|Technologies for detecting absorption of electromagnetic radiation
traveling through a measurement volume of interest are described herein.
In a general embodiment, a laser is used to emit electromagnetic
radiation through the measurement volume where absorption is desirably
detected. An optical collector receives a portion of the radiation and
directs a first fraction of the portion back to a gain medium of the
laser, where the radiation is amplified and emitted again, and directs a
second fraction to an optical sensor that can detect absorption in the
measurement volume based upon attenuation of energy of the radiation. As
the radiation feeds back to the gain medium and is emitted again, energy
at attenuated wavelengths is amplified less than at other wavelengths.
Thus, attenuation of energy of the radiation due to absorption in the
measurement volume is cumulative, and relatively small absorptions are
amplified, allowing smaller absorptions to be detected more easily.