Experimental device for coupling optical acting force and optical nonlinear measurement of suspension

Abstract

The invention relates to an experimental device for coupling optical acting force and suspension liquid optical nonlinear measurement, which comprises a laser control module and a microscopic imaging module, and the laser control module and the microscopic imaging module are respectively arranged in two orthogonal directions of a suspension liquid; the suspension liquid is placed in a transparent sample pool; the laser control module comprises a laser, a beam expander, a focusing lens, an imaging lens and a light beam analyzer which are arranged in sequence; the sample cell is positioned between the focusing lens and the imaging lens; the microscopic imaging module comprises a light source, a lighting lens, an imaging lens and an imaging camera which are arranged in sequence; the sample cell is located between the illumination lens and the imaging lens. Compared with the prior art, the device is provided with the laser control module, so that backward acting force for inducing particles in the suspension can be formed, and meanwhile, the focusing nonlinear effect in the suspension can be researched; and the microscopic imaging module can record moving images of particles in the suspension for subsequent analysis.

Description

Technical Field

[0001] This invention relates to nonlinear optics of suspensions, and more particularly to an experimental apparatus for measuring optical nonlinearity of suspensions by coupling optical forces. Background Technology

[0002] Nature is filled with numerous micro and nanoparticles existing in suspension, such as the various microplastic particles in the ocean, algal cells, and red blood cells in the human body. During drug encapsulation, plastic particles are often introduced to varying degrees from packaging materials; therefore, the research and control of plastic particulate matter is of great interest in drug manufacturing. More generally, the study of particles in suspensions has increasingly important applications in controlling environmental pollution, disease detection, and evaluating drug treatment efficacy, and is gradually gaining attention.

[0003] The measurement of optical forces and the optical nonlinear properties of suspensions involves measuring two different physical properties of suspensions at both the microscopic and macroscopic levels. Optical forces study the mechanical interaction between light and suspended particles at the single-particle level, while optical nonlinearity studies the novel effects caused by the nonlinear transmission of light through a suspended particle system at the macroscopic level. Understanding the study of optical forces at the single-particle level helps to understand the mechanism of optical nonlinearity.

[0004] Optical technology enables contactless, pollution-free, and non-destructive study of the interaction between light and particulate matter in suspensions, providing crucial information for drug quality control and disease detection. Since most suspended particles are composed of dielectric particles, metallic particles, or a combination of both, and these particles are subjected to forces from light irradiation, and at resonant wavelengths, they also exert a significant influence on the spatial distribution of the light field, an experimental setup is needed to efficiently study the interaction between light and these particles.

[0005] International research has largely focused on novel phenomena arising from the nonlinear transmission of light in solid materials. Reports have documented studies on the self-focusing of light in biological material solutions, such as tea water, marine algae cells, red blood cells, and chlorophyll suspensions or solutions. Nonlinear light transmission in soft matter systems has also become a popular research area in the last decade. However, effective methods for studying the mechanical interactions between light and individual particles during nonlinear transmission, as well as an effective experimental platform for understanding the structure-property relationship between microscopic single-particle optical forces and macroscopic nonlinear light transmission, remain lacking.

[0006] A search revealed that application publication number CN115406878A discloses a rapid three-dimensional multi-parameter nonlinear optical characterization microscopic imaging system, specifically comprising a signal generation and detection device and an imaging processing terminal. The signal generation and detection device includes: an excitation optical path module for generating excitation light to realize various nonlinear processes and spatially collinearly incident on a scanning microscope; a sample control module for carrying and moving the sample; a scanning and focusing module for focusing the laser from the excitation optical path module onto the sample on the sample carrier and realizing scanning excitation; and a nonlinear signal detection module for detecting the multi-parameter nonlinear signals generated by the sample on the sample carrier. The imaging processing terminal includes: a signal demodulation module for demodulating the multi-parameter nonlinear signals; and signal acquisition and synchronization control for synchronous acquisition of multi-parameter nonlinear signals, synchronous control of the scanning microscope, and image reconstruction and storage. However, this prior art only involves nonlinear optical characterization imaging and is based on a pump-probe multi-parameter process, without addressing the nonlinear transmission of light.

[0007] In summary, the technical problem that needs to be solved is how to design an experimental device that integrates optical force manipulation and measurement of optical nonlinear transmission in suspension. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art, which makes it difficult to simultaneously measure optical forces and the optical nonlinear characteristics of suspensions, and to provide an experimental device that couples the measurement of optical forces and the optical nonlinear characteristics of suspensions.

[0009] The objective of this invention can be achieved through the following technical solutions.

[0010] According to one aspect of the present invention, an experimental apparatus for coupling optical forces and measuring the optical nonlinearity of a suspension is provided, comprising a laser control module and a microscopic imaging module, wherein the laser control module and the microscopic imaging module are respectively arranged in two orthogonal directions of the suspension; the suspension is placed in a transparent sample cell; The laser control module includes a laser, a beam expander, a focusing lens, an imaging lens, and a beam analyzer arranged in sequence; the sample cell is located between the focusing lens and the imaging lens. The microscopic imaging module includes a light source, an illumination lens, an imaging lens, and an imaging camera arranged in sequence; the sample cell is located between the illumination lens and the imaging lens.

[0011] As a preferred technical solution, a filter is also provided between the sample cell and the imaging lens.

[0012] As a preferred technical solution, a beam attenuator is also provided between the imaging lens and the beam analyzer.

[0013] As a preferred technical solution, the light source is an LED light source or a laser light source; the laser includes one or more sub-lasers, and different sub-lasers are turned on when the experimental device is in different working states.

[0014] As a preferred technical solution, the sub-laser includes a green laser with a wavelength of 532nm.

[0015] As a preferred technical solution, the laser control module further includes a dichroic mirror, an auxiliary laser, and a reflector sequentially disposed between the laser and the beam expander; the auxiliary laser includes a near-infrared laser with a wavelength of 1.5 μm.

[0016] As a preferred technical solution, the imaging camera performs single-particle tracking to locate the position and instantaneous velocity of a single particle in the suspension in different video frames.

[0017] As a preferred technical solution, the imaging camera records the spatial distribution of the nonlinear beam in the light field at the output end of the suspension.

[0018] As a preferred technical solution, the beam analyzer measures the spatial distribution of the laser spot before and after the laser is incident on the sample cell.

[0019] As a preferred technical solution, the sample cell is a cuvette, and the particles in the suspension are micron-sized or nano-sized particles.

[0020] Compared with the prior art, the present invention has the following beneficial effects.

[0021] 1) The laser manipulation module of this invention can generate a backward force to induce particles in a suspension, and can also study the focusing nonlinear effect in the suspension; the microscopic imaging module can record the motion images of particles in the suspension for subsequent analysis. An imaging camera directly facing the laser can measure the size and distribution of the output light spot after the laser passes through the suspension. When the laser power is relatively low, such as 1mW, the light undergoes linear diffraction in the suspension system, resulting in a large output light spot. When the laser power increases, due to the interaction between the light and the substances in the suspension, the nonlinearity of the suspension system increases, and self-focusing occurs during light propagation, causing the output light spot to shrink to the same size as the input light spot.

[0022] 2) The present invention sets a filter between the sample cell and the imaging lens, which can remove the influence of nonlinear laser scattered by particles in the suspension on the tracking of the movement position of suspended particles; and sets a beam attenuator between the imaging lens and the beam analyzer, which can avoid damage to the optical receiving equipment by excessive light signals. At the same time, the attenuation ratio of the beam attenuator can be adjusted to achieve accurate detection of the spatial distribution of output laser with different laser powers.

[0023] 3) The laser of this invention includes multiple sub-lasers, which can be used to apply optical forces to microscopic particles at the same time and study the nonlinear transmission of light in the suspension system. Different sub-lasers can also be used to carry out different types of research: for example, a near-infrared laser with a wavelength of 1.5 μm can be used to form a backward force that induces micron particles in the suspension, and a green laser with a wavelength of 532 nm can be used to study the nonlinear transmission of light in the suspension.

[0024] 4) The dichroic mirror of this invention is used to couple two lasers with different wavelengths, so that the two lasers can simultaneously irradiate the sample cell; the auxiliary laser is a near-infrared laser, which is used to generate optical force on the particulate matter; the reflector is used to deflect the near-infrared laser.

[0025] 5) The imaging camera of this invention can perform single-particle tracking and can also record the spatial distribution of the light field at the output end of the nonlinear beam, which can be used for different experimental requirements. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0028] Figure 3 This is a schematic diagram of the state of the suspension under linear beam conditions according to the present invention.

[0029] Figure 4 This is a schematic diagram of the state of the suspension under the nonlinearity of the beam according to the present invention.

[0030] Figure 5 This is a schematic diagram of the state of the suspension when optical scattering force exists, according to the present invention.

[0031] Figure 6 This is a schematic diagram of the state of the suspension when an optical backward force exists, according to the present invention.

[0032] The numbers in the diagram are as follows: 1. Sample cell; 201. Laser; 202. Beam expander; 203. Focusing lens; 204. Imaging lens; 205. Beam analyzer; 206. Beam attenuator; 207. Dichroic mirror; 208. Auxiliary laser; 209. Mirror; 301. Light source; 302. Illumination lens; 303. Imaging lens; 304. Imaging camera. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] Example 1 like Figure 1 As shown, this embodiment provides an experimental apparatus for coupling optical forces and nonlinear optical measurements of suspensions, used for optical force observation and nonlinear optical experiments. It includes a laser control module, a microscopic imaging module, and a sample cell 1. The suspension is placed in the sample cell 1, which is transparent in all four directions. The laser control module and the microscopic imaging module are respectively arranged in two orthogonal directions of the suspension. The sample cell 1 is a cuvette.

[0035] The laser control module includes a laser 201, a beam expander 202, a focusing lens 203, an imaging lens 204, a beam attenuator 206, and a beam analyzer 205 arranged sequentially. The sample cell 1 is located between the focusing lens 203 and the imaging lens 204. The beam expander 202 is a beam expander. The beam attenuator 206 is used to attenuate the laser power. A filter can be installed between the sample cell 1 and the imaging lens 204 to filter out nonlinear laser light scattered from the imaging system.

[0036] The laser 201 can be a green laser with a wavelength of 0.532 μm, which is used to generate optical scattering force for micron particles in the induced suspension, and can also be used to study the focusing nonlinear effect in the photo-suspension. The beam analyzer 205 is used to measure the spatial distribution of the laser spot before and after the laser is incident on the cuvette.

[0037] The microscopic imaging module includes a light source 301, an illumination lens 302, an imaging lens 204 and an imaging camera 304 arranged in sequence; the sample cell 1 is located between the illumination lens 302 and the imaging lens 204.

[0038] Preferably, the light source 301 can be an LED illumination source for illuminating the suspension sample. Through the imaging lens 204, particles in the suspension can be acquired and recorded by the imaging camera 304; single-particle tracking can be performed on multiple particles in the experimental video. Subsequent single-particle tracking can locate the position and instantaneous velocity of a single particle in different video frames.

[0039] Example 2 like Figure 2As shown, this embodiment provides an experimental apparatus for coupling optical forces and measuring the optical nonlinearity of suspensions, including a laser control module and a microscopic imaging module. This embodiment uses a laser 201 to study the propagation nonlinearity of light in a suspension, and an auxiliary laser 208 to apply optical forces to particles in the suspension, investigating how the propagation nonlinearity of the laser is affected by the optical backward force when optical forces are present. The nonlinear measurement process involves measuring the light field distribution at the rear end of the suspension sample cell 1 after linear and nonlinear transmission using an imaging camera 304 in the nonlinear optical path. Generally, in the linear case, the output light spot is larger; in the nonlinear case, the light spot traps and shrinks to a size close to the incident light spot; in more general cases, novel nonlinear phenomena such as distorted waves and chaos may also occur.

[0040] Unlike Embodiment 1, the laser control module includes a laser 201, a dichroic mirror 207, an auxiliary laser 208, a reflector 209, a beam expander, a focusing lens 203, an imaging lens 204, a beam attenuator 206, and a beam analyzer 205 arranged in sequence, with the sample cell 1 located between the focusing lens 203 and the imaging lens 204.

[0041] Laser 201 and auxiliary laser 208 are coupled together via dichroic mirror 207.

[0042] Laser 201 can use a 532nm wavelength laser for nonlinear self-focusing experiments.

[0043] The auxiliary laser 208 can be a near-infrared laser with a wavelength of 1.5 μm to generate optical force, thereby allowing the study of the effect of optical force on nonlinear self-focusing; the auxiliary laser 208 can also be replaced with a laser with a wavelength of 650 nm to apply forward scattering force to particles in suspension, thereby studying the effect of forward scattering force on focusing nonlinearity.

[0044] In the nonlinear optical path, imaging camera 304 records the spatial distribution of the nonlinear beam's optical field at the output end of the suspension. In the microscopic imaging optical path, light source 301 can be an LED light source or a laser light source, such as a blue laser with a wavelength of 488 nm. Imaging camera 304 records images of particle motion in the suspension for subsequent offline analysis.

[0045] The relationship between the nonlinearity of light propagation in suspension and the optical forces acting on suspended particles is as follows: Figure 3 As shown in Figure (a), under linear conditions, the incident power of laser 201 is relatively small, generally less than 10mW. The force exerted by light on the particles in the suspension is negligible, and the particles undergo random Brownian motion in the suspension system, except for gravity. Figure 3(b) indicates that the light in the suspension system has a large output spot after linear diffraction. Here, laser 201 is used to study the nonlinear propagation of light in the suspension, and an auxiliary laser 208 is used to apply optical forces to the particles in the suspension. The study investigates how the propagation nonlinearity of the laser emitted by laser 201 is affected by the optical backward force when optical forces are present. How to achieve nonlinear measurement: The imaging camera 304 in the nonlinear optical path measures the light field distribution at the rear end of the suspension sample cell 1 after linear and nonlinear transmission. Generally speaking, the output spot is larger in the linear case, and in the nonlinear case, the spot is trapped and shrinks to a size close to the incident spot. In more general cases, novel nonlinear phenomena such as distorted waves and chaos will also occur.

[0046] Figure 4 (a) indicates that when nonlinear enhancement occurs, the power of laser 201 is relatively large, typically ranging from tens to hundreds of milliwatts. Due to the self-focusing effect, the lateral profile of the light remains constant. Figure 4 (b) shows the corresponding output spot, compared to Figure 3 In the linear case of (b), the output spot shrinks when the nonlinear case occurs.

[0047] Figure 5 (a) indicates that when optical scattering force is present, the particles move away from the light source 301 under the action of the auxiliary laser 208. The nonlinear propagation of light is affected by the directional motion of the particles. The blue solid line represents the lateral propagation range of light after self-focusing, and the orange dashed line represents the range of near-infrared light. Under the action of the auxiliary laser 208, the particles in the suspension will be subjected to forward scattering force, and the arrows on the particles indicate the direction of the force. Figure 5 (b) represents the size of the corresponding output spot.

[0048] Figure 6 (a) indicates that when an optical backward force is present, the particles move towards the light source 301 under the action of the auxiliary laser 208. The nonlinear propagation of light is affected by the directional motion of the particles. The blue solid line represents the lateral propagation range of the light after self-focusing, and the orange dashed line represents the range of near-infrared light. Under the action of near-infrared light, the particles in the suspension will be subjected to an optical backward force, and the arrows on the particles indicate the direction of the backward force. Figure 6 (b) represents the size of the corresponding output spot.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An experimental apparatus for coupling optical forces and optical nonlinear measurement of suspensions, characterized in that, It includes a laser control module and a microscopic imaging module, which are respectively arranged in two orthogonal directions of the suspension; the suspension is placed in a transparent sample cell (1); The laser control module includes a laser (201), a beam expander (202), a focusing lens (203), an imaging lens (204), and a beam analyzer (205) arranged in sequence; the sample cell (1) is located between the focusing lens (203) and the imaging lens (204); The microscopic imaging module includes a light source (301), an illumination lens (302), an imaging lens (204), and an imaging camera (304) arranged in sequence; the sample cell (1) is located between the illumination lens (302) and the imaging lens (204).

2. The experimental apparatus for coupling optical forces and optical nonlinear measurement of suspensions according to claim 1, characterized in that, A filter is also provided between the sample cell (1) and the imaging lens (204).

3. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, A beam attenuator (206) is also provided between the imaging lens (204) and the beam analyzer (205).

4. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, The light source (301) is an LED light source or a laser light source; the laser (201) includes one or more sub-lasers, and different sub-lasers are turned on when the experimental device is in different working states.

5. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 4, characterized in that, The sub-laser includes a green laser with a wavelength of 532 nm.

6. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, The laser control module further includes a dichroic mirror (207), an auxiliary laser (208), and a reflector (209) arranged sequentially between the laser (201) and the beam expander (202); the auxiliary laser (208) includes a near-infrared laser with a wavelength of 1.5 μm.

7. The experimental apparatus for coupled optical force and optical nonlinear measurement of suspension according to claim 1, characterized in that, The imaging camera (304) performs single-particle tracking to locate the position and instantaneous velocity of a single particle in the suspension in different video frames.

8. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, The imaging camera (304) records the spatial distribution of the nonlinear beam in the light field at the output end of the suspension.

9. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, The beam analyzer (205) measures the spatial distribution of the laser spot before and after the laser is incident on the sample cell (1).

10. The experimental apparatus for measuring coupled optical forces and optical nonlinearity of suspensions according to claim 1, characterized in that, The sample cell (1) is a cuvette, and the particles in the suspension are micron-sized or nano-sized particles.

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