Reasearch On The Key Technology Of Small Optically Pumped Cesium Beam Frequency Standard

Cesium beam atomic frequency standard is the representative of time-keeping atomic clocks, the early magnetic state of cesium clock reaches a limit, the heavy state selecting magnet and the electron multiplier has seriously restricted the continued development of magnetic state of cesium clock. The use of optically pumped cesium beam frequency standard to replace the magnetic state of cesium beam frequency standard is the development trend of this type of atomic clock.The paper first introduced the basic research of theory of optically pumped cesium beam frequency standard, based on comparison of the characteristics of optically pumped cesium clock and magnetic state of smal cesium clock on the analysis method, the cesium atomic level preparation, the final choice of preparation and detection using single laser for cesium atomic level system. From the theoretical analysis of the various factors affecting the atomic clock signal output accuracy and stability, which laid a theoretical foundation for the following research.Implementation of optical pumping cesium clock is capable of automatic laser frequency locking, which is the key of the paper. From the theoretical analysis of the optically pumped cesium clock requirements for automatic frequency stabilized laser functional requirements and performance, according to the laser output frequency, line width and other requirements, analyzes the influence of work environment on the line width, according to the technical characteristics of the present, the whole structure of automatic frequency stabilized laser system planning and design the function of each module, carried out research and analysis.For the temperature control circuit, the stability of laser output required working temperature fluctuations in the range of less than 0.002 degrees, the temperature control range at home can mostly achieve the highest of only 0.01 degrees, the need for independent design and development, implementation of the requirements of the circuit. Design of non balance precision bridge temperature measuring method based on laser diode, reduces the judgement on the bridge zero output burden; studied on the optimal analog-to-digital converter magnification, selected magnification 2.976; in order to reduce system burden, analog design using a unipolar conversion chip bipolar digital to analog conversion function, the difference through the current direction, the switching control heating and refrigeration functions, to achieve a rapid, accurate control of the temperature; it designs a test platform of high precision of temperature control, the performance is tested and analyzed, 300000 test data of 120 hour show, the precision of the temperature control system meet the requirements of use.On the basis of completion of each module of the software and the hardware, the research of automatic frequency locking of the lasers and the parameter self recovery. The basic analysis of various errors caused by the disturbance of laser output frequency in theory on the research on the control method of the parameters, the proposed overall mentality, parameters self recovery. Design of small modulation light intensity information extraction method based on spectral intensity changes, according to obtain the laser frequency offset information, generates the feedback control parameters, the output optical frequency control in the reference frequency. Proposes and implements current scanning auxiliary saturated absorption peak detection method, the peak position of F=4�'F’=5 transition digital judgment method, realized the automatic laser lock self recovery and parameters. The final test indicators show that the output frequency, laser line width for 1.8MHz seconds after locking, stable 10-10/s, enough to meet the application of optically pumped cesium clock.On this basis, established the dynamic experimental research platform of optically pumped cesium beam frequency standard, for each stage theory of optically pumped cesium beam frequency standard are verified. To obtain the optical pumping cesium clock Rabi signal, Ramsey signal symbolic signal, dynamic tube line width, signal-tonoise ratio and other indicators were measured, and achieve closed-loop locking.Finally, the automatic frequency stabilized laser is applied to the whole optical pumping cesium clock, realizes miniaturization system optically pumped cesium clock. Stability data of the prototype: 6.3 × 10-12/s 、 9.1 × 10-13/100 s 、 9.2 × 10-14/10000s、6.5×10-14/100000 s.