Patent ID: 7253903
Filing Date: 2007-08-07
Classification: G01N

Abstract:
1. A system comprising: a gas concentration monitoring system that monitors concentration changes of a gas along a path irradiated by electromagnetic radiation, wherein a change of absorption of at least some of said electromagnetic radiation at a specific wavelength by said gas is indicative of a measure of said concentration changes of said gas along said path, said gas concentration monitoring system including first and second sensors positioned to simultaneously detect said absorption along said path, each of said first and second sensors being calibrated to thereby define a unique response curve associated therewith that relates a voltage output change per optical density change for each of said first and second sensors as a function of optical density, wherein each said response curve includes a unique non-linear response region thereof, and wherein a ratio-of-responses curve is defined by a ratio of said response curve associated with said first sensor to said response curve associated with said second sensor; and a processor coupled to said gas concentration monitoring system for generating a ratio of sensor output changes defined as a ratio of output changes associated with said first sensor to output changes associated with said second sensor, said ratio of sensor output changes being used to establish an operating point on said ratio-of-responses curve that is indicative of an optical density wherein, when said operating point is in said non-linear response region of at least one of said first and second sensors, said operating point and said optical density corresponding thereto can be used to establish an actual response of at least one of said first and second sensors that is used in determining changes in said optical density.