Study On Parameter Feedback Cooling Control Technology Of Dual-beam Vacuum Optical Tweezers

There was almost no energy exchange with the outside world of the captured particle in the double-beam vacuum optical tweezers.It was regarded as the"ideal platform"for basic physics research and precision measurement.The feedback cooling of the captured particle was one of the key technologies of the double-beam vacuum optical tweezers.The parameter feedback cooling scheme was a mainstream scheme with a simple structure.Simulation and experimental research were carried out in this paper,and the main work was as follows:1.The feasibility of the parameter feedback cooling scheme of the dual-beam vacuum optical tweezers were verified by simulation.According to the simulation results,the influence degree of each parameter on the cooling effect was roughly as follows:Resonance frequency>Ambient temperature>Ambient air pressure>Quality>Control depth;2.A parameter feedback cooling control circuit system based on the Lab VIEW FPGA module was designed,which could perform Kalman filtering,signal delay compensation,single-axis feedback control signal generation,three-axis feedback control signal synthesis,etc.The circuit conditions for parameter feedback cooling experiments were available.3.A new method for dual-beam precise alignment was proposed.By using the principle of optical path reversibility and the characteristic that the far-field spot could amplify the characteristics of the double-beam misalignment,to realize the coaxial and confocal of dual-beam optical trap.Compared with the traditional alignment method,only the detection device needed to be applied outside the optical path of the dual-beam optical trap,which had little interference to the original optical path of the trapped microspheres,could detect the coaxial and focal coincidence of the two beams in real time.The detection accuracy reached sub-micron level.4.The parameter feedback cooling experiment of Si O₂ microspheres with a diameter of 4μm was carried out in the dual-beam vacuum optical tweezers.By finding the best delay phase compensation point of the single-axis feedback control signal,the one-dimensional center of mass motion was equivalently cooled from 298K to 48K.