Principle and development progress of fiber-optic gravity gradiometer for deep earth exploration

It is of great significance to develop deep earth exploration technology for advancing the development of geophysics. Deep earth exploration technology based on gravity gradient has its own unique advantages and can effectively make up for the limitations of existing methods. In this paper, a gravity gradient measurement principle based on fiber-optic Sagnac interferometer is proposed. The gravity gradient is converted into angular acceleration and the fiber-optic angular accelerometer is used for precision sensing. The structure of the prototype is designed, and its feasibility and stability are demonstrated by finite element simulation using ANSYS software. On this basis, the static test of the prototype is carried out continuously for 14 days. The results show that the self-noise of angular acceleration measurement is lower than 3x10(-10) rad center dot s(-2) center dot Hz (1/2), and the corresponding contribution for the gravity gradient measurement is estimated to 0. 68 E center dot Hz (1/2). The gravity gradient measurement based on fiber-optic Sagnac interferometer has no requirement on the consistency of sensing units and the complex environmental control equipment. The test results show its high sensitivity and great potential for deep earth exploration.