阅读说明：本技术 通过预加热脱附增强光悬浮微粒真空耐受度的方法与装置 (Method and device for enhancing vacuum tolerance of light suspended particles through preheating desorption ) 是由 李翠红 马园园 高晓文 蒋静 陈志明 胡慧珠 于 2021-09-17 设计创作，主要内容包括：本发明公开通过预加热脱附增强光悬浮微粒真空耐受度的方法与装置。方法包括以下几个步骤：首先开启捕获激光,形成捕获光阱,将微粒投送到光阱所在区域,实现微粒的捕获,并通过光电探测器收集被捕获微粒的散射光信号；打开预加热激光器,调整预加热激光器光束对准被捕获的微粒；调节预加热激光器功率至微粒加热速率大于散热速率,使得微粒内部温度升高,实现预加热；打开真空泵,将真空度抽至大于光阱有效捕获区域第一次缩小的真空拐点时,停止抽真空；光电探测器收集的微球散射光信号不再发生变化时关闭预加热激光器。本发明可以提高微粒在高真空环境下的稳定捕获概率,推动真空光镊技术的应用,同时也为微纳尺寸微粒的物性研究提供方法与手段。(The invention discloses a method and a device for enhancing the vacuum tolerance of light suspended particles through preheating desorption. The method comprises the following steps: firstly, starting capture laser to form a capture optical trap, sending particles to the area where the optical trap is located to realize the capture of the particles, and collecting scattered light signals of the captured particles through a photoelectric detector; turning on the preheating laser, and adjusting the light beam of the preheating laser to be aligned with the captured particles; adjusting the power of a preheating laser until the heating rate of the particles is greater than the heat dissipation rate, so that the internal temperature of the particles is increased, and preheating is realized; opening a vacuum pump, and stopping vacuumizing when the vacuum degree is greater than the vacuum inflection point of the first reduction of the effective capture area of the optical trap; and turning off the preheating laser when the microsphere scattered light signals collected by the photoelectric detector do not change any more. The invention can improve the stable capture probability of particles in a high vacuum environment, promote the application of the vacuum optical tweezers technology, and provide a method and means for researching the physical properties of micro-nano particles.)

1. The method for enhancing the vacuum tolerance of the light suspended particles through preheating desorption is characterized by comprising the following steps:

(1) firstly, starting capture laser to form a capture optical trap, sending particles to the area where the optical trap is located to realize the capture of the particles, and collecting scattered light signals of the captured particles through a photoelectric detector;

(2) turning on the preheating laser, and adjusting the light beam of the preheating laser to be aligned with the captured particles;

(3) adjusting the power of a preheating laser until the heating rate of the particles is greater than the heat dissipation rate, so that the internal temperature of the particles is increased, and preheating is realized;

(4) opening a vacuum pump, and stopping vacuumizing when the vacuum degree is greater than the vacuum inflection point of the first reduction of the effective capture area of the optical trap;

(5) and turning off the preheating laser when the microsphere scattered light signals collected by the photoelectric detector do not change any more.

2. The method of claim 1 wherein the preheating the laser wavelength is selected to provide a wavelength range having a high particle absorption.

3. The method of claim 1, wherein the particles are preheated by a laser selected from the wavelengths in the far infrared band for particles made of silica.

4. The method of claim 1, wherein the pressure at which the evacuation is stopped in step (4) is higher than a vacuum level corresponding to a reduction in the effective trapping area of the optical trap.

5. An apparatus for enhancing the vacuum tolerance of an aerosol by pre-heating desorption using the method according to claim 1, characterized in that the apparatus comprises a first laser (1), a second laser (2), a first light modulator (3), a second light modulator (4), a first lens (5), a particle (6), a second lens (7), a vacuum chamber (8), a vacuum pump (9), a photodetector (10), a control display system (11); the first optical modulator (3), the first lens (5) and the second lens (7) are sequentially arranged on an emergent light path of the first laser (1), the first lens (5) and the second lens (7) are both positioned in the vacuum cavity (8), the photoelectric detector (10) is positioned on a refraction path of the second lens (7), and the second optical modulator (4) is positioned on an emergent light path of the second laser (2); the vacuum cavity (8) is connected with the vacuum pump (9), and the first light modulator (3), the second light modulator (4), the photoelectric detector (10) and the vacuum pump (9) are respectively connected with the control display system (11).

6. The apparatus for enhancing vacuum tolerance of light aerosols by pre-heating desorption of claim 5 wherein the automatic control means of the lasers is added and the switching and intensity of the first laser (1) and the second laser (2) is adjusted by controlling the signal output of the first light modulator (3) and the second light modulator (4) by the control display system (11).

7. Device for enhancing the vacuum tolerance of aerosols by means of pre-heated desorption according to claim 5, characterized in that the vacuum level in the vacuum chamber (8) is regulated by controlling the vacuum pump (9) by means of a control display system (11).

8. The apparatus for enhancing the vacuum tolerance of aerosuspension particles through preheated desorption according to claim 5, wherein the application steps are as follows:

opening a first laser (1) to emit trapping laser, processing the trapping laser by a first light modulator (3), then injecting the trapping laser into a vacuum cavity (8), focusing the trapping laser through a first lens (5) with a high numerical aperture to form a trapping optical trap, and delivering particles to an area where the optical trap is located to realize the trapping of the particles; opening a second laser (2) to emit laser for preheating particles, processing the laser by a second light modulator (4) and then injecting the laser into a vacuum cavity (8), and adjusting light beams passing through the second laser (2) and the second light modulator (4) before heating so as to align the light beams to the captured particles (6); opening a vacuum pump (9) to vacuumize the vacuum cavity (8), and adjusting the output power of the second laser (2) to enable the heating rate of the laser to the particles to be greater than the heat dissipation rate, so that the temperature of the particles is increased; when the vacuum degree in the vacuum cavity (8) is slightly larger than the vacuum inflection point of the first reduction of the effective capture area of the optical trap, stopping vacuumizing, continuing to heat the microspheres until the residual adsorption is released, and closing the second laser (2); the second lens (7) is used for collecting the change of the scattered light of the particles, collecting signals entering the photoelectric detector (10), monitoring the desorption state of the particles, and controlling the display system (11) to be used for signal collection and control of the system.

Technical Field

The invention relates to the field of sensing calibration, in particular to a method and a device for enhancing the vacuum tolerance of light suspended particles through preheating and desorption.

Background

Since the seventies of the last century, the optical tweezers technology was pioneered by aster ashiki and has been widely studied and applied in the fields of molecular biology, nanotechnology, experimental physics, and the like as a general tool for capturing and manipulating microparticles. Particles suspended by laser beams in the optical tweezers technology can be understood as a simple harmonic oscillator model, and compared with the traditional oscillator model, the optical tweezers technology has no contact mechanical dissipation; further, unlike optical tweezers systems in liquid or air media, optical tweezers systems operating in vacuum can achieve complete isolation of the suspension unit from the environment. Based on the above advantages, scientists in the field of applied physics have conducted a great deal of research on the vacuum optical tweezers technology in the fields of basic physics such as thermodynamics, quantum physics and sensing.

The research on the physical properties of micro-nano particles has important application significance to the optical tweezers technology based on the vacuum optical suspension principle, and the basic principle of optical suspension is to realize the suspension of micro particles by utilizing the combined action of the gradient force and the scattering force of a tightly focused optical field. Silica particles widely used in the vacuum optical tweezers technology are not specifically designed and synthesized for vacuum optical suspension systems, but are synthesized by hydrolysis of tetraethyl orthosilicate in an ethanol solution using ammonia as a catalyst using a Sorber synthesis method proposed by Stobbe et al in 1968. The silica particles obtained by the baby synthesis process are generally amorphous silica having a porous structure, as shown in fig. 1, having a microporous structure on the surface (open pores) or inside (closed pores) of the particles, and thus easily adsorbing impurities on the surface and inside. In the vacuum optical tweezers experiment process, along with the promotion of vacuum, atmospheric pressure reduces gradually, and particle heat dissipation channel reduces, leads to the temperature to rise, and then makes the impurity on particle surface and inside take place the desorption. By theoretically calculating the change process of the effective capture range of the optical trap along with the vacuum degree, as shown in fig. 2, it can be found that when the vacuum degree of the particles suspended in the optical trap is reduced to the range of 10mbar to 0.1mbar, the effective capture range of the optical trap is suddenly reduced, the suspended particles are easily flushed out of the optical trap and lost, so that vacuum suspension failure is caused, and the suddenly reduced air pressure value is basically consistent with the vacuum degree of the microsphere lost observed in the experiment.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method and a device for enhancing the vacuum tolerance of light suspended particles through preheating and desorption, and the specific technical scheme is as follows:

a method for enhancing the vacuum tolerance of an optical aerosol by pre-heating desorption, comprising the steps of:

(1) firstly, starting capture laser to form a capture optical trap, sending particles to the area where the optical trap is located to realize the capture of the particles, and collecting scattered light signals of the captured particles through a photoelectric detector;

(2) turning on the preheating laser, and adjusting the light beam of the preheating laser to be aligned with the captured particles;

(3) adjusting the power of a preheating laser until the heating rate of the particles is greater than the heat dissipation rate, so that the internal temperature of the particles is increased, and preheating is realized;

(4) opening a vacuum pump, and stopping vacuumizing when the vacuum degree is greater than the vacuum inflection point of the first reduction of the effective capture area of the optical trap;

(5) and turning off the preheating laser when the microsphere scattered light signals collected by the photoelectric detector do not change any more.

According to the method for enhancing the vacuum tolerance of the optical suspended particles through preheating desorption, the wavelength range with higher particle absorption rate is selected as the preheating laser wavelength.

According to the method for enhancing the vacuum tolerance of the light suspended particles through preheating and desorption, for the particles made of silicon dioxide, a laser with the wavelength of a far infrared band is selected to preheat the particles.

According to the method for enhancing the vacuum tolerance of the optical suspended particles through preheating and desorption, in the step (4), the air pressure for stopping vacuumizing is higher than the vacuum degree corresponding to the reduction of the effective capture area of the optical trap.

The device for enhancing the vacuum tolerance of the light suspended particles by preheating and desorption comprises a first laser, a second laser, a first light modulator, a second light modulator, a first lens, particles, a second lens, a vacuum cavity, a vacuum pump, a photoelectric detector and a control display system; the first optical modulator, the first lens and the second lens are sequentially arranged on an emergent light path of the first laser, the first lens and the second lens are both positioned in the vacuum cavity, the photoelectric detector is positioned on a refraction path of the second lens, and the second optical modulator is positioned on an emergent light path of the second laser; the vacuum cavity is connected with the vacuum pump, and the first light modulator, the second light modulator, the photoelectric detector and the vacuum pump are respectively connected with the control display system.

The device for enhancing the vacuum tolerance of the light suspended particles through preheating and desorption is additionally provided with an automatic control device of the laser, and the switch and the intensity of the first laser and the second laser are adjusted by controlling the signal output of the first light modulator and the second light modulator through a control display system.

The device for enhancing the vacuum tolerance of the light suspended particles through preheating and desorption is characterized in that the vacuum degree in the vacuum cavity is adjusted by controlling the vacuum pump through the control display system.

The device for enhancing the vacuum tolerance of the light suspended particles through preheating and desorption comprises the following application steps:

opening a first laser to emit trapping laser, processing the trapping laser by a first light modulator, then injecting the trapping laser into a vacuum cavity, focusing the trapping laser by a first lens with a high numerical aperture to form a trapping optical trap, and delivering particles to an area where the optical trap is located to realize the trapping of the particles; opening a second laser to emit laser for preheating particles, processing the laser by a second light modulator, then injecting the laser into the vacuum cavity, and adjusting light beams passing through the second laser and the second light modulator before heating so as to align the light beams to the captured particles; opening a vacuum pump to vacuumize the vacuum cavity, and adjusting the output power of a second laser to enable the heating rate of the laser to the particles to be greater than the heat dissipation rate, so that the temperature of the particles is increased; when the vacuum degree in the vacuum cavity is slightly larger than the vacuum inflection point of the first reduction of the effective capture area of the optical trap, stopping vacuumizing, continuously heating the microspheres until the residual adsorption is released, and closing the second laser; the second lens is used for collecting the change of particle scattering light, collecting signals entering the photoelectric detector, monitoring the particle desorption state, and controlling the display system to be used for signal acquisition and control of the system.

The invention has the beneficial effects that:

(1) the method improves the stable capture probability of particles in a high vacuum environment, reduces the limit of a microsphere preparation technology on a vacuum optical tweezers technology, further promotes the application of the vacuum optical tweezers technology, and is beneficial to stably constructing ultra-sensitive detectors such as zeptonewton-level weak force detectors, sub-femtogram-level nanoparticle quality detectors, micro-Gal-level accelerometers and the like;

(2) the stable capture of the particles in the high vacuum environment is beneficial to the research of macroscopic quantum phenomena, microscopic thermodynamics, ultra-high speed rotors, near-distance mechanical phenomena and the like.

Drawings

FIG. 1 is a schematic view of the structure of microparticles.

FIG. 2 is a graph of the variation of the three-axis effective trapping range with vacuum degree in an optical trap, wherein the optical trap is composed of continuous light with a numerical aperture of 0.8, a focused laser power of 100 mW, and a wavelength of 1064 nm.

FIG. 3 is a graph showing the variation of scattered light signal with vacuum degree during the release of impurities from the inside and the surface of the particle without preheating.

FIG. 4 is a flow diagram of a method for enhancing the vacuum tolerance of an aerosol by pre-heating desorption.

Figure 5 is a schematic diagram of an apparatus for enhancing the vacuum tolerance of an aerosol by pre-heating desorption.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and examples, and objects and effects of the present invention will become more apparent, it being understood that the specific examples described herein are merely illustrative of the present invention and are not intended to limit the present invention.

The method and design principles of the present invention are first set forth.

In a high-sensitivity weak force and acceleration sensing device built on the basis of an optical trap technology and the mechanical sensitivity characteristic of optical suspended particles, because an ideal suspension medium which does not absorb light does not exist, an important reason for particle loss is that microspheres absorb heat, the movement is intensified, and further the microspheres are separated from the constraint of an optical trap. As shown in FIG. 2, the scattered light intensity of the particles is gradually reduced along with the reduction process of the vacuum degree in the absence of external heating, the scattered light intensity of the microspheres is suddenly reduced near 1mbar, the desorption process of a larger impurity corresponds to the scattered light intensity of the particles, and then the scattered light intensity of the particles is basically kept constant. The intensity of scattered light from the particles is proportional to the square of the particle radius, so that a decrease in the intensity of scattered light corresponds to a process of liberating impurities with a smaller volume of the particles. Therefore, under the action of the capture light forming the optical trap, the particles can absorb heat, the temperature is increased to a certain degree, impurities on the surface and in the particles are desorbed, the movement is accelerated, and the probability of the particles being out of the constraint of the optical trap is increased.

In addition, under the condition of low vacuum, the air has more molecules, is easy to radiate heat, has large air damping and large effective capture range, and particles are not easy to lose; with the increase of the vacuum degree, the air molecule density is reduced, the heat dissipation rate is slowed down, the air damping is reduced, the effective capture range of the optical trap is reduced, particles are easy to be separated from the constraint of the optical trap force, and therefore the particles are flushed out of the optical trap and lost. It can be seen from FIG. 3 that the scattered light of the particles decreases with time and then remains stable, consistent with the trend of vacuum over time. In the process from the chamber pressure to 1mbar, the light intensity of the scattered light of the microspheres is continuously weakened, and near 1mbar, the light intensity of the scattered light of the microspheres is suddenly reduced, corresponding to a larger impurity desorption process, and then the scattered light of the microspheres is basically kept constant along with the reduction of the air pressure. The intensity of scattered light from the particles is proportional to the square of the particle radius, so that a decrease in the intensity of scattered light corresponds to a process of liberating impurities with a smaller volume of the particles.

Therefore, under the great atmospheric pressure of the effective capture zone of optical trap, make the particle temperature that is caught by the optical trap rise through initiative laser preheating technology, impel particle surface and inside impurity desorption, judge when the microballon scattered light signal that the photoelectric detector was collected no longer changes that the impurity desorption is complete, close and preheat the laser instrument. The impulse is released in advance, the trapping range is prevented from being rushed out in the high vacuum degree, the stable trapping probability of the particles in the high vacuum environment is improved, and the application research of the vacuum optical tweezers technology in the aspects of weak force detection, acceleration measurement and the like is facilitated.

Application examples

The individual silica particles are suspended in the optical trap under high vacuum conditions.

This is illustrated by the pre-heating process of suspending silica microspheres, as shown in FIG. 4.

(1) Under the condition of room pressure, silica particles with the diameter of 200 nanometers prepared by a sol-gel method are highly diluted into an isopropanol solvent, and then are delivered into a light trap through an atomization spraying method, and are captured by the light trap to realize microsphere suspension;

(2) turning on a preheating laser, wherein the preheating laser adopts a laser with the wavelength of 9 microns, and adjusting a light beam to be aligned with the captured particles;

(3) opening a vacuum pump, and slowly vacuumizing;

(4) adjusting the output power of the preheating laser to make the power density higher thanThe heating rate of the particles is larger than the heat dissipation rate, so that the temperature of the particles is increased, and impurities on the surfaces and in the particles are desorbed;

(5) when the vacuum degree in the vacuum cavity reaches 30mbar, stopping vacuumizing, continuously heating the microspheres, and collecting microsphere scattered light signals through a photoelectric detector;

(6) when the scattered light power of the collected signal of the photoelectric detector is attenuated to no longer change or the resonance frequency is reduced by 5 percent as shown in FIG. 2, the release of the residual adsorption is finished;

(7) the preheat laser is turned off.

The high vacuum experiment was continued.

Device embodiment

The device for enhancing the vacuum tolerance of the optically suspended particles by preheating and desorption comprises a first laser 1, a second laser 2, a first optical modulator 3, a second optical modulator 4, a first lens 5, particles 6, a second lens 7, a vacuum chamber 8, a vacuum pump 9, a photoelectric detector 10 and a control display system 11, as shown in fig. 5.

The first optical modulator 3, the first lens 5 and the second lens 7 are sequentially arranged on an emergent light path of the first laser 1, the first lens 5 and the second lens 7 are both positioned in the vacuum cavity 8, the photoelectric detector 10 is positioned on a refraction path of the second lens 7, and the second optical modulator 4 is positioned on an emergent light path of the second laser 2; the vacuum cavity 8 is connected with the vacuum pump 9, and the first light modulator 3, the second light modulator 4, the photoelectric detector 10 and the vacuum pump 9 are respectively connected with the control display system 11. Wherein, the switch and intensity of the first laser 1 and the second laser 2 are adjusted by controlling the signal output of the first light modulator 3 and the second light modulator 4 by the control display system 11; the vacuum degree in the vacuum cavity 8 is adjusted by controlling the vacuum pump 9 by the control display system 11; the second lens 7 is used for collecting the change of the scattered light of the particles, collecting signals to enter the photoelectric detector 10, and monitoring the desorption state of the particles.

The first laser 1 emits trapping laser, the trapping laser is processed by the first light modulator 3 and then enters the vacuum cavity 8, a trapping optical trap is formed by focusing through the first lens 5 with a high numerical aperture, and particles are delivered to the area where the optical trap is located to realize the trapping of the particles; opening the second laser 2 to emit laser for preheating particles, processing the laser by the second light modulator 4 and then injecting the laser into the vacuum cavity 8, and adjusting light beams passing through the second laser 2 and the second light modulator 4 before heating so as to align the light beams to the captured particles 6; opening a vacuum pump 9 to vacuumize the vacuum cavity 8, and adjusting the output power of the second laser 2 to enable the heating rate of the laser to the particles to be greater than the heat dissipation rate, so that the temperature of the particles is increased; when the vacuum degree in the vacuum cavity 8 is slightly larger than the vacuum inflection point of the first reduction of the effective capture area of the optical trap, the vacuumizing is stopped, the microspheres are continuously heated until the residual adsorption release is finished, and the second laser 2 is closed.

The foregoing is merely a preferred embodiment of the invention and is not to be taken as limiting the invention, which is described in detail and with reference to the accompanying drawings, which are not to be construed as limiting the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.