Patent ID: 7324204

Claim:
A method for quantitatively determining a trace gas component in a measuring gas, comprising: introducing the measuring gas into a measuring volume; emitting light from a light source; passing a first portion of the light along a first optical path from the light source through the measuring volume to a measuring detector; generating a measuring detector output dependent on the light absorption in the first optical path; flushing sections of the first optical path between the light source and the measuring volume and the measuring volume and the measuring detector with a purge gas; collecting the purge gas after flushing the first optical path sections; transmitting a second portion of the light along a second optical path from the light source to a compensation detector; flushing the second optical path with the collected purge gas; generating a compensation detector output dependent on the light absorption in the second optical path; and determining the trace gas component in the measuring gas based on a difference between the measuring detector output and the compensation detector output.