Determination of the Gravitational Potential Difference in the Earth's Field Based on the Measurement of the Gravitational Delay of Light Waves in an Optical Fiber.

The possibility of determining the difference in gravitational potentials and orthometric heights in the Earth's field based on measurements of the phase difference of laser radiation in an optical fiber is proposed and investigated in this study. Such a phase difference is attributed to the effect of the gravitational delay of light waves. A block diagram of a measuring complex designed to measure the phase difference of light waves caused by this effect is proposed. The measurements use two coherent light waves from a single laser, each propagating along a separate fiber-optic communication line. The composition of each fiber-optic communication line includes the same coils of a long optical fiber, spaced apart in height. The analysis of the factors influencing the phase relations of waves propagating along two communication lines of the measuring complex is performed. The phase effects of the delay, caused by the influence of the true gravitational field of the Earth, and the influence of the fields of inertial forces and gyroscopic effects due to the Earth's rotation are determined. Methods for suppressing interfering effects are proposed. The achievable errors in measuring the differences in gravitational potentials and corresponding orthometric heights are estimated. With a fiber length in coils of 100 km and a height difference of 100 m, the errors are 0.2 m2/s2 and 2 cm, respectively. The measuring complex under study is called a laser gravipotentiometer. It is an optical analog of the well-known radio-frequency quantum-level unit, but it does not require ultrastable frequency and time standards. The research results of the proposed measuring complex are relevant for the development and improvement of measuring instruments for the parameters of the Earth's gravitational field and a means of the high-precision synchronization of time scales of remote standards. [ABSTRACT FROM AUTHOR]