Orthometric height determination based upon optical clocks and fiber frequency transfer technique

A previous report at GGHS 2012 meeting in Italy suggested that the gravity potential difference as well as the orthometric height difference between two points P and Q connected by optical fibers might be determined by remote optical fiber frequency transfer technique under the assumption that electromagnetic signals transmit in optical fiber just as they propagate in vacuum. The present study is a further improvement of the same topic with more details and without the mentioned assumption. After synchronization, two optical clocks Cp and Cq are set at points P and Q, which are connected by optical fibers. After measuring the signal's frequency shift by comparing the emitting and receiving frequencies between the optical clocks Cp and Cq via remote optical fiber frequency transfer technique, the orthometric height between the two points could be measured, and its accuracy depends on both the accuracy of the optical clocks and the transmitting frequency comparison accuracy. The present accuracy level 10E-17 to 10E18 of optical clocks provides an equivalent accuracy of decimeter to centimeter level in height measurement, while the frequency comparison technique at present can provide transmitting frequency comparison accuracy as high as 10E-19 level. Future 10E-18 to 10E-19 level accuracy of optical clocks provides potential of measuring the orthometric height with centimeter to millimeter accuracy level using remote optical fiber frequency transfer technique.