Pseudohigh-Resolution Spectral Interrogation Scheme for Small Signals From FBG Sensors

In this paper, we proposed a spectral interrogation scheme for the detection of small wavelength shift of fiber Bragg grating (FBG) accelerometer in a vibration test. Our findings indicate that the adopted upsampling procedure in the algorithm can effectively reconstruct small signals (wavelength shift < pixel resolution of diffraction grating-based interrogator) from low-resolution spectra that cannot be achieved by using other interrogation schemes. The reconstructed signals have good SNR and excellent coherence with the reference signal from a standard integrated electronic piezoelectric accelerometer in both time and frequency domains, as if they are extracted from the high-resolution spectra. The proposed method has opened a new possibility of employing low-cost FBG interrogation for accurate measurement and dynamic modal analysis in various industrial applications.