The research of control system for Cesium atomic fountain clock

The control system for Cesium atomic fountain clock is described in detail in this paper. It consists of five parts, automatic digital frequency locking system of extended cavity diode laser (ECDL), the time serial control system, the data acquisition system, the microwave frequency synthesizer control system and the servo control system. With automatic digital frequency locking system, the frequency of ECDL can be locked to any saturated absorption curve automatically and remains locked throughout a series of abrupt disturbance. And moreover, the laser system can relock itself in few seconds when the frequency of the laser is out of range. The time serial control system generate thirteen time serial signals synchronously, including Transistor-Transistor Logic (TTL) signals and arbitrary waveform signals. Moreover, the result shows that these signals are synchronized within 10 μs. The time of flight (TOF) signals are obtained combined with data acquisition system. The resulting Ramsey resonance signal is obtained by sweeping frequency of the synthesizer. The frequency of the 9.2 GHz synthesizer is square-wave modulated by the servo control system so that the frequency of the quartz crystal oscillator is locked to the atomic resonance of the fountain.