| Miniaturized cesium?Cs?beam clocks can be widely used in time keeping,communication,electric power system,satellite navigation and military.It can be divided into two classes,optically pumped Cs beam clock and magnetic state-selecting Cs beam clock,according to the atomic state preparation method.Optical pumping technology instead of magnetic state-selecting technology was used to prepare and detect atomic state in it.The technical bottleneck restricting development of magnetic state-selection miniaturized Cs beam clocks of our country can be avoided.Realizing nationalization of miniaturized optically pumped Cs beam clocks can break the overseas technical monopoly and has significant meanings for national economy and the people's livelihood.Frequency stabilized laser is an significant part of miniaturized optically pumped Cs beam clock.The atomic state preparation and detection are completed by the interaction of lasers and atoms in the miniaturized optically pumped Cs beam clock.Long-locked frequency stabilized laser is the foundation to guarantee the smooth operation of miniaturized optically pumped Cs beam clock.Fuorescence collector is the necessary component performing optical state detection.And,it is a guaranteed functional device to avoid technical bottleneck restricting development of magnetic state-selection miniaturized Cs beam clocks of our country.In this paper,these two critical components of miniaturized optically pumped Cs beam clocks are studied.A fluorescence collector with high collection efficiency and three kinds of frequency stabilized laser for miniaturized optically pumped Cs beam clocks are designed.Finally,on the basis of the theory of the Cs atomic level transition,a microwave magnetic field sensor based on atomic Rabi resonance is designed by using the frequency stabilized laser for miniaturized optically pumped Cs beam clocks.Some research achievements are obtained.By means of simulating method,a smaller fluorescence collector with the high collection efficiency is designed.Three designing schemes of fluorescence collector are presented and their structures and operating principles are compared.The practical type fluorescence collector with excellent performance,plain structure and high collection efficiency,is selected as the design framework.The fluorescence collector with high collection efficiency is designed by used with ray tracing method.It meets the application requirements of miniaturized optically pumped Cs beam clock.Three design schemes of frequency stabilized lasers for miniaturized optically pumped Cs beam clocks are proposed.The optical structure is simplified and the power dissipation is reduced.But,the measured frequency stabilitys of the compact frequency stabilized lasers are essentially equal.Firstly,the frequency stabilized laser locked by Cs atom saturated absorption spectrum is designed.Two frequency stabilized lasers can be produced by it.And,it can work independently and not depends on Cs beam tube.When laser is stabilized at the frequency of transition D2:F=4?F'=5 of Cs atom,the laser frequency stability is measured as 1.03×10-1010 at 1 s.Secondly,to promote the engineering application level of the miniaturized optically pumped Cs beam clocks,a frequency stabilized laser with compact optical path is designed.The fluorescence signal,generated by the interaction between laser and a Cs atomic beam,is used as reference signal and the frequency stabilized laser is designed.The production process of fluorescence signal is closely related to the shape of Cs atomic beam.And,the shape of Cs atomic beam is relative to atom source collimator.The atom source collimator formed by an array of channels is designed.Its length is 9 mm and cross-sectional dimension is 4 mm×0.6 mm.The designed fluorescence collector is used to produce fluorescence signal.When laser is stabilized at the frequency of cycling transition D2:F=4?F'=5 of Cs atom,the laser frequency stability is measured as 3.25×10-1010 at 1 s.Thirdly,to further simplify optical path of the frequency stabilized laser,a concise laser system by using single optical frequency laser for both atomic state preparation and detection is designed.The fluorescence signal generated by the pumping transition D2:F=4?F'=4 of the Cs atom is used as the reference signal to lock laser.The induced saturation probe laser intensity corresponding to the pumping transition D2:F=4?F'=4 of the Cs atom is studied.The amplitude of the fluorescence signal produced by the pumping transition tend to be stable when the adopted laser intensity is greater than or equal to the saturation probe laser intensity.The fluorescence signal generated by the interaction of Cs atom beam and laser with saturation probe laser intensity is used as the reference signal to lock laser.The measured stability of the designed frequency stabilized laser system is about 2.64×10-10 at 1 s.A quantum-based microwave magnetic field sensor by exploring atomic Rabi resonance in the clock transition of Cs is designed.A concise Cs vapor cell serving as the microwave magnetic field detecting unit is used to measures the magnetic field distribution of microwave,radiated from an open-ended waveguide antenna.The microwave field is not restricted by other devices.The designed frequency stabilized laser is used to produce laser light.The laser locked at the frequency of pumping transition D2:F=4?F'=4 of Cs atom is used to interact with Cs atoms sealed in Cs vapor cell.The transmission laser is detected to measure the number of atoms transferring to the upper level of ground state from the lower level of ground state.The atomic ground state energy level transition is induced by microwave field.The experimental result that Rabi frequency is in proportion to the microwave magnetic field strength is measured by the experimental setup.And,the measurement method is validated.Besides,the longitudinal distribution of the magnetic field is measured by the quantum-based mothed.And,the distribution is calculated by simulation softwave.The experimental results show that measured magnetic field distribution is consistent with the simulating calculation result.And,the experimental measurement result is verified. |
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