A novel fiber Bragg grating(FBG) geophone based on double-diaphragm is presented in this paper.The double-diaphragm structure effectively limits transverse vibration of the FBG geophone.The important parameters such as longitudinal acceleration sensitivity and amplitude-frequency response function of the FBG geophone are analyzed theoretically.In addition,we pointed out the factors that affect the longitudinal acceleration sensitivity of the FBG geophone.The experimental results show that the frequency resp...