# US 2014/0192347 A1 · Cavity enhanced laser based isotopic gas analyzer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192347 A1 - Document ID: US20140192347A1 - Status: Published application - Kind: A1 - Application number: 14/156,842 - Filed: 2014-01-16 - Published: 2014-07-10 - Earliest claimed: 2011-08-18 - Assignees: LI-COR, Inc. - Inventors: Serguei Koulikov; Alexander Kachanov - Web page: https://patentgrep.com/patent/US20140192347A1 ## CPC - G01N 21/39: using tunable lasers - G01J 3/4338: {Frequency modulated spectrometry} - G01N 21/1702: {with opto-acoustic detection, e.g. for gases or analysing solids} - G01N 21/59: Transmissivity (G01N21/25 takes precedence) - G01N 21/61: Non-dispersive gas analysers {(G01N21/3504 takes precedence)} - G01N 29/2425: {optoacoustic fluid cells therefor} - G01N 2021/1704: {in gases} - G01N 2201/023: Controlling conditions in casing - G01N 2201/06113: Coherent sources; lasers - G01N 2291/021: Gases - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract Systems and methods for measuring the isotope ratio of one or more trace gases and/or components of gas mixtures such as different gas species present in a gas mixture. The system includes a resonant optical cavity having two or more mirrors and containing a gas, the cavity having a free spectral range that equals the difference between frequencies of two measured absorption lines of different gas species in the gas, or of two different isotopes, divided onto an integer number. The system also includes a continuous-wave tunable laser optically coupled with the resonant optical cavity, and a detector system for measuring an absorption of laser light by the gas in the cavity. The detector system includes one of a photo-detector configured to measure an intensity of the intra-cavity light or both a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity and a photo-detector configured to measure an intensity of the intra-cavity light. ## Claims ### Claim 1 A gas analyzer system for measuring a concentration of two or more components in a gas mixture, the system comprising: a resonant optical cavity having two or more mirrors and containing a gas having chemical species to be measured, the cavity having a free spectral range that equals the difference between frequencies of two measured absorption lines of two different gas species divided onto an integer number; a continuous-wave tunable laser optically coupled with the resonant optical cavity; a detector system for measuring an absorption of laser light by the gas in the cavity; and an intelligence module adapted to determine the concentration of the two different as species, wherein the laser is tuned to a first wavelength corresponding to an absorption line of a first one of the two gas species and the detector system measures a first signal corresponding to an absorption at the first wavelength, wherein the laser is tuned to a second wavelength corresponding to an absorption line of a second one of the two gas species and the detector system measures a second signal corresponding to an absorption at the second wavelength, and wherein the intelligence module processes the first and second signals and generates an output signal representing concentrations of the first and second gas species. ### Claim 2 (depends on 1) The system of claim 1, further including; a temperature sensor for measuring a temperature of the gas in the cavity; and a pressure sensor for measuring a pressure of the gas in the cavity. ### Claim 3 (depends on 1) The system of claim 1, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light. ### Claim 4 (depends on 1) The system of claim 1, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light and a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity. ### Claim at position 5 -15. (canceled) ### Claim 6 A gas analyzer system for measuring an isotopic ratio of a gas, the system comprising: a resonant optical cavity having two or more mirrors and containing a gas having a chemical species to be measured, the cavity having a free spectral range that equals the difference between frequencies of the measured absorption lines of two different isotopes divided onto an integer number; a continuous-wave tunable laser optically coupled to the resonant optical cavity; a detector system for measuring an absorption of laser light by the gas in the cavity; and an intelligence module adapted to determine an isotope ratio of the two different isotopes, wherein the laser is tuned to a first wavelength corresponding to an absorption line of a first one of the two isotopes and the detector system measures a first signal corresponding to an absorption at the first wavelength, wherein the laser is tuned to a second wavelength corresponding to an absorption line of a second one of the two isotopes and the detector system measures a second signal corresponding to an absorption at the second wavelength, and wherein the intelligence module processes the first and second signals and generates an output signal representing an isotope ratio of the two different isotopes. ### Claim 7 (depends on 16) The system of claim 16, further including: a temperature sensor for measuring a temperature of the gas in the cavity; and a pressure sensor for measuring a pressure of the gas in the cavity. ### Claim 8 (depends on 16) The system of claim 16, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light. ### Claim 9 (depends on 16) The system of claim 16, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light and a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity. ### Claim 10 (canceled) ### Claim 21 A gas analyzer system for measuring concentrations of isotopes in a gas, the system comprising: a resonant optical cavity having two or more mirrors and containing a gas having a chemical species to be measured, the cavity having a free spectral range that equals the difference between frequencies of the measured absorption lines of two different isotopes of the chemical species divided onto an integer number; a continuous-wave tunable laser optically coupled to the resonant optical cavity; a detector system for measuring an absorption of laser light by the gas in the cavity and an intelligence module adapted to determine concentrations of the two different isotopes, wherein the laser is tuned to a first wavelength corresponding to an absorption line of a first one of the two isotopes and the detector system measures a first signal corresponding to an absorption at the first wavelength, wherein the laser is tuned to a second wavelength corresponding to an absorption line of a second one of the two isotopes and the detector system measures a second signal corresponding to an absorption at the second wavelength, and wherein the intelligence module processes the first and second signals and generates an output signal representing concentrations of the first and second isotopes. ### Claim 22 (depends on 21) The system of claim 21, further including: a temperature sensor for measuring a temperature of the gas in the cavity; and a pressure sensor for measuring a pressure of the gas in the cavity. ### Claim 23 (depends on 21) The system of claim 21, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light. ### Claim 24 (depends on 21) The system of claim 21, wherein the detector system includes a photo-detector configured to measure an intensity of the intra-cavity light and a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity. ### Claim 25 (depends on 21) The system of claim 21, wherein the laser is tuned to a third wavelength that does not correspond with an absorption line of any of the isotopes being measured or analyzed, and wherein the detector system measures a third signal at the third wavelength and wherein the intelligence module is further adapted to determine a baseline based on the third signal. ### Claim 26 (depends on 16) The system of claim 16, wherein the laser is tuned to a third wavelength that does not correspond with an absorption line of any of the isotopes being measured or analyzed, and wherein the detector system measures a third signal at the third wavelength and wherein the intelligence module is further adapted to determine a baseline based on the third signal. ### Claim 27 (depends on 1) The system of claim 1, wherein the laser is tuned to a third wavelength that does not correspond with an absorption line of any of the gas species being measured or analyzed, and wherein the detector system measures a third signal at the third wavelength and wherein the intelligence module is further adapted to determine a baseline based on the third signal.