High sensitivity methane analyzer based on tuned near infrared diode laser

A portable automatized high sensitive gas analyzer was developed for the detection of trace gas concentration measurements in the atmosphere. Methane was chosen as an example gas for demonstration of the possibilities of the device. Main features of the instrument are long path Chernin optical multipass cell (50 cm base and up to 100 m optical path length) and original data processing. A. near infrared (IR) tunable diode laser (DL) operating at wavelength 1.65 mu m at room temperature allowed the avoidance of coolants. The measurements can be produced in open atmosphere as well as with gas mixture samples at various pressures. Short term sensitivity of methane detection in the open atmosphere was found to be 30 ppb, long term stability-100 ppb, which is enough for methane concentration monitoring in the open atmosphere. (C) 1999 Elsevier Science B.V. All rights reserved.