Patent ID: 8729475

Claim:
A Non-Dispersive Infrared (“NDIR”) gas sensor for detecting the presence of a chosen gas, comprising: a single infrared source for generating infrared radiation into a sample chamber to illuminate a signal channel path length and a reference channel path length, the signal channel path length being longer than the reference channel path length, the reference channel path length being a non-zero length; a detector with a specific spectral filter for detecting the chosen gas; a motion device that alternates the distance between the single source and the detector representing respectively the signal channel path length and the reference channel path length; and electronics for determining a sample concentration of the chosen gas by use of an absorption biased methodology; wherein the absorption bias methodology uses a ratio of a signal channel output (“V S ”) obtained by the detector at a first point of time when the distance between the single infrared source and the detector is the signal channel path length over a reference channel output (“V R ”) obtained by the detector at a second point of time when the distance between the single infrared source and the detector is the reference channel path length; wherein the ratio is based upon a successive time sequence between the first and the second points of time that approximates a simultaneous time sequence for purposes of the absorption bias methodology.