阅读说明：本技术 基于空心光对空气中吸光粒子的光捕获和三维操纵装置 (Light capture and three-dimensional manipulation device for light absorption particles in air based on hollow light ) 是由 程雪梅 张文定 牛晨 陈浩伟 白晋涛 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种基于空心光对空气中吸光粒子的光捕获和三维操纵装置,包括依次设置的激光器、空心光产生单元、偏振分光镜,还包括照明单元、横向捕获单元和竖向捕获单元；所述的横向捕获单元中包括第一偏折镜,所述的竖向捕获单元包括第二偏折镜。本发明通过分别旋转设置在横向捕获单元和竖向捕获单元中的第一偏折镜和第二偏折镜,实现了被捕获粒子分别在横向和竖向的垂直于捕获激光传播方向的平面二维旋转,且其旋转方向可控,解决了现有技术中对空气中吸光粒子的捕获时无法在低捕获功率下控制粒子旋转方向；此外,由于采用空心光来捕获吸光粒子,捕获功率可低至25mW,因此也解决了微粒在二维旋转过程中捕获光能量过高问题。(The invention discloses a light capturing and three-dimensional manipulation device for light absorption particles in air based on hollow light, which comprises a laser, a hollow light generating unit and a polarization spectroscope, and further comprises an illuminating unit, a transverse capturing unit and a vertical capturing unit, wherein the laser, the hollow light generating unit and the polarization spectroscope are sequentially arranged; the transverse capturing unit comprises a first deflection mirror, and the vertical capturing unit comprises a second deflection mirror. According to the invention, the first deflection mirror and the second deflection mirror which are respectively arranged in the transverse capturing unit and the vertical capturing unit are respectively rotated, so that the two-dimensional rotation of the captured particles in the transverse and vertical planes perpendicular to the propagation direction of the captured laser is realized, the rotation direction of the particles is controllable, and the problem that the rotation direction of the particles cannot be controlled under low capturing power when the light absorption particles in the air are captured in the prior art is solved; in addition, as the hollow light is adopted to capture the light-absorbing particles, the capture power can be as low as 25mW, and the problem that the light energy captured by the particles in the two-dimensional rotation process is too high is solved.)

1. The light capturing and three-dimensional manipulation device for light absorption particles in air based on hollow light comprises a laser (1), a hollow light generating unit (2) and a polarizing beam splitter (3) which are sequentially arranged, and is characterized by further comprising a transverse capturing unit (4), a vertical capturing unit (5) and a lighting unit (6); the horizontal capturing unit (4) is arranged in the P light direction of the polarizing beam splitter (3), the vertical capturing unit (5) is arranged in the S light direction of the polarizing beam splitter (3), and the illuminating unit (6) is arranged in the reverse direction of the S light of the polarizing beam splitter (3);

the transverse capturing unit (4) comprises a first deflection mirror (401); the vertical capturing unit (5) comprises a second deflection mirror (501).

2. The hollow light-based light capturing and three-dimensional manipulating device for light-absorbing particles in air according to claim 1, wherein the lateral capturing unit (4) further comprises a second convex lens (402), a first sample cell (403) and a lateral image collecting mechanism (404) which are arranged in sequence; the vertical capturing unit (5) further comprises a third convex lens (502), a second sample pool (503) and a vertical image collecting mechanism (504) which are sequentially arranged.

3. The hollow light-based light capture and three-dimensional manipulation apparatus for absorbing particles in air as claimed in claim 1, wherein the lateral image collection mechanism (404) comprises a first microscope objective (40401), a first notch filter (40402) and a first imaging structure (40403) fixedly connected in sequence; the vertical image collecting mechanism (504) comprises a second microscope objective (50401), a second notch filter (50402) and a second imaging structure (50403) which are fixedly connected in sequence.

4. The hollow light-based light capture and three-dimensional manipulation device for light-absorbing particles in air as claimed in claim 1, wherein the vertical upper side of the first sample cell (403) is provided with a fixedly connected third microscope objective (405) and a third imaging structure (406); and a fourth microscope objective (505) and a fourth imaging structure (506) which are fixedly connected are arranged on the transverse front side of the second sample cell (503).

5. The hollow light-based light trapping and three-dimensional manipulation device for light-absorbing particles in air according to claim 1, wherein the first deflection mirror (401) and the second deflection mirror (501) are wedge prisms.

6. The hollow light-based light trapping and three-dimensional manipulation device for light-absorbing particles in air according to claim 1, wherein the illumination unit (6) comprises a first convex lens (601) and an incandescent lamp (602) which are sequentially disposed at a vertically lower side of the polarization beam splitter (3).

7. The hollow light-based light trapping and three-dimensional manipulation device for light-absorbing particles in air according to claim 1, wherein the hollow light generation unit (2) is a cross-phase spatial light beam modulation system or a spatial light modulator.

8. The hollow light-based light trapping and three-dimensional manipulation device for light-absorbing particles in air according to claim 1, wherein said laser (1) is a 532nm semiconductor continuous laser or an all-solid-state tunable titanium sapphire dye continuous laser.

9. The hollow light-based light capture and three-dimensional manipulation apparatus for light absorbing particles in air according to claim 1, wherein the first imaging structure (40403), the second imaging structure (50403), the third imaging structure (406), and the fourth imaging structure (506) are a CCD camera, an ICCD camera, or a CMOS camera.

Technical Field

The invention belongs to the field of nonlinear optics application, relates to a light capture and three-dimensional control device, and particularly relates to a light capture and three-dimensional control device for light absorption particles in air based on hollow light.

Background

In recent years, with the increasing demand for in situ analysis of air borne particles, optical trapping and manipulation of light absorbing particles has attracted attention. Three-dimensional optical manipulation with high precision is a challenging technique because of the need to shift the captured particles to the focal position of the excitation laser for spectroscopic analysis. Currently, manipulation of particles along the z-direction (the propagation direction of the trapping laser light) is typically achieved by varying the power of the trapping laser light. However, this displacement method requires a large trapping laser power. And due to the variation of the trapped laser power, the scattered light on the particles will also vary, thus interfering with the extraction of the spectral signal.

More seriously, for some particles with poor light stability, the physicochemical properties of the particles change with the change of the power of the irradiated light, so that the non-destructive analysis of the particles cannot be realized. While for optical manipulation of the trapped particles in the x-y plane (the plane perpendicular to the propagation direction of the trapped laser light) there are two main types, one is by using a focused optical trap and a conical ring optical trap diffracted from a circular aperture; another is a new method by using a combination of cylindrical lenses and circular diaphragms. Both methods have disadvantages, and the use of a focusing optical trap and a conical ring optical trap diffracting from a circular aperture can achieve continuous rotation of the light absorbing particles, but cannot control the direction of particle rotation; and the new method using the combination of the cylindrical lens and the circular diaphragm cannot capture the laser with a power lower than 100mW, otherwise the particles easily escape from the capture device, and the one-dimensional manipulation of the captured particles and the two-dimensional rotation (three-dimensional manipulation) of the particles cannot be simultaneously realized.

Disclosure of Invention

In view of the defects of the prior art, an object of the present invention is to provide a light trapping and three-dimensional manipulation device for light-absorbing particles in air based on hollow light, which solves the technical problems that the rotation direction of the particles cannot be controlled at low trapping power and the one-dimensional manipulation and two-dimensional rotation of the trapped particles cannot be simultaneously realized when the light-absorbing particles in air are trapped in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme:

the light capture and three-dimensional manipulation device for light absorption particles in air based on hollow light comprises a laser, a hollow light generation unit and a polarization spectroscope, and further comprises a transverse capture unit, a vertical capture unit and a lighting unit, wherein the laser, the hollow light generation unit and the polarization spectroscope are sequentially arranged; the horizontal capturing unit is arranged in the P light direction of the polarizing beam splitter, the vertical capturing unit is arranged in the S light direction of the polarizing beam splitter, and the illuminating unit is arranged in the reverse direction of the S light of the polarizing beam splitter;

the transverse capturing unit comprises a first deflection mirror; the vertical capturing unit comprises a second deflection mirror.

The invention also has the following technical characteristics:

specifically, the transverse capturing unit further comprises a second convex lens, a first sample cell and a transverse image collecting mechanism which are sequentially arranged; the vertical capturing unit further comprises a third convex lens, a second sample pool and a vertical image collecting mechanism which are sequentially arranged.

Specifically, the transverse image collecting mechanism comprises a first microscope objective, a first notch filter and a first imaging structure which are fixedly connected in sequence; the vertical image collecting mechanism comprises a second microscope objective, a second notch filter and a second imaging structure which are fixedly connected in sequence.

Specifically, a third microscope objective and a third imaging structure which are fixedly connected are arranged on the vertical upper side of the first sample cell; and a fourth microscope objective and a fourth imaging structure which are fixedly connected are arranged on the transverse front side of the second sample cell.

Specifically, the first deflection mirror and the second deflection mirror are wedge prisms.

Specifically, the illumination unit comprises a first convex lens and an incandescent lamp which are sequentially arranged at the vertical lower side of the polarization beam splitter.

Specifically, the hollow light generating unit is a cross-phase spatial light beam modulation system or a spatial light modulator.

Specifically, the laser is a 532nm semiconductor continuous laser or an all-solid-state tunable titanium sapphire dye continuous laser.

Specifically, the first imaging structure, the second imaging structure, the third imaging structure and the fourth imaging structure are a CCD camera, an ICCD camera or a CMOS camera.

Compared with the prior art, the invention has the beneficial technical effects that:

according to the invention, two-dimensional rotation of captured particles on a horizontal plane and a vertical plane which are perpendicular to the propagation direction of captured laser is realized by respectively rotating a first deflection mirror and a second deflection mirror which are arranged in a horizontal capture unit and a vertical capture unit, the rotation direction of the particles is controllable, and the problem that the rotation direction of the particles cannot be controlled under low capture power when light absorption particles in air are captured in the prior art is solved; in addition, as the hollow light is adopted to capture the light-absorbing particles, the capture power can be as low as 25mW, and the problem that the light energy captured by the particles in the two-dimensional rotation process is too high is solved.

The invention realizes the one-dimensional manipulation of the captured particles in the propagation direction of the captured laser by changing the size of the hollow light; in addition, due to the addition of the deflection mirror, the one-dimensional manipulation and the two-dimensional rotation of the captured particles are effectively combined, so that the micron-level three-dimensional manipulation of the captured particles in the vertical capturing unit and the horizontal capturing unit is realized, and the technical problem that the one-dimensional manipulation and the two-dimensional rotation of the captured particles cannot be realized simultaneously in the prior art is solved.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a rotation diagram of a captured particle in a vertical lasing plane within a horizontal device collected in accordance with the present invention;

FIG. 3 is a rotation diagram of a vertical device collected by the present invention with particles captured in a plane perpendicular to the direction of laser light;

FIG. 4 is a schematic illustration of modulated laser power versus hollow light size variation;

FIG. 5 shows a linear fit of the modulated light power to the hollow core light size;

FIG. 6 is a graph of the hollow core light dimension versus the distance the trapped particle has traveled in the direction of laser propagation, horizontally;

FIG. 7 is a plot of hollow core light size versus distance traveled by a trapped particle in the direction of laser propagation, in the vertical direction.

The meaning of the individual reference symbols in the figures is: 1-a laser, 2-a hollow light generating unit, 3-a polarizing beam splitter, 4-a transverse capturing unit, 5-a vertical capturing unit and 6-an illuminating unit;

401-a first deflection mirror, 402-a second convex lens, 403-a sample cell, 404-a transverse image collecting mechanism, 405-a third microscope objective and 406-a third imaging structure;

40401-a first microscope objective, 40402-a first notch filter, 40403-a first imaging structure;

501-a second deflection mirror, 502-a third convex lens, 503-a second sample cell, 504-a vertical image collecting mechanism, 505-a fourth microscope objective and 506-a fourth imaging structure;

50401-a second microscope objective, 50402-a second notch filter, 50403-a second imaging setup;

601-first convex lens, 602-incandescent lamp.

The present invention will be explained in further detail with reference to examples.

Detailed Description

It should be noted that the reason why the hollow beam is used in the present invention is: when a beam of light irradiates the surface of the light-absorbing particle, the temperature of the irradiated surface of the particle is increased, so that the thermal motion of gas molecules attached to the surface of the particle is further increased, the gas molecules can bounce off the surface of the particle at a higher speed, and the thermal motion of the gas molecules on the irradiated surface is larger than that of the non-irradiated surface, so that the particle generates a net acting force directed from the irradiated surface to the non-irradiated surface under the combined action. For a hollow beam, the force it exerts on the particle surface can be expressed as:

where ρ is_αIs the density of air, m_αIs the mass of the air molecules, B is the universal air constant, T is the particle surface temperature, M is the molar mass of the air molecules, and S is the area of the light irradiation region on the particles;

for irregular particles:

gamma is the specific heat ratio of the gas environment, Pgas pressure, P^*Is the characteristic pressure of the gas flow,average velocity of gas molecules, P_lCapturing effective power of laser beam irradiated particle, delta alpha-alpha₁-α₂，

Under the action of gravity, F_ΔTAnd F_ΔαUnder the combined action of the two components, the particles can be captured behind the focus; while in the control process, the resistance, the gravity and the F_ΔTAnd F_ΔαThe particles can be stably captured in the process of being manipulated, so that the captured particles can be manipulated in three dimensions.

Therefore, the particles can be stably captured by the hollow light and three-dimensional manipulation can be carried out.

It should be noted that fig. 4 and 5 illustrate that the linear variation of the hollow light size can be effectively controlled under the condition that the energy of the trapped laser (hollow light) is not changed.

All parts in the present invention are those known in the art, unless otherwise specified.

The following embodiments of the present invention are provided, and it should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.

Example (b):

the embodiment provides a light capture and three-dimensional manipulation device for light absorption particles in air based on hollow light, and as shown in fig. 1, the light capture and three-dimensional manipulation device comprises a laser 1, a hollow light generation unit 2 and a polarization beam splitter 3 which are sequentially arranged, and further comprises a transverse capture unit 4, a vertical capture unit 5 and an illumination unit 6; the transverse capturing unit 4 is arranged in the P light direction of the polarizing beam splitter 3, the vertical capturing unit 5 is arranged in the S light direction of the polarizing beam splitter 3, and the illuminating unit 6 is arranged in the reverse direction of the S light of the polarizing beam splitter 3;

the lateral capturing unit 4 includes a first deflection mirror 401 therein; the vertical capturing unit 5 includes a second deflection mirror 501.

In this embodiment, the first deflecting mirror and the second deflecting mirror function to deflect the two hollow light beams obtained by the polarizing beam splitter 3 by a certain angle, and the hollow light beams passing through the deflecting mirror also rotate around the optical axis by rotating the deflecting mirror.

In the technical scheme, the two-dimensional rotation of the captured particles on a plane which is perpendicular to the propagation direction of the captured laser in the transverse direction and the vertical direction is realized by respectively rotating the first deflection mirror and the second deflection mirror which are arranged in the transverse capturing unit and the vertical capturing unit, the rotation direction of the two-dimensional rotation is controllable, and the problem that the rotation direction of the particles cannot be controlled under low capturing power when light absorption particles in air are captured in the prior art is solved; in addition, as the hollow light is adopted to capture the light-absorbing particles, the capture power can be as low as 25mW, and the problem that the light energy captured by the particles in the two-dimensional rotation process is too high is solved.

As a preferable scheme of the present embodiment, the lateral capturing unit 4 further includes a second convex lens 402, a first sample cell 403, and a lateral image collecting mechanism 404, which are sequentially arranged; the vertical capturing unit 5 further includes a third convex lens 502, a second sample cell 503, and a vertical image collecting mechanism 504, which are sequentially provided.

In this embodiment, the second convex lens 402 and the third convex lens 502 are used for focusing the generated hollow light beam, so as to form a light trap, wherein the focal lengths of the second convex lens and the third convex lens are both 45 mm; the sample cell No. one 403 and the sample cell No. two 503 are used to reduce the influence from the disturbance of the air flow when capturing particles.

As a preferable solution of this embodiment, the transverse image collecting mechanism 404 includes a first microscope objective 40401, a first notch filter 40402, and a first imaging structure 40403, which are fixedly connected in sequence; the vertical image collection mechanism 504 includes a second microscope objective 50401, a second notch filter 50402, and a second imaging structure 50403 fixedly connected in that order.

In the present embodiment, in the lateral image collecting mechanism 404, the images of the captured particles are respectively passed through the first microscope objective, the light intensity is attenuated by the first notch filter, and the distance between the first microscope objective and the first imaging structure is adjusted to image the particles onto the first imaging structure, as shown in fig. 2, and the particle rotation direction is controllable; in the vertical image collecting mechanism 504, the image of the captured particle is imaged through the second microscope objective, the light intensity is attenuated by the second notch filter, and the distance between the second microscope objective and the second imaging structure is adjusted to image the captured particle on the second imaging structure, as shown in fig. 3, and the particle rotation direction is controllable.

As a preferable scheme of this embodiment, a third microscope objective 405 and a third imaging structure 406 which are fixedly connected are arranged on the vertical upper side of the first sample cell 403; the second sample cell 503 is provided with a fourth microscope objective 505 and a fourth imaging structure 506 which are fixedly connected with each other at the transverse front side.

In this embodiment, the third microscope objective 405 and the fourth microscope objective 505 are used to collect the scattered light on the captured particles, and the third microscope objective and the third imaging structure are imaged on the third imaging structure by adjusting the distance between the third microscope objective and the third imaging structure, as shown in fig. 6; the fourth microscope objective lens is imaged on the fourth imaging structure by adjusting the distance between the fourth microscope objective lens and the fourth imaging structure, as shown in fig. 7. By combining the above imaging with fig. 2 and 3, it can be obtained that the invention achieves three-dimensional manipulation of the captured particles.

As a preferable aspect of this embodiment, the first deflection mirror 401 and the second deflection mirror 501 are wedge prisms, and the rotation direction of the particles can be changed by rotating the wedge prisms.

As a preferable aspect of the present embodiment, the illumination unit 6 includes a first convex lens 601 and an incandescent lamp 602 which are sequentially disposed at a vertically lower side of the polarization beam splitter 3.

In this embodiment, the captured particles are made observable by adjusting the distance between the incandescent lamp, the first convex lens and the polarizing beam splitter, which has a focal length of 30mm, to provide illumination for the fields of view of the lateral image collecting means and the vertical image collecting means.

As a preferable solution of this embodiment, the hollow light generating unit 2 is a cross-phase spatial light beam modulation system or a spatial light modulator.

As a preferable scheme of this embodiment, the laser 1 is a 532nm semiconductor continuous laser or an all-solid-state tunable titanium sapphire dye continuous laser.

In this example, a 532nm semiconductor continuous laser was used.

As a preferable solution of this embodiment, the first imaging structure 40403, the second imaging structure 50403, the third imaging structure 406, and the fourth imaging structure 506 are CCD cameras, ICCD cameras, or CMOS cameras.

Used in this example is a CMOS camera.

The working process of the invention is as follows:

obtaining a continuous laser beam with Gaussian distribution from a laser 1, and passing the obtained continuous laser beam through a hollow light generating unit 2 to obtain a hollow beam; the obtained hollow light beams are incident to a polarization beam splitter 3 to obtain two hollow light beams with vertical directions, then the two hollow light beams respectively enter a transverse capturing unit 4 and a vertical capturing unit 5, and firstly the two hollow light beams are respectively incident to a first deflection mirror 401 and a second deflection mirror 501; the two hollow beams are deflected at a certain angle, and then are respectively incident to the second convex lens 402 and the third convex lens 502 to form converged hollow beams, and the converged hollow beams are incident to the first sample cell 403 and the second sample cell 503; spraying sample particles into the sample cell, and observing the captured particles near the focus; by changing the size of the hollow light beam, the captured particles can be imaged in a third imaging structure 406 by a third microscope objective 405 to obtain a graph of the transverse particle moving distance along with the size of the hollow light; by rotating the first deflection mirror 401, a two-dimensional rotation map of the particles in the transverse direction can be obtained by the transverse image collecting mechanism 404; similarly, by changing the size of the hollow light beam, the captured particles can be imaged in the fourth imaging structure 506 by the fourth microscope objective 505 to obtain a graph of the vertical particle moving distance along with the size of the hollow light; by rotating the second deflection mirror 501, a two-dimensional rotation map of particles in the vertical direction can be obtained by the vertical image collecting mechanism 504.