SPECTROSCOPY OF METHANE USING A ND-YAG LASER AT 1.34-MU-M

We present measurements of the absorption coefficient of methane in the nu(2) + 2-nu(3) band obtained with a neodymium:yttrium aluminum garnet (Nd:YAG) laser tuned by the use of an intracavity etalon to 7472 cm-1 (1.3383-mu-m). The linewidth of the laser was shown to be comparable to that of the pressure-broadened methane feature while the absorption coefficient of methane at 1-atm pressure was measured to be 0.59 m-1 atm-1. These basic findings indicate that a practical methane detection system using laser radar (lidar) based on a Nd:YAG laser may be possible.