Abstract: Noise in cavity enhanced spectroscopy due to higher order mode excitation in a resonant cavity is reduced. There are two main points. The first point is that the source and detector are both fiber coupled, to provide the spatial filtering and other general advantages of fiber coupling. The second point is that the cavity is designed to ensure sufficient separation in frequency between the desired TEM00 mode and the first few higher order spatial modes.

Abstract: Noise in cavity enhanced spectroscopy due to higher order mode excitation in a resonant cavity is reduced. There are two main points. The first point is that the source and detector are both fiber coupled, to provide the spatial filtering and other general advantages of fiber coupling. The second point is that the cavity is designed to ensure sufficient separation in frequency between the desired TEM00 mode and the first few higher order spatial modes.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising an optical cell containing a gas mixture, a continuous-wave tunable laser, a detector system for measuring an absorption of laser light by the gas in the optical cell, and a processor to conduct an absorption spectroscopy analysis of the gas mixture based on light intensity measured by the detector system at one or more laser frequencies.

Abstract: 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.

Abstract: 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.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: 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.

Abstract: 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.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: 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.

Abstract: 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.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: 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.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using the absorption spectroscopy method. The system comprising an optical cell containing a gas mixture, a continuous-wave tunable laser, a detector system for measuring an absorption of laser light by the gas in the optical cell, and a processor to conduct an absorption spectroscopy analysis of the gas mixture based on light intensity measured by the detector system at one or more laser frequencies.

Abstract: 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 5 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.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.

Abstract: The present invention provides a system for measuring concentrations of trace gases in gas mixtures using an absorption spectroscopy method. The system comprising: a resonant optical cavity containing a gas mixture, a continuous-wave external cavity laser, a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, wherein the ratio of the round-trip length of the external cavity laser to the round-trip length of the resonant optical cavity or its inverse value is between N?0.2 and N+0.2, where N is a positive integer number.