TDL-based Spectroscopy for Simultaneous Measurement of Multiple Gas Properties Using a Single Absorption Line

Abstract

This study presents a single-line absorption spectroscopy method for the simultaneous measurement of gas pressure and temperature through diode laser absorption spectroscopy using a single absorption line. In the proposed method, the absorbance loss of an absorption line that may occur during baseline subtraction is predicted, and the gas properties are determined by matching a calculated absorbance to a recovered absorbance using the predicted loss. To verify the proposed method, gas property measurements are conducted for air conditions with a pressure range of 10-100 kPa and a temperature range of 300-500 K. An absorption line in the oxygen A band is selected to measure the gas properties of air. Using the proposed method, it is confirmed that the gas pressure and temperature could be measured within errors of 25 % and 18 %, respectively. When the gas pressure is predetermined using a pressure gauge, the gas temperature can be measured within an error of 14 %.