A sensor using a single distributed-feedback (DFB) diode laser at 1.57 μm for the simultaneous measurement of CO2 and CO concentration at elevated temperatures is developed. A proper line pair near 6361.250 and 6361.344 cm–1 is chosen based on absorption strength, separation of the two lines, and isolation from interference of neighboring transitions of the major combustion gases. The concentrations of CO2 and CO are inferred from their wavelength modulation spectroscopy (WMS) 1ƒ-normalized absorption-based WMS-2ƒ signal peak heights. The CO2 and CO concentration measurements are within 3.3% and 5% of the expected values over the full temperature range.
Tingdong Cai, Guangzhen Gao, Weidong Chen, Gang Liu, and Xiaoming Gao, "Simultaneous Measurements of CO2 and CO Using a Single Distributed-Feedback (DFB) Diode Laser Near 1.57 μm at Elevated Temperatures," Appl. Spectrosc. 65, 108-112 (2011)