Inventors:
Joel A. Brand - Colorado Springs CO
Garth A. Monlux - Castle Rock CO
Patrick Zmarzly - Boulder CO
Gregory J. Fetzer - Littleton CO
Benjamin C. Halsted - Littleton CO
Kenneth W. Groff - Littleton CO
Jamine Lee - Burlington MA
Neil Goldstein - Belmont MA
Steven Richtsmeier - Tewksbury MA
Fritz Bien - Concord MA
Assignee:
Monitor Labs, Inc. - Englewood CO
International Classification:
G01N 2100
Abstract:
A method and apparatus for in situ measurement of the concentration of a gas with a frequency modulated tunable diode laser is disclosed. The sampling cell, which is mounted in the flow of gases to be measured, is a Herriott cell. Gas enters the sampling cell through sintered metal filters that prevent entrance of particulates. Signals from a sample detector and a null detector are compared to eliminate interference patterns from the laser optics. High accuracy dynamic calibration of the apparatus is also disclosed.