Abstract: Optical spectrometer apparatus, systems, and methods for analysis of carbon-14 including a resonant optical cavity configured to accept a sample gas including carbon-14, an optical source configured to deliver optical radiation to the resonant optical cavity, an optical detector configured to detect optical radiation emitted from the resonant cavity and to provide a detector signal; and a processor configured to compute a carbon-14 concentration from the detector signal, wherein computing the carbon-14 concentration from the detector signal includes fitting a spectroscopic model to a measured spectrogram, wherein the spectroscopic model accounts for contributions from one or more interfering species that spectroscopically interfere with carbon-14.

Abstract: Optical spectrometer apparatus, systems, and methods for analysis of carbon-14 including a resonant optical cavity configured to accept a sample gas including carbon-14, an optical source configured to deliver optical radiation to the resonant optical cavity, an optical detector configured to detect optical radiation emitted from the resonant cavity and to provide a detector signal; and a processor configured to compute a carbon-14 concentration from the detector signal, wherein computing the carbon-14 concentration from the detector signal includes fitting a spectroscopic model to a measured spectrogram, wherein the spectroscopic model accounts for contributions from one or more interfering species that spectroscopically interfere with carbon-14.

Abstract: Preparation methods for introducing liquid samples to gas analysis instruments include 1) complete evaporation of a liquid sample in a sample chamber, and 2) allowing the sample vapor in the sample chamber to equilibrate for a predetermined time. An inert carrier gas (e.g., dry nitrogen or zero air) is also admitted to the sample chamber. After equilibration, the sample vapor is admitted as a conditioned sample to an analysis instrument. Preferably, the predetermined equilibration time is sufficiently long that the sample vapor in the sample chamber becomes substantially homogeneous with respect to both concentration and isotopic ratio. Vapor derived from a liquid calibration standard in this manner can be employed as an accurate gas-phase calibration reference.

Abstract: Preparation methods for introducing liquid samples to gas analysis instruments include 1) complete evaporation of a liquid sample in a sample chamber, and 2) allowing the sample vapor in the sample chamber to equilibrate for a predetermined time. An inert carrier gas (e.g., dry nitrogen or zero air) is also admitted to the sample chamber. After equilibration, the sample vapor is admitted as a conditioned sample to an analysis instrument. Preferably, the predetermined equilibration time is sufficiently long that the sample vapor in the sample chamber becomes substantially homogeneous with respect to both concentration and isotopic ratio. Vapor derived from a liquid calibration standard in this manner can be employed as an accurate gas-phase calibration reference.

Abstract: A gaseous target analyte present as a minor constituent in an admixture with at least one other gaseous species can be detected using a cavity enhanced optical spectrometer by a process comprising the steps of: i) identifying a plurality of strong spectral absorption peaks of the target analyte which are present within the scanning range of the spectrometer, ii) determining for the identified peaks the pressure region above which the peak width increases substantially with increasing pressure and below which the peak width is substantially independent of pressure, iii) determining which of the peaks identified in step i) are, within the pressure region determined in step ii), free from spectral interference by any of the other components of the admixture. iv) measuring the spectrum of the admixture at the pressure region identified in step ii).

Abstract: A cavity ring-down spectrometer includes: a) multiple detectors for monitoring the intensity of the radiation emitted from the cavity and the wavelength of the radiation injected into the cavity; b) controllers which turn off the radiation into the cavity and precisely adjust the temperature of, and current to, the laser gain medium; and c) means for adjusting the beam path length of the optical cavit to bring the cavity into resonance with the injected radiation. Additionally, disclosed is a method for using the spectrometer to detect a target analyte.

Abstract: Stable single mode operation of an external cavity semiconductor laser is obtained by a laser control method that monitors at least one optical beam which is generated by reflection from a wavelength selective element within the laser cavity. The method of the present invention provides stable single mode operation and significantly decreases the mode hop rate, because the signal obtained by reflection from a wavelength selective element within the laser cavity provides a clear indication of an impending mode hop.

Abstract: A gaseous target analyte present as a minor constituent in an admixture with at least one other gaseous species can be detected using a cavity enhanced optical spectrometer by a process comprising the steps of: i) identifying a plurality of strong spectral absorption peaks of the target analyte which are present within the scanning range of the spectrometer, ii) determining for the identified peaks the pressure region above which the peak width increases substantially with increasing pressure and below which the peak width is substantially independent of pressure, iii) determining which of the peaks identified in step i) are, within the pressure region determined in step ii), free from spectral interference by any of the other components of the admixture. iv) measuring the spectrum of the admixture at the pressure region identified in step ii).

Abstract: Target analytes present in low concentration as components in a gaseous admixture can be detected using a cavity enhanced optical spectrometer by a process comprising: i) identifying from the spectrum of the pure target analyte a series of absorption peaks free from spectral interference by peaks of any additional gaseous species which are present, the first member of the series being the strongest spectral absorption peak of said target analyte ii) identifying one or more successive peaks of the series which have an absorption that is weaker than the immediately previously identified peak of the series, iii) performing a spectral scan at the wavelengths of the peaks identified in steps i) and ii), and iv) calculating the concentration of the target analyte from the spectral scan of the admixture performed at the wavelength determined in step iii).

Abstract: A tunable laser and laser tuning method, based on the interaction of a spectrally dependent beam distortion and a spatial filter within a laser cavity. One embodiment of this laser is an external cavity semiconductor laser in which broad tunability is obtained by the insertion of an acousto-optic tunable filter (AOTF) into the laser cavity such that the intra-cavity laser beam passes through the AOTF in zeroth order.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.

Abstract: A tunable laser and laser tuning method, based on the interaction of a spectrally dependent beam distortion and a spatial filter within a laser cavity. One embodiment of this laser is an external cavity semiconductor laser in which broad tunability is obtained by the insertion of an acousto-optic tunable filter (AOTF) into the laser cavity such that the intra-cavity laser beam passes through the AOTF in zeroth order.

Abstract: Stable single mode operation of an external cavity semiconductor laser is obtained by a laser control method that monitors at least one optical beam which is generated by reflection from a wavelength selective element within the laser cavity. The method of the present invention provides stable single mode operation and significantly decreases the mode hop rate, because the signal obtained by reflection from a wavelength selective element within the laser cavity provides a clear indication of an impending mode hop.

Abstract: A laser tuning mechanism which embodies “spectrally dependent spatial filtering” (SDSF) and contemplates two key elements of the tuning mechanism. The first element of the SDSF tuning mechanism is a spectrally dependent beam distortion (i.e. alteration of the amplitude and/or phase profile of the beam) provided by an SDSF tuning element in a laser cavity. The second element of the SDSF tuning mechanism is an intracavity spatial filter which makes the round trip cavity loss a sensitive function of both beam distortion and cavity alignment. Such a laser can be aligned so that a specific beam distortion, which is provided by the SDSF tuning element at a tunable wavelength, is required to obtain minimum round trip cavity loss, thereby providing tunable laser emission. A preferred embodiment of the SDSF tuning mechanism is an external cavity semiconductor laser having a zeroth order acousto-optic tuning element.