Gas Filter Correlation Wheel

By using a gas filter correlation wheel, a high energy IR light source is alternately passed through a target gas filled chamber and a chamber​ with no target gas present. The light path then travels through the sample cell, with a variable length folded path depending on the gas being detected. The energy lost through the sample cell is compared with the reference signal provided by the filter wheel to produce a signal proportional to concentration, with little effect from interfering gases within the sample. This design produces excellent zero and span stability and high signal to noise ratio, allowing excellent performance over a wide concentration range.​​