Fiber optic displacement measuring system for high-temperature seismic sensor

摘要

Fiber optic interferometry is applied to the measurement of seismic vibrations at temperatures of about 300 degrees Celsius and several km of signal transmission lines. The measuring system consists of three orthogonal seismic receivers which are coupled via free propagating light beams to fiber optic Michelson interferometers. White light interferometry with fiber optic phase modulation in the readout interferometer is used for less than 1 micrometer resolution of absolute position of seismic mass, high- resolution monochromatic interferometry using wavelength modulation of the laser diode yields less than 0.1 nm sensitivity of seismic vibrations.