The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising: a resonant optical cavity, a continuous-wave stepwise tunable external cavity laser having a DFB laser as a gain media; a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the roundtrip optical cavity length of the external cavity laser are the roundtrip optical cavity length of the resonant cavity are close

A method of monitoring blockage of a sight tube attached to a wall of a process chamber, the sight tube being operatively associated with a TDLAS optical head with a window between the sight tube and the TDLAS optical head. The method includes the steps of providing a photo sensor in the TDLAS optical head, the photo sensor being positioned to receive light emitted by a light emitting process within the process chamber. An emission signal produced by light emitted by the light emitting process within the process chamber being received by the photo sensor is monitored. A determination is made if the emission signal is degrading.

The present invention provides systems and methods for measuring the isotope ratios of one or more trace gases based on optical absorption spectroscopy methods. The system includes an optical cavity containing a gas. The system also includes a laser optically coupled with the optical cavity, and a detector system for measuring absorption of laser light by the gas in the cavity.

Method of measuring a ratio of concentrations of two isotopologues of a chemical species in a first gas mixture using an optical absorption spectroscopy based gas analyzer; the method includes measuring the line intensity of a rotational-vibrational line of one isotopologue and the line intensity of another rotational-vibrational line of another isotopologue. The method also includes determining the ratio of two line intensities and comparing it with another ratio measured using another gas analyzer for a gas mixture with known concentration of isotopologues. The second ratio can be measured for the same pair of lines or for different pair of lines. The second ratio can be measured at the same gas temperature or at different gas temperature. The method includes determining a ratio of concentrations of two isotopologues based on two ratios of line intensities and two temperatures.

The present invention provides systems and methods for measuring the isotope ratios of one or more trace gases based on optical absorption spectroscopy methods. The system includes an optical cavity containing a gas. The system also includes a laser optically coupled with the optical cavity, and a detector system for measuring absorption of laser light by the gas in the cavity.

Method of measuring a ratio of concentrations of two isotopologues of a chemical species in a first gas mixture using an optical absorption spectroscopy based gas analyzer; the method includes measuring the line intensity of a rotational-vibrational line of one isotopologue and the line intensity of another rotational-vibrational line of another isotopologue. The method also includes determining the ratio of two line intensities and comparing it with another ratio measured using another gas analyzer for a gas mixture with known concentration of isotopologues. The second ratio can be measured for the same pair of lines or for different pair of lines. The second ratio can be measured at the same gas temperature or at different gas temperature. The method includes determining a ratio of concentrations of two isotopologues based on two ratios of line intensities and two temperatures.

The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising: a resonant optical cavity, a continuous-wave stepwise tunable external cavity laser having a DFB laser as a gain media; a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the roundtrip optical cavity length of the external cavity laser are the roundtrip optical cavity length of the resonant cavity are close

Systems and methods for measuring the isotope ratio of one or more gaseous oxides produced during combustion of drugs, pharmaceuticals, or medicines aiming to detect counterfeit drugs, pharmaceuticals, or medicines based on comparison of the isotopic composition of the tested drugs, pharmaceuticals, or medicines with the isotopic composition of the authentic products.