Patent ID: 7965391

Claim:
An apparatus for measuring target gas concentrations in an atmosphere, comprising: a laser source tunable to an infrared molecular absorption line of a target gas, and configured to emit in the atmosphere a laser beam tuned to the infrared molecular absorption line of the target gas and having a spectral bandwidth greater than a full width of the molecular absorption line of the target gas; and a receiver configured to receive a reflected signal affected by gas absorption of the target gas in the atmosphere, said receiver including, a first optical path and a second optical path, the first optical path including at least one correlation gas cell filled with a predetermined concentration of the target gas, the second optical path including a reference cell filled with air or filled with a gas different than the target gas, wherein the receiver divides and directs the received reflected signal into the first optical path and the second optical path; at least one detector configured to detect transmitted signals through the first optical path and the second optical path; and a processor configured to calculate a target gas concentration by comparing a first signal transmitted through the first optical path to a second signal transmitted through the second optical path.