Measurements on CO concentration and gas temperature at 1.58 um with tunable diode laser absorption spectroscopy

The technique based on tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion-generated pollutants. In this paper the fundamental of concentration and temperature measurement with TDLAS is presented. To validate the method, an experimental system of TDLAS is set up. A simple VCSEL diode without temperature controller is used for direct absorption and WMS setup. Restricted by modulation voltage and noise from diode laser and detector, concentration of 0.2% for I in path length can be detected. Temperature measurement in tube furnace is also carried out by CO2 absorption lines near 1.58um, and below 800K the difference between calculation by TDLAS and temperature signal by K-thermocouple is less than 60K. The method to eliminate the effects of the particles is also discussed here. By using three-order polynomial program, the measurement can be not affected by particles and power fluctuation.