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Appl Opt. 2007 Jul 1;46(19):3946-57.

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

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School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907-2088, USA.


A diode-laser-based sensor has been developed to measure nitric oxide mole fractions using absorption spectroscopy. The sensor is based on sum-frequency mixing of a 395 nm external-cavity diode laser (ECDL) and a 532 nm laser in a beta-barium-borate crystal. Using a new tuning scheme, the GaN ECDL wavelength was modulated over 90 GHz without mode hops. The sensor was applied for measurements of the NO mole fraction in the exhaust of a laboratory-scale, 30 kW(t) coal-fired boiler burner. Absorption measurements were successfully performed despite severe attenuation by scattering from ash particles in the exhaust stream and on the exhaust-section windows. A detection limit (1sigma) of 4.5 ppm m/(square root)Hz at 700 K was demonstrated in coal- combustion exhaust at a maximum detection rate of 5 Hz.

[Indexed for MEDLINE]

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