| 摘要 |
<p>A gas sensor for measuring concentration of a predetermined gas comprises a light source 2 arranged to emit pulses of light, a measurement volume 10, a detector 4 arranged to receive light that has passed through the measurement volume, and an adaptable filter 6 disposed between the light source and the detector. The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. The adaptable filter is arranged to change between one of said measurement state and said reference state to the other at least once during each pulse.</p> |
