Patent ID: 6476911
Filing Date: 2002-11-05
Classification: G01N

Abstract:
A backscatter instrument for monitoring the level of particulates in a gas stream flowing through a stack or duct, said backscatter instrument comprising:a radiant energy source for delivering a narrow beam of radiant energy across the stack or duct through an opening in the stack or duct wall; a lens positioned behind the radiant energy source for receiving radiant energy backscattered from particulates in the stack or duct and focusing the radiant energy at a focal point; the radiant energy source being positioned on the lens; a photodetector sensitive to the band of radiant energy emitted by the radiant energy source, said photodetector being located at or near the focal point of the lens; means responsive to the radiant energy incident on the photodetector for generating a signal representative of the intensity of incident radiant energy; and signal processing means for providing the facility operator with an indication of the particulate level in the gas stream.