spectra of interest). By controlling the combination of independent variables, the dependent variable is changed, and the degree of change of the independent variable, i.e., the growth rate, is calculated, providing a basis for exploring the role of the independent variables. Figure 5 Figure (c) directly compares the spectral differences produced by radially polarized light and angularly polarized light excitation at the same excitation wavelength (533.7 nm). This difference stems directly from the longitudinal electric field and longitudinal magnetic field components generated by the two light sources in the focal region, respectively, affecting Eu. 3+ Selective coupling of ions with different transition moments. This series of data strongly confirms that polarization-resolved excitation achieved through optical field manipulation can effectively separate and enhance specific types of transition signals, providing experimental evidence for the highly specific identification of rare earth elements using spectral fingerprint differences. Based on this, further multi-element analysis and spatial scanning imaging can be carried out.

[0068] On the other hand, the present invention provides a laser-induced fluorescence spectroscopy rare earth element detection system with light field modulation, applied to the aforementioned method, specifically including:

[0069] The excitation unit, used to generate a wavelength-tunable and polarization-controllable tightly focused excitation light field and apply it to the sample, includes a wavelength selection module, a light field modulation module and a high-resolution focusing module optically connected in sequence along the optical axis;

[0070] The collection unit, which is optically connected to the excitation unit, is used to collect and analyze the fluorescence signal generated by the excited sample.

[0071] The calibration unit, which is optically switchably connected to the collection unit, is used to output precise sample spatial coordinates through imaging positioning and transmit them to the excitation unit to ensure the accuracy of the excitation action.

[0072] Thirdly, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors enable the aforementioned laser-induced fluorescence spectroscopy method for detecting rare earth elements with light field modulation.

[0073] Fourthly, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enable the processor to implement the aforementioned laser-induced fluorescence spectroscopy method for detecting rare earth elements with light field modulation.

[0074] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser-induced fluorescence spectroscopy method for detecting rare earth elements using light field modulation, characterized in that, include: Step 1: Construct an integrated optical detection system, which includes an excitation unit, a collection unit, and a correction unit. The excitation unit includes a wavelength selection module, a light field modulation module, and a high-resolution focusing module arranged sequentially along the optical axis. Step 2: Using the wavelength selection module, select an excitation light of a specific wavelength from the supercontinuum source; using the light field modulation module, convert the excitation light into a vector beam of angularly polarized light or radially polarized light; using the high-resolution focusing module, focus the vector beam onto the sample surface. Step 3: Using the calibration unit, observe the excitation spot image corresponding to the vector beam acting on the sample surface, and adjust the sample position so that the excitation spot image is precisely aligned with the test area of ​​the sample. Step 4: Using the collection unit, collect the fluorescence signal generated by the sample under stimulation and acquire the spectrum or image; Step 5: Based on the acquired spectral or image data, perform specific identification and quantitative analysis of rare earth elements; The high-resolution focusing module includes an objective lens with a numerical aperture (NA) ≥ 0.8 and a nano-displacement platform. The objective lens is positioned on the output optical path of the optical field control module. The nano-displacement platform is used to support the sample and is positioned near the focal plane of the objective lens. It is used to focus the vector beam tightly onto the sample surface and form a local enhancement field of longitudinal electric or magnetic field in the focal region, thereby selectively enhancing the fluorescence signal of electric dipole transition or magnetic dipole transition of rare earth ions. The correction unit includes a flip mirror, an imaging lens, and an area array camera. The flip mirror is disposed in the optical path of the collection unit and can switch the beam to the imaging lens. The output end of the imaging lens is optically connected to the input end of the area array camera to realize conjugate imaging of the sample surface and the excitation spot, and to monitor and accurately locate the area to be tested in real time.

2. The method for detecting rare earth elements using laser-induced fluorescence spectroscopy with light field modulation according to claim 1, characterized in that, The wavelength selection module includes a supercontinuum light source and an acousto-optic tunable filter. The output end of the supercontinuum light source is optically connected to the input end of the acousto-optic tunable filter. The acousto-optic tunable filter is used to achieve rapid, mechanical-free tuning of the excitation wavelength through electronic control of radio frequency signals to match the characteristic absorption energy level of the target rare earth element.

3. The laser-induced fluorescence spectroscopy method for rare earth element detection with light field modulation according to claim 1, characterized in that, The optical field modulation module includes a half-wave plate and a vortex wave plate. The output end of the half-wave plate is optically connected to the input end of the vortex wave plate. The half-wave plate is used to adjust the linear polarization direction of the excitation light, and the vortex wave plate is used to convert the linearly polarized light into angularly polarized light or radially polarized light. The fast axis direction of the vortex wave plate changes linearly with the azimuth angle of its location.

4. The method for detecting rare earth elements using laser-induced fluorescence spectroscopy with light field modulation according to claim 1, characterized in that, The collecting unit includes a beam splitter, a filter, a focusing lens, and a spectrometer. The beam splitter is located at the intersection of the optical paths of the excitation unit and the collecting unit. The output end of the beam splitter is optically connected to the input end of the filter, the output end of the filter is optically connected to the input end of the focusing lens, and the output end of the focusing lens is optically connected to the input end of the spectrometer. The filter is a long-pass or band-pass filter used to filter out excitation light scattering and collect target fluorescence signals.

5. The laser-induced fluorescence spectroscopy method for rare earth element detection with light field modulation according to claim 1, characterized in that, Step 5 further includes: simultaneously identifying multiple rare earth elements by combining excitation wavelength scanning with polarization-resolved spectroscopy; and obtaining a two-dimensional spatial distribution image of rare earth elements on the sample surface by performing point-by-point scanning through a nano-displacement platform and reconstructing characteristic fluorescence intensity.

6. A laser-induced fluorescence spectroscopy rare earth element detection system with light field modulation, applied to the method described in any one of claims 1-5, characterized in that, include: The excitation unit, used to generate a wavelength-tunable and polarization-controllable tightly focused excitation light field and apply it to the sample, includes a wavelength selection module, a light field modulation module and a high-resolution focusing module optically connected in sequence along the optical axis; The collection unit, which is optically connected to the excitation unit, is used to collect and analyze the fluorescence signal generated by the excited sample. The calibration unit, which is optically switchably connected to the collection unit, is used to output precise sample spatial coordinates through imaging positioning and transmit them to the excitation unit to ensure the accuracy of the excitation action.

7. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the laser-induced fluorescence spectroscopy rare earth element detection method with light field modulation as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, enable the processor to implement the laser-induced fluorescence spectroscopy rare earth element detection method with light field modulation as described in any one of claims 1-5.

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