Precise measurements of highly stable laser radiation frequency and phase

Precise measurements of frequency stability of laser frequency standards require very special instrumentation: precision high-speed digital frequency meter with zero 'dead time'. New hardware and software instrumentation has been designed and successfully tested on highest accuracy laser heterodyne systems. Original methods of measuring and data processing allow estimation of frequency stability with the accuracy of 1 5-th order. This instrumentation was used in measurements of frequency stability of He-Ne/CH4 laser during a period of the time of 0.005s with a resolution better than 1Hz. With hardware based on Pentium-! ! ! the possibility of real-time counting and plotting in several windows frequency vs time, Allen variance vs period and others useful dependences are demonstrated and used. The data throughput with simultaneous real-time renewal of statistics is 1000 samples per second.