Land Instruments International Limited

Derek D Stuart

Stuart Francis Metcalfe

Richard Andrew Hovan

An improved light source for use in an opacity monitor (transmissometer) that reduces the variation in light intensity across a projected light beam to enable a more accurate and stable method for measuring the opacity of gases in a stack/duct, especially at low values (e.g., <10%) of opacity while operating within specific performance requirements.

Light source for open-path gas monitoring

The invention relates to apparatus for open-path gas monitoring and is particularly concerned with measuring the opacity of stack gases. Single and double pass systems to provide an optical across the stack, are known, but to provide meaningful data, gain compensation is required to deal with temperature variations and the possibility of ageing of electronic components. The object of the present invention is to provide an instrument that meets the above requirement but without moving components, which objective is met by a construction comprising a transceiver unit adapted to be mounted on one side of the optical path; a passive reflector adapted to be mounted on the other side of the path; and electronic control circuitry, the transceiver unit comprising:

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Derbyshire, United Kingdom

Derek D Stuart