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The sensor-e® CO2 measures carbon
dioxide by comparing infrared
energy absorbed by a sample to that
absorbed by a reference gas according
to the Beer-Lambert law. This is
accomplished with a Gas Filter wheel
which alternately allows a high energy
infrared light source to pass through
a CO2 filled chamber and a chamber
with no CO2 present.
The light then travels through the
sample cell, which has a folded path.
The energy loss through the sample
cell is compared with the zero reference
signal provided by the gas filter
to produce an output proportional to
concentration, with little effect from
interfering gases within the sample.