CN110097994A - A kind of system and method for repeating to capture microballoon based on pulse laser - Google Patents

Abstract

The invention discloses a system and method for repeatedly capturing microspheres based on pulsed laser. The left optical fiber is connected to the input side of the left optical coupler, the output side of the left optical coupler is connected to the left fusion fiber, the left fusion fiber is welded to the capillary, the capillary is welded to the right fusion fiber, the right fusion fiber is connected to the output side of the right optical coupler, the right The input side of the optical coupler is connected to the right optical fiber; the left continuous laser and the right continuous laser are simultaneously emitted to the inside of the capillary to form an optical trap capture area; the left and right pulsed lasers act on the microspheres, and the power of the right pulsed laser is adjusted so that the left pulsed laser Simultaneously acting on the microsphere with the right pulse laser, the microsphere bounces away from the original position and moves to the inside of the optical trap capture area, thereby achieving stable capture of the microsphere. The invention adopts the pulsed laser to separate the microspheres from the surface of the microcavity and enter the trapping area of the optical trap to achieve branching and trapping of the microspheres and repeated capture of single particles without repeated loading of particles, and can be applied to environments such as air and vacuum.

Description

A system and method for repeatedly trapping microspheres based on pulsed laser

technical field

The invention belongs to a microsphere capture system and method in the fields of optical engineering and microparticle suspension, and in particular relates to a system and method for repeatedly capturing microspheres based on pulsed laser light.

Background technique

The optical levitation measurement technology has been continuously improved in recent years, and the measurement requirements are getting higher and higher. The precise control and repeated throwing of microspheres have always been the difficulties of the optical levitation measurement technology. The traditional particle throwing method uses piezoelectric ceramics to separate the microspheres from the surface of the carrier by mechanical high-frequency vibration, or uses ultrasonic atomization to lift the microspheres. Both of these methods require throwing a large number of microspheres in free space, cannot precisely control the number of microspheres falling into the optical trap, and need to continuously add new microspheres. Since there is a certain probability that the microspheres enter the range of the optical trap, the capture efficiency is low, resulting in the waste of a large number of microspheres, and the excess microspheres will pollute the interior of the vacuum chamber. Therefore, in the field of optical levitation measurement, a rapid, repeatable and high-precision starting method is urgently needed.

There are adhesion forces between microspheres and the surface of objects, including van der Waals force, capillary force and electrostatic force. When the diameter of the microsphere is large, the surface adhesion is negligible, because when the diameter of the microsphere is less than 100 microns, the adhesion is affected by the environmental humidity, the surface morphology of the substrate, the material and geometric characteristics of the microsphere and the substrate, etc. Influenced by factors, it is more than 10 ⁴ times of its own gravity. In order to detach the microspheres from the base surface, a huge acceleration must be generated to overcome the adhesion force, so that the microspheres detach from the base surface and enter the trapping area of the light trap.

In the field of cleaning, the method of using pulsed laser to remove impurity particles attached to the surface of substrate materials such as silicon wafers has been widely used. The cleaning principle is to use laser pulses to act on the base surface to cause the base surface to expand. Although the amount of expansion is very small, the action time is extremely short, generally tens of nanoseconds, which can generate a huge acceleration to overcome the adhesion force and push the microspheres. The diameter of these impurity particles is between tens of microns and tens of nanometers, and the materials include metal materials, organic materials and dielectric materials. In the ultraviolet band, the oscillating pulse laser has a large absorption rate and thermal expansion coefficient of the excitation light on the substrate or microspheres, and can achieve a removal efficiency as high as 100% without damaging the substrate. The speed and position of particles after throwing impurities depend on the energy of a single pulse laser and the surface characteristics of the substrate: above the cleaning threshold, the rising height of the microspheres has a linear relationship with the pulse energy. When the cleaning threshold is exceeded, the throwing height of the particles rises linearly with the energy of the laser pulse, so the speed and rising position of the microspheres can be precisely controlled. At the same time, the diameter of the particles should not be too small. When the diameter of the particles is less than 1 micron, as the size of the microspheres decreases, the throwing efficiency becomes lower and lower until the microspheres cannot be separated from the base surface at all. The diameter of impurity particles is basically the same as that used in the field of small ball suspension, so it can be applied to the particle vibration in the field of optical suspension.

Contents of the invention

In order to solve the problems existing in the background technology, the present invention provides a system and method based on pulsed laser repeatedly trapping microspheres, which can realize fast, repeatable, high-precision, and parameter-invariant particle suspension.

The invention adopts the pulse laser to make the microspheres break away from the surface of the microcavity and enter into the trapping area of the light trap, so as to realize the branching of the microspheres. When the microspheres are out of the optical trap, the pulsed laser can be used to achieve the branching of the microspheres again, so as to achieve the purpose of repeated trapping.

The technical scheme adopted in the present invention is as follows:

1. A system based on pulsed laser repeatedly capturing microspheres:

Including left first fiber, left second fiber, left optical coupler, left fusion fiber, capillary, microsphere, right fusion fiber, right optical coupler, right first fiber and right second fiber; left first fiber and left The second optical fiber is respectively connected to both ends of the input side of the left optical coupler, one end of the output side of the left optical coupler is connected to one end of the left fusion splicing fiber, the other end of the left fusion splicing fiber is fused to one end of the capillary, the microsphere is located inside the capillary, and the other end of the capillary is One end is fused with one end of the right fusion splicing fiber, the other end of the right fusion splicing fiber is connected with one end of the output side of the right optical coupler, and the two ends of the input side of the right optical coupler are respectively connected with the first right optical fiber and the second right optical fiber.

The capillary adopts a silica capillary, and the pore size is larger than the diameter of the microsphere. If the pore size is too large, it will be difficult to confine the range of microspheres, and if it is too small, the assembly will be more difficult. Generally, if the size of the microspheres is 10 microns, the pore size should be 20 to 30 microns.

The left fusion-splicing fiber, the capillary and the right fusion-splicing fiber are fusion-spliced to form a closed microcavity structure.

The inner surface of the capillary is completely clean, and can be a vacuum or an environment filled with gas or liquid.

2. A method for repeatedly capturing microspheres based on a pulsed laser, comprising the steps of:

Step 1. The left continuous laser is input to the left optical coupler through the first left optical fiber, and the left optical coupler couples the left continuous laser into the left fusion fiber and emits it to the inside of the capillary; at the same time, the right continuous laser is input to the right light through the first right optical fiber Coupler, the right optical coupler couples the right continuous laser light into the right fusion splicing fiber and emits it to the inside of the capillary; the left continuous laser and the right continuous laser emit to the inside of the capillary at the same time to form an optical trap capture area;

Step 2. The left pulsed laser is input to the left optical coupler through the left first optical fiber, and the left optical coupler couples the left pulsed laser into the left fusion splicing fiber to emit to the inside of the capillary and irradiate the microsphere, so that the left pulsed laser acts on the microsphere At the same time, the right pulse laser is input to the right optical coupler through the right first optical fiber, and the right optical coupler couples the right pulse laser into the right fusion fiber to emit to the inside of the capillary and irradiate the microsphere, so that the right pulse laser acts on the microsphere On the ball; adjust the power of the right pulse laser so that the left pulse laser and the right pulse laser act on the microsphere at the same time, and the microsphere bounces away from the original position and moves to the inside of the optical trap capture area, thereby achieving stable capture of the microsphere;

Step 3. After the microspheres are separated from the capture area of the optical trap, repeat the above steps to achieve repeated capture of the microspheres without replacing the microspheres.

In the present invention, the inner cavity of the capillary is used as the microcavity structure, and the microcavity structure is used as the storage carrier of the microspheres to limit the movement range of the microparticles.

The present invention adopts fiber-optic coupling to drive the pulsed laser of the microsphere, and realizes the precise control of the microsphere's position, motion direction, and the height of the separation from the cavity through the separate control of the spot size, pulse energy, and pulse time of the bidirectional pulsed laser, so that the microsphere can move Enter the optical trap capture region to achieve capture.

The present invention specifically adopts continuous laser light coupled with fiber optics to capture microspheres, and creates an optical trap capture area through the continuous laser light emitted in opposite directions, thereby realizing the suspension of particles in the microcavity structure. If the microsphere is out of the optical trap capture area, the microsphere can be controlled to enter the optical trap capture area by adjusting the opposite pulse laser again, so as to realize the repeated capture of a single microsphere.

Compared with the traditional microsphere optical suspension method, the present invention has several advantages:

The present invention uses a closed microcavity structure to limit the number of microspheres, and can precisely control the microspheres to achieve accurate and repeated capture of the same particle. The position of the particle and the speed and position of the particle leaving the capillary wall can be precisely controlled separately by bidirectional laser pulses.

The success rate of optical levitation can be as high as 100%. At the same time, the closed microcavity structure is suitable for the vacuum environment. Without polluting the vacuum environment at all, and without replacing the particles, it can achieve precise and repeated suspension of particles in a short time.

Description of drawings

Fig. 1 is the structural representation of the system of the present invention;

Fig. 2 When the left continuous laser light (S11) and the right continuous laser light (S13) are incident simultaneously, an optical trap capture region (S12) is formed.

Fig. 3 is a schematic diagram of the microsphere (S9) moving from position A to position B when the left pulse laser (S14) is incident.

Fig. 4 is a schematic diagram of the microsphere (S9) moving from position D to position E when the left pulse laser (S15) is incident.

Fig. 5 is a schematic diagram of the structure of the stable suspension of the microsphere (S9) after entering the optical trap capture region (S12).

In the figure: left first optical fiber S1, left optical coupler S2, left fusion fiber S3, capillary S4, right fusion fiber S5, right optical coupler S6, right first optical fiber S7, right second optical fiber S8, microsphere S9, Left second optical fiber S10, left continuous laser S11, optical trap capture area S12, right continuous laser S13, left pulsed laser S14, right pulsed laser S15.

Detailed ways

Further illustrate the present invention below in conjunction with accompanying drawing.

The system includes a capillary microcavity storing one or more microspheres, and two ends of the microcavity are fused with two sections of optical fibers to form a closed environment. One end of the two optical fibers is fused with a capillary, and the other end is coupled with two lasers, one of which is a continuous laser and the other is a pulsed laser. Two continuous laser beams traveling oppositely form an optical trap inside the capillary microcavity. Two beams of pulsed light are used to excite the microspheres to achieve branching.

As shown in Figure 1, the specific implementation includes the left first optical fiber S1, the left second optical fiber S10, the left optical coupler S2, the left fusion splicing optical fiber S3, the capillary S4, the microsphere S9, the right fusion splicing optical fiber S5, the right optical coupler S6, The first right optical fiber S7 and the second right optical fiber S8; the first left optical fiber S1 and the second left optical fiber S10 are respectively connected to both ends of the input side of the left optical coupler S2, and one end of the output side of the left optical coupler S2 is spliced through the left optical fiber One end of S3 is connected, the other end of the left fusion fiber S3 is fused with the end of the capillary S4, the microsphere S9 is located inside the capillary S4, the other end of the capillary S4 is fused with one end of the right fusion fiber S5, and the other end of the right fusion fiber S5 is connected with the right optical coupler S6 One end on the output side is connected, and the two ends on the input side of the right optical coupler S6 are respectively connected to the first right optical fiber S7 and the second right optical fiber S8.

The left fusion-splicing optical fiber S3, the capillary S4 and the right fusion-splicing optical fiber S5 are fused and spliced to form a closed microcavity structure without gaps, and the microsphere S9 is placed inside the capillary S4.

The specific implementation of capillary S4 adopts silica capillary, which needs to be larger than the diameter of the microsphere. If the aperture size is too large, it will be difficult to constrain the range of microspheres, and if it is too small, the assembly difficulty will increase. Generally, if the size of the microsphere is 10 microns, the aperture size is 20 to 30 microns. The microspheres are 10-20 microns in diameter.

The capillary S4 is made of silicon material, which can have a great influence on the absorption rate and thermal expansion coefficient of the pulsed light. The inner surface of the capillary S4 is completely clean, which can be vacuum or gas-filled or liquid-filled environment, and there are no impurities other than the target microsphere S9.

The present invention is specifically implemented in the case of the known initial position of the microsphere S9, and the process of repeating the capture of the microsphere is as follows:

Step 1. The left continuous laser S11 is input to the left optical coupler S2 through the left first optical fiber S1, and the left optical coupler S2 couples the left continuous laser S11 into the left fusion fiber S3 and transmits it to the inside of the capillary S4; at the same time, the right continuous laser S13 passes through The right first optical fiber S7 is input to the right optical coupler S6, and the right optical coupler S6 couples the right continuous laser S13 into the right fusion splicing optical fiber S5 and emits it to the inside of the capillary S4; the left continuous laser S11 and the right continuous laser S13 are simultaneously emitted to the capillary An optical trap region S12 is formed inside S4.

Step 2. The left pulsed laser S14 is input to the left optical coupler S2 through the left first optical fiber S1, and the left optical coupler S2 couples the left pulsed laser S14 into the left fusion fiber S3 to emit to the inside of the capillary S4 and irradiate the microsphere S9. Make the left pulse laser S14 act on the microsphere S9; at the same time, the right pulse laser S15 is input to the right optical coupler S6 through the right first optical fiber S8, and the right optical coupler S6 couples the right pulse laser S15 into the right fusion splicing fiber S5 to emit to The inside of the capillary S4 is irradiated onto the microsphere S9, so that the right pulse laser S15 acts on the microsphere S9; the power of the right pulse laser S15 is adjusted so that the left pulse laser S14 and the right pulse laser S15 act on the microsphere S9 at the same time, and the microsphere S9 bounces away from its original position and moves to the inside of the optical trap capture area S12, thereby achieving stable capture of the microsphere S9.

Step 3: After the microsphere S9 escapes from the inside of the optical trap capture region S12, the above steps are repeated to achieve repeated capture of the microsphere S9 without replacing the microsphere S9.

In the specific implementation of the present invention, in the case of unknown initial position of microsphere S9, the process of repeatedly capturing microspheres is as follows:

Step 1, as shown in Figure 2, the left continuous laser S11 is input to the left optical coupler S2 through the left first optical fiber S1, and the left optical coupler S2 couples the left continuous laser S11 into the left fusion fiber S3 and emits it to the inside of the capillary S4; at the same time , the right continuous laser S13 is input to the right optical coupler S6 through the right first optical fiber S7, and the right optical coupler S6 couples the right continuous laser S13 into the right fusion fiber S5 and emits it into the capillary S4. The left CW laser S11 and the right CW laser S13 are simultaneously emitted towards the inside of the capillary S4 to form an optical trap capture region S12.

Step 2, as shown in Figure 3, the left pulse laser S14 is input to the left optical coupler S2 through the left first optical fiber S1, and the left optical coupler S2 couples the left pulse laser S14 into the left fusion fiber S3 and emits it into the capillary S4.

If the microsphere S9 is initially at position A, that is, the bottom inside the capillary S4 is radially close to the position of the left optical coupler S2. After the left pulse laser S14 is incident, it acts on the microsphere S9, so that the microsphere S9 breaks away from the inner wall of the capillary S4, moves away from the left optical coupler S2 from position A, and emits upward to position B. After arriving at position B, since the left pulse laser S14 does not continue to act, the microsphere S9 naturally falls to position D, that is, the bottom of the capillary S4 is radially close to the position of the right optical coupler S6.

Step 3, as shown in Figure 4, the right pulsed laser S15 is input to the right optical coupler S6 through the right first optical fiber S8, and the right optical coupler S6 couples the right pulsed laser S15 into the right fusion splicing optical fiber S5 and emits it into the capillary S4. After the right pulse laser S15 is incident, it acts on the microsphere S9, so that the microsphere S9 breaks away from the inner wall of the capillary S4, moves away from the left optical coupler S2 from the position D, and emits upward to the position E closer.

Step 4, as shown in Figure 5, repeat steps 2 and 3, turn on the left pulse laser S14 and the right pulse laser S15 respectively, and adjust the power, and launch the microsphere S9 into the optical trap capture area S12 to realize the microsphere S9 Steady catch.

Step 5: After the microsphere S9 escapes from the inside of the optical trap capture region S12, repeat step 1, step 2, step 3 and step 4, and achieve repeated capture of the microsphere S9 without replacing the microsphere S9.

It can be seen from the above implementation that the advantage of the present invention is that microcavities can be used to achieve repeated capture of particles without repeated loading of particles, and can be applied to environments such as air and vacuum.

The above specific embodiments are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (5)

1. A system based on pulsed laser repeatedly trapping microspheres, characterized in that: comprising left first optical fiber (S1), left second optical fiber (S10), left optical coupler (S2), left fusion splicing optical fiber (S3), Capillary (S4), microsphere (S9), right fusion splice fiber (S5), right optical coupler (S6), right first fiber (S7) and right second fiber (S8); left first fiber (S1) and The second left optical fiber (S10) is respectively connected to both ends of the input side of the left optical coupler (S2), one end of the output side of the left optical coupler (S2) is connected to one end of the left fusion splicing fiber (S3), and the left fusion splicing fiber (S3) ) is fused with one end of the capillary (S4), the microsphere (S9) is located inside the capillary (S4), the other end of the capillary (S4) is fused with one end of the right fusion fiber (S5), and the other end of the right fusion fiber (S5) is fused with the right One end of the output side of the optical coupler (S6) is connected, and the two ends of the input side of the right optical coupler (S6) are respectively connected with the first right optical fiber (S7) and the second right optical fiber (S8). 2. A kind of system based on pulsed laser repeatedly capturing microspheres as claimed in claim 1, is characterized in that: The capillary (S4) is a silica capillary, and the pore size is larger than the diameter of the microsphere. 3. A kind of system based on pulsed laser repeatedly trapping microspheres as claimed in claim 1, is characterized in that: The left fusion-splicing optical fiber (S3), the capillary (S4) and the right fusion-splicing optical fiber (S5) are fusion-spliced to form a closed microcavity structure. 4. A kind of system based on pulsed laser repeatedly trapping microspheres as claimed in claim 1, is characterized in that: The inner surface of the capillary (S4) is completely clean, and may be a vacuum or an environment filled with gas or liquid. 5. A method for repeatedly capturing microspheres based on pulsed laser, characterized in that it comprises the steps: Step 1. The left continuous laser light (S11) is input to the left optical coupler (S2) through the left first optical fiber (S1), and the left optical coupler (S2) couples the left continuous laser light (S11) into the left fusion splicing optical fiber (S3) for emission to the inside of the capillary (S4); at the same time, the right continuous laser light (S13) is input to the right optical coupler (S6) through the right first optical fiber (S7), and the right optical coupler (S6) couples the right continuous laser light (S13) into the right The fusion-spliced optical fiber (S5) is emitted into the capillary (S4); the left continuous laser (S11) and the right continuous laser (S13) are simultaneously emitted to the inside of the capillary (S4) to form an optical trap capture area (S12); Step 2. The left pulse laser (S14) is input to the left optical coupler (S2) through the left first optical fiber (S1), and the left optical coupler (S2) couples the left pulse laser (S14) into the left fusion fiber (S3) for emission To the inside of the capillary (S4) and irradiate on the microsphere (S9), so that the left pulse laser (S14) acts on the microsphere (S9); at the same time, the right pulse laser (S15) is input to the microsphere through the first right optical fiber (S8) The right optical coupler (S6), the right optical coupler (S6) couples the right pulse laser (S15) into the right fusion fiber (S5), emits it into the capillary (S4) and irradiates it on the microsphere (S9), so that the right pulse The laser (S15) acts on the microsphere (S9); the power of the right pulse laser (S15) is adjusted so that the left pulse laser (S14) and the right pulse laser (S15) act on the microsphere (S9) simultaneously, and the microsphere (S9 ) bounces away from the original position and moves to the inside of the optical trap capture area (S12), thereby achieving stable capture of the microspheres (S9); Step 3: After the microspheres (S9) are separated from the inside of the optical trap capture region (S12), the above steps are repeated to achieve repeated capture of the microspheres (S9) without replacing the microspheres (S9).