Apparatus and method for spontaneous / stimulated raman spatially resolved measurement of double droplet based on confocal system

Abstract

This invention relates to a device and method for spontaneous / stimulated Raman spatial resolution measurement of dual-droplet optical tweezers based on a confocal system, belonging to the field of aerosol microdroplet spectral trace analysis technology. It solves the problem that existing aerosol dual-droplet detection devices typically rely on traditional single-beam optical systems, which cannot capture dual droplets and have insufficient spatial resolution, making it difficult to achieve high-precision spatial resolution for dual-droplet capture and dynamic monitoring. The device of this invention includes a dual-droplet suspension system, an environmental atmosphere control system, an optical path coupling system, a dynamic signal processing system, a microdroplet imaging system, and a confocal optical system. The environmental atmosphere control system is connected to the dual-droplet suspension system, and the confocal optical system is connected to the dual-droplet suspension system, the dynamic signal processing system, the microdroplet imaging system, and the optical path coupling system. The confocal optical system includes a microscope objective and a long-wavelength reverse short-wavelength lens, with the microscope objective positioned between the long-wavelength reverse short-wavelength lens and the dual-droplet suspension system.

Description

Technical Field

[0001] This invention relates to the field of aerosol microdroplet spectral trace analysis technology, specifically to a device and method for spontaneous / stimulated Raman spatial resolution measurement using dual-droplet optical tweezers based on a confocal system. This device enables non-contact manipulation of dual droplets, high spatial resolution imaging, and multi-component measurement, thereby improving spectral resolution and measurement accuracy. Background Technology

[0002] In existing technologies, optical tweezers have been widely used to capture and manipulate single-droplet aerosol particles, enabling non-contact in-situ measurements. For example, aerosol optical tweezers systems can be combined with Raman spectroscopy to perform phase transition, morphological, and chemical composition analysis on suspended single droplets, supporting signal enhancement in whispering-gallery mode and Mie scattering inversion models for retrieving droplet radius, refractive index, and reaction kinetic parameters. However, existing technologies, primarily focused on the capture and analysis of single droplets, lack sufficient spatial resolution for measurements in dual-droplet or multi-droplet systems.

[0003] Traditional optical tweezers systems struggle to simultaneously capture and precisely locate two droplets, hindering effective analysis of droplet interactions, dynamic changes, and chemical composition distribution. Furthermore, confocal imaging in aerosol droplet applications is limited by focal plane matching and synchronous signal acquisition, making it difficult to achieve high-precision spatial resolution measurements at the micrometer and submicrometer levels (e.g., axial resolution of only 1-2 μm). Additionally, while existing stimulated Raman scattering can monitor single-droplet reaction kinetics, it lacks the capability to simultaneously monitor two-droplet systems, failing to support simultaneous, real-time, in-situ observations of multiple components within different droplets (e.g., organic / inorganic mixed aerosols). These limitations restrict the measurement accuracy and parallel measurement capabilities of multi-droplet systems in atmospheric pollutant monitoring and droplet dynamics research.

[0004] In the confocal system-based dual-droplet optical tweezers device, the innovation of confocal technology is mainly reflected in its unique integration with optical tweezers and high numerical aperture (NA) objectives, which significantly improves spatial resolution, signal synchronization and multi-droplet parallel analysis capabilities. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a device and method for spontaneous / stimulated Raman spatial resolution measurement of dual droplets using optical tweezers based on a confocal system, in order to solve the problem that existing aerosol dual droplet detection devices usually rely on traditional single-beam optical systems, which cannot capture dual droplets and have insufficient spatial resolution, making it difficult to achieve high-precision spatial resolution for the capture and dynamic monitoring of dual droplets.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] This invention provides a spatial resolution device for dual-droplet optical tweezers based on a confocal system, comprising a dual-droplet suspension system, an environmental atmosphere control system, an optical path coupling system, a dynamic signal processing system, a microdroplet imaging system, and a confocal optical system;

[0008] The environmental atmosphere control system is connected to the dual-droplet suspension system, and the confocal optical system is connected to the dual-droplet suspension system, the dynamic signal processing system, the microdroplet imaging system, and the optical path coupling system, respectively.

[0009] The confocal optical system includes a microscope objective and a long-wavelength reverse short-wavelength lens, with the microscope objective positioned between the long-wavelength reverse short-wavelength lens and the dual-droplet suspension system.

[0010] Optionally, the droplet imaging system includes a long-wavelength-pass short-wavelength mirror, a second focusing lens, an imaging CCD, and a real-time imaging system arranged sequentially.

[0011] Optionally, the long-wavelength reflector with short-wavelength pass is a dichroic mirror with both long-wavelength reflector and short-wavelength pass, and the long-wavelength pass with short-wavelength reflector is a dichroic mirror with both long-wavelength pass and short-wavelength reflector.

[0012] Optionally, the dynamic signal processing system includes a first focusing lens, a spectrometer, an electronic gain CCD, and a data processing system; the electronic gain CCD and the data processing system are electrically connected to the spectrometer, respectively.

[0013] Optionally, the microscope objective is a high numerical aperture (NA) microscope objective with an aperture of 1.49.

[0014] Optionally, the environmental atmosphere control system includes a gas generation branch and a gas collection branch, wherein a gas generating device, a mass flow meter, a moisture cylinder and a temperature and humidity recorder are sequentially arranged on the gas generation branch.

[0015] This invention provides a method for spontaneous / stimulated Raman spatial resolution measurement using dual-droplet optical tweezers based on a confocal system, employing the aforementioned apparatus and comprising the following steps:

[0016] Step 1: Calibrate the optical path and adjust the phase of the droplet displayed in the imaging CCD and the phase of the droplet displayed in front of the spectrometer slit to a confocal state;

[0017] Step 2: Aerosols are generated by an aerosol generator and pumped into the sample cell of the dual-droplet suspension system in the form of aerosol droplets.

[0018] Step 3: Introduce the required reaction gas into the sample cell through the environmental atmosphere control system;

[0019] Step 4: The scattered light signals from the two droplets are input into the dynamic signal processing system and the microdroplet imaging system, respectively;

[0020] Step 5: Obtain dynamic changes based on the spatial resolution imaging of the optical signal provided by the droplet imaging system and the spectral data provided by the dynamic signal processing system.

[0021] Optionally, in step 1, calibrating the optical path includes connecting the laser source, the semi-transparent mirror, and the first reflecting mirror, and setting the parameters.

[0022] Optionally, in step 3, introducing the required reaction gas into the sample cell through an environmental atmosphere control system includes the following steps:

[0023] Step 3-1: Turn on the gas generator;

[0024] Step 3-2: Introduce a dry / wet mixed gas;

[0025] Step 3-3: Control relative humidity using a moisture bottle;

[0026] Steps 3-4: Use a temperature and humidity recorder to monitor and adjust the temperature and relative humidity in real time;

[0027] Steps 3-5: Continue ventilation until the environment stabilizes.

[0028] The present invention provides the application of the above-described apparatus and method in inverting droplet radii.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] 1. This invention achieves spatial resolution capture and suspension of two droplets by combining a high numerical aperture microscope objective of a confocal optical system with a spectrometer slit, supporting the simulation of multi-component aerosols. Compared with existing single-droplet systems, the axial resolution is improved to the submicron level (0.5-1 μm), making it suitable for fields such as environmental monitoring and biological particle detection, and improving the synchronous measurement categories, accuracy and flexibility of detection.

[0031] 2. The laser source supports multiple beam modes. Combined with the beam expander, it can generate a uniform light field, reduce stray signal interference, and improve the signal-to-noise ratio and acquisition stability.

[0032] 3. The apparatus and method of the present invention are applicable to a variety of aerosol and particle experiments, especially to particle manipulation in environmental monitoring and biological research, providing a more flexible and economical solution for the application of optical capture technology.

[0033] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0034] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0035] Figure 1 This is a schematic diagram of a dual-droplet optical tweezers spatial resolution device based on a confocal system, which relates to the present invention.

[0036] Figure 2 This is a schematic diagram showing that the focal plane of the suspended droplet in the microscope objective is confocal with the focal plane of the image on the slit of the spectrometer.

[0037] Figure 3 (a) Spatial-resolved spectra of two ammonium sulfate droplets; (b) Imaging of the droplets; (c) and (d) Stimulated Raman spectra of each droplet; (e) Stimulated Raman spectra of the combined two droplets.

[0038] Figure 4 This is a comparison of the spectrum of the merged droplets (a) with the individual spectra of each droplet ((b) and (c)).

[0039] Figure 5 The graph shows the relationship between the radius of the characteristic peaks of stimulated Raman spectra obtained by inversion using existing technology (the apparatus and method described in CN120778608A) and time.

[0040] Figure 6 The graph shows the radius versus time relationship obtained after improving the signal-to-noise ratio of the characteristic peaks in stimulated Raman spectroscopy using the confocal system of the present invention.

[0041] Figure label:

[0042] 1-Dual droplet suspension system; 101-Sample cell; 102-Aerosol generator; 2-Environmental atmosphere control system; 201-Gas generator; 202-Gas filter plug; 203-Mass flow meter; 204-Moisture bottle; 205-Temperature and humidity recorder; 3-Optical path coupling system; 301-Laser source; 302-1, 302-2-Semi-transparent and semi-reflective mirrors; 303-1, 303-2-First reflecting mirror; 304-Expanding... Beam assembly; 305-Second reflecting mirror; 4-Dynamic signal processing system; 401-First focusing lens; 402-Spectrometer; 403-Electronic gain CCD; 404-Data processing system; 5-Microdroplet imaging system; 501-Long-wavelength to short-wavelength reflecting mirror; 502-Second focusing lens; 503-Imaging CCD; 504-Real-time imaging system; 6-Confocal optical system; 601-Microscopic objective lens; 602-Long-wavelength to short-wavelength reflecting mirror. Detailed Implementation

[0043] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and, together with the embodiments, serve to illustrate the principles of the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are all available from commercially available sources.

[0044] The inventors discovered in their research that existing aerosol dual-droplet detection devices typically rely on traditional single-beam optical systems, which suffer from insufficient spatial resolution, making it difficult to achieve high-precision spatial resolution for the capture and dynamic monitoring of dual droplets. While laser light sources can provide high-intensity beams, the signal is susceptible to stray light interference, resulting in a low signal-to-noise ratio, and they are also costly.

[0045] In contrast, this invention, based on the design of a confocal system, achieves high-precision spatial resolution capture and detection of dual droplets by optimizing optical path coupling, providing a more accurate and reliable solution for atmospheric aerosol research.

[0046] In a first aspect, the present invention provides a spatial resolution device for dual-droplet optical tweezers based on a confocal system, such as... Figure 1 As shown, it includes a dual-droplet suspension system 1, an environmental atmosphere control system 2, an optical path coupling system 3, a dynamic signal processing system 4, a microdroplet imaging system 5, and a confocal optical system 6.

[0047] The environmental atmosphere control system 2 is connected to the dual droplet suspension system 1, and the confocal optical system 6 is connected to the dual droplet suspension system 1, the dynamic signal processing system 4, the microdroplet imaging system 5, and the optical path coupling system 3, respectively.

[0048] The dual-droplet suspension system 1 is used to generate and suspend dual droplets. Specifically, the dual-droplet suspension system 1 includes a sample cell 101 and an aerosol generator 102. The aerosol generator is used to atomize the sample solution and includes an aerosol nebulizer. The aerosol nebulizer pumps aerosol droplets into the sample cell, realizing the generation of dual droplets while maintaining the original composition of particulate matter. This supports the simulation of organic / inorganic mixed aerosols and the generation and spatially resolved measurement of droplets with multiple components.

[0049] The environmental atmosphere control system 2 includes a gas generation branch and a gas collection branch. The gas generation branch is equipped with a gas generating device 201, a mass flow meter 203, a moisture bottle 204 and a temperature and humidity recorder 205 (± 0.1 ℃, ± 0.1%RH) in sequence. The gas generating device is used to simulate the composition of the atmosphere, and the moisture bottle is used to adjust the humidity of the gas generated by the gas generating device.

[0050] The gas generation branch is used to bring the entire device to a stable state before introducing the real gas collected by the gas acquisition branch into the entire device for measurement.

[0051] The gas generating branch includes a gas generating device 201, a gas filter plug 202, a mass flow meter 203, a moisture bottle 204, and a temperature and humidity recorder 205.

[0052] The gas collection branch is equipped with a gas collection device, a gas filter plug 202 and a mass flow meter in sequence. The gas collection device is located between the moisture cylinder 204 and the temperature and humidity recorder 205. It is used to collect the atmosphere in the real environment and for subsequent measurement.

[0053] The optical path coupling system 3 includes two semi-transparent mirrors 302-1 and 302-2, two first reflecting mirrors 303-1 and 303-2, and a beam expander 304. These components are used to collimate, split, shape, and expand the laser beam emitted from the laser source, achieving high-precision spatial resolution capture of the two droplets. The beam expander can employ a microlens array or an axonoid assembly to optimize the optical field distribution and improve capture efficiency and stability. The laser can emit Gaussian beams, ring beams, and Bessel beams, encompassing both continuous and pulsed laser types.

[0054] The dynamic signal processing system 4 includes a first focusing lens 401, a spectrometer 402, an electronic gain CCD 403, and a data processing system 404. The electronic gain CCD and the data processing system are electrically connected to the spectrometer.

[0055] The droplet imaging system 5 includes a long-wavelength to short-wavelength mirror 501, a second focusing lens 502, an imaging CCD 503, and a real-time imaging system 504 arranged sequentially.

[0056] The dynamic signal processing system 4 and the microdroplet imaging system 5 are used to monitor the position, shape, chemical composition, and dynamic response changes of the two droplets in real time. The two droplets, in conjunction with the real-time dynamic microdroplet imaging system and the dynamic signal processing system, enable in-situ observation of the aerosol two droplets. A super-thin silica optical substrate window (not shown in the figure) at the bottom of the sample cell ensures synchronous and accurate acquisition of optical capture and spectral signals. The radius, refractive index, and peak position information of the two droplets are inverted using Mie scattering theory to analyze the chemical composition and component changes.

[0057] The confocal optical system 6 includes a microscope objective 601 and a long-wavelength reverse short-wavelength lens 602.

[0058] The microscope objective 601 is used to introduce a light beam into the sample cell 101 for optical tweezing, and it is positioned between the long-wavelength reverse short-wavelength lens 602 and the dual-droplet suspension system 1.

[0059] Specifically, the microscope objective 601 is a high numerical aperture (NA) 1.49 microscope objective, which can obtain higher light gradient forces, making it easier to capture and suspend droplets.

[0060] Specifically, the long-wavelength anti-short-wavelength lens 602 uses a dichroic mirror (long-wavelength anti-short-wavelength lens), which does not affect the 532nm capture light path and short-wavelength illumination light path, and can transmit the spontaneous Raman signal and stimulated Raman signal of the droplet to the spectrometer, greatly reducing the interference of stray light.

[0061] Specifically, the long-pass short-pass mirror 501 uses a dichroic mirror (short-pass mirror and long-pass mirror). Under the condition of not affecting the 532nm capture optical path, it only reflects light in the short-wave illumination band, which improves the brightness and clarity of the droplet in the macroscopic morphology of the droplet in the visualization CCD camera, so as to make it easier to observe the real-time dynamics of the droplet in detail.

[0062] Two semi-transparent and semi-reflective mirrors 302-1 and 302-2 and two first reflecting mirrors 303-1 and 303-2, starting from the laser source, split the laser beam and focus it at the microscope objective 601, without affecting the signal acquisition and imaging systems, while ensuring the integrity of the overall optical path system.

[0063] In implementation, the laser source 301 in the optical path coupling system 3 emits a laser beam. The beams that pass sequentially through two semi-transparent mirrors 302-1 and 302-2, and the beams that pass sequentially through semi-transparent mirror 302-1, two first reflecting mirrors 303-1 and 303-2, and the beams reflected by semi-transparent mirror 302-2, are expanded by the beam expander 304. The expanded parallel light is then focused by the second reflecting mirror 305 and the microscope objective 601 and forms an optical trap in the sample cell 101 of the dual-droplet suspension system 1. Subsequently, the nebulizer atomizes the sample solution and pumps it into the dual-droplet suspension system 1 by a microdroplet pump. The microdroplets are captured when passing through the optical trap. After the microdroplets are stably suspended, the gas generator 201 in the ambient atmosphere control system 2 is turned on, allowing outside air to enter the gas path through the gas filter plug 202. The temperature and humidity of the ambient atmosphere control system are recorded in real time by the temperature and humidity recorder 205, and the gas flow rate is monitored and controlled by the mass flow meter 203.

[0064] The signal passes through the long-wavelength-to-short-wavelength reflecting mirror 501 and the second focusing lens 502 in the microdroplet imaging system 5, and is focused onto the imaging CCD 503 to observe the morphological characteristics of the microdroplets. The backscattered light from the microdroplets passes through the microscope objective 601, the long-wavelength-to-short-wavelength reflecting mirror 602, the long-wavelength-to-short-wavelength reflecting mirror 501, and the first focusing lens 401. The light signal after passing through the first focusing lens 401 is processed and collected by the spectrometer 402 and the electronic gain CCD 403, and uploaded to the data processing system 404 to analyze the physicochemical properties of the microdroplets after the reaction.

[0065] Compared with the prior art, the device of the present invention has the following advantages in the stage of acquiring spatially resolved signals from two droplets:

[0066] Improved Axial Resolution: Traditional optical systems are susceptible to interference from light outside the focal plane, leading to blurred images. The confocal optical system filters out off-focal-plane light signals through the slit in the spectrometer 402, allowing only light from the focal plane to pass through the detector (specifically, for a signal to enter the spectrometer confocally, the working distance and focal length of the first focusing lens 401 need to be adjusted so that the signal focused at the focal point enters the slit precisely). This significantly improves axial resolution, typically reaching sub-micron levels (e.g., 0.5-1 μm), making it suitable for scenarios requiring precise 3D imaging, such as the fine resolution of microdroplet spatial positions in a dual-droplet optical tweezers system.

[0067] Lateral resolution optimization: Compared to non-confocal systems, confocal systems reduce aberrations and stray light interference, resulting in clearer images. Even in complex environments (such as multiple droplets coexisting in a sample cell), they can achieve precise spatial resolution capture and measurement, reduce artifact interference, and clearly distinguish the boundaries and internal structures of adjacent droplets. Specifically, the electronic gain CCD connected to the spectrometer 402, after entering the slit of the spectrometer through the signal focus, transmits the signal to the electronic gain CCD, producing a point-like stimulated signal, whereas previously stimulated signals were in the form of vertical bars, demonstrating the improved resolution.

[0068] Overall improvement in spatial resolution: In optical tweezers applications, the confocal optics system can be combined with a laser beam to generate a uniform light field, further enhancing capture efficiency and stability. This makes the system more accurate and sensitive in resolving dynamic changes in two droplets (such as radius and refractive index), suitable for high-precision applications such as environmental monitoring or biological particle detection.

[0069] Advantages of optical paths:

[0070] Compared to traditional optical tweezers, a high numerical aperture (NA) of 1.49 microscope objective is used to obtain a higher optical gradient force, making it easier to capture and suspend droplets.

[0071] In the confocal optical system, the droplet at the microscope objective 601 and the spectrometer 402 is in a confocal state, that is, the droplet in the focal plane of the microscope objective and the phase entering the slit of the spectrometer are in a confocal state. Its advantage and purpose is to maximize the resolution of the droplet, so as to ensure spatially resolved analysis and ensure the similarity and difference of the spatial distribution of spontaneous Raman signal and stimulated Raman signal in the whole droplet.

[0072] Secondly, the present invention also provides a method for spontaneous / stimulated Raman spatial resolution measurement using dual-droplet optical tweezers based on a confocal system. The method includes: pumping an aerosol into a sample cell 101 via an aerosol generator 102 to form dual droplets; capturing and suspending the dual droplets with a laser beam via a beam splitting system; introducing the required gas through an environmental atmosphere control system 2; transmitting the droplet signal to a spectrometer via a confocal optical system 6; and analyzing the scattered light signal using a dynamic signal processing system 4 to invert the changes in dual-droplet parameters.

[0073] Specifically, the method of the present invention includes the following steps:

[0074] Step 1: Calibrate the optical path and adjust the phase of the droplet displayed in the imaging CCD 503 and the phase of the droplet displayed in front of the slit of the spectrometer 402 to a confocal state;

[0075] Step 2: Aerosols are generated by aerosol generator 102 and pumped into sample cell 101 of dual-droplet suspension system 1 in the form of aerosol dual droplets.

[0076] Step 3: Introduce the required reaction gas into the sample cell 101 through the ambient atmosphere control system 2;

[0077] Step 4: The scattered light signals from the two droplets are input to the dynamic signal processing system 4 and the microdroplet imaging system 5, respectively;

[0078] Step 5: Obtain dynamic changes based on the spatial resolution imaging of the optical signal provided by the microdroplet imaging system 5 and the spectral data provided by the dynamic signal processing system 4.

[0079] In step 1, the purpose of calibrating the optical path is to ensure the stability of the droplet capture optical path and the controllability of the humidity in the droplet's environment. The principle is to adjust the optical path of the in-situ droplet monitoring system until the optical path is collimated and meets the requirements for droplet capture.

[0080] Specifically, the requirements for droplet capture include: ensuring that the droplets pumped out by the aerosol generator 102 can be stably suspended in the sample cell, and that the imaging CCD 503 displays a clear image of the droplets, while the electronic gain CCD 403 displays clear spatially resolved images of the stimulated signal and spectral signal.

[0081] In step 1, calibrating the optical path includes connecting the laser source 301, the semi-transparent and semi-reflective mirrors 302-1 and 302-2, and the first reflecting mirrors 303-1 and 303-2, and setting parameters to ensure beam collimation.

[0082] Specifically, the wavelength of the laser source 301 is 532nm and the power is initially set to 200mW; the reflection / transmission ratio of the semi-transparent mirrors 302-1 and 302-2 is adjusted to 50:50; and the angle of the first reflecting mirrors 303-1 and 303-2 is adjusted to 45°.

[0083] Step 1, adjusting the phase of the droplet displayed in the imaging CCD 503 and the phase of the droplet displayed in front of the slit of the spectrometer 402 to a confocal state includes the following steps:

[0084] Step 1-1: Turn on the laser source 301 and gradually increase the power to the range of 200-400mW, for example, 200mW, 300mW, 400mW, and observe the beam path;

[0085] Steps 1-2: Adjust the working distance of the first focusing lens 401 within the focal length range;

[0086] Steps 1-3: Adjust the slit width of the spectrometer 402 to 50-100 μm, for example, 50 μm, 80 μm, 100 μm, and observe the signal focus on the electronic gain CCD 403 (gain set to 100-500) to ensure that the signal is presented as a dot rather than a strip. This step ensures confocal matching, thereby increasing the signal intensity and reducing stray light other than the effective signal entering the spectrometer.

[0087] The process of introducing the required gas into the sample cell through the ambient atmosphere control system 2 includes: turning on the gas generator 201 and adjusting the flow valve to the appropriate dry and wet gas flow rates.

[0088] In addition, step 1, before calibrating the optical path, includes: assembling each device in sequence and checking the airtightness of the sample cell and gas path system.

[0089] Specifically, step 2 includes the following steps:

[0090] Step 2-1: Prepare the sample solution (ammonium sulfate concentration 1.0-2.0 mol / L, for example, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, volume 10-20 mL, for example, 10 mL, 15 mL, 20 mL);

[0091] Step 2-2: Start the atomizer of aerosol generator 102;

[0092] Steps 2-3: Pump the atomized aerosol into sample cell 101 using a microdroplet pump, and suspend two droplets (radius 2-10 μm, e.g., 2μm, 4μm, 6μm, 8μm, 10μm, droplet spacing 5-12 μm, e.g., 5μm, 7μm, 9μm, 10μm, 12μm) in the dual optical trap.

[0093] Specifically, in step 3, the process of introducing the required reaction gas into the sample cell through the environmental atmosphere control system includes the following steps:

[0094] Step 3-1: Turn on the gas generator 201;

[0095] Step 3-2: Adjust the flow valve of mass flow meter 203 to the range of 150-250 sccm, for example, 150 sccm, 200 sccm, 250 sccm, and introduce a dry / wet mixed gas (e.g., air or a specific reactive gas such as O3 / NH3).

[0096] Step 3-3: Control relative humidity using a 204 moisture bottle;

[0097] Steps 3-4: Use a temperature and humidity recorder 205 to monitor and adjust the temperature and relative humidity to the target values ​​in real time (deviation <0.2%RH);

[0098] Steps 3-5: Continuously ventilate for 30 minutes until the environment stabilizes. This step ensures controllable reaction conditions, with a droplet dynamic response time of <1 second, supporting real-time monitoring of component changes.

[0099] The present invention also provides the application of the above-mentioned confocal system-based dual-droplet optical tweezers spatial resolution device and the above-mentioned confocal system-based dual-droplet optical tweezers spontaneous / stimulated Raman spatial resolution measurement method in inverting droplet radius, including: inverting droplet radius based on stimulated Raman scattering or stimulated elastic scattering signals presented by electronic gain CCD 403.

[0100] The droplet radius was inverted using the existing Mie Resonance Fitting (MRFIT) software model. Results show that the device and method of this invention significantly improve the signal-to-noise ratio of the spectrum, making the shift trajectories of characteristic peaks more obvious and easier to identify. Therefore, the effective data points for dr / dt obtained after radius inversion are more dense, and a good linear relationship can be observed (see...). Figure 6 This helps in subsequent judgments about the conditions and relationships of parameters in atmospheric haze pollution.

[0101] To facilitate understanding of the present invention, specific embodiments are described below. The present invention can be implemented in different forms and is not limited to the embodiments described in this specification.

[0102] Example 1

[0103] Using the apparatus and method of this invention, the spatial resolution, real-time dynamic imaging, stimulated Raman spectra of each droplet, and stimulated Raman spectra of the combined two droplets of ammonium sulfate suspended by optical tweezers are measured on a spectrometer.

[0104] The method in this embodiment includes the following steps:

[0105] (1) Connect the laser source 301 (wavelength 532nm, power initially set to 200mW), the semi-transparent mirrors 302-1 and 302-2 (reflection / transmission ratio adjusted to 50:50), and the first mirrors 303-1 and 303-2 (angle adjusted to 45° to ensure beam collimation, deviation <1°).

[0106] (2) Turn on the laser source 301 and gradually increase the power to the range of 400mW, and observe the beam path;

[0107] (3) Adjust the working distance of the first focusing lens 401 within the focal length range;

[0108] (4) Adjust the slit width of the spectrometer 402 to 50 μm and observe the signal focus on the electronic gain CCD 403 (low noise mode) to ensure that the signal is presented as a dot rather than a strip. This step ensures confocal matching, thereby increasing the signal intensity and reducing stray light other than the effective signal from entering the spectrometer.

[0109] (5) Prepare the sample solution (ammonium sulfate concentration 1.5 mol / L, volume 20 mL);

[0110] (6) Start the atomizer of aerosol generator 102;

[0111] (7) The atomized aerosol is pumped into the sample cell 101 by a micro-droplet pump, so that the two light traps suspend two droplets (radius 2-10 μm, droplet spacing 5 μm).

[0112] (8) Turn on the gas generator 201;

[0113] (9) Adjust the flow valve of mass flow meter 203 to the range of 200 sccm and introduce dry / wet mixed gas (e.g., air or specific reactive gas such as O3 / NH3).

[0114] (10) Control relative humidity using moisture bottle 204;

[0115] (11) Use a temperature and humidity recorder 205 to monitor and adjust the temperature to 22.1 ℃ and the relative humidity to 60%RH (deviation <0.2%RH) in real time.

[0116] (12) Continuously ventilate for 30 minutes until the environment stabilizes. This step ensures that the reaction conditions are controllable, the droplet dynamic response time is <1s, and supports real-time monitoring of component changes;

[0117] (13) The scattered light signals from the two droplets are input to the dynamic signal processing system 4 and the microdroplet imaging system 5, respectively;

[0118] (14) Dynamic changes are obtained by spatial resolution imaging of the optical signal provided by the microdroplet imaging system 5 and spectral data provided by the dynamic signal processing system 4.

[0119] Figure 3 (a) Spatial-resolved spectra of two ammonium sulfate droplets; (b) Imaging of the droplets; (c) and (d) Stimulated Raman spectra of each droplet; (d) Stimulated Raman spectra of the combined two droplets.

[0120] Figure 4 This is a comparison of the spectrum of the merged droplets (a) with the individual spectra of each droplet ((b) and (c)).

[0121] Depend on Figure 3 It can be seen that the stimulated Raman scattering peaks of droplet-1 and droplet-2 are presented as pixels under high spatial resolution, rather than as diffraction bright lines as previously reported, thus indicating that the present invention can obtain droplet focal plane spatial resolution with higher precision.

[0122] Depend on Figure 3 and Figure 4 It can be seen that, during synchronous measurement, the sum of the stimulated Raman scattering peaks of each droplet corresponds one-to-one with the spectrum of the merged two droplets. This indicates that the spatial resolution of the system is high enough to independently capture the spectral information of each droplet, and there is no significant signal distortion or interference during the merging process. This verifies the accuracy of confocal optical integration and the reliability of multi-droplet parallel analysis, and supports the accuracy of real-time monitoring of droplet interactions and compositional changes.

[0123] This embodiment can demonstrate that:

[0124] This invention relates to a spatial resolution device and method for dual-droplet optical tweezers based on a confocal system. It enables high-precision spatial resolution measurement and simultaneous spectral analysis of suspended dual droplets. It not only clearly presents stimulated Raman scattering peaks in pixel form, improving the focal plane resolution accuracy, but also ensures the precise correspondence between the summation of the independent spectra of the two droplets and the combined spectrum. This verifies the reliability and versatility of the device in real-time dynamic imaging and chemical composition monitoring, providing effective technical support for trace analysis of aerosol droplets.

[0125] Application Example 1

[0126] The droplet radius was obtained by inversion of the characteristic peaks of stimulated Raman spectroscopy in Example 1 of this invention and Example 1 of CN120778608A, and the results are shown in [the table below]. Figure 5 and Figure 6 .

[0127] Figure 5 This is a graph showing the relationship between the radius of the characteristic peaks obtained by inversion from stimulated Raman spectra using the apparatus and method described in CN120778608A and the time-varying process. Figure 5 As shown, although the relationship between dr / dt is obtained, the effective data points for the subsequent model inversion radius are sparse due to the need to improve the signal-to-noise ratio of the original spectrum.

[0128] Figure 6 The graph shows the radius versus time relationship after improving the signal-to-noise ratio of characteristic peaks in stimulated Raman spectroscopy using the confocal system of this invention. Figure 6 As shown, the confocal system significantly improves the signal-to-noise ratio of the spectrum, making the shift trajectories of characteristic peaks more obvious and easier to identify. Consequently, the effective data points of dr / dt obtained after radius inversion are more concentrated, and a good linear relationship can be observed, which helps in subsequent judgment of the parameters and their relationships in atmospheric haze pollution.

[0129] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for spontaneous / stimulated Raman spatial resolution measurement using dual-droplet optical tweezers based on a confocal system, comprising a dual-droplet optical tweezers spatial resolution device based on a confocal system, characterized in that... Includes the following steps: Step 1: Calibrate the optical path and adjust the phase of the droplet displayed in the imaging CCD and the phase of the droplet displayed in front of the spectrometer slit to a confocal state; Step 2: Aerosols are generated by an aerosol generator and pumped into the sample cell of the dual-droplet suspension system in the form of aerosol droplets. Step 3: Introduce the required reaction gas into the sample cell through the environmental atmosphere control system; Step 4: The scattered light signals from the two droplets are input into the dynamic signal processing system and the microdroplet imaging system, respectively; Step 5: Obtain dynamic changes based on the spatial resolution imaging of the optical signal provided by the microdroplet imaging system and the spectral data provided by the dynamic signal processing system; The device includes a dual-droplet suspension system, an environmental atmosphere control system, an optical path coupling system, a dynamic signal processing system, a microdroplet imaging system, and a confocal optical system; The environmental atmosphere control system is connected to the dual-droplet suspension system, and the confocal optical system is connected to the dual-droplet suspension system, the dynamic signal processing system, the microdroplet imaging system, and the optical path coupling system, respectively. The confocal optical system includes a microscope objective and a long-wavelength reverse short-wavelength lens, with the microscope objective positioned between the long-wavelength reverse short-wavelength lens and the dual-droplet suspension system. The microdroplet imaging system includes a long-wavelength short-wavelength mirror, a second focusing lens, an imaging CCD, and a real-time imaging system arranged in sequence. The long-wave anti-short-wave pass mirror is a dichroic mirror with long-wave anti and short-wave pass, and the long-wave pass short-wave anti-reflection mirror is a dichroic mirror with long-wave pass and short-wave anti. The dynamic signal processing system includes a first focusing lens, a spectrometer, an electronic gain CCD, and a data processing system; the electronic gain CCD and the data processing system are electrically connected to the spectrometer, respectively.

2. The method according to claim 1, characterized in that, In step 1, calibrating the optical path includes connecting the laser source, the semi-transparent mirror, and the first reflecting mirror, and setting the parameters.

3. The method according to claim 1, characterized in that, Step 3, introducing the required reaction gas into the sample cell through the environmental atmosphere control system, includes the following steps: Step 3-1: Turn on the gas generator; Step 3-2: Introduce a dry / wet mixed gas; Step 3-3: Control relative humidity using a moisture bottle; Steps 3-4: Use a temperature and humidity recorder to monitor and adjust the temperature and relative humidity in real time; Steps 3-5: Continue ventilation until the environment stabilizes.

4. The method according to any one of claims 1-3, characterized in that, The microscope objective is a high numerical aperture (NA) microscope objective with an aperture of 1.

49.

5. The method according to claim 1, characterized in that, The environmental atmosphere control system includes a gas generation branch and a gas collection branch. The gas generation branch is equipped with a gas generating device, a mass flow meter, a moisture bottle, and a temperature and humidity recorder in sequence.

6. The application of the method according to any one of claims 1-5 in the inversion of droplet radius.

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