A Fast Local Monitoring of Dilute NO by a Tunable Laser

This paper describes a real-time noncontacting, point-monitoring system for nitrogen monoxide. The monitoring system uses a grating-tuned pulsed dye laser and a specially developed microcomputer-assisted signal processor system. The system is sensitive for analyzing a gas concentration from 0.03 parts per million per meter (ppm/m) theoretically (which should be divided by an optical path length) to 0.4 ppm/m experimentally. The system reliability as well as the capability to detect sulfur dioxide which shares the spectral region with nitrogen monoxide was investigated.