A Methane Gas Sensor using Correlation Spectroscopy - Theoretical Study and Application

摘要

A new correlation spectroscopy detecting scheme with respect to gas sensing is presented in this paper, which revolves the cross interference problem induced by the gas mixture's absorption in all range of source wavelength. A complementary source modulation approach based on compact light-emitting diode (LED) source is employed in the detecting system. This new method inherits the excellence of the correlation spectroscopy and makes the modulation easy. Compared with the traditional correlation spectroscopy method, the new modulation technique has advantages including easy implementations, high modulation index and low cost, etc. A 150 nm filter is used to achieve an optimum signal-to-noise ratio (SNR) through many experiments. The cross-sensitivity to water vapor is also derived.