Method and apparatus for the photo-acoustic identification and quantification of analyte species in a gaseous or liquid medium
AssigneeLI-COR, Inc.
InventorsAlexander Kachanov, Serguei Koulikov
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Abstract
A method and apparatus for the photo-acoustic identification and quantification of one or more analyte species present in a gaseous or liquid medium in low concentration utilizing a laser and a resonant optical cavity containing the medium and having within the cavity at least two partially transparent mirrors, one of which is a cavity coupling mirror and one of which is moveably mounted on an assembly responsive to an input signal.
Claims21
A method for the identification and quantification of one or more analyte species present in a gaseous or liquid medium utilizing a laser that outputs a laser beam and a resonant optical cavity containing said medium and having at least two cavity mirrors, one of which is a cavity coupling mirror, the method comprising:
- coupling the laser beam to the cavity via the cavity coupling mirror using mode matching optics;
- applying a periodic dither or modulation waveform to the optical frequency of the laser beam or to the laser itself to thereby induce modulation of the intracavity optical power;
- and
- detecting, at the frequency of the applied dither or modulation waveform or harmonics thereof, a signal representing a varying pressure of the medium within the cavity.
Dependencies are inferred from the claim text.