Times for measuring concentrations of gases can be as short as a few seconds.

A compact, portable, mid-infrared, laser-based instrument that operates at room temperature has been developed for use in detecting trace concentrations of CO or any of several other gases in air. The instrument utilizes infrared absorption spectroscopy in a sample cell which either holds an air sample or is exposed to an airflow. The laser beam that interrogates the cell is formed by difference-frequency generation (DFG) in a bulk nonlinear optical medium excited by two laser beams.