A new method for the control of the speed of an ultrasonic motor and its implementation are proposed. The method is merely used by detecting the time when motor′s monitor signal reaches a non zero reference valu...A new method for the control of the speed of an ultrasonic motor and its implementation are proposed. The method is merely used by detecting the time when motor′s monitor signal reaches a non zero reference value than a zero one, the direction, in which the driving frequency of the motor should be shifted, can be promptly calculated. With the aid of a CPU and the phase locked frequency doubling technique, the motor can be steadily driven in a wide range of frequency and the optimum frequency can be captured rapidly and precisely. Experiment shows that the above method is available.展开更多
We demonstrate a simple and fast way to produce 87Rb Bose–Einstein condensates. A digital optical phase lock loop(OPLL) board is introduced to lock and adjust the frequency of the trap laser, which simplifies the opt...We demonstrate a simple and fast way to produce 87Rb Bose–Einstein condensates. A digital optical phase lock loop(OPLL) board is introduced to lock and adjust the frequency of the trap laser, which simplifies the optical design and improves the experimental efficiency. We collect atoms in a magneto-optical trap, then compress the cloud and cut off hot atoms by rf knife in a magnetic quadrupole trap. The atom clouds are then transferred into a spatially mode-matched optical dipole trap by lowering the quadrupole field gradient. Our system reliably produces a condensate with 2 × 106 atoms every7.5 s. The compact optical design and rapid preparation speed of our system will open the gate for mobile quantum sensing.展开更多
An S-band wideband chirp generator using specially designed fast lock phase lock loop（FL-PLL） was demonstrated.To realize high linearity,structure of direct digital synthesizer（DDS） plus FL-PLL was used.DDS gives ...An S-band wideband chirp generator using specially designed fast lock phase lock loop（FL-PLL） was demonstrated.To realize high linearity,structure of direct digital synthesizer（DDS） plus FL-PLL was used.DDS gives ideal linearity while FL-PLL retains the linearity and provides radio frequency.The system block diagrams were showed and the timing relationships of the components were provided.Two important considerations of the system,wideband loop and wideband voltage control oscillator（VCO）,were discussed;meanwhile,after analyzing the considerations,corresponding solutions were presented.Measurement results show that the generated 2560MHz to 2960MHz chirp reaches a high FM linearity of 0.003%.展开更多
文摘A new method for the control of the speed of an ultrasonic motor and its implementation are proposed. The method is merely used by detecting the time when motor′s monitor signal reaches a non zero reference value than a zero one, the direction, in which the driving frequency of the motor should be shifted, can be promptly calculated. With the aid of a CPU and the phase locked frequency doubling technique, the motor can be steadily driven in a wide range of frequency and the optimum frequency can be captured rapidly and precisely. Experiment shows that the above method is available.
基金National Natural Science Foundation of China(Grant No.51275523)and the State Key Laboratory of Aerodynamics Research Fund,China(Grant No.SKLA2019040302).
文摘We demonstrate a simple and fast way to produce 87Rb Bose–Einstein condensates. A digital optical phase lock loop(OPLL) board is introduced to lock and adjust the frequency of the trap laser, which simplifies the optical design and improves the experimental efficiency. We collect atoms in a magneto-optical trap, then compress the cloud and cut off hot atoms by rf knife in a magnetic quadrupole trap. The atom clouds are then transferred into a spatially mode-matched optical dipole trap by lowering the quadrupole field gradient. Our system reliably produces a condensate with 2 × 106 atoms every7.5 s. The compact optical design and rapid preparation speed of our system will open the gate for mobile quantum sensing.
基金Supported by the Fund of National Defense Industry Innovative Team (231)
文摘An S-band wideband chirp generator using specially designed fast lock phase lock loop（FL-PLL） was demonstrated.To realize high linearity,structure of direct digital synthesizer（DDS） plus FL-PLL was used.DDS gives ideal linearity while FL-PLL retains the linearity and provides radio frequency.The system block diagrams were showed and the timing relationships of the components were provided.Two important considerations of the system,wideband loop and wideband voltage control oscillator（VCO）,were discussed;meanwhile,after analyzing the considerations,corresponding solutions were presented.Measurement results show that the generated 2560MHz to 2960MHz chirp reaches a high FM linearity of 0.003%.
