A new diode-laser-based UV-absorption sensor for high-speed detection of the hydroxyl radical (OH) is described. The sensor is based on sum-frequency generation of UV radiation at 313.5 nm by mixing the output of a 763-nm distributed-feedback diode laser with that of a 532-nm high-power, diode-pumped, frequency-doubled Nd:YVO4 laser in a beta-barium borate crystal. Approximately 25 µW of UV radiation is generated and used to probe rotational transitions in the A²Sigma+-X²Pi (v'=0, v"=0) electronic transition of OH. Single-sweep, single-pass measurements of temperature and OH concentration in a stoichiometric C2H4-air flame are demonstrated at rates up to 20 kHz.
© 2005 Optical Society of America
(120.1740) Instrumentation, measurement, and metrology : Combustion diagnostics
(190.1900) Nonlinear optics : Diagnostic applications of nonlinear optics
(300.1030) Spectroscopy : Absorption
(300.6260) Spectroscopy : Spectroscopy, diode lasers
(300.6540) Spectroscopy : Spectroscopy, ultraviolet
Thomas N. Anderson, Robert P. Lucht, Terrence R. Meyer, Sukesh Roy, and James R. Gord, "Diode-laser-based ultraviolet-absorption sensor for high-speed detection of the hydroxyl radical," Opt. Lett. 30, 1321-1323 (2005)