Pulsed Absorption Diffractometer for Detecting Trace Species

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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 proposes the development of an instrument called a Pulsed Absorption Diffractometer (PAD) to fill this need. The basis of this instrument is the detection of a transient, volumetric diffraction grating that is formed after a pulsed laser beam is absorbed by trace species present in the illuminated region. The PAD will be sensitive to parts-per-trillion trace-gas concentrations, 2-3 orders of magnitude better than instruments based on other approaches to monitor trace species in the field.