Laser Absorptometer for Detection of Trace Species

点击翻译按钮获取中文摘要

9301915 Flusberg With the increase in atmospheric pollution and a new, growing public awareness of resulting environmental damage, there is a need for new technology to measure the concentration of trace species in the atmosphere. Extractive methods, in which a sealed sample of air is analyzed in a laboratory, are expensive and are inapplicable to continuous, in situ monitoring of concentrations. Science Research Laboratory (SRL) will develop an instrument called a laser interferometric absorptiometer (LIA) to fill this need. The basis of this instrument is the interferometric measurement of the optical-path change that occurs immediately after a pulsed laser beam is absorbed by trace species present in one arm of the interferometer. This novel approach will lead to a breakthrough in the technology of monitoring trace gases. It will allow rapid in situ measurements of trace-gas concentrations to be made for the first time at parts-per-trillion (ppt) levels, 100-1000 times more sensitively than instruments based on other approaches to monitor trace species in the field. In Phase I the characteristics of a LIA were determined, and an LIA suitable for ppt trace-gas measurements was designed. IN Phase II, SRL will experimentally research and demonstrate rapid ppt detection of several trace gases including chlorofluorocarbons (CFCs), major pollutants that are responsible for depletion of the ozone layer and are considered significant contributors to global warming. In a privately funded Phase III follow-on program, SRL will develop a commercial instrument capable of measuring industrial emissions of CFCs and other pollutants.