Wide-Frequency-Range Vibration Sensing System Based on Simple Chirped Pulse Interferometry

Vibration sensing is vital in the health monitoring of critical structures such as aerospace engines. Although there are many mature vibration techniques in the market, there is still a lack of simple sensors suitable for high temperatures with a wide frequency range. In this article, we proposed a chirped pulse interferometer (CPI) empowered by a pair of gold-coated optical fiber partial reflectors. Information of the vibration is obtained by demodulating the phase change of the interference fringes from the reflection of the reflector pair. Both simulation and experimental results show that the CPI is reliable in detecting vibrations from 1 Hz to 30 kHz, with an operating temperature of up to 600 °C. Furthermore, the CPI was compared to a commercial accelerometer and a high-precision fiber Bragg grating (FBG) interrogator in the same testing environment. The results show that the difference in frequency response between CPI and the accelerometer is less than 1%, and the signal-to-noise ratio (SNR) of the signal detected by CPI is higher than that of the interrogator by more than 14 dB. The novel vibration detection system provides a sensitive and cost-effective vibration detection scheme with a wide frequency range, even at high temperatures. The simple structure makes it an attractive option for various applications.