A Triaxial Dual FBG Accelerometer That Can Be Used for Seismic Wave Detection

In order to pick up the low-frequency vibration signal, a triaxial dual fiber Bragg grating (FBG) accelerometer based on a vibration-sensitive structure of cross diaphragm spring is proposed in this article, then the modal analysis and parameter optimization are done by simulation analysis software, and the structure parameters of the triaxial dual FBG accelerometer are determined by combining the actual processing, at last, a very-low-frequency (VLF) vibration testing system is built to test its vibration characteristics. The test results show that the natural frequency of the FBG accelerometer is 85 Hz, and the operating frequency is 0.1–50 Hz. The sensitivity of the three components are 590, 390, and 395 pm/g, respectively; the minimum detectable acceleration of the accelerometer is 0.01 g, and the maximum detectable acceleration is 3.0 g. This kind of FBG accelerometer with high sensitivity in the low-frequency band provides an important reference value for the design of similar accelerometers.