Apparatus and method for capturing and manipulating biological aerosols based on fiber-optic optical tweezers

Abstract

The application discloses a device and method for capturing and operating biomass aerosol based on fiber optical tweezers, which comprises a laser, an isolator, a beam expander assembly, a first half-wave plate and a polarization beam splitter for splitting the laser beam into a first laser beam and a second laser beam, which are arranged along the optical path of the laser beam in sequence, and a single-mode optical fiber, a multi-mode optical fiber, a spatial light modulator and an aerosol capture chamber; the first laser beam and the second laser beam are coupled into the input ends of the multi-mode optical fiber and the single-mode optical fiber respectively, and the output ends of the multi-mode optical fiber and the single-mode optical fiber enter the aerosol capture chamber; the spatial light modulator is used for modulating the input light field of the multi-mode optical fiber to create an optimized focal point in the output light field; and the aerosol capture chamber is provided with a first CMOS camera, a long-focus objective lens and a Kohler illumination system. The device for capturing and operating biomass aerosol of the application overcomes the two major limiting problems of traditional single biomass aerosol particle capture and operation.

Description

Technical Field

[0001] This invention relates to the field of fiber optic tweezers technology, and more specifically, to an apparatus and method for capturing and manipulating biomass aerosols based on fiber optic tweezers. Background Technology

[0002] Biomass aerosols refer to tiny solid and liquid biomass particles dispersed in the air, with wide-ranging applications and economic impacts. These aerosols are not only present in the smoke from biomass fuel combustion but are also released in large quantities through factory emissions and forest fires, causing local and global pollution. Simultaneously, biomass aerosols exert a significant impact on climate through atmospheric processes, playing a crucial role in global cooling and preventing uncontrolled warming. However, studying and isolating individual biomass aerosol processes is extremely difficult, with many significant unresolved uncertainties. A major reason for the current uncertainty in the properties of biomass aerosols is that they are typically fast-moving small particles that constantly interact with the environment, making traditional in-situ biomass aerosol analysis both challenging and destructive. Currently, a feasible solution is to capture and manipulate individual biomass aerosols using optical trapping (optical tweezers) techniques. This technique uses focused lasers to capture particles. Optical trapping (optical tweezers) techniques have been widely applied in multiple disciplines due to their non-contact, low-damage, and highly versatile nature. Since Ashkin first proposed the technology in 1970, it has been developed for over 50 years and won the Nobel Prize in Physics in 2018. In the last decade, the use of this technology to capture and manipulate the dynamics of individual biomass aerosols and to study their physicochemical properties has attracted considerable interest and attention. In biomass aerosol research, significant progress has been made both domestically and internationally in areas such as the design of optical capture devices, the analysis of the dynamic characteristics of captured biomass aerosol particles, and the analysis and study of their physical and chemical properties.

[0003] Traditional optical capture devices for biomass aerosols rely on high numerical aperture microscope objectives and complex optical systems, resulting in bulky, expensive, and difficult-to-reconfigure systems that require specialized operators. Furthermore, the stability of biomass aerosol capture and manipulation in air using traditional optical capture devices presents another significant challenge. This is primarily due to two factors: first, the low viscosity of the suspension medium, making suspended biomass aerosols more sensitive to surrounding fluctuations, leading to unstable capture; and second, the relatively high refractive index, making biomass aerosols more susceptible to scattering forces and more easily pushed away from the capture field. Therefore, improving the stability of biomass aerosol particle capture and manipulation in gaseous environments has become a critical technical bottleneck that current traditional optical capture devices urgently need to overcome. Summary of the Invention

[0004] Based on this, the present invention aims to overcome at least one defect of the prior art and provide a device for capturing and manipulating biomass aerosols based on fiber optic tweezers capture technology, thus overcoming the two major limitations of traditional single biomass aerosol particle capture and manipulation difficulties.

[0005] Another object of the present invention is to provide a method for capturing and manipulating biomass aerosols based on optical fiber tweezers.

[0006] The technical solution is as follows:

[0007] A device for capturing and manipulating biomass aerosols based on fiber optic tweezers includes a laser that emits a laser beam, an isolator, a beam expander, a first half-wave plate, and a polarizing beam splitter for splitting the laser beam into a first laser beam and a second laser beam. The device also includes a single-mode fiber, a multimode fiber, a spatial light modulator, and an aerosol capture chamber.

[0008] The first laser beam and the second laser beam are coupled into the input ends of the multimode fiber and the single-mode fiber, respectively. The output ends of the multimode fiber and the single-mode fiber enter the aerosol capture chamber and are located on opposite sides of the aerosol capture chamber. The spatial light modulator is used to modulate the input light field of the multimode fiber to create an optimized focus in the output light field.

[0009] The aerosol capture chamber is equipped with a first CMOS camera and a long focal length objective lens above it, with the long focal length objective lens located on the side closer to the capture chamber. The capture chamber is equipped with a Kohler illumination system below it.

[0010] In one embodiment, the beam expander is a 6x telescope system beam expander assembly for expanding the diameter of the laser beam; and / or the telephoto objective is a 20x distance objective.

[0011] In one embodiment, the second laser beam is coupled into a single-mode fiber through a third objective lens, which is a 10x objective lens.

[0012] In one embodiment, the device further includes an optical fiber clamp for holding single-mode optical fibers and dual-mode optical fibers.

[0013] In one embodiment, the device for capturing and manipulating biomass aerosols based on fiber optic tweezers prepares and delivers aerosols via an aerosol delivery structure, which includes an ultrasonic atomizer and a nozzle disposed at the end of the ultrasonic atomizer, wherein the length and angle of the nozzle are adjustable.

[0014] A method for capturing and manipulating biomass aerosols based on fiber optic tweezers includes the following steps:

[0015] (1) Setting up the device: Assemble the device for capturing and manipulating biomass aerosols based on fiber optic tweezers, so that the laser beam of the laser can enter the aerosol capture chamber in the following optical path: first through the isolator and then through the beam expander to obtain a uniform laser beam after beam expansion, the laser beam is split into a first laser beam and a second laser beam by the first half-wave plate and the polarization beam splitter, the power ratio of the two laser beams is controlled by adjusting the first half-wave plate, the first laser beam and the second laser beam are coupled into the input ends of the multimode fiber and the single-mode fiber respectively, the input optical field of the multimode fiber is modulated by the spatial light modulator to create an optimized focus in the output optical field, the output ends of the multimode fiber and the single-mode fiber enter the aerosol capture chamber and are located on the two opposite sides of the aerosol capture chamber, thereby forming fiber optic tweezers on the two opposite sides of the aerosol capture chamber;

[0016] (2) Environmental control: The aerosol capture chamber is designed as a sealed structure, and wet paper towels are placed inside the aerosol capture chamber to maintain the humidity environment;

[0017] (3) Preparation and transport of aerosols: aerosols are captured and transported through aerosol transport structures;

[0018] (4) Recording and analysis: The aerosol capture chamber is illuminated by the Kohler illumination system to obtain clear images of captured aerosols. The dynamics of individual aerosols are recorded and analyzed by the first CMOS camera and long focal length objective lens. The video data during the capture process is then analyzed by MATLAB algorithm to accurately analyze the physical properties of aerosols.

[0019] (5) Fiber processing: After each experiment, the end faces of multimode and single-mode fibers are cleaned and re-aligned precisely to ensure high repeatability and accuracy of the system.

[0020] In one embodiment, the spatial light modulator modulates the input optical field of the multimode fiber to optimize the output optical field shaping, comprising the following steps:

[0021] (1) The laser beam is split into two beams by an isolator, a first half-wave plate, and a polarization beam splitter. The power ratio of the two beams is controlled by rotating the first half-wave plate. One laser beam is coupled to a single-mode fiber as a reference beam, and the other laser beam is used as a signal beam. The signal beam is incident on the spatial light modulator through a beam expander and a second half-wave plate. The polarization between the signal beam and the spatial light modulator is aligned by the second half-wave plate.

[0022] (2) A grating is loaded onto the spatial light modulator, and the input end face of the multimode fiber is sequentially scanned through the diffraction limit point. This point is modulated by the spatial light modulator, and the phase of the light is shifted sequentially within the range of 2π at each point. By scanning each point of the input end face of the multimode fiber, a speckle pattern is generated at the output end of the multimode fiber.

[0023] (3) The speckle pattern interferes with the reference beam output from the single-mode fiber to form an interference pattern. The optimal phase and amplitude of the detection position are extracted by the second CMOS camera.

[0024] (4) Repeat steps (2) and (3) to obtain the image generated by the optimal phase and amplitude of all scanning points, generate the optimized hologram, and calculate it by fast Fourier transform;

[0025] (5) Finally, the optimized hologram is sent to the spatial light modulator to generate a shaping field at the output end of the multimode fiber and create an optimized focus.

[0026] In one embodiment, the step of sequentially scanning the input end face of the multimode fiber through diffraction-limited points includes the following steps:

[0027] (1) A third lens, an aperture, a fourth lens, a first quarter glass plate, and a first objective lens are sequentially arranged on the optical path from the spatial light modulator to the input end of the multimode fiber; wherein the third lens and the fourth lens constitute the first 4f system, and the fourth lens and the first objective lens constitute the second 4f system.

[0028] (2) The first 4f system images the spatial light modulator onto the first objective lens, and the second 4f system images the selected diffraction limit point onto the input end face of the multimode fiber, wherein the aperture is selected as the first diffraction order, and the first quarter glass plate is used to control the polarization state of the signal beam propagating in the multimode fiber.

[0029] In one embodiment, a first beam splitter is provided in the optical path from the fourth lens to the first quarter-wave plate. The first beam splitter splits the laser beam from the fourth lens into a third laser beam and a fourth laser beam. The third laser beam is incident on the first quarter-wave plate, and a third CMOS camera is provided in the path of the fourth laser beam to monitor and modulate the fourth laser beam.

[0030] In one embodiment, the output end of the multimode fiber is provided with a second objective lens, a second quarter glass slide, and a second beam splitter. The second beam splitter combines the output light of the single-mode fiber and the output light of the multimode fiber, and a second CMOS camera is placed in the optical path after beam combining.

[0031] In one embodiment, before sequentially scanning the input end of the multimode fiber through diffraction-limited points, a spatial light modulator calibration step is also included: the spatial light modulator is calibrated by generating a LOOP-UP-TABLE or creating a compensation hologram by capturing the amplitude of the interference pattern of the interference fringes.

[0032] In one embodiment, the aerosol capture and delivery structure involves: setting up an ultrasonic atomizer containing a NaCl solution, and setting a nozzle with adjustable length and angle at the end of the ultrasonic atomizer; capturing aerosol particles to generate aerosols through the ultrasonic atomizer; and precisely controlling the speed and direction of the aerosols entering the aerosol capture chamber through the nozzle.

[0033] The beneficial effects of this invention are as follows: This invention employs an optical trapping device based on fiber optic tweezers to trap and manipulate biomass aerosols, which has unique advantages such as miniaturization, easy integration, and no need for expensive optical components. Through the reverse-oriented dual-fiber oriented structure, a trapping potential well for individual biomass aerosol particles can be constructed, forming a stable potential field for trapping and manipulating biomass aerosol particles. The entire trapping device is easy to operate and is very suitable as a platform for developing trapping and manipulating individual biomass aerosols. By modulating the input optical field of the multimode fiber with a spatial light modulator to create an optimized focus in the output optical field, the trapping field is optimized, trapping stability is improved, and the light scattering problem caused by the trapping chamber and the surface covering of the fiber end is effectively solved, ensuring that the system can operate efficiently in various dynamic processes. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the device for capturing and manipulating biomass aerosols based on optical fiber tweezers, as described in Example 1.

[0035] Figure 2 A schematic diagram of a device for modulating the input optical field of a multimode fiber using a spatial light modulator.

[0036] Figure 3 A schematic diagram illustrating the principle of generating an optimized focus by modulating multimode fiber for a spatial light modulator.

[0037] Figure 4 A schematic diagram of the optical setup for phase modulation calibration of a spatial light modulator.

[0038] Figure 5 This is a simplified schematic diagram of an aerosol delivery structure.

[0039] Explanation of reference numerals in the attached figures: 1. Laser; 2. Isolator; 3. Mirror; 4. Beam expander assembly; 5. First half-wave plate; 6. Polarizing beam splitter; 7. Single-mode fiber; 8. Multimode fiber; 9. Spatial light modulator; 10. Aerosol capture chamber; 11. First CMOS camera; 12. Long focal length objective lens; 13. Kohler illumination system; 14. Second half-wave plate; 15. Third lens; 16. Aperture stop; 17. Fourth lens; 18. First quarter-slide; 19. First objective lens; 20. First beam splitter; 21. Third CMOS camera; 22. Second objective lens; 23. Second quarter-slide; 24. Second beam splitter; 25. Second CMOS camera; 26. Optimized multimode fiber; 27. Third objective lens; 28. Fiber optic clamp. Detailed Implementation

[0040] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate the following embodiments, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment discloses a device for capturing and manipulating biomass aerosols based on fiber optic tweezers. The device includes a laser 1 emitting a laser beam, an isolator 2 (Thorlabs IO-3-532-LP) arranged sequentially along the optical path of the laser beam, a beam expander 4, a first half-wave plate 5, and a polarizing beam splitter 6 for splitting the laser beam into a first laser beam and a second laser beam. The device also includes a single-mode fiber 7 (Thorlabs...). P1-460AR-2), multimode fiber 8, spatial light modulator 9, and aerosol capture chamber 10; the first laser beam is coupled into the input end of the multimode fiber 8, and the second laser beam is coupled into the input end of the single-mode fiber 7. The output ends of the multimode fiber 8 and the single-mode fiber 7 enter the aerosol capture chamber 10 and are located on opposite sides of the aerosol capture chamber 10; the spatial light modulator 9 is used to modulate the input light field of the multimode fiber 8 to create an optimized focus in the output light field; a first CMOS camera 11 (Baslerac A2040-120μm) and a long focal length objective lens 12 (Motic ELWD 20X) are provided above the aerosol capture chamber 10, with the long focal length objective lens 12 located on the side closer to the capture chamber 10; a Kohler illumination system 13 is provided below the capture chamber 10.

[0043] The working principle and process of the device for capturing and manipulating biomass aerosols based on fiber optic tweezers described in this embodiment are as follows: The laser beam first passes through an isolator 2 to eliminate feedback interference, and then passes through a beam expander 4 to expand the beam diameter. The expanded laser beam then passes through a first half-wave plate 5 and a polarization beam splitter 6 to split the beam into two beams. By precisely rotating the first half-wave plate 5, the power distribution of the two laser beams can be flexibly adjusted, thereby achieving adaptive adjustment to different experimental conditions. Two optical fibers are introduced into the aerosol capture chamber 10. The aerosol capture chamber 10 is equipped with a long focal length objective lens 12 and a first CMOS camera 11 for observing and recording the captured individual biomass aerosol particles. To ensure clear imaging of the captured aerosol particles, a Kohler illumination system 13 is configured to illuminate the aerosol particles using Kohler illumination technology. Subsequently, the video data during the capture process is analyzed by an algorithm to accurately resolve the size and other physical properties of the aerosol particles.

[0044] Specifically, in this embodiment, the laser 1 is a 532nm wavelength laser (Torus Laser Quantum 891mW), which has high stability and high power output, ensuring a stable light source during the experiment.

[0045] Specifically, in this embodiment, the beam expander 4 is a 6x telescope system beam expander assembly used to expand the diameter of the laser beam, including a first lens and a second lens.

[0046] Specifically, in this embodiment, the telephoto objective 12 is a 20x distance objective.

[0047] Specifically, in this embodiment, the mode field diameter of the single-mode fiber 7 is 2.8 μm to 4.1 μm at 488 nm.

[0048] Specifically, in this embodiment, the second laser beam is coupled into the single-mode fiber 7 through the third objective lens 27. More specifically, the third objective lens 27 is a 10x objective lens.

[0049] The device also includes an optical fiber clamp 28 for holding single-mode optical fiber 7 and multimode optical fiber 8 to ensure stable control of optical fiber coupling.

[0050] Devices based on fiber optic tweezers for capturing and manipulating biomass aerosols prepare and transport aerosols via aerosol delivery structures, such as... Figure 5As shown, the aerosol delivery structure includes an ultrasonic atomizer (OMRON NE-U100-E) and a nozzle disposed at the end of the ultrasonic atomizer, and the length and angle of the nozzle are adjustable. More specifically, the ultrasonic atomizer is prepared with a 50 g / L NaCl solution to maintain the stability of the aerosol particles and prevent their rapid evaporation. The adjustable length and angle of the nozzle allow for precise control of the aerosol's entry speed and direction, ensuring that the aerosol particles can effectively enter the aerosol capture chamber 10.

[0051] Furthermore, a reflector 3 is provided along the optical path of the laser beam as needed. The function of the reflector 3 is to change the propagation direction of the laser beam, so as to make the structure of the device for capturing and manipulating biomass aerosols based on fiber optic tweezers more compact. In this embodiment, the specific locations where the reflector 3 should be placed will not be described in detail. Those skilled in the art can set it as needed to make the device more compact.

[0052] This embodiment also discloses a method for capturing and manipulating biomass aerosols based on fiber optic tweezers, including the following steps:

[0053] (1) Setting up the device: Assemble as follows Figure 1 The apparatus shown is based on fiber optic tweezers for capturing and manipulating biomass aerosols. The laser beam from laser 1 enters the aerosol capture chamber 10 via the following optical path: first, it passes through isolator 2, then through beam expander 4 to obtain a uniformly expanded laser beam. The laser beam is then split into a first laser beam and a second laser beam by a first half-wave plate 5 and a polarization beam splitter 6. The power ratio of the two laser beams is controlled by adjusting the first half-wave plate 5. The first and second laser beams are coupled into the input ends of multimode fiber 8 and single-mode fiber 7, respectively. The input optical field of the multimode fiber 8 is modulated by a spatial light modulator 9 to create an optimized focal point in the output optical field, forming an optimized multimode fiber 26. The output ends of the multimode fiber 8 and single-mode fiber 7 enter the aerosol capture chamber 10 and are located on opposite sides of the aerosol capture chamber 10, thus forming fiber optic tweezers on opposite sides of the aerosol capture chamber 10.

[0054] (2) Environmental control: The aerosol capture chamber 10 is designed as a sealed structure, and wet paper towels are placed inside the aerosol capture chamber 10 to maintain the humidity environment. This can reduce airflow interference and provide stable experimental conditions.

[0055] (3) Aerosol preparation and delivery: Aerosols are captured and delivered using an aerosol delivery structure. An ultrasonic atomizer (OMRON NE-U100-E) is used to generate aerosols, which are then delivered to the aerosol capture chamber 10 through a customized nozzle. The length and angle of the nozzle are adjustable to precisely control the entry speed and direction of the aerosols, ensuring that particles can effectively enter the aerosol capture chamber 10.

[0056] (4) Recording and analysis: The aerosol capture chamber 10 is illuminated by the Kohler illumination system 13 to obtain clear images of captured aerosols. The dynamics of individual aerosols are recorded and analyzed by the first CMOS camera 11 and the telephoto objective lens 12. The video data during the capture process is then analyzed by the MATLAB algorithm to accurately analyze the physical properties of the aerosols.

[0057] (5) Fiber processing: After each experiment, the end faces of multimode fiber 8 and single-mode fiber 7 are cleaned and re-aligned precisely to ensure the high repeatability and accuracy of the system.

[0058] To improve capture stability and efficiency, this embodiment employs beam shaping technology. Beam shaping enhances the depth and uniformity of the capture potential well, thereby increasing capture efficiency. Furthermore, when capturing a single liquid aerosol, the surfaces of the aerosol capture chamber 10 and the fiber end face can be covered by droplets or absorbing particles, leading to light scattering or distortion, thus reducing capture efficiency or causing capture failure. To improve capture stability, capture efficiency, and address scattering issues, this embodiment uses a spatial light modulator 9 to modulate the input optical field of the multimode fiber 8, focusing on optimizing the output optical field shaping. A schematic diagram of the device for modulating the input optical field of the multimode fiber using a spatial light modulator is shown below. Figure 2 As shown, the specific steps include the following:

[0059] (1) The laser beam is split into two beams through isolator 2, first half-wave plate 5, and polarization beam splitter 6. The power ratio of the two beams is controlled by rotating the first half-wave plate 5. One laser beam is coupled to a single-mode fiber 7 as a reference beam, and the other laser beam is used as a signal beam. The signal beam is incident on the spatial light modulator 9 through beam expander 4 and second half-wave plate 14. The polarization between the signal beam and the spatial light modulator 9 is aligned by the second half-wave plate 14.

[0060] (2) A grating is loaded on the spatial light modulator 9, and the input end face of the multimode fiber 8 is scanned sequentially through the diffraction limit point. The point is modulated by the spatial light modulator 9, and the phase of the light is shifted sequentially within the range of 2π at each point. By scanning each point of the input end face of the multimode fiber 8, a speckle pattern is generated at the output end of the multimode fiber 8.

[0061] (3) The speckle pattern interferes with the reference beam output from the single-mode fiber 7 to form an interference pattern. The optimal phase and amplitude of the detection position are extracted by the second CMOS camera 25 (Basler acA2040-120μm).

[0062] (4) Repeat steps (2) and (3) to obtain the image generated by the optimal phase and amplitude of all scanning points, generate the optimized hologram, and calculate it by fast Fourier transform;

[0063] (5) Finally, the optimized hologram is sent to the spatial light modulator 9 to generate a shaping field at the output end of the multimode fiber 8 and create an optimized focus.

[0064] like Figure 3 The diagram shows the principle of spatial light modulator 9 modulating multimode fiber to generate an optimized focus. Figure 3 (a): The input end face of the multimode fiber is sequentially scanned by a diffraction-limited point, which is modulated by a spatial light modulator 9 with an applied grating. In addition, at each point, the phase of the light is shifted sequentially within a range of 2π. Figure 3 (b): When scanning each point on the input end face of the multimode fiber 8, the output field of the multimode fiber 8 is a speckle pattern. Figure 3 (c): The interference pattern generated by the superposition of the output field of the multimode fiber 8 and the collimated Gaussian beam transmitted through the single-mode fiber 7 is captured by the second CMOS camera 25. After phase shifting within the range of 2π, the optimal phase and amplitude of the detection position can be extracted at the current scanning point. Figure 3 (d): Once all scans and corresponding phase shifts are complete, all optimal phases and amplitudes at the probe location can be obtained and used to generate an optimized hologram. Figure 3 (e): By sending the optimized hologram to the spatial light modulator 9 to generate a shaping field on the input side of the multimode fiber 8, an optimized focus is created at the output of the multimode fiber 8.

[0065] Furthermore, the step of sequentially scanning the input end face of the multimode fiber 8 through the diffraction-limited points includes the following steps:

[0066] (1) A third lens 15, an aperture 16 (Thorlabs SM1D12D), a fourth lens 17, a first quarter glass plate 18, and a first objective lens 19 are sequentially arranged on the optical path from the spatial light modulator 9 to the input end of the multimode fiber 8; wherein the third lens 15 and the fourth lens 17 constitute the first 4f system, and the fourth lens 17 and the first objective lens 19 constitute the second 4f system;

[0067] (2) The first 4f system images the spatial light modulator 9 onto the first objective lens 19, and the second 4f system images the selected diffraction limit point onto the input end face of the multimode fiber 8, wherein the aperture 16 selects the first diffraction order, and the first quarter glass plate 18 is used to control the polarization state of the signal beam propagating in the multimode fiber 8.

[0068] Furthermore, a first beam splitter 20 is provided in the optical path from the fourth lens 17 to the first quarter-wave plate 18. The first beam splitter 20 splits the laser beam from the fourth lens 17 into a third laser beam and a fourth laser beam. The third laser beam is incident on the first quarter-wave plate 18, and a third CMOS camera 21 (Basler acA1920-150μm) is provided in the path of the fourth laser beam to monitor and modulate the fourth laser beam.

[0069] Furthermore, the output end of the multimode fiber 8 is provided with a second objective lens 22, a second quarter glass slide 23, and a second beam splitter 24. The second beam splitter 24 combines the output light of the single-mode fiber 7 and the output light of the multimode fiber 8, and the second CMOS camera 25 is set in the optical path after beam combining.

[0070] Furthermore, before sequentially scanning the input end of the multimode fiber using diffraction-limited points, a spatial light modulator 9 calibration step is included: calibration of the spatial light modulator is completed by generating a look-up table or creating a compensated hologram by capturing the amplitude of the interference pattern of the interference fringes. Furthermore, the calibrated spatial light modulator 9 is used to modulate the phase of light, such as... Figure 4 The diagram shows the optical setup for phase modulation calibration of the spatial light modulator 9, in which 256 grayscale patterns will be sequentially displayed on the spatial light modulator 9 to modulate the phase, and the second CMOS camera 25 will capture the resulting interference fringes.

[0071] Through the above method, this embodiment achieves efficient capture and stable control of individual biomass aerosols, overcomes the technical bottleneck of traditional optical capture devices, and provides a novel and practical solution for the research of biomass aerosols.

[0072] The apparatus and method for capturing and manipulating biomass aerosols based on fiber optic tweezers in this embodiment have the following advantages:

[0073] (1) On the one hand, fiber-optic-based optical trapping devices have unique advantages such as miniaturization, easy integration, and no need for expensive optical components. By using a reverse-oriented dual-fiber oriented structure, a trapping potential well for individual biomass aerosol particles can be constructed, forming a stable potential field for trapping and manipulating biomass aerosol particles. The entire trapping device is easy to operate and is very suitable as a platform for developing the trapping and manipulation of individual biomass aerosols.

[0074] (2) On the other hand, by introducing beam shaping technology, the shortcomings of traditional optical tweezers systems in terms of the stability of capturing aerosol particles are overcome. Beam shaping technology optimizes the capture field, improves capture stability, and effectively solves the light scattering problem caused by the surface covering of the capture cavity and fiber end, ensuring that the system can operate efficiently in various dynamic processes. Based on the above improvements and optimizations, the proposed method and device for capturing and manipulating biomass aerosols using fiber optic tweezers achieves real-time dynamic analysis of individual biomass aerosol particles with low cost, ease of operation, compact size, and high stability.

[0075] (3) This system provides a flexible and user-friendly platform designed for a more comprehensive understanding of biomass aerosol processes that underpin the climate system and major industrial applications. Through this platform, researchers can more effectively capture and analyze biomass aerosols, providing strong technical support for in-depth research in related fields.

[0076] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A device for capturing and manipulating biomass aerosols based on fiber optic tweezers, characterized in that, The device includes a laser that emits a laser beam, an isolator arranged sequentially along the optical path of the laser beam, a beam expander, a first half-wave plate, and a polarizing beam splitter for splitting the laser beam into a first laser beam and a second laser beam. The device also includes a single-mode fiber, a multimode fiber, a spatial light modulator, and an aerosol trapping chamber. The first laser beam and the second laser beam are coupled into the input ends of the multimode fiber and the single-mode fiber, respectively. The output ends of the multimode fiber and the single-mode fiber enter the aerosol capture chamber and are located on opposite sides of the aerosol capture chamber. The spatial light modulator is used to modulate the input light field of the multimode fiber to create an optimized focus in the output light field. The aerosol capture chamber is equipped with a first CMOS camera and a long focal length objective lens above it, with the long focal length objective lens located on the side close to the aerosol capture chamber. The aerosol capture chamber is equipped with a Kohler illumination system below it.

2. The device for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 1, characterized in that, The beam expander is a 6x telescope system beam expander assembly used to expand the diameter of the laser beam; and / or the telephoto objective is a 20x distance objective.

3. The device for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 1, characterized in that, The second laser beam is coupled into a single-mode fiber through a third objective lens, which is a 10x objective lens.

4. The device for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 1, characterized in that, The device for capturing and manipulating biomass aerosols based on fiber optic tweezers prepares and delivers aerosols through an aerosol delivery structure, which includes an ultrasonic atomizer and a nozzle disposed at the end of the ultrasonic atomizer, and the length and angle of the nozzle are adjustable.

5. A method for capturing and manipulating biomass aerosols based on fiber optic tweezers, characterized in that, Includes the following steps: (1) Setting device: Assemble and set the device for capturing and manipulating biomass aerosols based on fiber optic tweezers as described in any one of claims 1 to 4, so that the laser beam of the laser can enter the aerosol capture chamber in the following optical path: first through an isolator and then through a beam expander to obtain a uniform laser beam after beam expansion, the laser beam is split into a first laser beam and a second laser beam by a first half-wave plate and a polarization beam splitter, the power ratio of the two laser beams is controlled by adjusting the first half-wave plate, the first laser beam and the second laser beam are coupled into the input ends of the multimode fiber and the single-mode fiber respectively, the input optical field of the multimode fiber is modulated by a spatial light modulator to create an optimized focus in the output optical field, the output ends of the multimode fiber and the single-mode fiber enter the aerosol capture chamber and are located on two opposite sides of the aerosol capture chamber, thereby forming fiber optic tweezers on two opposite sides of the aerosol capture chamber; (2) Environmental control: The aerosol capture chamber is designed as a sealed structure, and wet paper towels are placed inside the aerosol capture chamber to maintain the humidity environment; (3) Preparation and transport of aerosols: aerosols are captured and transported through aerosol transport structures; (4) Recording and analysis: The aerosol capture chamber is illuminated by the Kohler illumination system to obtain clear images of captured aerosols. The dynamics of individual aerosols are recorded and analyzed by the first CMOS camera and long focal length objective lens. The video data during the capture process is then analyzed by MATLAB algorithm to accurately analyze the physical properties of aerosols. (5) Fiber processing: After each experiment, the end faces of multimode and single-mode fibers are cleaned and re-aligned precisely to ensure high repeatability and accuracy of the system.

6. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 5, characterized in that, The spatial light modulator modulates the input optical field of the multimode fiber to optimize the shaping of the output optical field, comprising the following steps: (1) The laser beam is split into two beams by an isolator, a first half-wave plate, and a polarization beam splitter. The power ratio of the two beams is controlled by rotating the first half-wave plate. One laser beam is coupled to a single-mode fiber as a reference beam, and the other laser beam is used as a signal beam. The signal beam is incident on the spatial light modulator through a beam expander and a second half-wave plate. The polarization between the signal beam and the spatial light modulator is aligned by the second half-wave plate. (2) A grating is loaded onto the spatial light modulator, and the input end face of the multimode fiber is sequentially scanned through the diffraction limit point. This point is modulated by the spatial light modulator, and the phase of the light is shifted sequentially within the range of 2π at each point. By scanning each point of the input end face of the multimode fiber, a speckle pattern is generated at the output end of the multimode fiber. (3) The speckle pattern interferes with the reference beam output from the single-mode fiber to form an interference pattern. The optimal phase and amplitude of the detection position are extracted by the second CMOS camera. (4) Repeat steps (2) and (3) to obtain the image generated by the optimal phase and amplitude of all scanning points, generate the optimized hologram, and calculate it by fast Fourier transform; (5) Finally, the optimized hologram is sent to the spatial light modulator to generate a shaping field at the output end of the multimode fiber and create an optimized focus.

7. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 6, characterized in that, The step of sequentially scanning the input end face of the multimode fiber through the diffraction limit point includes the following steps: (1) A third lens, an aperture, a fourth lens, a first quarter glass plate, and a first objective lens are sequentially arranged on the optical path from the spatial light modulator to the input end of the multimode fiber; wherein the third lens and the fourth lens constitute the first 4f system, and the fourth lens and the first objective lens constitute the second 4f system. (2) The first 4f system images the spatial light modulator onto the first objective lens, and the second 4f system images the selected diffraction limit point onto the input end face of the multimode fiber, wherein the aperture is selected as the first diffraction order, and the first quarter glass plate is used to control the polarization state of the signal beam propagating in the multimode fiber.

8. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 7, characterized in that, A first beam splitter is also provided in the optical path from the fourth lens to the first quarter-wave plate. The first beam splitter splits the laser beam from the fourth lens into a third laser beam and a fourth laser beam. The third laser beam is incident on the first quarter-wave plate, and a third CMOS camera is provided in the path of the fourth laser beam to monitor and modulate the fourth laser beam.

9. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 6, characterized in that, The output end of the multimode fiber is provided with a second objective lens, a second quarter glass slide, and a second beam splitter. The second beam splitter combines the output light of the single-mode fiber and the output light of the multimode fiber. The second CMOS camera is set in the optical path after the beam is combined.

10. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 8, characterized in that, Before sequentially scanning the input end of a multimode fiber using diffraction-limited points, a spatial light modulator calibration step is also included: the spatial light modulator is calibrated by generating a loop-up table or creating a compensated hologram by capturing the amplitude of the interference pattern of the interference fringes.

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