The optical cell of an elongated shape has an inner space into which gas is introduced and includes: a cell main body forming the inner space; a manifold member being separably connected to an outer surface of the cell main body extending in a longitudinal direction; and a heating mechanism heating the manifold member, in which the cell main body has a through hole penetrating from the outer surface into the inner space, and the manifold member has a gas introduction path extending along the longitudinal direction and guiding the gas, which has been taken in from the outside, from one side to another side in the longitudinal direction and then guiding the gas to the inner space through the through hole.

Improved optical absorption spectroscopy of species having broad spectral features is provided by choosing frequencies to cover the spectral feature(s) of interest, where the frequencies are slightly adjusted as needed to avoid narrow spectral features from interfering chemical species (i.e., clutter). The resulting clutter avoidance provides improved optical spectroscopy of species having broad spectral features.

In one aspect, a method of detecting a trace gas is disclosed. The method includes containing the trace gas in an optical cavity. The method further includes injecting a first laser light from a first laser into the optical cavity causing the trace gas to transition from an energy state lower that a first excited energy state to the first excited energy state, and injecting a second laser light from a second laser into the optical cavity causing the trace gas to transition from the first excited energy state to a second excited energy state. The method includes measuring, by a detector, a first cavity ringdown intensity as a function of time after turning off the second laser with the first laser on, and a second cavity ringdown intensity as a function of time after turning off the second laser with the first laser off.

A spectroscopy system is disclosed, and includes a resonant cavity, a first conduit configured to couple at a first end thereof to a gas source, and at a second end thereof to a first end of a sorbent tube containing a sample for analysis, and a second conduit configured to couple at a first end thereof to a second end of the sorbent tube, and at a second end thereof to the resonant cavity.

In one aspect, a method of detecting a trace gas is disclosed. The method includes containing the trace gas in an optical cavity. The method further includes injecting a first laser light from a first laser into the optical cavity causing the trace gas to transition from an energy state lower that a first excited energy state to the first excited energy state, and injecting a second laser light from a second laser into the optical cavity causing the trace gas to transition from the first excited energy state to a second excited energy state. The method includes measuring, by a detector, a first cavity ringdown intensity as a function of time after turning off the second laser with the first laser on, and a second cavity ringdown intensity as a function of time after turning off the second laser with the first laser off.

Systems and methods for skewed basis set fitting may include obtaining measured absorption data indicative of an amount of absorption of light by a sample gas at each of multiple frequencies, determining an absorption dependent cavity time constant indicative of a skew to the measured absorption data caused by light reflections within a cavity in which the sample gas is contained, obtaining reference absorption data including basis sets indicative of reference amounts of light absorbed by each of multiple gases at each of the multiple frequencies, skewing the reference absorption data based on the absorption dependent cavity time constant to generate skewed reference absorption data, and fitting the measured absorption data to the skewed reference absorption data to identify an amount of at least one constituent gas within the sample gas.

The present invention provides a self-aligned high finesse optical sensor cell for analyzing a gaseous sample using highly reflective optical mirrors with a light source and a detector coupled on either end of the cell, having flexibility and/or serviceability in self-aligning the highly reflective mirrors to the optical cell without any mechanical manipulations.

In some embodiments, vehicle-based natural gas leak detection methods include assembling a collection of measured concentration peaks originating from a common natural gas leak according to wind direction, wind variability and inter-peak distance data, and selecting from the collection a subset of one or more representative peaks for display. Assigning peaks to a collection may be performed according to a peak overlap condition dependent upon a scaling (overlap) factor which scales the spatial reach of a peak, and according to a wind condition which determines whether a downwind event points toward an upwind event. The scaling factor may depend on wind variability and on an orientation of an inter-peak vector relative to a representative wind direction. Peak filtering is particularly useful in urban environments, where buildings channel gas plumes and one leak may lead to sequential detections of multiple concentration peaks along a path.

An apparatus and a method for quantitative detection of gases are provided. The apparatus for quantitative detection of gases includes: a cavity ring-down spectroscopy device configured to quantitatively detect any characteristic gas in gases to be detected; a sample processing device disposed in a downstream of the cavity ring-down spectroscopy device and connected to the cavity ring-down spectroscopy device; and a mass spectrometry device disposed in a downstream of the sample processing device and configured to detect all the gases to be detected. Quantitative analysis of any variety of gases may be achieved without using standard gas in the technical solution proposed by the present application. Since no standard gas is required, the technology has significantly increased flexibility, and can be used for routine laboratory testing, for online analysis at industrial sites, as well as detection and analysis in environmental protection, national defense, aviation, aerospace, military and other fields.

The gas absorption spectroscopic measurement device according to one embodiment of the present invention is provided with: a laser irradiation unit (1); and optical resonator (2), and a first detection unit (3) for detecting light taken out of the optical resonator (2). The gas absorption spectroscopic measurement device acquires the component concentration of a gas to be measured by CRDS (Cavity Ring-Down Spectroscopy) measurement. The laser irradiation unit (1) is provided with: a laser light source (10); a frequency conversion unit (12) configured to selectively output either laser light having the same frequency as the irradiation light source or laser light having a frequency of the laser light source multiplied by a prescribed number of times; a frequency modulation unit (13, 14) for modulating the frequency of the emitted laser light using a modulation signal, a second detection unit for detecting returning light derived from the irradiation light returning to the optical resonator (2); and a feedback control unit (191, 11) for generating an error signal affected by the difference between the frequency of the laser light emitted to the optical resonator (2) and the modulation signal based on the detection signal from the second detector (18), thereby controlling the oscillation frequency in the laser light source (10) in accordance with the error signal.