Double-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device

Abstract

The invention discloses a double-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device, and belongs to the field of optics. The device comprises a double-beam single-light-trap optical tweezers generation device, a signal acquisition device and an optical resonant cavity, the signal acquisition device comprises a lighting source, a Raman spectrometer, a photodiode, a first camera and a second camera; two opposite light beams can be utilized to form a double-light-beam light trap, stable capturing of liquid drops is achieved, and the signal collecting device can collect Raman scattering signals, elastic scattering signals, cavity ring-down spectrum signals and photoelectric signals and collect images of the captured liquid drops at the same time. In addition, a CRDS detector is further arranged, and extinction signals of the captured liquid drops can be obtained by detecting signals of a ring-down spectrum. The light absorption capability of the captured liquid drop is obtained through the extinction signal and the elastic scattering signal, so that the light absorption capability and the scattering capability of the liquid drop are measured, and the optical property of the liquid drop is represented.

Description

Technical Field

[0001] This invention belongs to the fields of atmospheric chemistry and optics, and particularly relates to a dual-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device. Background Technology

[0002] Atmospheric aerosols refer to liquid or solid particles dispersed in the atmosphere. They are a significant contributor to haze and have substantial impacts on the environment, climate, and human health. Due to their scattering and absorption of solar radiation, they directly affect atmospheric radiation transfer and energy balance, thus significantly influencing global climate change. Therefore, clarifying the optical properties and evolution of aerosols is of great scientific significance for studying global climate change. The optical properties of aerosols are closely related to their physicochemical properties, such as chemical composition, particle size, morphology, and mixing state. Therefore, clarifying the physicochemical properties of individual aerosol particles is crucial for studying their optical properties in the atmosphere. Currently, commonly used methods for detecting the physicochemical properties of aerosols include mass spectrometry and chromatography for grouped aerosols (such as flow tubes and smoke chambers), as well as substrate-based single-particle electron microscopy and light microscopy. However, these methods cannot characterize the physicochemical properties of individual droplets under actual atmospheric conditions in situ, which can introduce errors into the characterization results.

[0003] Aerosol optical tweezers-Raman spectroscopy is a technique that enables the capture of suspended single droplets and the in-situ measurement of their physicochemical properties, allowing for the retrieval of information such as droplet size, refractive index, and mixing state. However, it lacks characterization capabilities for the optical properties of single droplets. Therefore, it can be coupled with other techniques, such as cavity ring-down spectroscopy (CRDS), to achieve the desired optical properties. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a dual-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a dual-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device, comprising an optical tweezers generating device, a signal acquisition device, and an optical resonant reaction cavity; The signal acquisition device includes an illumination light source, a spectrometer, a photodiode, a first camera, a second camera, a CRDS laser, and a CRDS detector; The optical resonant cavity has a first transparent window and a second transparent window at its front and rear ends for receiving the output light from the optical tweezers generating device; the optical resonant cavity has a third transparent window and a fourth transparent window at its upper and lower ends for receiving the output light from the illumination light source, the light after the output light from the illumination light source illuminates the droplet, and the Raman scattering signal and elastic scattering signal generated on the droplet by the output light from the optical tweezers generating device; the optical resonant cavity has a fifth transparent window and a sixth transparent window at its left and right ends, and the laser emitted by the CRDS laser enters the CRDS detector for detection after signal attenuation in the optical resonant cavity; The optical resonant reaction cavity is obliquely equipped with a first adapter connected to the air inlet pipe and a second adapter connected to the air outlet pipe, which are used to generate aerosols and discharge exhaust gas; the light output from the illumination light source after illuminating the droplets enters the first and second cameras, the Raman scattering signal is sent to the spectrometer for detection, and the elastic scattering signal is sent to the photodiode for detection.

[0006] Furthermore, the optical tweezers generating device includes a capture laser, an optical isolator, and a first beam splitter arranged sequentially along the optical path; the first beam splitter divides the output light generated by the capture laser into a first beam and a second beam at 90° angles, and a first convex lens, a second convex lens, and a first objective lens are arranged sequentially along the optical path of the first beam; a third convex lens, a fourth convex lens, and a second objective lens are arranged sequentially along the optical path of the second beam.

[0007] Furthermore, a first reflecting mirror is provided between the first beam splitter and the first convex lens, and a second reflecting mirror is provided between the second convex lens and the first objective lens; a third reflecting mirror is provided between the first beam splitter and the third convex lens, and a second beam splitter and a third beam splitter are provided sequentially between the fourth convex lens and the second objective lens.

[0008] Furthermore, the device includes a third objective lens, a fourth beam splitter, a fifth beam splitter, a fifth convex lens, and a notch filter. The light from the output light source irradiating the droplet is split into a third beam and a fourth beam at a 90° angle after passing through the third objective lens and the fourth beam splitter. The third beam enters the second camera. The fourth beam consists of Raman scattering and elastic scattering signals obtained after the output light irradiates the droplet. After passing through the fifth beam splitter 21, the Raman scattering signal is sequentially sent to the spectrometer for detection through the fifth convex lens and the notch filter, while the elastic scattering signal is sent to the photodiode for detection.

[0009] Furthermore, a fourth reflecting mirror is provided between the third objective lens and the fifth convex lens; a fifth reflecting mirror is provided between the fifth convex lens and the notch filter; a sixth reflecting mirror and a seventh reflecting mirror are provided sequentially between the second beam splitter and the notch filter; and a sixth convex lens is provided between the notch filter and the spectrometer.

[0010] Furthermore, the first transparent window is fixed to the front end of the cavity from the outside of the cavity by a first window cover and a first O-ring; the second transparent window is fixed to the rear end of the cavity from the outside of the cavity by a second window cover and a second O-ring; the third transparent window is fixed to the upper end of the cavity from the outside of the cavity by a third window cover and a third O-ring; the fourth transparent window is fixed to the lower end of the cavity from the outside of the cavity by a fourth window cover and a fourth O-ring; the fifth transparent window is fixed to the left side of the cavity from the outside of the cavity by a fifth window cover and a fifth O-ring; and the sixth transparent window is fixed to the right side of the cavity from the outside of the cavity by a sixth window cover and a sixth O-ring.

[0011] The beneficial effects of this invention are: it enables stable capture of micron-sized aerosol droplets and precise control of the relative humidity of the environment in which the droplets are located. Furthermore, by using opposing dual beams to form an optical trap, it provides high capture stability and robustness, overcoming the limitation of working distance in traditional optical tweezers and optical traps. While analyzing the Raman and photoelectric signals of the captured droplets, it utilizes an optical resonant cavity to collect ring-down spectral signals, further obtaining their extinction signals, elastic scattering patterns, and inelastic scattering signals. This allows for analysis of their phase, morphology, particle size, refractive index, functional group information, absorption, and scattering properties. The difference between the extinction signal and the elastic scattering signal yields the light absorption capacity of the captured droplet, thus enabling the measurement of the droplet's light absorption and scattering capabilities and characterizing its optical properties. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the device of the present invention; Figure 2 This is a schematic diagram of the specific structure of the optical resonant reaction cavity of the present invention; In the diagram: 1. Capturing laser; 2. Optical isolator; 3. First beam splitter; 4. First reflector; 5. First convex lens; 6. Second convex lens; 7. Second reflector; 8. First objective lens; 9. Second objective lens; 10. Output illumination light source; 11. Third reflector; 12. Third convex lens; 13. Fourth convex lens; 14. Second beam splitter; 15. Third beam splitter; 16. First camera; 17. Third objective lens; 18. Fourth reflector; 19. Fourth beam splitter; 20. Second camera; 21. Fifth beam splitter; 22. Fifth convex lens; 23. Fifth reflector; 24. Photodiode; 25. Sixth reflector; 26. Seventh reflector; 27. Notch filter. 28. Sixth convex lens; 29. ​​Spectrometer; 30. CRDS detector; 31. Optical resonant cavity; 32. First window cover; 33. First window piece; 34. First O-ring; 35. Second O-ring; 36. Second window piece; 37. Second window cover; 38. Third window cover; 39. Third window piece; 40. Third O-ring; 41. Fourth O-ring; 42. Fourth window piece; 43. Fourth window cover; 44. Fifth window cover; 45. Fifth window piece; 46. Fifth O-ring; 47. Sixth O-ring; 48. Sixth window piece; 49. Sixth window cover; 50. First adapter; 51. Second adapter; 52. CRDS laser. Detailed Implementation

[0014] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0015] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0016] It should be understood that although the terms first, second, third, etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of this invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0017] The present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0018] To address the limitations of current single-beam optical tweezers for measuring aerosol properties, this invention provides a dual-beam optical tweezers device for single-particle aerosol reaction and in-situ optical detection. For example... Figure 1 As shown, this device includes an optical tweezers generating device, a signal acquisition device, and an optical resonant reaction cavity 31.

[0019] The signal acquisition device includes an illumination light source 10 (an LED lamp is used in this embodiment), a spectrometer 29, a photodiode 24, a first camera 16, a second camera 20, a CRDS laser 52, and a CRDS detector 30.

[0020] The optical resonant cavity 31 has a first transparent window and a second transparent window at its front and rear ends for receiving the output light from the optical tweezers generating device; the optical resonant cavity 31 has a third transparent window and a fourth transparent window at its upper and lower ends for receiving the output light from the illumination light source 10, the light after the output light from the illumination light source 10 illuminates the droplet, and the Raman scattering signal and elastic scattering signal generated on the droplet by the output light from the optical tweezers generating device; the optical resonant cavity 31 has a fifth transparent window and a sixth transparent window at its left and right ends. The laser emitted by the CRDS laser 52 undergoes signal attenuation in the optical resonant cavity 31 before entering the CRDS detector 30 for detection.

[0021] The optical resonant reaction cavity 31 is obliquely provided with a first adapter 50 connected to the air inlet pipe and a second adapter 51 connected to the air outlet pipe, which are used to generate aerosols and discharge exhaust gas; the light output from the illumination light source 10 after irradiating the droplets enters the first camera 16 and the second camera 20, the Raman scattering signal is sent to the spectrometer 29 for detection, and the elastic scattering signal is sent to the photodiode 24 for detection.

[0022] As a preferred embodiment, such as Figure 2As shown, the first transparent window is fixed to the front end of the cavity from the outside of the cavity by the first window cover 32 and the first window piece 33 via the first O-ring 34; the second transparent window is fixed to the rear end of the cavity from the outside of the cavity by the second window cover 37 and the second O-ring 35; the third transparent window is fixed to the upper end of the cavity from the outside of the cavity by the third window cover 38 and the third O-ring 40; the fourth transparent window is fixed to the lower end of the cavity from the outside of the cavity by the fourth window cover 43 and the fourth O-ring 41; the fifth transparent window is fixed to the left side of the cavity from the outside of the cavity by the fifth window cover 44 and the fifth O-ring 46; and the sixth transparent window is fixed to the right side of the cavity from the outside of the cavity by the sixth window cover 49 and the sixth window piece 48 via the sixth O-ring 47.

[0023] In a preferred embodiment, the optical tweezers generating device includes a trapping laser 1, an optical isolator 2, and a first beam splitter 3 arranged sequentially along the optical path. The trapping laser 1 generates a Gaussian laser beam, and the optical isolator 2 eliminates the influence of the return beam on the trapping laser 1, preventing damage to the trapping laser 1. The first beam splitter 3 divides the output light generated by the trapping laser 1 into a first beam and a second beam at a 90° angle. The first beam has a first convex lens 5, a second convex lens 6, and a first objective lens 8 arranged sequentially along its optical path, and finally enters the optical resonant cavity 31. The second beam has a third convex lens 12, a fourth convex lens 13, and a second objective lens 9 arranged sequentially along its optical path, and finally enters the optical resonant cavity 31. Two objective lenses are respectively attached to the first and second transparent windows of the optical resonant reaction cavity 31, and oil is impregnated between the lens and the window to increase the numerical aperture. The first objective lens 8 and the second objective lens 9 converge the incident laser beam and form an optical trap in the optical resonant reaction cavity 31. When the aerosol droplet is sent into the optical resonant reaction cavity 31, it will be captured by the optical trap. At the same time, the light after the illumination light irradiates the droplet and the signal of the light output by the optical tweezers generating device being scattered by the droplet can be collected in reverse.

[0024] In a preferred embodiment, a first reflecting mirror 4 is provided between the first beam splitter 3 and the first convex lens 5, and a second reflecting mirror 7 is provided between the second convex lens 6 and the first objective lens 8; a third reflecting mirror 11 is provided between the first beam splitter 3 and the third convex lens 12, and a second beam splitter 14 and a third beam splitter 15 are sequentially provided between the fourth convex lens 13 and the second objective lens 9. All beam splitters are used to change the direction of light propagation and to transmit the generated signal.

[0025] In a preferred embodiment, the device includes a third objective lens 17, a fourth beam splitter 19, a fifth beam splitter 21, a fifth convex lens 22, and a notch filter 27. The light from the illumination source 10, after illuminating the droplet, is split into a third beam and a fourth beam at a 90° angle by the third objective lens 17 and the fourth beam splitter 19. The third beam enters the second camera 20 for real-time image capture of the captured droplet. Once the droplet is stably captured, the incident laser light is scattered on the droplet. In addition to the elastic scattering signal with the same frequency as the laser, the scattered light also contains components with higher or lower frequencies than the laser, i.e., Raman scattering signals. Part of the Raman scattering signal passes through the second objective lens 9, is reflected by the third beam splitter 15, then by the second beam splitter 14, the sixth mirror 25, and the seventh mirror 26, before entering the notch filter 27. Another part passes through the third objective lens 17, is reflected by the fourth mirror 18, the fourth beam splitter 19, and the fifth beam splitter 21, then by the fifth convex lens 22 and the fifth mirror 23 before entering the notch filter 27. The two signals converge at the sixth convex lens 28 and then enter the spectrometer 29. The notch filter 27 is used to filter strongly elastic scattering signals. The elastic scattering signal is detected by a photodiode 24 to measure the photoelectric signal.

[0026] In a preferred embodiment, a fourth reflecting mirror 18 is provided between the third objective lens 17 and the fifth convex lens 22; a fifth reflecting mirror 23 is provided between the fifth convex lens 22 and the notch filter 27; a sixth reflecting mirror 25 and a seventh reflecting mirror 26 are provided sequentially between the second beam splitter 14 and the notch filter 27; and a sixth convex lens 28 is provided between the notch filter 27 and the spectrometer 29.

[0027] During the overall implementation, the laser is emitted from the laser trapping unit 1, passes through the optical isolator 2, and is split into two beams, a first beam and a second beam, in the first beam splitter 3. The first beam is reflected by the first mirror 4, expanded by the first convex lens 5, collimated by the second convex lens 6, and then enters the first objective lens 8 through the second mirror 7, passing through the first transparent window into the optical resonant cavity 31. The second beam is reflected by the third mirror 11, expanded by the third convex lens 12, collimated by the fourth convex lens 13, and then reflected by the second beam splitter 14 and the third beam splitter 15 before entering the second objective lens 9 and passing through the second transparent window into the optical resonant cavity 31. The two beams converge in the optical resonant cavity 31 to form an optical trap. Aerosols enter the cavity from the first adapter 50 and exit from the second adapter 51. Individual particles within the aerosols are captured by the optical trap formed by the two laser beams, generating a series of elastic scattering and Raman scattering signals. Illumination light is output from the output illumination light source 10, enters the optical resonant reaction cavity 31 through the third transparent window, and a portion of the light signal after irradiating the droplet is emitted from the second transparent window, enters the first camera 16 after passing through the third beam splitter 15, and the other portion of the light signal is emitted from the fourth transparent window, passes through the fourth reflector 18, and is split into a third beam and a fourth beam at 90° after passing through the third objective lens 17 and the fourth beam splitter 19. The third beam enters the second camera 20 for real-time image capture of the captured droplet. Part of the generated Raman signal is emitted from the second transparent window, reflected by the third beam splitter 15, and then reflected by the sixth and seventh mirrors 25 and into the notch filter 27. Another part of the Raman scattering signal and the generated elastic scattering signal are output from the fourth transparent window. The elastic scattering signal, along with the fourth beam, passes through the fifth beam splitter 21 and enters the photodiode 24, where it is captured and detected. The Raman scattering signal is reflected in the fifth beam splitter 21, expanded by the fifth convex lens 22, reflected by the fifth mirror 23, and then enters the notch filter 27. Both parts of the Raman signal are filtered in the notch filter 27, focused by the sixth convex lens 28, and then enter the spectrometer 29, where they are captured and detected. The CRDS laser is emitted from the CRDS laser 52, passes through the fifth transparent window into the optical resonant cavity 31, and the generated CRDS signal is emitted from the sixth transparent window, enters the CRDS detector 30, and is captured and detected therein.

[0028] By analyzing the Raman scattering signal detected by spectrometer 29, the elastic scattering signal detected by photodiode 24, and the ring-down spectrum detected by CRDS detector 30, the physicochemical properties of the droplets during the reaction process, such as phase, morphology, particle size, refractive index, and functional group information, can be investigated.

[0029] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A dual-beam optical tweezers aerosol single-particle reaction and in-situ optical detection device, characterized in that, It includes an optical tweezers generating device, a signal acquisition device, and an optical resonant reaction cavity (31); The signal acquisition device includes an illumination light source (10), a spectrometer (29), a photodiode (24), a first camera (16), a second camera (20), a CRDS laser (52), and a CRDS detector (30). The optical resonant reaction cavity (31) is provided with a first transparent window and a second transparent window at both ends for receiving the output light of the optical tweezers generating device; the optical resonant reaction cavity (31) is provided with a third transparent window and a fourth transparent window at both ends for receiving the output light of the illumination light source (10), the light after the output light of the illumination light source (10) irradiates the droplet, and the Raman scattering signal and elastic scattering signal generated on the droplet by the output light of the optical tweezers generating device. The optical resonant reaction cavity (31) is provided with a fifth transparent window and a sixth transparent window at its left and right ends. The laser emitted by the CRDS laser (52) is attenuated in the optical resonant reaction cavity (31) and then enters the CRDS detector (30) for detection. The optical resonant reaction cavity (31) is obliquely provided with a first adapter (50) connected to the air inlet pipe and a second adapter (51) connected to the air outlet pipe, for generating aerosol and discharging exhaust gas; the output light of the illumination light source (10) after irradiating the droplet enters the first camera (16) and the second camera (20), the Raman scattering signal is sent to the spectrometer (29) for detection, and the elastic scattering signal is sent to the photodiode (24) for detection.

2. The apparatus according to claim 1, characterized in that, The optical tweezers generating device includes a capture laser (1), an optical isolator (2), and a first beam splitter (3) arranged sequentially along the optical path; the first beam splitter (3) divides the output light generated by the capture laser (1) into a first beam and a second beam at 90°, and a first convex lens (5), a second convex lens (6), and a first objective lens (8) are arranged sequentially along the optical path of the first beam; a third convex lens (12), a fourth convex lens (13), and a second objective lens (9) are arranged sequentially along the optical path of the second beam.

3. The apparatus according to claim 2, characterized in that, A first reflecting mirror (4) is provided between the first beam splitter (3) and the first convex lens (5), and a second reflecting mirror (7) is provided between the second convex lens (6) and the first objective lens (8); a third reflecting mirror (11) is provided between the first beam splitter (3) and the third convex lens (12), and a second beam splitter (14) and a third beam splitter (15) are provided sequentially between the fourth convex lens (13) and the second objective lens (9).

4. The apparatus according to claim 3, characterized in that, The device includes a third objective lens (17), a fourth beam splitter (19), a fifth beam splitter (21), a fifth convex lens (22), and a notch filter (27). The light from the output light source (10) that irradiates the droplet is split into a third beam and a fourth beam at 90° after passing through the third objective lens (17) and the fourth beam splitter (19). The third beam enters the second camera (20). The fourth beam consists of Raman scattering signal and elastic scattering signal obtained by the output light irradiating the droplet. After passing through the fifth beam splitter (21), the Raman scattering signal is sent to the spectrometer (29) for detection after passing through the fifth convex lens (22) and the notch filter (27). The elastic scattering signal is sent to the photodiode (24) for detection.

5. The apparatus according to claim 4, characterized in that, A fourth reflecting mirror (18) is provided between the third objective lens (17) and the fifth convex lens (22); a fifth reflecting mirror (23) is provided between the fifth convex lens (22) and the notch filter (27); a sixth reflecting mirror (25) and a seventh reflecting mirror (26) are provided sequentially between the second beam splitter (14) and the notch filter (27); and a sixth convex lens (28) is provided between the notch filter (27) and the spectrometer (29).

6. The apparatus according to claim 1, characterized in that, The first transparent window is fixed to the front end of the cavity from the outside of the cavity by the first window cover (32) and the first O-ring (34); the second transparent window is fixed to the rear end of the cavity from the outside of the cavity by the second window cover (37) and the second O-ring (35); the third transparent window is fixed to the upper end of the cavity from the outside of the cavity by the third window cover (38) and the third O-ring (40); the fourth transparent window is fixed to the lower end of the cavity from the outside of the cavity by the fourth window cover (43) and the fourth O-ring (41); the fifth transparent window is fixed to the left side of the cavity from the outside of the cavity by the fifth window cover (44) and the fifth O-ring (46); the sixth transparent window is fixed to the right side of the cavity from the outside of the cavity by the sixth window cover (49) and the sixth O-ring (47).

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