CN110262029B - Light trapping particle control device and method - Google Patents
Light trapping particle control device and method Download PDFInfo
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- CN110262029B CN110262029B CN201910432244.XA CN201910432244A CN110262029B CN 110262029 B CN110262029 B CN 110262029B CN 201910432244 A CN201910432244 A CN 201910432244A CN 110262029 B CN110262029 B CN 110262029B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/32—Micromanipulators structurally combined with microscopes
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
Abstract
A control device for light capture particles is applied to the technical field of photoelectricity and comprises: the optical capturing device comprises an optical capturing unit, a digital feedback control unit and an upper computer, wherein the optical capturing unit is used for measuring three-dimensional position signals of captured micro-nano particles, transmitting the three-dimensional position signals to the digital feedback control unit and the upper computer, the upper computer is used for generating feedback control parameters according to the three-dimensional position signals and sending the feedback control parameters to the digital feedback control unit, and the digital feedback control unit is used for generating feedback control signals to the optical capturing unit according to the three-dimensional position signals, the feedback control parameters and target motion states so as to perform feedback control on the optical capturing unit. The invention also discloses a control method of the light capturing particles, which can realize the control of the motion states of vibration cooling, vibration amplitude, vibration frequency and the like of the light capturing particles.
Description
Technical Field
The invention relates to the technical field of photoelectricity, in particular to a control device and a control method for light capture particles.
Background
The optical tweezers technology or the light capturing technology is used for capturing micro-nano particles by applying a light intensity gradient force pointing to the center of an optical potential well to particles in an optical field through a focused light beam. The technology of capturing light in liquid has been developed and widely put into practical use since the invention of optical tweezers in 1986. The ability of optical tweezers to control micro-nano particles is utilized, and optical trapping techniques are used in the fields of nano-processing, micro-mechanical assembly, and the like. Meanwhile, as the size of the captured particles is usually in the micrometer and nanometer dimensions, the movement of the captured particles is particularly easy to be influenced by the external environment, and the light capturing technology utilizing the characteristics is also applied to the fields of weak force measurement, research on the mechanical properties of macromolecules and biomolecules and the like.
In recent years, vacuum light capturing technology has been increasingly studied and focused, unlike conventional light capturing in liquids. Because the periphery of the captured micro-nano particles is not interfered by liquid or air molecules, the capture which is relatively isolated from the outside environment is realized, and the micro-nano particles can perform almost perfect simple harmonic vibration in an optical potential well. The method has outstanding research potential in the leading-edge fields of extremely weak force measurement, macroscopic quantum state research, gravitational wave measurement and the like. And controlling the state of motion of the captured particles is a necessary working step before further investigation. Several control schemes have been proposed, such as parametric feedback cooling based on light intensity control; cooling based on the optical resonator; cooling based on light pressure, etc. However, in the proposed solutions, cooling of the particle movement or reduction of the particle amplitude is mostly emphasized, lacking the ability to control other movement patterns. Meanwhile, the traditional control device is complex, expensive and difficult to debug, and is difficult to switch between different control modes.
Disclosure of Invention
The invention mainly aims to provide a device and a method for controlling light trapping particles, which can realize the control of the motion states of vibration cooling, vibration amplitude, vibration frequency and the like of the light trapping particles.
To achieve the above object, a first aspect of an embodiment of the present invention provides a control device for light trapping particles, including:
the system comprises a light capturing unit, a digital feedback control unit and an upper computer;
the light capturing unit is used for measuring three-dimensional position signals of captured micro-nano particles and transmitting the three-dimensional position signals to the digital feedback control unit and the upper computer;
the upper computer is used for generating feedback control parameters according to the three-dimensional position signals and sending the feedback control parameters to the digital feedback control unit;
the digital feedback control unit is used for generating a feedback control signal to the light capturing unit according to the three-dimensional position signal, the feedback control parameter and the target motion state so as to perform feedback control on the light capturing unit.
Further, the light capturing unit includes:
a laser 1, a rotatable half-wave plate 2, a polarization beam splitter prism 3, an acousto-optic modulator 4, 90:10 beam splitting prism 5, iris 6, rotatable polarizer 7, beam expander group 8, first vacuum chamber window 9, microscope objective 10, particle delivery 11, aspherical lens 12, second vacuum chamber window 13, vacuum chamber 14, vacuum pump group 15, 30:70 beam splitting prisms 16, 50:50 beam splitting prism 17, dove prism 18, first D-shaped mirror 19, second D-shaped mirror 20, X-axis balanced photodetector 21, Y-axis balanced photodetector 22, Z-axis balanced photodetector 23;
the laser 1 is used for emitting laser beams, the laser beams pass through the rotatable half wave plate 2 to enable the polarization of the laser beams to rotate, and the laser beams with the polarization rotated pass through the polarization beam splitting prism 3 to screen out the laser beams parallel to the polarization direction of the X-axis;
the digital feedback control unit 24 controls the acousto-optic modulator 4 to adjust the optical power of the laser beam to change the vibration frequency of the micro-nano particles 26 to be optically captured;
90: the 10 beam splitting prism 5, the iris 6 and the rotatable polarizer 7 are used for adjusting the light beam with the light intensity lower than a first preset value in the laser beams to be received by the Z-axis balance photoelectric detector 23;
the beam expander group 8 is used for adjusting the diameter of the light beam with the light intensity higher than a second preset value in the laser beam, so that the diameter of the light beam is larger than the rear pupil diameter of the microscope objective 10;
the laser beam enters the rear pupil of the microscope objective 10 through the first vacuum cavity window 9, and after being focused by the microscope objective 10, a light potential well capable of capturing micro-nano particles is generated near the focal point of the microscope objective 10;
the particle projector 11 is used for delivering the micro-nano particles 26 to the vicinity of the focal point of the microscope objective lens 10, so that the micro-nano particles 26 are captured by light;
the vacuum pump 15 is used for vacuumizing the vacuum cavity 14;
the laser beam focused by the microscope objective lens 10 is changed into parallel light after passing through the aspherical mirror 12, and then is emitted by 30:70 the beam splitting prism 16 splits the beam into two beams so that a beam having a light intensity lower than the third preset value is received by the Z-axis balanced photodetector 23 and a beam having a light intensity higher than the fourth preset value is received by 50: the 50 beam splitting prism 17 splits two light beams, wherein one light beam is split into two light beams from the middle by the first D-shaped mirror 19 after rotating by 90 degrees through the beam splitting prism 18, and the two light beams are received by the Y-axis balance photoelectric detector 22; the other beam is split from the middle by a second D-mirror 20 into two beams, both of which are received by an X-axis balanced photodetector 21;
the X-axis balanced photodetector 21, the Y-axis balanced photodetector 22, and the Z-axis balanced photodetector 23 measure three-dimensional position signals of the micro-nano particles 26, and transmit the three-dimensional position signals to the digital feedback control unit 24 and the upper computer 25.
Further, the digital feedback control unit includes:
the device comprises an analog-to-digital conversion module 27, an FPGA module 28, a digital-to-analog conversion module 29 and an upper computer communication module 30;
the analog-to-digital conversion module 27 is configured to convert the three-dimensional position signals sent by the X-axis balanced photodetector 21, the Y-axis balanced photodetector 22, and the Z-axis balanced photodetector 23 into digital position signals, and send the digital position signals to the FPGA module 28;
the upper computer communication module 30 is configured to send feedback control parameters sent by the upper computer 25 to the FPGA module 28;
the FPGA module 28 is configured to generate a digital feedback control signal according to the digital position signal, the target motion state, and the feedback control parameter, and send the digital feedback control signal to the digital-to-analog conversion module 29;
the digital-to-analog conversion module 29 is configured to convert the digital feedback control signal into a voltage feedback control signal and send the voltage feedback control signal to the acousto-optic modulator 4.
Further, the FPGA module 28 includes:
the digital band-pass filter 31, the first delay module 32, the second delay module 33, the amplitude module 34, the frequency measurement module 35, the single-axis feedback signal generation module 36, the signal synthesis module 37 and the output module 38;
a digital band-pass filter 31 for filtering noise of any one of the axis displacement signals in the three-dimensional position signal;
a first delay module 32 for generating a first signal in phase with the shaft displacement signal;
a second delay module 33 for generating a second signal having a phase difference pi/2 from the axis displacement signal;
an amplitude module 34 for generating a third signal when the first and second signals pass, and calculating a current vibration amplitude of the light-captured micro-nano particles 26;
a frequency measurement module 35 for generating a fourth signal when the first signal passes through, and calculating a current vibration frequency of the micro-nano particles 26 captured by the light;
a uniaxial feedback signal generating module 36, configured to generate a uniaxial feedback signal according to the first signal, the second signal, the third signal, and the fourth signal;
a signal synthesis module 37 for synthesizing the uniaxial feedback signals of the respective axes to generate digital feedback control signals;
an output module 38 for sending the digital feedback control signal to the digital to analog conversion module 29.
Further, the output voltages of the X-axis balanced photodetector 21, the Y-axis balanced photodetector 22, and the Z-axis balanced photodetector 23 are proportional to the displacement components of the captured micro-nano particles 26 in the X-axis, the Y-axis, and the Z-axis, respectively.
Further, the microscope objective 10 and the aspherical mirror 12 are mounted within a vacuum chamber 14.
A second aspect of an embodiment of the present invention provides a method for controlling light trapping particles, including:
delivering micro-nano particles 26 to be captured near the focal point of the microscope objective lens 10 with a particle delivery device 11;
observing the signal output of the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 through the upper computer 25, and confirming that the micro-nano particles 26 are captured by light when the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 have stable position signal output of the captured micro-nano particles 26;
taking out the particle feeder 11 from the vacuum cavity 14, locking the vacuum cavity 14, opening the vacuum pump 15, and pumping the air pressure in the vacuum cavity 14 to a preset vacuum degree;
the size of the adjustable aperture 6 and the positions of the first D-shaped mirror 19 and the second D-shaped mirror 20 are adjusted so that noise of output signals of the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 is minimum;
according to different vibration frequencies of the micro-nano particles 26 in the X, Y, Z axial direction, the upper computer 25 respectively sets the bandpass frequency of the digital bandpass filter 31 in the FPGA module 28 so as to reserve the vibration signals in the X, Y, Z axial direction and inhibit noise signals of other frequencies;
the delay parameters of the first delay module 32 and the second delay module 33 are set so that the first delay module 32 in the X, Y, Z axial direction generates a signal in phase with the displacement signal, and the second delay module 33 generates a signal in phase with the displacement signal by pi/2.
Further, when the motion state of the micro-nano particles 26 on a certain axis is vibration cooling, the amplitude of the micro-nano particles 26 on the axis is set to 0.
Further, when the motion state of the micro-nano particles 26 on a certain axis is amplitude locking, the amplitude of the micro-nano particles 26 on the axis is set to a preset fixed value not exceeding the vibration limit of the particles.
Further, when the motion state of the micro-nano particles 26 is frequency locked, the motion state control can be applied only on one axis at a time.
As can be seen from the above embodiments of the present invention, the control device and method for optical capturing particles provided by the present invention include an optical capturing unit, a digital feedback control unit, and an upper computer, where the optical capturing unit is configured to measure a three-dimensional position signal of a micro-nano particle to be captured, and transmit the three-dimensional position signal to the digital feedback control unit and the upper computer, and the upper computer is configured to generate a feedback control parameter according to the three-dimensional position signal, and send the feedback control parameter to the digital feedback control unit, and the digital feedback control unit is configured to generate a feedback control signal to the optical capturing unit according to the three-dimensional position signal, the feedback control parameter, and a target motion state, so as to perform feedback control on the optical capturing unit, thereby implementing control on motion states such as vibration cooling, vibration amplitude, vibration frequency, and the like of the optical capturing particles.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are necessary for the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention and that other drawings may be obtained from them without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a light capturing unit in a light capturing particle control device according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a digital feedback control unit and an upper computer in a light trapping particle control device according to an embodiment of the present invention;
fig. 3 is a flow chart of a method for controlling light trapping particles according to another embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions in the embodiments of the present invention will be clearly described in conjunction with the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 and 2, fig. 1 is a schematic structural diagram of a light capturing unit in a light capturing particle control device according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of a digital feedback control unit and an upper computer in a light capturing particle control device according to an embodiment of the present invention, where the device includes:
the system comprises a light capturing unit, a digital feedback control unit and an upper computer;
the light capturing unit is used for measuring a three-dimensional position signal of the micro-nano particles to be captured and transmitting the three-dimensional position signal to the digital feedback control unit and the upper computer;
the upper computer is used for generating feedback control parameters according to the three-dimensional position signals and sending the feedback control parameters to the digital feedback control unit;
the digital feedback control unit is used for generating a feedback control signal to the light capturing unit according to the three-dimensional position signal, the feedback control parameter and the target motion state so as to perform feedback control on the light capturing unit.
The following describes the device specifically, the device includes:
a laser 1, a rotatable half-wave plate 2, a polarization beam splitter prism 3, an acousto-optic modulator 4, 90:10 beam splitting prism 5, iris 6, rotatable polarizer 7, beam expander group 8, first vacuum chamber window 9, microscope objective 10, particle delivery 11, aspherical lens 12, second vacuum chamber window 13, vacuum chamber 14, vacuum pump group 15, 30:70 beam splitting prisms 16, 50:50 beam splitting prism 17, dove prism 18, first D mirror 19, second D mirror 20, X-axis balanced photodetector 21, Y-axis balanced photodetector 22, Z-axis balanced photodetector 23, digital feedback control unit 24, host computer 25, micro-nano particles 26.
In the device, a laser 1 emits a laser beam for light capture, the laser beam passes through a rotatable half-wave plate 2 to rotate the polarization of the laser beam, and then a fixed polarization beam splitter prism 3 screens out laser components in the polarization direction parallel to the X-axis, so that the primary control of the laser beam power is realized.
The laser then passes through the acousto-optic modulator 4, and the acousto-optic modulator 4 can control the laser intensity at a high speed according to the modulation signal. The laser then passes through 90:10, wherein the light beam with weak light intensity (lower than the first preset value) passes through the iris 6 and the rotatable polarizer 7, and then the light intensity and shape are adjusted to be the most appropriate, and then is received by a photoelectric probe of the Z-axis balance photoelectric detector 23. After the light beam with strong light intensity (higher than the second preset value) passes through the beam expander group 8, the beam diameter is adjusted to be slightly larger than the rear pupil diameter of the microscope objective lens 10.
The microscope objective 10 and the aspherical mirror 12 are mounted in a vacuum chamber 14. The vacuum pump 15 can evacuate the vacuum chamber 14. The laser beam enters the rear pupil of the microscope objective lens 10 through the first vacuum cavity window 9, and after being focused by the microscope objective lens 10, an optical potential well capable of capturing micro-nano particles by light is generated near the focal point of the objective lens 10. The particle projector 11 delivers the micro-nano particles 26 near the focal point of the microscope objective lens 10, and the particles 26 are captured by the optical potential well. The laser beam focused by the microscope objective lens 10 passes through the aspherical mirror 12 and then is converted into parallel light to be emitted. Passing through the second vacuum chamber window 13, the vacuum chamber is then cooled by 30:70 the beam splitting prism 16 splits the laser light into two beams, and weaker (below a third preset value) light is received by the other photo-detector of the Z-axis balanced photo-detector 23. The stronger (higher than the fourth preset value) light is reflected 50: the 50 beam splitting prism 17 splits the laser beam into two beams. One of the beams is split into two beams from the middle by a first D-shaped mirror 19 after being rotated 90 degrees by a through-the-wire prism 18, and the two beams are respectively received by two photoelectric probes of a Y-axis balanced photoelectric detector 22. The other beam is split from the middle by a second D-mirror 20 into two beams which are received by two photodetectors of an X-axis balanced photodetector 21, respectively.
The output voltages of the X-axis balanced photodetector 21, the Y-axis balanced photodetector 22 and the Z-axis balanced photodetector 23 are respectively proportional to the displacement components of the captured micro-nano particles in the X-axis, the Y-axis and the Z-axis. The motion components of the micro-nano particles 26 in the X-axis, Y-axis, and Z-axis are independent of each other due to the asymmetry of the optical potential well. The measured three-dimensional position signal is transmitted to the digital feedback control unit 24 and the upper computer 25.
The digital feedback control unit 24 is constituted by: the device comprises an analog-to-digital conversion module 27, an FPGA module 28, a digital-to-analog conversion module 29 and an upper computer communication module 30. The three-dimensional position signals from the detectors 21, 22, 23 are first converted into digital signals by an analog-to-digital conversion module 27. The digitized position signals are passed to FPGA module 28. Appropriate digital feedback control signals are generated in the FPGA module 28 based on the position signals of the captured particles 26, the conditions of the captured particles 26, the targets and parameters of the motion state control and sent to the digital to analog conversion module 29. The digital-to-analog conversion module 29 converts the digital feedback control signal into a voltage feedback control signal and sends the voltage feedback control signal to the acousto-optic modulator 4 for feedback control of the light intensity. The upper computer communication module 30 is responsible for forwarding the feedback control parameters sent by the upper computer 25 to the FPGA module 28.
In the FPGA module 28, the processing of the X-axis displacement signal is considered first. The X-axis displacement signal is first filtered by a digital band-pass filter 31 for noise outside the frequency range of the target signal. And then through a first delay module 32 and a second delay module 33. The first delay module 32 and the second delay module 33 compensate for the phase difference caused by the delay of the feedback loop by changing the phase of the input signal in a manner of adding additional delay. The first delay module 32 generates a signal in phase with the X-axis displacement signal. The second delay module 33 generates a signal that is pi/2 out of phase with the X-axis displacement signal. The signals of the first delay module 32 and the second delay module 33 calculate the current amplitude of the captured particle through the amplitude module 34, the signal of the first delay module 32 calculates the current vibration frequency of the captured particle through the frequency measurement module 35, the first signal, the second signal, the third signal and the fourth signal respectively generated by the first delay module 32, the second delay module 33, the amplitude module 34 and the frequency measurement module 35 enter the single-axis feedback signal generating module 36, and corresponding single-axis feedback control signals are generated according to the target amplitude and the target frequency input by the upper computer 25, and the single-axis feedback control signals can switch the laser intensity between strong light intensity and weak light intensity, or integrally improve or reduce the laser intensity. The ratio of the light intensity difference between the strong and weak switched light intensities to the average light intensity is a modulation depth, and the modulation depth is set by the upper computer 25. In the uniaxial feedback signal generating module, it can be determined from the signals of the first delay module 32 and the second delay module 33 whether the particle is far away or near an equilibrium position, and if we want to increase (decrease) the particle amplitude, the module will require switching to a weak (strong) intensity when the particle 26 is far away and to a strong (weak) intensity when the particle 26 is near. If it is desired to amplitude lock particles 26 to a target amplitude, the target amplitude is compared to the amplitude module 34 signal and the amplitude is increased or decreased depending on the magnitude of the two. If the vibration frequency of the particles 26 needs to be locked at the target frequency, the target frequency is compared with the signal of the frequency measuring module 35, the measured frequency is smaller, the light intensity is increased, the measured frequency is higher, and the light intensity is reduced. The processing of the Y-axis displacement signal and the Z-axis displacement signal is the same as the processing of the X-axis displacement signal described above. The three single-axis feedback control signals X, Y, Z thus obtained generate a three-dimensional control signal through the signal synthesis module 37, and the three-dimensional control signal is output by the signal synthesis module 37 according to the principle that the majority is obeyed in a minority and the control target light intensity of which the majority is the control target light intensity of the three single-axis feedback control signals. The signal of the signal synthesizing module 37 passes through the output module 38. The output module 38 outputs an output digital signal for properly controlling the light intensity according to the target according to the diffraction order and diffraction efficiency used by the acousto-optic modulator 4. The signal is finally sent to a digital to analogue conversion module 29. And the control of the motion state of the light capturing particles is realized by controlling the light intensity through the acousto-optic modulator 4.
Alternatively, the laser 1 may be a 2W power 1064nm continuous light laser.
Alternatively, the micro-nano particles 26 may be 165nm diameter silica spheres.
The device generates the feedback control signal in a digital signal processing mode, and the required equipment is simple and easy to construct and implement. Different light capturing micro-nano particle motion state control can be completed by setting and modifying parameters of the digital feedback module.
The device, when used for feedback cooling of light capturing particle motion, can reduce the equivalent temperature of the particle motion on the X, Y, Z axis independent motion component to below 100 mK.
The device is used for amplitude locking of the movement of the light capturing particles, and can control the amplitude of the particles on the X, Y, Z axis independent movement component to be near a set value. The accuracy of the control is better than 1% of the target amplitude.
The device can control the frequency of the particles on one of the X, Y, Z axis independent motion components to be near a set value when being used for locking the frequency of the motion of the light capturing particles. The accuracy of the frequency control is better than 1Hz.
Referring to fig. 3, fig. 3 is a flowchart of a method for controlling light trapping particles according to another embodiment of the present invention, which mainly includes the following steps:
s101, delivering micro-nano particles 26 to be captured to the vicinity of a focal point of a microscope objective lens 10 by a particle delivery device 11;
all detectors 21, 22, 23 are powered on, and the host computer 25, the digital feedback control unit 24 and the acousto-optic modulator 4 are turned on. The laser 1 was turned on and the half wave plate 2 was rotated to adjust the laser beam power to 200mW. The micro-nano particles 26 to be captured are delivered by the particle deliverer 11 to the vicinity of the focal point of the microscope objective lens 10.
S102, observing the signal output of the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 through the upper computer 25, and confirming that the micro-nano particles 26 are captured by light when the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 have stable position signal output of the captured micro-nano particles 26.
S103, taking out the particle feeder 11 from the vacuum cavity 14, locking the vacuum cavity 14, opening the vacuum pump 15, and pumping the air pressure in the vacuum cavity 14 to a preset vacuum degree;
s104, adjusting the size of the adjustable aperture 6 and the positions of the first D-shaped mirror 19 and the second D-shaped mirror 20 to enable noise of output signals of the X-axis balanced photoelectric detector 21, the Y-axis balanced photoelectric detector 22 and the Z-axis balanced photoelectric detector 23 to be minimum;
s105, respectively setting the bandpass frequencies of the digital bandpass filters 31 in the FPGA module 28 through the upper computer 25 according to different vibration frequencies of the micro-nano particles 26 in the X, Y, Z axial direction so as to reserve the vibration signals in the X, Y, Z axial direction and inhibit noise signals of other frequencies;
the vibration frequencies of the particles 26 in the X, Y, Z axis direction were 124.5kHz, 158.1kHz, and 51.7kHz, respectively. The upper computer 25 is used for setting the band-pass center frequency of the digital band-pass filter of the X axis in the FPGA module 28 through the upper computer communication module 30 to be 124.5kHz and 10kHz; the band-pass center frequency of the digital band-pass filter of the Y axis is 158.1kHz and the bandwidth is 10kHz; the digital band pass filter band pass center frequency of the Z axis is 51.7kHz and the bandwidth is 10kHz.
S106, setting delay parameters of the first delay module 32 and the second delay module 33 so that the first delay module 32 generates a signal in phase with the displacement signal in the X, Y, Z axial direction, and the second delay module 33 generates a signal in phase with the displacement signal by pi/2.
And setting delay parameters of the first delay module and the second delay module according to the total delay of the feedback loop of 650 ns. The first delay module determining each axis generates a signal in phase with the displacement signal. The second delay module generates a signal having a phase difference pi/2 with the displacement signal.
The amplitude of the Y-axis motion was determined to be controlled at 0.9V and the vibration frequency of the Y-axis motion was determined to be 155563Hz. Cooling the X and Z axis motion if vibration cooling sets the target amplitude to 0, i.e. the amplitude is reduced as much as possible. Setting the target amplitudes of the X and Z axes to 0 through the upper computer 25; setting the target amplitude of the Y axis to be 0.9V and the target frequency to be 155563Hz; the modulation depth was set to 0.5%.
In the various embodiments provided herein, it should be understood that the disclosed apparatus and methods may be implemented in other ways. For example, the embodiments described above are merely illustrative, e.g., the division of the modules is merely a logical function division, and there may be additional divisions of actual implementation, e.g., multiple modules or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication links shown or discussed with each other may be indirect coupling or communication links through interfaces, modules, or in electrical, mechanical, or other forms.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed over a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist alone physically, or two or more modules may be integrated into one module. The integrated modules may be implemented in hardware or in software functional modules.
It should be noted that, for the sake of simplicity of description, the foregoing method embodiments are all expressed as a series of combinations of actions, but it should be understood by those skilled in the art that the present invention is not limited by the order of actions described, as some steps may be performed in other order or simultaneously in accordance with the present invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are all preferred embodiments, and that the acts and modules referred to are not necessarily all required for the present invention.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
The foregoing is a description of the apparatus and method for controlling light trapping particles according to the present invention, and is not to be construed as limiting the invention, since modifications in the detailed description and the application scope will be apparent to those skilled in the art from consideration of the invention.
Claims (9)
1. A control device for light trapping particles, comprising:
the system comprises a light capturing unit, a digital feedback control unit and an upper computer;
the light capturing unit is used for measuring a three-dimensional position signal of the captured micro-nano particles and transmitting the three-dimensional position signal to the digital feedback control unit and the upper computer, and comprises: the device comprises a laser (1), a rotatable half-wave plate (2), a polarization beam splitter prism (3), an acousto-optic modulator (4) and a polarization beam splitter prism (90): 10 beam splitting prism (5), iris (6), rotatable polarizer (7), beam expander group (8), first vacuum cavity window (9), microscope objective (10), particle delivery ware (11), aspheric lens (12), second vacuum cavity window (13), vacuum cavity (14), vacuum pump group (15), 30:70 beam splitting prisms (16), 50:50 beam splitting prisms (17), a dove prism (18), a first D-shaped mirror (19), a second D-shaped mirror (20), an X-axis balance photoelectric detector (21), a Y-axis balance photoelectric detector (22) and a Z-axis balance photoelectric detector (23); the laser (1) is used for emitting laser beams, the laser beams pass through the rotatable half wave plate (2) to enable the polarization of the laser beams to rotate, and the laser beams after polarization rotation pass through the polarization beam splitting prism (3) to screen out the laser beams parallel to the polarization direction of the X-axis; a digital feedback control unit (24) controls the acousto-optic modulator (4) to adjust the optical power of the laser beam so as to change the vibration frequency of the optical captured micro-nano particles (26); 90: the 10 beam splitting prism (5), the iris diaphragm (6) and the rotatable polaroid (7) are used for adjusting the light beam with the light intensity lower than a first preset value in the laser beams to be received by the Z-axis balance photoelectric detector (23); the beam expander group (8) is used for adjusting the diameter of the light beam with the light intensity higher than a second preset value in the laser beam, so that the diameter of the light beam is larger than the rear pupil diameter of the microscope objective (10); the laser beam enters the rear pupil of the micro-objective lens (10) through the first vacuum cavity window (9), and after being focused by the micro-objective lens (10), a light potential well capable of capturing micro-nano particles is generated near the focus of the micro-objective lens (10); the particle feeder (11) is used for feeding the micro-nano particles (26) to the vicinity of the focal point of the micro-objective lens (10) so that the micro-nano particles (26) are captured by light; the vacuum pump (15) is used for vacuumizing the vacuum cavity (14); the laser beam focused by the microscope objective lens (10) is changed into parallel light after passing through the aspherical mirror (12) and then is emitted out, and the laser beam passes through the second vacuum cavity window (13) and is then emitted by a lens 30:70 splitting prism (16) split into two beams so that the beam with intensity lower than the third preset value is received by Z-axis balance photodetector (23), and the beam with intensity higher than the fourth preset value is received by 50: the 50 beam splitting prism (17) is divided into two beams, one beam is rotated by 90 degrees through the beam splitting prism (18) and then split into two beams from the middle by the first D-shaped mirror (19), and the two beams are received by the Y-axis balanced photoelectric detector (22); the other beam is split from the middle by a second D-mirror (20) into two beams, both of which are received by an X-axis balanced photodetector (21); the X-axis balance photoelectric detector (21), the Y-axis balance photoelectric detector (22) and the Z-axis balance photoelectric detector (23) measure three-dimensional position signals of the micro-nano particles (26) and transmit the three-dimensional position signals to the digital feedback control unit (24) and the upper computer (25);
the upper computer is used for generating feedback control parameters according to the three-dimensional position signals and sending the feedback control parameters to the digital feedback control unit;
the digital feedback control unit is used for generating a feedback control signal to the light capturing unit according to the three-dimensional position signal, the feedback control parameter and the target motion state so as to perform feedback control on the light capturing unit.
2. The light-trapping particle control device of claim 1, wherein the digital feedback control unit comprises:
the device comprises an analog-to-digital conversion module (27), an FPGA module (28), a digital-to-analog conversion module (29) and an upper computer communication module (30);
the analog-to-digital conversion module (27) is used for converting the three-dimensional position signals sent by the X-axis balance photoelectric detector (21), the Y-axis balance photoelectric detector (22) and the Z-axis balance photoelectric detector (23) into digital position signals and sending the digital position signals to the FPGA module (28);
the upper computer communication module (30) is used for sending feedback control parameters sent by the upper computer (25) to the FPGA module (28);
the FPGA module (28) is used for generating a digital feedback control signal according to the digital position signal, the target motion state and the feedback control parameter and sending the digital feedback control signal to the digital-to-analog conversion module (29);
and the digital-to-analog conversion module (29) is used for converting the digital feedback control signal into a voltage feedback control signal and sending the voltage feedback control signal to the acousto-optic modulator (4).
3. The control device of light capturing particles according to claim 2, wherein the FPGA module (28) comprises:
the digital band-pass filter (31), a first delay module (32), a second delay module (33), an amplitude module (34), a frequency measurement module (35), a single-axis feedback signal generation module (36), a signal synthesis module (37) and an output module (38);
a digital band-pass filter (31) for filtering noise of any one of the axis displacement signals in the three-dimensional position signal;
a first delay module (32) for generating a first signal in phase with the shaft displacement signal;
a second delay module (33) for generating a second signal having a phase difference pi/2 from the axis displacement signal;
an amplitude module (34) for generating a third signal when the first and second signals pass, and calculating a current vibration amplitude of the light-captured micro-nano particles (26);
a frequency measurement module (35) for generating a fourth signal when the first signal passes, and calculating a current vibration frequency of the light-captured micro-nano particles (26);
a uniaxial feedback signal generating module (36) for generating a uniaxial feedback signal from the first, second, third, and fourth signals;
a signal synthesis module 37) for synthesizing the uniaxial feedback signals of the respective axes to generate digital feedback control signals;
and the output module (38) is used for sending the digital feedback control signal to the digital-to-analog conversion module (29).
4. The control device for capturing particles according to claim 1, wherein the output voltages of the X-axis balanced photodetector (21), the Y-axis balanced photodetector (22), and the Z-axis balanced photodetector (23) are proportional to the displacement components of the captured micro-nano particles (26) in the X-axis, the Y-axis, and the Z-axis, respectively.
5. A control device for light-trapping particles according to claim 1, wherein the microscope objective (10) and the aspherical mirror (12) are mounted in a vacuum chamber (14).
6. A method of controlling light trapping particles, comprising:
measuring a three-dimensional position signal of the captured micro-nano particles with a light capturing unit, comprising: a laser (1) is used for emitting a laser beam, the laser beam passes through a rotatable half wave plate (2) to enable the polarization of the laser beam to rotate, and the laser beam after polarization rotation passes through a polarization beam splitting prism (3) to screen out the laser beam parallel to the polarization direction of the X-axis; controlling an acousto-optic modulator (4) with a digital feedback control unit (24) to adjust the optical power of the laser beam to change the vibration frequency of micro-nano particles (26) to be optically captured; using 90: a 10 beam splitting prism (5), a variable aperture (6) and a rotatable polaroid (7) are used for adjusting the light beam with the light intensity lower than a first preset value in the laser beams so as to be received by a Z-axis balance photoelectric detector (23); the diameter of a light beam with the light intensity higher than a second preset value in the laser beam is adjusted by a beam expander group (8), so that the diameter of the light beam is larger than the rear pupil diameter of a microscope objective (10); the laser beam enters the rear pupil of the micro-objective lens (10) through the first vacuum cavity window (9), and after being focused by the micro-objective lens (10), a light potential well capable of capturing micro-nano particles is generated near the focus of the micro-objective lens (10); delivering the micro-nano particles (26) to be captured to the vicinity of the focus of the microscope objective lens (10) by using a particle delivery device (11), so that the micro-nano particles (26) are captured by light; vacuumizing the vacuum cavity (14) by using a vacuum pump (15); the aspherical mirror (12) converts the laser beam focused by the microscope objective (10) into parallel light to be emitted, and the parallel light passes through the second vacuum cavity window (13) and then is emitted by a lens 30:70 splitting prism (16) split into two beams so that the beam with intensity lower than the third preset value is received by Z-axis balance photodetector (23), and the beam with intensity higher than the fourth preset value is received by 50: the 50 beam splitting prism (17) is divided into two beams, one beam is rotated by 90 degrees through the beam splitting prism (18) and then split into two beams from the middle by the first D-shaped mirror (19), and the two beams are received by the Y-axis balanced photoelectric detector (22); the other beam is split from the middle by a second D-mirror (20) into two beams, both of which are received by an X-axis balanced photodetector (21); the X-axis balance photoelectric detector (21), the Y-axis balance photoelectric detector (22) and the Z-axis balance photoelectric detector (23) measure three-dimensional position signals of the micro-nano particles (26) and transmit the three-dimensional position signals to the digital feedback control unit (24) and the upper computer (25);
observing signal output of the X-axis balance photoelectric detector (21), the Y-axis balance photoelectric detector (22) and the Z-axis balance photoelectric detector (23) through the upper computer (25), and confirming that the micro-nano particles (26) are captured by light when the X-axis balance photoelectric detector (21), the Y-axis balance photoelectric detector (22) and the Z-axis balance photoelectric detector (23) have stable position signal output of the captured micro-nano particles (26);
taking out the particle feeder (11) from the vacuum cavity (14), locking the vacuum cavity (14), opening the vacuum pump (15), and pumping the air pressure in the vacuum cavity (14) to a preset vacuum degree;
the size of the adjustable aperture (6) and the positions of the first D-shaped mirror (19) and the second D-shaped mirror (20) are adjusted to enable noise of output signals of the X-axis balanced photoelectric detector (21), the Y-axis balanced photoelectric detector (22) and the Z-axis balanced photoelectric detector (23) to be minimum;
according to different vibration frequencies of the micro-nano particles (26) in the X, Y, Z axial direction, respectively setting the bandpass frequencies of the digital bandpass filters (31) in the FPGA module (28) through the upper computer (25) so as to reserve the vibration signals in the X, Y, Z axial direction and inhibit noise signals of other frequencies;
delay parameters of the first delay module (32) and the second delay module (33) are set so that the first delay module (32) in the X, Y, Z axial direction generates a signal in phase with a displacement signal, and the second delay module (33) generates a signal in phase difference pi/2 with the displacement signal.
7. The method according to claim 6, wherein when the motion state of the micro-nano particles (26) on a certain axis is vibration cooling, the amplitude of the micro-nano particles (26) on the axis is set to 0.
8. The method according to claim 6, wherein when the motion state of the micro-nano particles (26) on a certain axis is amplitude-locked, the amplitude of the micro-nano particles (26) on the axis is set to a preset fixed value not exceeding the vibration limit of the particles.
9. A method of controlling light trapping particles according to claim 6, wherein when the motion state of the micro-nano particles (26) is frequency locked, the frequency locked motion state control can be applied only on one axis at a time.
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| CN111750778B (en) * | 2020-07-01 | 2021-04-20 | 浙江大学 | Particle position detection device based on double-optical-tweezers system and precision improvement method |
| CN111855505B (en) * | 2020-07-07 | 2021-12-28 | 浙江大学 | Microsphere cluster state detection device and detection method applied to vacuum optical trap system |
| CN113380436B (en) * | 2021-04-28 | 2022-12-20 | 浙江大学 | Frequency-adjustable stable rotating device in vacuum optical tweezers system and use method |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102230934A (en) * | 2011-03-30 | 2011-11-02 | 杭州锐光生物技术有限公司 | Method and detector for detecting tumor microsomes by using laser tweezers and micro fluidics |
| CN102645754A (en) * | 2012-04-13 | 2012-08-22 | 北京信息科技大学 | Far-field multiple optical trapping device and method |
| CN103674814A (en) * | 2012-09-13 | 2014-03-26 | 香港城市大学 | Methods and means for manipulating particles |
| CN104216103A (en) * | 2014-09-05 | 2014-12-17 | 华中科技大学 | Micropipe and optical tweezers measurement and control system |
| CN207440383U (en) * | 2017-11-20 | 2018-06-01 | 中国计量大学 | A kind of extended focal depth micro imaging system of combination optical tweezer function |
-
2019
- 2019-05-22 CN CN201910432244.XA patent/CN110262029B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102230934A (en) * | 2011-03-30 | 2011-11-02 | 杭州锐光生物技术有限公司 | Method and detector for detecting tumor microsomes by using laser tweezers and micro fluidics |
| CN102645754A (en) * | 2012-04-13 | 2012-08-22 | 北京信息科技大学 | Far-field multiple optical trapping device and method |
| CN103674814A (en) * | 2012-09-13 | 2014-03-26 | 香港城市大学 | Methods and means for manipulating particles |
| CN104216103A (en) * | 2014-09-05 | 2014-12-17 | 华中科技大学 | Micropipe and optical tweezers measurement and control system |
| CN207440383U (en) * | 2017-11-20 | 2018-06-01 | 中国计量大学 | A kind of extended focal depth micro imaging system of combination optical tweezer function |
Non-Patent Citations (1)
| Title |
|---|
| Cavity cooling of an optically levitated submicron particle;Nikolai Kiesel 等;Physical Review Letters;第110卷(第35期);第14180–14185页 * |
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