Abstract

A diode-laser-based sensor has been developed for ultraviolet absorption measurements of the nitric oxide (NO) molecule. The sensor is based on the sum-frequency mixing (SFM) of the output of a tunable, 395-nm external-cavity diode laser and a 532-nm diode-pumped, frequency-doubled Nd:YAG laser in a β-barium borate crystal. The SFM process generates 325 ± 75 nW of ultraviolet radiation at 226.8 nm, corresponding to the (v′ = 0, v″ = 0) band of the A²∑⁺–X²Π electronic transition of NO. Results from initial laboratory experiments in a gas cell are briefly discussed, followed by results from field demonstrations of the sensor for measurements in the exhaust streams of a gas turbine engine and a well-stirred reactor. It is demonstrated that the sensor is capable of fully resolving the absorption spectrum and accurately measuring the NO concentration in actual combustion environments. Absorption is clearly visible in the gas turbine exhaust even for the lowest concentrations of 9 parts per million (ppm) for idle conditions and for a path length of 0.51 m. The sensitivity of the current system is estimated at 0.23%, which corresponds to a detection limit of 0.8 ppm in 1 m for 1000 K gas. The estimated uncertainty in the absolute concentrations that we obtained using the sensor is 10%.

© 2005 Optical Society of America

In situ measurements of nitric oxide in coal-combustion exhaust using a sensor based on a widely tunable external-cavity GaN diode laser

Thomas N. Anderson, Robert P. Lucht, Soyuz Priyadarsan, Kalyan Annamalai, and Jerald A. Caton
Appl. Opt. 46(19) 3946-3957 (2007)

Measurements of OH mole fraction and temperature up to 20 kHz by using a diode-laser-based UV absorption sensor

Terrence R. Meyer, Sukesh Roy, Thomas N. Anderson, Joseph D. Miller, Viswanath R. Katta, Robert P. Lucht, and James R. Gord
Appl. Opt. 44(31) 6729-6740 (2005)

Detection of nitric oxide at low ppb∙m concentrations by differential absorption spectrometry using a fully diode-laser-based ultraviolet laser system

Jie Shao, Lemthong Lathdavong, Phaythoune Thavixay, and Ove Axner
J. Opt. Soc. Am. B 24(9) 2294-2306 (2007)

In situ combustion measurements of CO with diode-laser absorption near 2.3 µm

Jian Wang, Mikhail Maiorov, Douglas S. Baer, Dmitri Z. Garbuzov, John C. Connolly, and Ronald K. Hanson
Appl. Opt. 39(30) 5579-5589 (2000)

Multipass open-path Fourier-transform infrared measurements for nonintrusive monitoring of gas turbine exhaust composition

Klaus Schäfer, Klaus Brockmann, Jörg Heland, Peter Wiesen, Carsten Jahn, and Olivier Legras
Appl. Opt. 44(11) 2189-2201 (2005)