CN114577681A - Aerosol weak Raman spectrum signal detection device and application method thereof - Google Patents
Aerosol weak Raman spectrum signal detection device and application method thereof Download PDFInfo
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Abstract
The invention discloses an aerosol weak Raman spectrum signal detection device and an application method thereof. The device comprises a computer, a spatial light modulator unit, an optical tweezers unit, an aerosol sample chamber environment condition regulation unit and a spectrometer unit. The application method comprises the following steps: loading a hologram into a spatial light modulator cell; opening a laser of the optical tweezers unit, and forming an optical trap array in the aerosol sample chamber; spraying aerosol to be detected into the aerosol sample chamber; the optical trap array captures a plurality of aerosols; regulating and controlling the relative humidity of the environmental condition of the aerosol sample chamber; raman spectral signals of a plurality of aerosols are collected to a spectrometer unit. According to the invention, the spatial light modulator is used for forming the light trap array in the aerosol sample chamber, capturing a plurality of aerosols simultaneously, and simultaneously collecting Raman spectrum signals of the plurality of aerosols to the spectrometer unit, so that the detection performance of the aerosol weak Raman spectrum signals is improved, and the high-resolution detection of the aerosol weak Raman spectrum signals can be realized.
Description
Technical Field
The invention relates to the field of optical trap sensing, atmospheric science and environmental science, in particular to an aerosol weak Raman spectrum signal detection device and an application method thereof.
Background
Aerosol refers to a colloidal dispersion of small particles of a solid or liquid dispersed and suspended in a gaseous medium, and the properties of the aerosol change with changing environmental conditions. When the relative humidity of the environment changes, the soluble aerosol can generate moisture absorption and deliquescence, volatilization, moisture absorption increase, phase state transition and the like, and changes in the aspects of radiation absorption, multiphase reaction process, activity of forming cloud condensation nuclei and the like are caused. When the oxidant in the atmospheric environment and the volatile organic aerosol are subjected to oxidation reaction, the generated secondary organic aerosol accounts for 30-70% of the total amount of the environmental organic aerosol, which is harmful to human health and can cause climate change and air pollution. Compared with the traditional aerosol particle characteristic measurement method (such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and the like), the aerosol particle characteristic measurement method has the advantages that when suspended optical tweezers are adopted for aerosol particle characteristic measurement, the aerosol particle characteristic measurement method has two advantages: on one hand, the optical tweezers can capture and suspend single aerosol particles to be detected in the air without substrate contact influence; on the other hand, the optical tweezers suspend the aerosol particles, so that the real state of the aerosol particles in the atmospheric environment can be simulated without influencing the aerosol particles to be detected and the environment. At present, when aerosol particle characteristics are measured by using suspended optical tweezers, the problem that Raman spectrum signals of aerosol are weak exists. Because the Raman scattering signal of the aerosol with the submicron size to be measured is about one thousandth to one ten thousandth of the Rayleigh scattering signal, and the smaller the particle size is, the smaller the Raman scattering cross section is, the weaker the corresponding Raman scattering signal is,therefore, the problem that the Raman scattering signal of the aerosol with the submicron size is weak exists. Although the prior surface enhanced Raman scattering method can enhance the Raman scattering signal by 102～1010However, the method is based on the raman scattering signal enhancement realized by adsorbing a substance to be detected on the surface of some metals (such as gold, silver, copper and the like), semiconductor nano materials or two-dimensional materials, and is not suitable for the raman scattering signal enhancement of suspended submicron aerosol in the raman optical tweezers. Therefore, a high-resolution detection scheme of a weak raman spectrum signal of the aerosol needs to be explored, the detection capability of the raman spectrum signal of the aerosol is improved, and finally the characteristic measurement of moisture absorption, volatilization, oxidation, phase state transition and the like of the aerosol is realized.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an aerosol weak Raman spectrum signal detection device and an application method thereof.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
the first aspect of the embodiment of the invention provides an aerosol weak Raman spectrum signal detection device, which comprises a computer, a spatial light modulator unit, an optical tweezers unit, an aerosol sample chamber environmental condition regulation and control unit and a spectrometer unit, wherein the spatial light modulator unit is used for modulating the spatial light modulator unit; the computer is used for generating a hologram and loading the hologram to the spatial light modulator unit; the spatial light modulator unit is used for regulating and controlling the optical field phase of the optical tweezers unit; the optical tweezers unit is used for capturing the aerosol in the aerosol sample chamber; the aerosol sample chamber environmental condition regulation and control unit is used for regulating and controlling the environmental condition in the aerosol sample chamber; the spectrometer unit is used for collecting Raman spectrum signals of the aerosol captured in the aerosol sample chamber. According to the research requirements of the aerosol, a computer is used for designing a hologram, the designed hologram is loaded to a spatial light modulator unit, a laser of the light tweezer unit is opened, the light field phase of the light tweezer unit is regulated and controlled by the spatial light modulator, different light trap arrays are formed in an aerosol sample chamber, then an ultrasonic atomizer is used for spraying the aerosol to be tested into the aerosol sample chamber, the light trap arrays capture a plurality of aerosols, the relative humidity of the environment of the aerosol sample chamber is regulated and controlled by an aerosol sample chamber environment condition regulation and control unit, and Raman spectrum signals of the plurality of aerosols are collected to a spectrometer unit.
Further, the computer generates a hologram which meets the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a dynamic theoretical model for capturing the aerosol in the air and combining a Fourier transform algorithm; the hologram generates an array pattern according to the requirement of the quantity of the optical trap arrays.
Further, the spatial light modulator unit is a liquid crystal spatial light modulator, and includes a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator.
Furthermore, the optical tweezers unit is matched with the spatial light modulator unit to realize the simultaneous capture of a plurality of aerosols.
Further, the built-in space of the aerosol sample chamber is 45 cubic centimeters.
Furthermore, the environment condition regulation and control unit of the aerosol sample chamber can simulate the real state of the aerosol in the atmospheric environment, and realizes the regulation and control of the environment relative humidity condition in the aerosol sample chamber by introducing mixed dry nitrogen and wet nitrogen into the aerosol sample chamber.
The second aspect of the embodiment of the invention provides an application method of a weak raman spectrum signal detection device based on aerosol, which specifically comprises the following steps:
1) loading a computer-designed hologram into a spatial light modulator unit;
2) opening a laser of the optical tweezers unit, and forming an optical trap array in the aerosol sample chamber;
3) spraying aerosol to be detected into the aerosol sample chamber by using an ultrasonic atomizer;
4) the optical trap array captures a plurality of aerosols;
5) regulating the relative humidity of the environmental condition of the aerosol sample chamber by using an environmental condition regulating unit of the aerosol sample chamber;
6) and Raman spectrum signals of a plurality of aerosols are collected to a spectrometer unit, so that in-situ, on-line and real-time measurement of the aerosols is realized.
Further, the computer generates a hologram which meets the research of the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a dynamic theoretical model for capturing the aerosol in the air and combining a Fourier transform algorithm.
Furthermore, the optical trap array captures a plurality of aerosols simultaneously, Raman spectrum signals of the plurality of aerosols are collected to the spectrometer unit simultaneously, the overall Raman spectrum signals of the aerosols are enhanced, and accordingly the detection performance of the weak Raman spectrum signals of the aerosols is improved.
The invention has the beneficial effects that: the method of the invention utilizes the spatial light modulator to form the light trap array in the aerosol sample chamber, simultaneously captures a plurality of aerosols, simultaneously collects Raman spectrum signals of the plurality of aerosols to the spectrometer unit, improves the detection performance of the aerosol weak Raman spectrum signals, and thus can realize the high resolution detection of the aerosol weak Raman spectrum signals. The device is simple, and a user can add elements in the optical path conveniently to expand the application function of the device.
Drawings
Fig. 1 is a schematic structural diagram of an aerosol weak raman spectrum signal detection device.
Fig. 2 is a flowchart of an application method of the detection device based on the aerosol weak raman spectrum signal.
Fig. 3 is a diagram of aerosol generated by capturing a sodium chloride droplet by an optical tweezers unit.
Fig. 4 is an aerosol diagram of an optical tweezers unit capturing two sodium chloride droplets simultaneously.
Fig. 5 is an aerosol diagram of an optical tweezers unit capturing three sodium chloride droplets simultaneously.
FIG. 6 is a graph of Raman spectra signals collected from a spectrometer unit for an aerosol of sodium chloride droplets.
Fig. 7 is a graph of raman spectroscopic signals collected by the spectrometer unit for two aerosols of sodium chloride droplets.
Fig. 8 is a graph of raman spectroscopic signals collected by the spectrometer unit for three aerosols of sodium chloride droplets.
In the figure, a computer 1, a spatial light modulator unit 2, an optical tweezers unit 3, an aerosol sample chamber 4, an aerosol sample chamber environment condition regulation unit 5 and a spectrometer unit 6.
Detailed Description
The invention is further illustrated below with reference to the figures and examples.
As shown in fig. 1, an aerosol weak raman spectrum signal detection device includes a computer 1, a spatial light modulator unit 2, an optical tweezers unit 3, an aerosol sample chamber 4, an aerosol sample chamber environmental condition regulation unit 5, and a spectrometer unit 6; the computer 1 is used for generating a hologram and loading the hologram into the spatial light modulator unit 2; the spatial light modulator unit 2 is used for regulating and controlling the light field phase of the optical tweezers unit 3; the optical tweezers unit 3 is used for capturing aerosol in the aerosol sample chamber 4; the aerosol sample chamber environmental condition regulating and controlling unit 5 is used for regulating and controlling the environmental condition in the aerosol sample chamber 4; the spectrometer unit 6 is used to collect raman spectral signals of the aerosol captured in the aerosol sample chamber 4. According to different research requirements of aerosol, different types of holograms are designed by a computer 1, the designed holograms are loaded to a spatial light modulator unit 2, a laser of an optical tweezers unit 3 is turned on, different optical trap arrays are formed in an aerosol sample chamber 4 by regulating and controlling the optical field phase of the optical tweezers unit 3 by the spatial light modulator, the different optical trap arrays are used for capturing different amounts of aerosol, then the aerosol to be detected is sprayed into the aerosol sample chamber 4 by an ultrasonic atomizer, after a plurality of aerosols are captured by the optical trap arrays, the relative humidity of the environment of the aerosol sample chamber is regulated and controlled by an aerosol sample chamber environment condition regulating and controlling unit 5, and then Raman spectrum signals of the aerosols are collected to a spectrometer unit 6.
The computer 1 generates a hologram which meets the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a dynamic theoretical model for capturing the aerosol in the air and combining a Fourier transform algorithm; the hologram generates an array pattern according to the requirement of the quantity of the optical trap arrays.
The spatial light modulator unit 2 is a liquid crystal spatial light modulator, and includes a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator. The liquid crystal spatial light modulator consists of a glass reflecting layer, a liquid crystal molecular layer and a reflecting electrode layer. When an electric signal is applied to the spatial light modulator, an electric field can be formed between the glass reflecting layer and the reflecting electrode layer, liquid crystal molecules can deflect to different degrees under the action of the electric field due to the birefringence characteristic of the liquid crystal molecules, the electric signal loaded to the spatial light modulator is regulated and controlled through different algorithms, the birefringence characteristic change of the liquid crystal molecules is realized, and the optical field phase change of the optical tweezer unit is realized.
The optical tweezers unit 3 is matched with the spatial light modulator unit 2 to realize the simultaneous capture of a plurality of aerosols.
The inner space of the aerosol sample chamber 4 is 45 cubic centimeters. Since the flow path of the aerosol in the aerosol sample chamber 4 is random, and the aerosol is likely to be captured by the optical trap only when the aerosol flows through the effective capture area of the optical trap, in order to improve the efficiency of capturing the aerosol by the optical trap array, the space of the aerosol sample chamber 4 should be as small as possible, preferably a rectangular aerosol sample chamber of 3 cm by 5 cm, and the built-in space is 45 cubic centimeters.
The aerosol sample chamber environmental condition regulation and control unit 5 can simulate the real state of the aerosol in the atmospheric environment, the moisture absorption and volatilization characteristics of the aerosol are the important properties of the atmospheric aerosol, and when the relative humidity of the environment changes, the soluble aerosol can generate the phenomena of deliquescence, weathering, moisture absorption increase and the like, so that the optical characteristics of the soluble aerosol are changed, and the influence on the environment is caused. Through leading into aerosol sample room 4 with dry nitrogen gas and the wet nitrogen gas after the mixture, can regulate and control the relative humidity of 4 environment of aerosol sample room to can study the moisture absorption that the aerosol takes place along with environment relative humidity changes and volatilize the characteristic change.
A method for applying the device, a flow chart of which is shown in fig. 2, comprises the following steps:
1) loading the hologram generated by the computer 1 to the spatial light modulator unit 2;
2) opening the laser of the optical tweezers unit 3, and forming an optical trap array in the aerosol sample chamber 4;
3) spraying aerosol to be detected into the aerosol sample chamber 4 by using an ultrasonic atomizer;
4) the optical trap array simultaneously captures a plurality of aerosols;
5) the relative humidity of the environmental condition of the aerosol sample chamber is regulated and controlled by an aerosol sample chamber environmental condition regulation and control unit 5;
6) and Raman spectrum signals of a plurality of aerosols are collected to the spectrometer unit 6, so that in-situ, on-line and real-time measurement of the aerosols is realized.
The computer 1 generates a hologram which meets the research of the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a dynamic theoretical model for capturing the aerosol in the air and combining a Fourier transform algorithm. Because the space range of the light field for effectively restraining the aerosol is relatively small, the aerosol can be successfully captured only by allowing the aerosol to enter a specific area in the light field. Therefore, in order to realize the efficient capture of the aerosol in the optical trap array formed by the spatial light modulator unit 2 in combination with the optical tweezers unit 3, firstly, a kinetic theory model of the aerosol capture process in the air needs to be established, a dynamic process from the desorption of the aerosol from a sample container to the capture of the aerosol entering the center of the optical trap is analyzed, and the initial condition and the effective capture area of the aerosol dynamic capture in the free space are quantified; and then, by combining a Fourier transform algorithm, the stability of forming the optical trap array is ensured, namely the stable capture of the aerosol is realized, and the study on the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristic of the aerosol and the phase separation characteristic of the aerosol is further realized.
The optical trap array captures a plurality of aerosols simultaneously, Raman spectrum signals of the aerosols are collected to the spectrometer unit 6 simultaneously, the overall Raman spectrum signals of the aerosols are enhanced, and accordingly the detection performance of the aerosol weak Raman spectrum signals is improved. The successful detection of the optical trap to capture the Raman spectrum signal of the aerosol is the key for analyzing the aerosol characteristics. However, the method is limited by the inherent weak characteristic of the aerosol raman spectrum signal, and the existing surface enhanced raman scattering method generally realizes raman signal enhancement based on the adsorption of a substance to be detected on the surface of a substrate modified by gold, silver, a two-dimensional material and the like, is not suitable for the raman spectrum signal enhancement of the aerosol suspended in the optical tweezers unit 3, and needs to explore a new method to realize the improvement of the detection performance of the aerosol weak raman spectrum signal.
Example 1
In this embodiment 1, an optical tweezers unit is used to capture a sodium chloride droplet aerosol and perform raman spectroscopy signal detection on the aerosol.
The laser of the optical tweezers unit adopts a 532nm optical fiber coupling solid-state laser, and the laser power output by the laser in the implementation process is continuously adjustable, namely the optical power of the formed three-dimensional optical trap can be continuously adjustable according to the requirement of capturing sodium chloride liquid drop aerosols with different diameters.
The diameter of the sodium chloride liquid drops atomized by the ultrasonic atomizer is 6 um.
The trapping power of each optical trap in the optical trap array is adjustable within 50-1000 mW.
The spatial light modulator used in the spatial light modulator unit is a phase type reflection type liquid crystal spatial light modulator produced by Xian Zhongkewei Star electro-optical technology Limited company, and the model is as follows: FSLM-2K 55-P.
The spectrometer in the spectrometer unit is sold under the brand Andor Shamrock 750.
Sodium chloride droplet aerosols belong to the sea salt aerosol class.
The method for detecting the weak Raman spectrum signal of the sodium chloride droplet aerosol specifically comprises the following steps:
1) loading the hologram designed by the computer 1 on the FSLM-2K55-P liquid crystal spatial light modulator of the spatial light modulator unit 2;
2) a laser of the optical tweezers unit 3 is turned on, an optical trap is formed in the aerosol sample chamber 4 and used for capturing sodium chloride droplet aerosol, and the capturing power of the optical trap is 50 mW;
3) spraying sodium chloride droplet aerosol to be detected with the diameter of 6um into the aerosol sample chamber 4 by using an ultrasonic atomizer;
4) the optical trap captures an aerosol of sodium chloride droplets, as shown in fig. 3;
5) controlling the total amount of dry nitrogen and wet nitrogen introduced into the aerosol sample chamber 4 by using a flow controller of the aerosol sample chamber environmental condition regulating unit 5 so as to regulate and control the relative humidity of the aerosol sample chamber environment;
6) the raman spectroscopic signal of the sodium chloride droplet aerosol is collected to the spectrometer unit 6 as shown in fig. 6.
Example 2
In this embodiment 2, an optical tweezers unit is taken as an example to capture two sodium chloride droplet aerosols simultaneously and perform raman spectrum signal detection on the two sodium chloride droplet aerosols.
The laser of the optical tweezers unit adopts a 532nm optical fiber coupling solid-state laser, and the laser power output by the laser in the implementation process is continuously adjustable, namely the optical power of the formed three-dimensional optical trap can be continuously adjustable according to the requirement of capturing sodium chloride liquid drop aerosols with different diameters.
The diameter of the sodium chloride liquid drops atomized by the ultrasonic atomizer is 6 um.
The trapping power of each optical trap in the optical trap array is adjustable within 50-1000 mW.
The spatial light modulator used in the spatial light modulator unit is a phase type reflection type liquid crystal spatial light modulator produced by Xian Zhongkewei Star electro-optical technology Limited company, and the model is as follows: FSLM-2K 55-P.
The spectrometer in the spectrometer unit is sold under the brand Andor Shamrock 750.
Sodium chloride droplet aerosols belong to the sea salt aerosol class.
The method for detecting the weak Raman spectrum signal of the sodium chloride droplet aerosol specifically comprises the following steps:
1) loading the hologram designed by the computer 1 on the FSLM-2K55-P liquid crystal spatial light modulator of the spatial light modulator unit 2;
2) the laser of the optical tweezers unit 3 is turned on, two optical traps are formed in the aerosol sample chamber 4 and used for capturing two sodium chloride droplet aerosols, and the capturing power of each optical trap is 100 mW;
3) spraying sodium chloride droplet aerosol to be detected with the diameter of 6um into the aerosol sample chamber 4 by using an ultrasonic atomizer;
4) two optical traps respectively capture a sodium chloride liquid drop aerosol, as shown in fig. 4;
5) controlling the total amount of dry nitrogen and wet nitrogen introduced into the aerosol sample chamber 4 by using a flow controller of the aerosol sample chamber environmental condition regulating unit 5 so as to regulate and control the relative humidity of the aerosol sample chamber environment;
6) raman spectroscopic signals of the sodium chloride droplet aerosol captured by the two optical traps are collected simultaneously to the spectrometer unit 6 as shown in fig. 7. As can be seen from fig. 7, the raman spectrum signals of two sodium chloride droplet aerosols are significantly stronger than the raman spectrum signal of one sodium chloride droplet aerosol, so that the raman spectrum signal enhancement of a single sodium chloride droplet aerosol can be realized by forming a plurality of optical traps in the optical tweezers unit by using the spatial light modulator and capturing a plurality of sodium chloride droplet aerosols simultaneously, thereby realizing the high-resolution detection of the aerosol weak raman spectrum signal.
Example 3
In this embodiment 3, an optical tweezers unit is taken as an example to capture three sodium chloride droplet aerosols simultaneously and perform raman spectrum signal detection on the aerosols.
The laser of the optical tweezers unit adopts a 532nm optical fiber coupling solid-state laser, and the laser power output by the laser in the implementation process is continuously adjustable, namely the optical power of the formed three-dimensional optical trap can be continuously adjustable according to the requirement of capturing sodium chloride liquid drop aerosols with different diameters.
The diameter of the sodium chloride liquid drops atomized by the ultrasonic atomizer is 6 um.
The trapping power of each optical trap in the optical trap array is adjustable within 50-1000 mW.
The spatial light modulator used in the spatial light modulator unit is a phase type reflection type liquid crystal spatial light modulator produced by Xian Zhongkewei Star electro-optical technology Limited company, and the model is as follows: FSLM-2K 55-P.
The spectrometer in the spectrometer unit is sold under the brand Andor Shamrock 750.
Sodium chloride droplet aerosols belong to the sea salt aerosol class.
The method for detecting the weak Raman spectrum signal of the sodium chloride droplet aerosol specifically comprises the following steps:
1) loading the hologram designed by the computer 1 on the FSLM-2K55-P liquid crystal spatial light modulator of the spatial light modulator unit 2;
2) the laser of the optical tweezers unit 3 is turned on, three optical traps are formed in the aerosol sample chamber 4 and used for simultaneously capturing three sodium chloride droplet aerosols, and the capturing power of each optical trap is 160 mW;
3) spraying sodium chloride droplet aerosol to be detected with the diameter of 6um into the aerosol sample chamber 4 by using an ultrasonic atomizer;
4) three optical traps capture one aerosol of sodium chloride droplets respectively, as shown in fig. 5;
5) controlling the total amount of dry nitrogen and wet nitrogen introduced into the aerosol sample chamber 4 by using a flow controller of the aerosol sample chamber environmental condition regulating unit 5 so as to regulate and control the relative humidity of the aerosol sample chamber environment;
6) raman spectroscopic signals of the sodium chloride droplet aerosol captured by the three optical traps were collected simultaneously to the spectrometer unit 6 as shown in fig. 8. As can be seen from fig. 8, the raman spectrum signals of the three sodium chloride droplet aerosols are significantly stronger than those of the two sodium chloride droplet aerosols, so that the raman spectrum signal enhancement of a single sodium chloride droplet aerosol can be realized by forming a plurality of optical traps in the optical tweezers unit by using the spatial light modulator and capturing a plurality of sodium chloride droplet aerosols simultaneously, thereby realizing the high-resolution detection of the aerosol weak raman spectrum signal.
Finally, it should be noted that the above examples and illustrations are only intended to illustrate the technical solutions of the present invention and are not intended to limit the present invention. It will be understood by those skilled in the art that various modifications and equivalent arrangements may be made without departing from the spirit and scope of the present disclosure and it should be understood that the present disclosure is to be limited only by the appended claims.
Claims (9)
1. An aerosol weak Raman spectrum signal detection device is characterized by comprising a computer (1), a spatial light modulator unit (2), an optical tweezers unit (3), an aerosol sample chamber (4), an aerosol sample chamber environmental condition regulation and control unit (5) and a spectrometer unit (6);
the computer (1) is used for generating a hologram and loading the hologram into the spatial light modulator unit (2);
the spatial light modulator unit (2) is used for regulating and controlling the optical field phase of the optical tweezers unit (3);
the optical tweezers unit (3) is used for capturing aerosol in the aerosol sample chamber (4);
the aerosol sample chamber environmental condition regulation and control unit (5) is used for regulating and controlling the environmental condition in the aerosol sample chamber (4);
the spectrometer unit (6) is used for collecting Raman spectrum signals of the aerosol captured in the aerosol sample chamber (4).
2. The device according to claim 1, characterized in that the computer (1) generates a hologram satisfying the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a theoretical model of the dynamics of trapping the aerosol in the air and combining a Fourier transform algorithm; the hologram generates an array pattern according to the requirement of the quantity of the optical trap arrays.
3. The apparatus according to claim 1, wherein the spatial light modulator unit (2) employs a liquid crystal spatial light modulator, the liquid crystal spatial light modulator comprising a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator.
4. The device according to claim 1, wherein the optical tweezer unit (3) is matched with the spatial light modulator unit (2) to realize the simultaneous capture of a plurality of aerosols.
5. Device according to claim 1, characterized in that the aerosol sample chamber (4) has an internal volume of 45 cubic centimeters.
6. The device according to claim 1, wherein the aerosol sample chamber environmental condition regulation unit (5) simulates the real state of the aerosol in the atmospheric environment, and realizes the regulation of the environmental relative humidity condition in the aerosol sample chamber (4) by introducing mixed dry nitrogen and wet nitrogen into the aerosol sample chamber (4).
7. A method for using the apparatus for detecting weak Raman spectrum signals of aerosol as claimed in any one of claims 1-6, comprising the steps of:
1) loading a hologram generated by a computer (1) into a spatial light modulator unit (2);
2) opening a laser of the optical tweezers unit (3) and forming an optical trap array in the aerosol sample chamber (4);
3) spraying aerosol to be detected into the aerosol sample chamber (4) by using an ultrasonic atomizer;
4) the optical trap array captures a plurality of aerosols simultaneously;
5) the relative humidity of the environmental condition of the aerosol sample chamber is regulated and controlled by an aerosol sample chamber environmental condition regulation and control unit (5);
6) raman spectral signals of a plurality of aerosols are collected to a spectrometer unit (6).
8. The method of application according to claim 7, characterized in that the computer (1) generates the hologram satisfying the study of the moisture absorption and volatilization characteristics of the aerosol, the oxidation characteristics of the aerosol and the phase separation characteristics of the aerosol by establishing a theoretical model of the dynamics of trapping the aerosol in the air and combining with a Fourier transform algorithm.
9. The method of claim 7, wherein the optical trap array captures a plurality of aerosols simultaneously, and simultaneously collects Raman spectral signals of the plurality of aerosols to the spectrometer unit (6).
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