PROJECT TITLE :

Fast White Light Interferometry Demodulation Algorithm for Low-Finesse Fabry–Pérot Sensors

ABSTRACT:

Over decades, the signal demodulation techniques of low-finesse Fabry–Pérot interferometer (FPI) sensors have been either slow with wide dynamic range and absolute measurement capability, or fast with slender dynamic range and relative measurement capability. The tradeoff between the speed and the measurement capability has greatly restricted the appliance of FPI-primarily based sensors. In this letter, a novel high-speed white light interferometry (WLI) demodulation algorithm for low-finesse FPI has been developed. By realizing high-speed absolute demodulation utilizing full spectra, the new algorithm has the advantage of spectral drift immunity, high precision, and simultaneous ac and dc signal measurement capability, like acoustic and temperature. A 70-kHz real-time WLI demodulation experiment was conducted in lab, in that the speed was restricted only by the spectrometer hardware.