Design of a compact optical carbon monoxide sensor with a threshold sensitivity of 1 mg/m$^3$ (0.85 ppm). Evaluation of measurement selectivity

The optical scheme of a compact carbon monoxide sensor with a threshold sensitivity level equal to 1 mg/m$^3$ has been designed. The narrow band filter parameters have been optimized to reduce the sensor’s cross-sensitivity to carbon dioxide and water vapor. The optimization takes into account the transmission characteristics of real filters with non-zero transmission in the tail region. For the found filter characteristics, the cross-sensitivity of the sensor was determined to interfering impurities common in cases of fire. Finally, maximum interfering impurity concentration have been evaluated whereby measurement error could be less than the signal from 1 mg/m$^3$ carbon monoxide.