BOFDA is a comprehensive system

which measures the pulse response of the baseband transfer function.The function is determined by Brillouin spectrum which is caused by the interaction between continuous pump laser and probe laser.The physical information along fibers is calculated by some relative math formulas.Compared with other distributed optical-fiber sensors

BOFDA has the advantages of low signal-to-noise-ratio

high special resolution and low cost.It provides the possibility of narrow-bandwidth operation and parallel measurements with different modulated frequencies.This paper gives an explicit introduction of the principles of temperature and strain measurement using BOFDA technology.This paper also summarized the results of laboratory and field tests that did by some researchers previously.