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Abstract

The invention relates to an infrared gas sensor for determining the concentration of a measuring gas that absorbs infrared radiation, comprising a sensor housing containing two infrared radiation detectors adjacently situated on one end of a measurement beam path, and on the other end containing a measurement radiation source that emits infrared radiation. According to the invention, a measuring chamber accessible to the measuring gas is situated in the measurement beam path between the measurement radiation source and the detectors, at a distance from the detectors and sealed essentially gastight with respect to the remainder of the measurement beam path by at least one infrared-transmitting window. Upstream from one detector, which functions as a measurement detector, an interference filter is provided whose transmission region lies at wavelengths that are absorbed by the measuring gas, and upstream from the other detector, which functions as a reference detector, an interference filter is provided whose transmission region lies at wavelengths that are not absorbed by gas that is present in the measuring chamber and in the measurement beam path. The invention is further characterized by the fact that an auxiliary radiation source is also provided inside the housing, and between this auxiliary radiation source and the detectors an auxiliary beam path is situated which is not accessible to the measuring gas and which is connected to the portion of the measurement beam path that is not accessible to the measuring gas, so that the same gas composition is present in the entire portion of the measurement beam path that is not accessible to the measuring gas and in the auxiliary beam path, the system being selected in such a way that the measurement detector and reference detector can receive optical signals from both the measurement radiation source and the auxiliary radiation source.

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First Claim