Device and method for capturing and operating biomass aerosol based on optical fiber optical tweezers

Abstract

The invention discloses a device and method for capturing and operating biomass aerosol based on optical fiber optical tweezers, and the device comprises a laser device, and an isolator, a beam expanding assembly, a first half-wave plate and a polarization beam splitter which are sequentially arranged along a light path of a laser beam, wherein the polarization beam splitter is used for dividing the laser beam into a first laser beam and a second laser beam; the system further comprises a single-mode optical fiber, a multimode optical fiber, a spatial light modulator and an aerosol capturing chamber. The first laser beam and the second laser beam are respectively coupled into the input ends of the multimode optical fiber and the single-mode optical fiber, and the output ends of the multimode optical fiber and the single-mode optical fiber enter the aerosol capturing chamber; the spatial light modulator is used for modulating an input light field of the multimode optical fiber to create an optimized focus in an output light field; the aerosol capture chamber is equipped with a first CMOS camera, a long focal length objective lens and a Kohler illumination system. According to the device for capturing and operating the biomass aerosol, the two limitation problems that traditional single biomass aerosol particles are difficult to capture and control are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic tweezers, and in particular to a device and method for capturing and manipulating biomass aerosols based on fiber optic tweezers. Background Art

[0002] Biomass aerosols refer to tiny solid and liquid particles of biomass dispersed in the air, which have a wide range of applications and economic impacts. These aerosols are not only present in the smoke produced by the burning of biomass fuels, but are also released in large quantities through factory emissions and forest fires, causing local and global pollution. At the same time, biomass aerosols have a significant impact on climate through atmospheric processes and play an important role in cooling the earth and preventing uncontrolled warming. However, the study and isolation of individual biomass aerosol processes are very difficult, and there are many significant unresolved uncertainties. One of the main reasons for the current uncertainty in the properties of biomass aerosols is that biomass aerosols are usually small particles that move quickly and constantly interact with the environment, so traditional in situ biomass aerosol analysis is both challenging and destructive. The current feasible solution is to capture and manipulate individual biomass aerosols using optical trapping (optical tweezers) technology. This technology uses a focused laser to capture particles. Optical trapping (optical tweezers) technology has been widely used in multiple disciplines due to its non-contact, low-damage and high versatility. Since Ashkin first proposed this technology in 1970, it has been developed for more than 50 years and won the Nobel Prize in Physics in 2018. In the past decade, the use of this technology to capture and manipulate the dynamics of individual biomass aerosols and study their physicochemical properties has attracted great interest and attention. In the study of biomass aerosols, whether it is the design of optical capture devices, the analysis of the dynamic characteristics of biomass aerosol particles after capture, or the analysis and study of the physical and chemical characteristics of biomass aerosol particles after capture, a lot of work has been carried out at home and abroad, and significant progress has been made.

[0003] Traditional optical capture devices for studying biomass aerosols rely on microscope objectives with high numerical apertures and their complex optical systems, which makes the entire system difficult to reconfigure, bulky, expensive, and requires professional operators. In addition, when capturing and manipulating biomass aerosols in the air based on traditional optical capture devices, the stability of capture is another major challenge. This is mainly due to two reasons: First, the low viscosity of the suspension medium: the suspended biomass aerosol is more sensitive to the surrounding fluctuations, resulting in unstable capture. Second, the relative refractive index is high: the relative refractive index of biomass aerosol in the air is high, making it more susceptible to scattering forces and being pushed away from the capture field. Therefore, improving the stability of biomass aerosol particle capture and manipulation in a gaseous environment has become a technical bottleneck that needs to be urgently solved by current traditional optical capture devices. Summary of the invention

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

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

[0006] The technical solution is as follows:

[0007] A device for capturing and manipulating biomass aerosol based on fiber optic tweezers, comprising a laser emitting a laser beam, an isolator arranged in sequence along the optical path of the laser beam, a beam expansion component, 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, the device also comprising a single-mode optical fiber, a multi-mode optical 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 optical fiber and the single-mode optical fiber respectively, and the output ends of the multimode optical fiber and the single-mode optical fiber enter the aerosol capture chamber and are located at two opposite sides of the aerosol capture chamber; the spatial light modulator is used to modulate the input light field of the multimode optical fiber to create an optimized focus in the output light field;

[0009] A first CMOS camera and a long focal length objective lens are arranged above the aerosol capture chamber, and the long focal length objective lens is located near one side of the capture chamber, and a Kohler illumination system is arranged below the capture chamber.

[0010] In one embodiment, the beam expansion component is a 6x telescope system beam expansion lens group for expanding the diameter of the laser beam; and / or the long focal length objective lens is a 20x distance objective lens.

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

[0012] In one embodiment, the device further comprises a fiber clamp for clamping a single-mode optical fiber or a dual-mode optical fiber.

[0013] In one embodiment, a device for capturing and manipulating biomass aerosols based on fiber optic tweezers prepares and delivers aerosols through an aerosol delivery structure, wherein the aerosol delivery structure 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.

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

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

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

[0017] (3) Aerosol preparation and delivery: Capturing and delivering aerosols through aerosol delivery structures;

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

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

[0020] In one embodiment, the spatial light modulator modulates the input light field of the multimode optical fiber to shape the output light field into an optimized focus, comprising the following steps:

[0021] (1) Splitting the laser into two beams through an isolator, a first half-wave plate, and a polarization beam splitter, controlling the power ratio of the two beams by rotating the first half-wave plate, coupling one laser beam to a single-mode optical fiber as a reference beam, and the other laser beam as a signal beam, the signal beam is incident on a spatial light modulator through a beam expansion component and a second half-wave plate, and aligning the polarization between the signal beam and the spatial light modulator through the second half-wave plate;

[0022] (2) A grating is loaded on a spatial light modulator, and the input end face of the multimode optical fiber is sequentially scanned through a diffraction-limited point. The point is modulated by the spatial light modulator, and at each point, the phase of the light is also sequentially shifted within a range of 2π; by scanning each point on the input end face of the multimode optical fiber, a speckle pattern is generated at the output end of the multimode optical fiber;

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

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

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

[0026] In one embodiment, sequentially scanning the input end face of the multimode optical fiber through the diffraction-limited points comprises the following steps: (1) a third lens, an aperture, a fourth lens, a first quarter glass, and a first objective lens are sequentially arranged on an optical path from a spatial light modulator to an input end of a multimode optical fiber; wherein the third lens and the fourth lens constitute a first group of 4f systems, and the fourth lens and the first objective lens constitute a second group of 4f systems; (2) The first group of 4f systems images the spatial light modulator onto the first objective lens, and the second group of 4f systems images the selected diffraction-limited point onto the input end face of the multimode optical fiber, where the aperture selects the first diffraction order and the first quarter glass is used to control the polarization state of the signal light beam propagating in the multimode optical fiber.

[0027] In one embodiment, a first beam splitter is further provided on the optical path from the fourth lens to the first quarter wave plate, and 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 on the path of the fourth laser beam for monitoring and modulating the fourth laser beam.

[0028] In one embodiment, the output end of the multimode optical fiber is provided with a second objective lens, a second quarter glass and a second beam splitter, the second beam splitter combines the output light of the single-mode optical fiber and the output light of the multimode optical fiber, and the second CMOS camera is arranged on the optical path after the combination.

[0029] In one embodiment, the step of sequentially scanning the input end face of the multimode optical fiber through the diffraction-limited points also includes a spatial light modulator calibration step: the calibration of the spatial light modulator is completed by capturing the amplitude of the interference fringe interference pattern to generate a LOOP-UP-TABLE or create a compensation hologram.

[0030] In one embodiment, the aerosol is captured and transported by the aerosol transport structure as follows: an ultrasonic nebulizer prepared with a NaCl solution is provided, and a nozzle with adjustable length and angle is provided at the end of the ultrasonic nebulizer, aerosol particles are captured by the ultrasonic nebulizer to generate an aerosol, and the speed and direction of the aerosol entering the aerosol capture chamber are precisely controlled by the nozzle.

[0031] The beneficial effects of the present invention are as follows: the present invention uses an optical capture device based on fiber optic tweezers to capture and manipulate biomass aerosols, which has the unique advantages of miniaturization, easy integration, and no need for expensive optical components. Through the reversely arranged dual-fiber opposing structure, a capture potential well for a single biomass aerosol particle can be constructed to form a stable potential field for capturing and manipulating biomass aerosol particles. The entire capture device is easy to operate and is very suitable as a platform for developing the capture and manipulation of a single biomass aerosol; the input light field of the multimode optical fiber is modulated by a spatial light modulator to create an optimized focus in the output light field, thereby optimizing the capture field and improving the capture stability, effectively solving the problem of light scattering caused by the capture chamber and the surface covering of the optical fiber end, and ensuring that the system can operate efficiently in various dynamic processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of the device for capturing and manipulating biomass aerosol based on fiber optic tweezers in Example 1.

[0033] Figure 2 Schematic diagram of the device for modulating the input light field of multimode optical fiber using a spatial light modulator.

[0034] Figure 3 Schematic diagram of how a multimode fiber is modulated to produce an optimized focus for a spatial light modulator.

[0035] Figure 4 Schematic diagram of the optical setup for phase modulation calibration of a spatial light modulator.

[0036] Figure 5 This is a schematic diagram of the aerosol delivery structure.

[0037] Explanation of the reference numerals: 1. laser; 2. isolator; 3. reflector; 4. beam expansion assembly; 5. first half-wave plate; 6. polarization beam splitter; 7. single-mode optical fiber; 8. multi-mode optical 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; 17. fourth lens; 18. first quarter glass; 19. first objective lens; 20. first beam splitter; 21. third CMOS camera; 22. second objective lens; 23. second quarter glass; 24. second beam splitter; 25. second CMOS camera; 26. optimized multi-mode optical fiber; 27. third objective lens; 28. optical fiber clamp. DETAILED DESCRIPTION

[0038] The drawings of the present invention are only for illustrative purposes and should not be construed as limiting the present invention. In order to better illustrate the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment discloses a device for capturing and manipulating biomass aerosol based on fiber optic tweezers, comprising a laser 1 for emitting a laser beam, an isolator 2 (Thorlabs IO-3-532-LP) arranged in sequence along the optical path of the laser beam, a beam expansion component 4, a first half-wave plate 5, and a polarization beam splitter 6 for splitting the laser beam into a first laser beam and a second laser beam, and the device further comprises a single-mode optical fiber 7 (Thorlabs P1-460AR-2), multimode optical fiber 8, spatial light modulator 9 and aerosol capture chamber 10; the first laser beam is coupled into the input end of the multimode optical fiber 8, the second laser beam is coupled into the input end of the single-mode optical fiber 7, the output ends of the multimode optical fiber 8 and the single-mode optical fiber 7 enter the aerosol capture chamber 10 and are located on two opposite sides of the aerosol capture chamber 10; the spatial light modulator 9 is used to modulate the input light field of the multimode optical fiber 8 to create an optimized focus in the output light field; the aerosol capture chamber 10 is equipped with a first CMOS camera 11 (BasleracA2040-120μm) and a long focal length objective lens 12 (Motic ELWD 20X) above the aerosol capture chamber 10 and the long focal length objective lens 12 is located close to the side of the capture chamber 10, and the capture chamber 10 is equipped with a Kohler illumination system 13 below.

[0041] 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 expands the beam diameter through a beam expander 4. 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 captured single biomass aerosol particles. In order to ensure clear imaging of the captured aerosol particles, a Kohler illumination system 13 is configured to illuminate the aerosol biomass sol particles by using Kohler illumination technology, and then the video data during the capture process is analyzed by an algorithm to accurately analyze the size and other physical properties of the aerosol particles.

[0042] Specifically, in this embodiment, the laser 1 is a laser with a wavelength of 532 nm (Torus Laser Quantum 891 mW), which has high stability and high power output, ensuring a stable light source during the experiment.

[0043] Specifically, in this embodiment, the beam expansion assembly 4 is a 6-fold telescope system beam expansion lens group for expanding the diameter of the laser beam, including a first lens and a second lens.

[0044] Specifically, in this embodiment, the long focal length objective lens 12 is a 20-fold distance objective lens.

[0045] Specifically, in this embodiment, the mode field diameter of the single-mode optical fiber 7 is 2.8 μm to 4.1 μm at 488 nm.

[0046] Specifically, in this embodiment, the second laser beam is coupled into the single-mode optical fiber 7 through the third objective lens 27. More specifically, the third objective lens 27 is a 10x objective lens.

[0047] The device further comprises an optical fiber clamp 28 for clamping the single-mode optical fiber 7 and the multi-mode optical fiber 8 to ensure stable control of optical fiber coupling.

[0048] The device based on fiber optic tweezers to capture and manipulate biomass aerosols is used to prepare and deliver aerosols through an aerosol delivery structure, 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 them from evaporating rapidly. The length and angle of the nozzle are adjustable, so that the entry speed and direction of the aerosol can be accurately controlled to ensure that the aerosol particles can effectively enter the aerosol capture chamber 10.

[0049] Furthermore, a reflector 3 is provided on the optical path of the laser beam due to actual needs. The reflector 3 is used to change the propagation direction of the laser beam so as to make the structure of the device for capturing and manipulating biomass aerosol based on optical fiber tweezers more compact. In this embodiment, the specific position where the reflector 3 should be set is not further elaborated. Those skilled in the art can set it as needed to make the device more compact.

[0050] This embodiment also discloses a method for capturing and manipulating biomass aerosol based on fiber optic tweezers, comprising the following steps:

[0051] (1) Setting device: Assemble as follows Figure 1 The device for capturing and manipulating biomass aerosols based on fiber optic tweezers shown in the figure enables the laser beam of the laser 1 to enter the aerosol capture chamber 10 according to the following optical path: first passing through the isolator 2 and then through the beam expansion component 4 to obtain a uniform laser beam after expansion, the laser beam is divided into a first laser beam and a second laser beam by the first half-wave plate 5 and the polarization beam splitter 6, the power ratio of the two laser beams is controlled by adjusting the first half-wave plate 5, the first laser beam and the second laser beam are coupled into the input ends of the multimode optical fiber 8 and the single-mode optical fiber 7 respectively, the input light field of the multimode optical fiber 8 is modulated by the spatial light modulator 9 to create an optimized focus in the output light field to form an optimized multimode optical fiber 26, the output ends of the multimode optical fiber 8 and the single-mode optical fiber 7 enter the aerosol capture chamber 10 and are located on two opposite sides of the aerosol capture chamber 10, thereby forming fiber optic tweezers on two opposite sides of the aerosol capture chamber 10.

[0052] (2) Environmental control: The aerosol capture chamber 10 is designed to be a sealed structure, and wet tissues are placed in the aerosol capture chamber 10 to maintain a humid environment. This can reduce airflow interference and provide stable experimental conditions.

[0053] (3) Aerosol preparation and delivery: Aerosols are captured and delivered by an aerosol delivery structure. Aerosols are generated using an ultrasonic atomizer (OMRON NE-U100-E) and delivered to the aerosol capture chamber 10 through a customized nozzle. The length and angle of the nozzle can be adjusted to precisely control the entry speed and direction of the aerosol, ensuring that the particles can effectively enter the aerosol capture chamber 10.

[0054] (4) Recording and analysis: The aerosol capture chamber 10 is illuminated by the configured Kohler illumination system 13 to obtain a clear image of the captured aerosol. The dynamics of a single aerosol are recorded and analyzed by the first CMOS camera 11 and the long focal length objective lens 12. The video data during the capture process is then analyzed by the MATLAB algorithm, thereby accurately analyzing the physical properties of the aerosol.

[0055] (5) Fiber processing: After each experiment, the end faces of the multimode fiber 8 and the single-mode fiber 7 were cleaned and accurately re-aligned to ensure high repeatability and accuracy of the system.

[0056] In order to improve the capture stability and capture efficiency, the present embodiment needs to use beam shaping technology. Through beam shaping, the depth and uniformity of the capture potential well are enhanced, thereby improving the capture efficiency. In addition, when capturing a single liquid aerosol, the surface of the aerosol capture chamber 10 and the optical fiber end face will be covered by droplets or absorbing particles, resulting in light scattering or distortion, thereby reducing the capture efficiency or causing capture failure. In order to improve the capture stability, capture efficiency and solve the scattering problem, the present embodiment modulates the input light field of the multimode optical fiber 8 through a spatial light modulator 9 to shape the output light field into an optimized focus. The schematic diagram of the device for modulating the input light field of the multimode optical fiber with a spatial light modulator is shown in FIG. Figure 2 As shown, the specific steps include:

[0057] (1) Splitting the laser into two beams through the isolator 2, the first half-wave plate 5, and the polarization beam splitter 6, controlling the power ratio of the two beams by rotating the first half-wave plate 5, coupling one laser beam to the single-mode optical fiber 7 as a reference beam, and the other laser beam as a signal beam, the signal beam is incident on the spatial light modulator 9 through the beam expansion component 4 and the second half-wave plate 14, and aligning the polarization between the signal beam and the spatial light modulator 9 through the second half-wave plate 14;

[0058] (2) A grating is loaded on the spatial light modulator 9, and the input end face of the multimode optical fiber 8 is sequentially scanned through the diffraction limit point. The point is modulated by the spatial light modulator 9, and at each point, the phase of the light is also sequentially shifted within the range of 2π; by scanning each point on the input end face of the multimode optical fiber 8, a speckle pattern is generated at the output end of the multimode optical fiber 8;

[0059] (3) The speckle pattern interferes with the reference beam output from the single-mode optical fiber 7 to form an interference pattern, and the optimal phase and amplitude of the detection position are extracted by the second CMOS camera 25 (Basler acA2040-120 μm);

[0060] (4) repeating steps (2) and (3) to obtain images generated by the optimal phase and amplitude of all scanning points, generate an optimized hologram, and calculate it through fast Fourier transform;

[0061] (5) The optimized hologram is finally sent to the spatial light modulator 9, which generates a shaped field at the output end of the multimode optical fiber 8 to create an optimized focus.

[0062] like Figure 3 The figure shows the principle diagram of spatial light modulator 9 modulating multimode optical fiber to produce optimized focus. Figure 3 (a): The input end face of a multimode optical fiber 8 is sequentially scanned by a diffraction-limited point, which is modulated by a spatial light modulator 9 to which a grating is applied. In addition, at each point, the phase of the light is also shifted in the range of 2π. Figure 3 (b): When scanning each point of the input end face of the multimode optical fiber 8, the output field of the multimode optical fiber 8 is a speckle pattern. Figure 3 (c): The interference pattern generated by the superposition of the output field of the multimode optical fiber 8 and the collimated Gaussian beam transmitted through the single-mode optical 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): When all scans and corresponding phase shifts are completed, all optimal phases and amplitudes at the detection positions can be obtained and used to generate the optimized hologram. Figure 3 (e): By sending the optimized hologram to the spatial light modulator 9 to generate a shaped field at the input side of the multimode optical fiber 8, an optimized focus is created at the output end of the multimode optical fiber 8.

[0063] Furthermore, the sequential scanning of the input end face of the multimode optical fiber 8 through the diffraction-limited points comprises the following steps:

[0064] (1) A third lens 15, an aperture 16 (Thorlabs SM1D12D), a fourth lens 17, a first quarter glass 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 optical fiber 8; wherein the third lens 15 and the fourth lens 17 constitute a first group 4f system, and the fourth lens 17 and the first objective lens 19 constitute a second group 4f system;

[0065] (2) The first group of 4f systems images the spatial light modulator 9 onto the first objective lens 19, and the second group of 4f systems images the selected diffraction limit point onto the input end face of the multimode optical fiber 8, where the aperture 16 selects the first diffraction order, and the first quarter glass 18 is used to control the polarization state of the signal light beam propagating in the multimode optical fiber 8.

[0066] Furthermore, a first beam splitter 20 is provided on 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. A third CMOS camera 21 (Basler acA1920-150μm) is provided on the path of the fourth laser beam for monitoring and modulating the fourth laser beam.

[0067] Furthermore, the output end of the multimode optical fiber 8 is provided with a second objective lens 22, a second quarter glass 23 and a second beam splitter 24, the second beam splitter 24 combines the output light of the single-mode optical fiber 7 and the output light of the multimode optical fiber 8, and the second CMOS camera 25 is arranged on the optical path after the combination.

[0068] Furthermore, the method further includes a spatial light modulator 9 calibration step before sequentially scanning the input end face of the multimode optical fiber through the diffraction-limited point: by capturing the amplitude of the interference fringe interference pattern to generate a LOOK-UP-TABLE or create a compensation hologram, the calibration of the spatial light modulator is completed. Furthermore, the calibrated spatial light modulator 9 is used to modulate the phase of the light, such as Figure 4 The optical setup for phase modulation calibration of the spatial light modulator 9 is shown, wherein 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.

[0069] Through the above method, this embodiment achieves efficient capture and stable manipulation of a single biomass aerosol, overcomes the technical bottleneck of traditional optical capture devices, and provides a novel and practical solution for the study of biomass aerosols.

[0070] The device and method for capturing and manipulating biomass aerosols based on fiber optic tweezers of this embodiment have the following advantages:

[0071] (1) On the one hand, the optical capture device based on optical fiber has the unique advantages of miniaturization, easy integration, and no need for expensive optical components. Through the reversely arranged dual optical fiber opposing structure, a capture potential well for a single biomass aerosol particle can be constructed, forming a stable potential field for capturing and manipulating biomass aerosol particles. The entire capture device is easy to operate and is very suitable as a platform for developing the capture and manipulation of a single biomass aerosol.

[0072] (2) On the other hand, the introduction of beam shaping technology overcomes the shortcomings of traditional optical tweezers systems in terms of stability in capturing aerosol particles. Beam shaping technology optimizes the capture field, improves capture stability, and effectively solves the light scattering problem caused by the capture cavity and the surface covering of the optical 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 based on fiber optic tweezers realizes real-time dynamic analysis of single biomass aerosol particles with low cost, easy operation, compact size, and high stability.

[0073] (3) The system provides a flexible and user-friendly platform designed to provide a more comprehensive understanding of biomass aerosol processes that support 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.

[0074] 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 methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in 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 comprises a laser for emitting a laser beam, an isolator arranged in sequence along the optical path of the laser beam, a beam expansion 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, the device also comprising 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 multimode optical fiber and the single-mode optical fiber respectively, and the output ends of the multimode optical fiber and the single-mode optical fiber enter the aerosol capture chamber and are located at two opposite sides of the aerosol capture chamber; the spatial light modulator is used to modulate the input light field of the multimode optical fiber to create an optimized focus in the output light field; A first CMOS camera and a long focal length objective lens are arranged above the aerosol capture chamber, and the long focal length objective lens is located near one side of the capture chamber, and a Kohler illumination system is arranged below the capture chamber.

2. The device for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 1, characterized in that: The beam expansion component is a 6-fold telescope system beam expansion lens group for expanding the diameter of the laser beam; and / or the long focal length objective lens is a 20-fold distance objective lens.

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 the single-mode optical fiber through a third objective lens, and the third objective lens 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 aerosol based on fiber optic tweezers prepares and transports aerosol through an aerosol transport structure, wherein the aerosol transport structure comprises an ultrasonic atomizer and a nozzle arranged 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: The steps include: (1) Setting up the device: Assemble and set up 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 according to the following optical path: first pass through the isolator and then pass through the beam expansion component to obtain a uniform laser beam after beam expansion, split the laser beam into a first laser beam and a second laser beam through a first half-wave plate and a polarization beam splitter, control the power ratio of the two laser beams by adjusting the first half-wave plate, couple the first laser beam and the second laser beam into the input end of the multimode optical fiber and the single-mode optical fiber respectively, modulate the input light field of the multimode optical fiber through a spatial light modulator to create an optimized focus in the output light field, and the output ends of the multimode optical fiber and the single-mode optical fiber enter the aerosol capture chamber and are located at 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 to be a sealed structure, and wet tissues are placed inside the aerosol capture chamber to maintain the humidity environment; (3) Aerosol preparation and delivery: Capturing and delivering aerosols through aerosol delivery structures; (4) Recording and analysis: The aerosol capture chamber is illuminated by a Kohler illumination system to obtain a clear image of the captured aerosol. The dynamics of a single aerosol are recorded and analyzed by the first CMOS camera and a long focal length objective lens. The video data during the capture process is analyzed by a MATLAB algorithm to accurately analyze the physical properties of the aerosol. (5) Fiber processing: After each experiment, the end faces of the multimode fiber and single-mode fiber are cleaned and accurately realigned 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 light field of the multimode optical fiber to shape the output light field into an optimized focus, comprising the following steps: (1) Splitting the laser into two beams through an isolator, a first half-wave plate, and a polarization beam splitter, controlling the power ratio of the two beams by rotating the first half-wave plate, coupling one laser beam to a single-mode optical fiber as a reference beam, and the other laser beam as a signal beam, the signal beam is incident on a spatial light modulator through a beam expansion component and a second half-wave plate, and aligning the polarization between the signal beam and the spatial light modulator through the second half-wave plate; (2) A grating is loaded on a spatial light modulator, and the input end face of the multimode optical fiber is sequentially scanned through a diffraction-limited point. The point is modulated by the spatial light modulator, and at each point, the phase of the light is also sequentially shifted within a range of 2π; by scanning each point on the input end face of the multimode optical fiber, a speckle pattern is generated at the output end of the multimode optical fiber; (3) The speckle pattern interferes with the reference beam output from the single-mode fiber to form an interference pattern, and the optimal phase and amplitude of the detection position are extracted by a second CMOS camera; (4) repeating steps (2) and (3) to obtain images generated by the optimal phase and amplitude of all scanning points, generate an optimized hologram, and calculate it through fast Fourier transform; (5) The optimized hologram is finally sent to a spatial light modulator to generate a shaped field at the output end of the multimode fiber to 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 optical fiber through the diffraction-limited points comprises the following steps: (1) a third lens, an aperture, a fourth lens, a first quarter glass, and a first objective lens are sequentially arranged on an optical path from a spatial light modulator to an input end of a multimode optical fiber; wherein the third lens and the fourth lens constitute a first group of 4f systems, and the fourth lens and the first objective lens constitute a second group of 4f systems; (2) The first group of 4f systems images the spatial light modulator onto the first objective lens, and the second group of 4f systems images the selected diffraction-limited point onto the input end face of the multimode optical fiber, where the aperture selects the first diffraction order and the first quarter glass is used to control the polarization state of the signal light beam propagating in the multimode optical 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 on 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. A third CMOS camera is provided on the path of the fourth laser beam for monitoring and modulating 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 optical fiber is provided with a second objective lens, a second quarter glass and a second beam splitter. The second beam splitter combines the output light of the single-mode optical fiber and the output light of the multimode optical fiber. The second CMOS camera is arranged on the combined optical path.

10. The method for capturing and manipulating biomass aerosols based on fiber optic tweezers according to claim 8, characterized in that: The spatial light modulator calibration step is also included in front of the input end face of the multimode optical fiber by sequentially scanning the diffraction-limited points: the calibration of the spatial light modulator is completed by capturing the amplitude of the interference fringe interference pattern to generate a loop-up table or create a compensation hologram.

Images