National Research Council of Canada. Energy, Mining and Environment
temperature coefficient of refractive index; peak analysis; frequency analysis; noise reduction
A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry–Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy’s formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes.
Review of Scientific Instruments87, no. 7, 073104.