Abstract

We have developed a new diode-laser-based sensor system for ultraviolet absorption measurements of the NO molecule. The laser system is illustrated schematically in Fig. 1. This system is based on sum-frequency-mixing (SFM) of a tunable, 395-nm external-cavity diode laser (ECDL) from Toptica Lasers with a frequency-doubled, diode-pumped Nd:YAG laser (CrystaLaser) in a beta barium borate (BBO) crystal. Because of the strength of the ultraviolet A²Σ⁺ - X²∏ electronic transition of NO, the detection limit of the system is approximately 0.1 ppm of NO per meter of path length. In addition, the simplicity, generality, and relatively low cost of the SFM-based sensor strategy discussed in this paper will enable the development of absorption sensors throughout the entire ultraviolet spectrum, opening up a wide range of new possibilities for sensing and control of chemically reacting flow processes.

© 2002 Optical Society of America