Simultaneous telemetry of temperature and vibration by laser dispersion spectroscopy

Abstract

In many industrial applications, temperature and mechanical vibration are closely coupled but measured separately. A novel, to the best of our knowledge, method for simultaneous telemetry of temperature and vibration parameters was proposed in this work from laser dispersion spectroscopy profiles at two different central wavelengths. The temperature was extracted from the peak-to-peak ratio of these two absorption spectra. The vibration amplitude as well as its frequency were derived from the time-varying baselines of the two spectra. A telemetry sensor was designed and evaluated on a thermal vibration coupled experiment platform. The extracted temperatures agree well with the readings of a reference thermocouple, and the signal-to-noise ratio is at least 18 dB higher than those by classical direct laser absorption spectroscopy (DLAS). The extracted vibration frequencies are the same as the outputs of a commercial laser Doppler vibrometer (LDV), and the sensitivity of the extracted vibration amplitudes is 3.64 micrometers, in terms of the Allan variance.