Abstract: A process interface of a process gas analyzer operating by a transmitted light method includes a purging tube, which extends between an optoelectronic element and an interior of a plant part carrying a process gas, wherein the purging tube is closed off, at its end opposite from the optoelectronic element by a window, in the vicinity of which a purging gas feed enters the purging tube, where an annular part is arranged in the interior of the purging tube opposite the entrance of the purging gas feed and is coaxial in relation to the purging tube, and the part has a convex outer side, the vertex line of which divides the entrance of the purging gas feed into a smaller region, open toward the window, and a larger region, open toward the interior of the plant part.

Abstract: For cavity enhanced optical spectroscopy, the cavity modes are used as a frequency reference. Data analysis methods are employed that assume the data points are at equally spaced frequencies. Parameters of interest such as line width, integrated absorption etc. can be determined from such data without knowledge of the frequencies of any of the data points.

Abstract: Validation verification data quantifying an intensity of light reaching a detector of a spectrometer from a light source of the spectrometer after the light passes through a validation gas across a known path length can be collected or received. The validation gas can include an amount of an analyte compound and an undisturbed background composition that is representative of a sample gas background composition of a sample gas to be analyzed using a spectrometer. The sample gas background composition can include one or more background components. The validation verification data can be compared with stored calibration data for the spectrometer to calculate a concentration adjustment factor, and sample measurement data collected with the spectrometer can be modified using this adjustment factor to compensate for collisional broadening of a spectral peak of the analyte compound by the background components. Related methods, articles of manufacture, systems, and the like are described.

Abstract: An organic diode operated in photovoltaic mode is used as a sensor for nitroaromatic electron accepting compounds. While illuminated by a light source with a wavelength within the organic materials absorption the device produces a small photovoltaic response due to inefficient separation of charges. Upon exposure to an electron accepting compound, the device produces an increase in photovoltaic activity due to more efficient charge separation, producing a larger measurable open circuit voltage. Upon removal of the compound the measured voltage decreases and returns to near its baseline value.

Abstract: A fiber laser gas detection system with a double wavelength combination using reference cavity compensation is provided. The system comprises an optical fiber laser respectively emitting beams having a first and second wavelengths, which consists of a laser diode pump source, a first wavelength division multiplexer, an active optical fiber, a first fiber bragg grating and a second fiber bragg grating connected successively; an optical isolator; a coupler for dividing the beams according to power ratio, the divided beams is introduced into a reference gas chamber and a detecting gas chamber respectively; a second wavelength division multiplexer connecting the reference room and a third wavelength division multiplexer connecting the detecting gas chamber; a first, a second, a third and a fourth photoelectric detector; a feedback control unit, receiving the first to fourth light intensity signals and adjusting the fiber laser using the comparison results as a feedback signal.

Abstract: A sensor arrangement for determining a concentration of a substance in an open sample in the presence of an interfering material is disclosed. The sensor arrangement comprises a first light source emitting pulsed light at a first wavelength being absorbed by said substance, a second light source emitting pulsed light at a second wavelength being transmitted through said substance, optical means for directing at least a part of the emitted pulsed light of said first and second wavelengths through the open sample along the same optical path, and a sample detector arranged at an end of the optical path for receiving the emitted light of said first and second wavelengths being transmitted through the sample. The interfering material is formed as deposits on at least one of said optical means being exposed to said substance, and said first wavelength and said second wavelength are absorbed by said interfering material.

Abstract: A laser spectrometer and method for measuring gas component concentration in a measurement gas, wherein light intensity from a wavelength-tunable laser diode is detected after irradiation of the measurement gas and a reference gas, and the concentration of the gas component is determined based on reduction of the light intensity by the absorption of light at the position of a selected absorption line of the gas component, and the position of the absorption line of the gas component is referenced based on a selected absorption line of the reference gas, and wherein there is a mixed operation consisting of actual measurements of fast concentration changes of the gas component to be measured and a short reference/standardization phase for wavelength referencing, line locking and standardization, where the duration of the actual measurement is measured such that measuring conditions remain constant and do not deviate from those during the reference/standardization phase.

Abstract: Light intensity data quantifying intensity of light generated by a light source and received at a detector during a validation mode of an absorption spectrometer can be compared with a stored data set representing at least one previous measurement in a validation mode of an analytical system. The validation mode can include causing the light to pass at least once through each of a zero gas and a reference gas contained within a validation cell and including a known amount of a target analyte. The zero gas can have at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source. A validation failure can be determined to have occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount. Related systems, methods, and articles of manufacture are also described.

Abstract: A gas detector including: an assembly of two coaxial parabolic reflective caps having opposite concavities, and a wafer arranged in the focal plane of the two caps, at the center of this focal plane, comprising, back-to-back: a diverging light emitter directed towards the first cap and a light receiver directed towards the second cap, wherein the two caps are distant substantially by the sum of their focal distances plus the thickness of the wafer.

Abstract: A photoacoustic detector wherein control circuits compensate for long term variations of components therein including a light source and sensing microphones. The control circuits intermittently energize the source to evaluate changes in at least source resistance. The control circuits intermittently energize an acoustic generator to evaluate changes in one or more generator responsive microphones.

Abstract: Described are methods for multi-wavelength cavity ring-down spectroscopy; comprising simultaneously and continuously irradiating an optical cavity with light at two or more different wavelengths, each light being intensity-modulated at a different modulation frequency, detecting the light of two or more wavelengths after the light has traveled through the optical cavity; measuring an optical loss of each detected light; and determining a characteristic of the optical cavity from the optical loss of each detected light. Also described are apparatus and systems for multi-wavelength cavity ring-down spectroscopy.

Abstract: One embodiment is directed towards a physics package of an atomic sensor. The physics package includes a plurality of panes of optically transparent material enclosing a vacuum chamber and one or more wedges attached to an external surface of one or more of the panes. The physics package also includes at least one of a light source, photodetector, or mirror attached to the one or more wedges, the light source configured to generate an input light beam for the vacuum chamber, the photodetector configured to detect an output light beam from the vacuum chamber, and the mirror configured to reflect a light beam from the vacuum chamber back into the vacuum chamber, wherein the wedge is configured to oriented such a light source, photodetector, or mirror such that a respective light beam corresponding thereto transmits through a corresponding pane at an acute angle with respect to the corresponding pane.

Abstract: Disclosed is a multi-band multiplexing intra-cavity gas sensing system and method. The system consists of a laser resonant cavity subsystem, a gas sensing subsystem and a detection-demodulation subsystem. The laser resonant cavity subsystem consists of the first beam splitter, two ways of gain paths composed of a pump light source, a wavelength division multiplexer, a rare earth doped fiber, an optical isolator and a tunable optical attenuator, a beam combiner and an F-P tunable optical filter. The gas sensing subsystem consists of a gas cell and an optical reflective mirror. The detection-demodulation subsystem consists of an optical coupler, the second beam splitter, two optical detectors, a data acquisition module and a computer. In this invention, different rare-earth doped fibers are multiplexing into one system, in order to cover more maser bands of different rare earth, which greatly expands the scanning range of wavelength, and is capable of detecting various gases simultaneously.

Abstract: A gas analysis apparatus includes: a first reflector that reflects measurement light from a light emitting unit disposed outside a gas flue wall and transmitted through a sample gas. A light receiving unit outside the gas flue wall receives measurement light reflected by the first reflector. A second reflector outside the gas flue wall reflects measurement light toward the light receiving unit. A computing unit analyzes sample gas by allowing the measurement light to be reflected by the first reflector and performs correction or calibration of the gas analysis apparatus using known substances within an associated containing unit along the light path between the light emitting unit and the second reflector by allowing measurement light to be reflected by the second reflector. A switching unit outside the gas flue wall selectively removes or inserts the second reflector from the light path during component concentration analysis and correction or calibration, respectively.

Abstract: A gas detection system using a semiconductor laser with a reference gas cavity compensation is provided, said system comprising a first light source emitting a first beam of a first wavelength as a detection beam; a second light source emitting a second beam of a second wavelength, which is different from the first wavelength, as a reference beam; a first wavelength division multiplexer connected with said first light source and said second light source; a broadband coupler connected with said first wavelength division multiplexer; a reference gas chamber, which is introduced with reference gas of the same composition as that of the gas to be detected and of a known concentration; a detection gas chamber, which is introduced with the gas to be detected.

Abstract: The invention subject of this disclosure teaches a method of determining a production factor for a carbonaceous material reservoir, the method comprising: providing a well in a carbonaceous material reservoir; providing unsampled fluid at a depth in the well; placing a sensor adjacent to the unsampled fluid and performing a measurement on the unsampled fluid; using data from the measurement to determine a partial pressure of a solution gas in the carbonaceous material reservoir; and determining a production factor for the carbonaceous material reservoir from the partial pressure of the solution gas.

Abstract: In the optical gas sensor of the application, a three-dimensional reaction chamber structure is used to replace the traditional simple structure, so that the performance of the gas sensor can be enhanced in a wafer-level size. Besides, a light source, a reaction chamber and a light detector are integrated into one wafer in an exemplary embodiment, so as to achieve the wafer-level integration. In addition, the optical gas sensor can detect various gases simultaneously and has wide application in fields such as home environment monitoring, industrial safety, and disease diagnosis and treatment.

Abstract: An apparatus and method for monitoring gas velocity, temperature, and pressure in combustion systems and flow devices, in particular at inlets and isolators of scramjet engines. The invention employs wavelength modulation spectroscopy with first harmonic detection and without the need to scan the full absorption spectra.

Abstract: A gas measurement apparatus measures a target gas. The gas measurement apparatus includes a light source, a first light receiving apparatus, a first phase-sensitive detection apparatus, an R calculation unit, and a setting unit. The light source oscillates a laser light that has a central wavelength determined by a main current and is modulated according to a modulation current, with the central wavelength being varied. The first light receiving apparatus outputs a detection signal according to an intensity of the laser light transmitted through a standard sample. The first phase-sensitive detection apparatus obtains a second harmonic component oscillated at a harmonic frequency ?2 twice as large as a modulation frequency ?1. The R calculation unit calculates a peak-bottom ratio R. The setting unit sets a width of wavelength modulation of the laser light so that the peak-bottom ratio R satisfies a predetermined condition.

Abstract: A gas analyzer includes: a first signal processing section for synchronously detecting a light detection signal at a frequency being an integral multiple of a modulation frequency fa of a laser light, to detect a harmonic signal intensity Signal(?) by a harmonic synchronous detection method; a second signal processing section for capturing a light detection signal and cutting off a frequency component not smaller than the frequency fa to detect a light intensity signal I(?) at a specific light frequency absorbed by a component to be measured in a sample gas; and an operation section. The operation section includes a first operation means for calculating a density c of the component from the harmonic signal intensity Signal(?) and a reference light intensity signal I0(?) and a second operation means for calculating the density c from the light intensity signal I(?) and the reference light intensity signal I0(?).

Abstract: The leak detection device comprises a plurality of measuring cells (10) in whose interior the absorption of a laser beam (17) is influenced by the presence of tracer gas. All of said measuring cells (10) are connected to a host unit (25) via light-conducting fibers (28,34). In the host unit (25), a laser (26) designed for modulation and a photodetector (37) are arranged. Modulation of the laser radiation is preferably performed by two-tone frequency modulation. This has the effect that the fiber length cannot significantly skew the result of the measurement.

Abstract: Cavity enhanced absorption spectroscopy systems and methods for detecting trace gases using a resonance optical cavity, which contains a gas mixture to be analyzed, and a laser coupled to the cavity by optical feedback. The cavity has any of a variety of configurations with two or more mirrors, including for example a linear cavity, a v-shaped cavity and a ring optical cavity. The cavity will have multiple cavity resonant modes, or a comb of frequencies spaced apart, as determined by the parameters of the cavity, including the length of the cavity, as is well known. Systems and methods herein also allow for optimization of the cavity modes excited during a scan and/or the repetition rate.

Abstract: An apparatus can include ablation chamber body having a transmission window and defining an accommodation region configured to accommodate a target that is movable relative to the transmission window. An aerosol transmission conduit is configured to transport an aerosol produced within the accommodation region to a sample receiving region of an analysis system along a substantially straight transport path.

Abstract: An inspection apparatus comprising, a light source configured to emit an inspection light, a table configured to mount an inspection target thereon, an illumination optical system configured to direct the inspection light from the light source toward the target, an objective lens unit configured to gather transmitting or reflected light generated after the illumination optical system illuminates the target with the inspection light, a light receiving unit configured to capture an optical image formed from the light illuminated through the objective lens unit, a chamber configured to house the table, light receiving unit, illumination optical system and objective lens unit, a temperature adjustment unit configured to adjust a temperature in the chamber, and a gas supply unit configured to be connected to the objective lens unit to supply an inert gas at a predetermined temperature into the unit.

Abstract: Systems and methods measure a physical parameter of a first substance having an absorption feature that varies based on the physical parameter. A tunable-frequency laser may transmit a first laser beam through the first substance and a second laser beam through a second substance having an isoclinic point. A first output is based on an intensity of the first laser beam transmitted through the first substance, and a second output is based on an intensity of the second laser beam transmitted through the second substance. Controller circuitry locks a first frequency of the first laser beam to the absorption feature based on the first output, and locks a second frequency of the second laser beam to the isoclinic point based on the second output. Measurement circuitry calculates the physical parameter of the first substance based on a difference between the first and second frequencies.

Abstract: The invention subject of this disclosure teaches a method of determining a production factor for a carbonaceous material reservoir, the method comprising: providing a well in a carbonaceous material reservoir; providing unsampled fluid at a depth in the well; placing a sensor adjacent to the unsampled fluid and performing a measurement on the unsampled fluid; using data from the measurement to determine a partial pressure of a solution gas in the carbonaceous material reservoir; and determining a production factor for the carbonaceous material reservoir from the partial pressure of the solution gas.

Abstract: An ammonia sensor can include a laser detector configured to provide stable sample readings.

Abstract: Disclosed are methods and apparatus for treating and analyzing a gas stream to determine the ammonia concentration. A gas stream is continuously monitored to determine the ammonia concentration by extracting gas samples from one or more locations and sending it to a tunable diode laser absorption spectroscopy instrument for analysis. By proper placement of sampling probes within a duct, depending on the particular flow patterns that have been determined by suitable modeling, e.g., computational fluid dynamics or cold flow modeling, the valves can be operated manually or by a controller to take samples at predetermined locations within the duct. This will enable taking samples from particular locations, samples representative of the entire cross section, or samples that are an average of a particular cross section. It will be possible by judicious placement of the probes and operation of the valves to map the concentrations of ammonia at a plurality of load settings and will permit continuous control.

Abstract: A laser emitting section 59A and a laser receiving section 59B for measuring an oxygen concentration are provided on two sides of an inspection area so as to be moved toward and away from a bag-shaped container 1. Gas-filled chambers 61 provided on the end faces of the laser emitting section 59A and the laser receiving section 59B are brought into contact with the gas phase portion of the container 1 to keep a constant thickness of the gas phase portion. A tilting device 81 is provided to press the container 1, which is held by a container holder 16, from both sides with a container pressing member 88 and tilts the container 1 in a vertical plane. When an oxygen concentration is measured, the tilting device 81 tilts the bag-shaped container 1 to measure the gas phase portion at the shoulders of the container 1.

Abstract: A photoacoustic sensing device includes a laser tuned to emit light to cause optical absorption by a gas to be detected, a resonant acoustic sensor positioned to receive pressure waves from the gas, wherein the laser is modulated to match a resonant frequency of the resonant acoustic sensor, and a first mirror positioned to receive light from the laser after the light has passed through the gas and to reflect the received light back through the gas to cause additional optical absorption.

Abstract: A spectrometer cell can include a spacer, at least one end cap, and at least one mirror with a reflective surface. The end cap can be positioned proximate to a first contact end of the spacer such that the end cap and spacer at least partially enclose an internal volume of the spectrometer cell. The mirror can be secured in place by a mechanical attachment that includes attachment materials that are chemically inert to at least one reactive gas compound. The mechanical attachment can hold an optical axis of the reflective surface in a fixed orientation relative to other components of the spectrometer cell and or a spectrometer device that comprises the spectrometer cell. The mirror can optionally be constructed of a material such as stainless steel, ceramic, or the like. Related methods, articles of manufacture, systems, and the like are described.

Abstract: An open-path gas analyzer is disclosed and is configured to prevent or reduce contamination of the analyzer over time.

Abstract: The disclosure relates to a method of detecting a change in a chemical composition by contacting a conducting oxide material with a monitored stream, illuminating the conducting oxide material with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The conducting metal oxide has a carrier concentration of at least 1017/cm3, a bandgap of at least 2 eV, and an electronic conductivity of at least 10?1 S/cm, where parameters are specified at the gas stream temperature. The optical response of the conducting oxide materials is proposed to result from the high carrier concentration and electronic conductivity of the conducting metal oxide, and the resulting impact of changing gas atmospheres on that relatively high carrier concentration and electronic conductivity.

Abstract: A reference harmonic absorption curve of a laser absorption spectrometer can have a reference curve shape derived from a reference signal generated by the detector in response to light passing from the laser light source through a reference gas or gas mixture. The reference gas or gas mixture can include one or more of a target analyte and a background gas expected to be present during analysis of the target analyte. A test harmonic absorption curve having a test curve shape is compared with the reference harmonic absorption curve to detect a difference between the test curve shape and the reference curve shape. Operating and/or analytical parameters of the laser absorption spectrometer are adjusted to correct the test curve shape to reduce the difference between the test curve shape and the reference curve shape.

Abstract: Provided are a nitric oxide detection element capable of detecting NO gas contained in a mixed gas at a high speed even when the amount thereof is a super trace amount of ten and several parts per billion; and a process for producing the element. In a nitric oxide detection element having a substrate 12 and a sensing film 11 formed on a surface of the substrate, the sensing film is composed of nitric oxide sensing particles and a polymer adhesive. The nitric oxide sensing particles are produced by adsorbing a dye having a porphyrin skeleton and having, as a central metal, divalent cobalt onto surfaces of inorganic particles.

Abstract: A method for measuring a concentration of at least one gas component in a measurement gas, wherein light of a light source is guided along a light path through a measuring volume containing the measuring gas to a detector unit, and the concentration of the gas component is determined from the wavelength-dependent absorption of the light detected there. The light path is guided outside of the measuring volume through a substitute gas held in a closed volume. A substitute gas comprising a substitute gas component in a predetermined concentration is used, and the concentration of the substitute gas component is monitored based on the detected wavelength-dependent absorption, and if the decrease in the concentration exceeds a predetermined degree, then an error message is generated.

Abstract: A method and a sensor for detecting a target gas by laser spectroscopy using a laser or a laser diode having a monochrome emission wavelength that can be modulated by varying the operating temperature or the operating current. The wavelength range of the target gas comprises a first modulation of the laser or the laser diode over a first large modulation width, in addition to at least two absorption lines of a reference gas and at least one absorption line of the target gas. The absorption lines are used to calibrate the wavelength scale of the laser or the laser diode in relation to the varied operating temperature or operating current, a second modulation of the laser or the laser diode being performed over a second small modulation width, with the at least one absorption line of the target gas, for detecting the target gas.

Abstract: A system, apparatus, and method is provided to remotely measure atmospheric species using a long path differential absorption technique. In one embodiment, a source and a detector are collocated and at the far end of the absorption path a retro-reflector is mounted on a vehicle. The source generates an outgoing laser beam that is transmitted to the retro-reflector and reflected towards the detector as an incoming laser beam, and the detector receives the incoming laser beam that was reflected by the retro-reflector.

Abstract: Optical computing devices are disclosed. One exemplary optical computing device includes an electromagnetic radiation source configured to optically interact with a sample and first and second integrated computational elements arranged in primary and reference channels, respectively, the first and second computational elements are configured to be either positively or negatively correlated to the characteristic of the sample. The first and second integrated computational elements produce first and second modified electromagnetic radiations, and a detector is arranged to receive the first and second modified electromagnetic radiations and generate an output signal corresponding to the characteristic of the sample.

Abstract: A method of providing real-time analysis of chemical gases in a transformer oil has been disclosed. The method includes the steps of providing an inspection probe adapted to measure a transmission spectrum of a solvent oil in a transformer, placing the probe inside a transformer, using the inspection probe to measure a transmission spectrum of the solvent oil, and determining the concentration of dissolved gases in the transmission oil.

Abstract: A method for detecting component concentrations in human gas emissions such as breath and gas emitted from skin. A gas sample containing a specified component is collected into a gas cell using a pump and a series of valves to draw the gas sample into the cell and control the gas pressure within the cell. A tunable optical radiation beam is passed through the gas cell and the amount of energy absorbed by the specified component may be measured indirectly by taking the difference between the incident and emerging beam energy or directly by optoacoustic methods. Concentrations of the specified component as small as 0.1 ppB may be determined. Additionally, the tunable optical radiation beam may be multiplexed for use with a plurality of systems utilizing the beam for medical purposes.

Abstract: A gas analysis apparatus includes: a first reflector that reflects measurement light from a light emitting unit disposed outside a gas flue wall and transmitted through a sample gas. A light receiving unit outside the gas flue wall receives measurement light reflected by the first reflector. A second reflector outside the gas flue wall reflects measurement light toward the light receiving unit. A computing unit analyzes sample gas by allowing the measurement light to be reflected by the first reflector and performs correction or calibration of the gas analysis apparatus using known substances within an associated containing unit along the light path between the light emitting unit and the second reflector by allowing measurement light to be reflected by the second reflector. A switching unit outside the gas flue wall selectively removes or inserts the second reflector from the light path during component concentration analysis and correction or calibration, respectively.

Abstract: An optical fiber includes a graphene oxide and a reduced graphene oxide and a gas sensor includes the optical fiber. A method for manufacturing the optical fiber includes coating a graphene oxide layer and reducing a part of the graphene oxide layer, and a method for manufacturing the gas sensor includes coating a graphene oxide layer and reducing a part of the graphene oxide layer.

Abstract: A closed path infrared sensor includes an enclosure, a first energy source within the enclosure, at least a second energy source within the enclosure, at least one detector system within the enclosure and a mirror system external to the enclosure and spaced from the enclosure. The mirror system reflects energy from the first energy source to the at least one detector system via a first analytical path and reflects energy from the second energy source to the at least one detector system via a second analytical path. Each of the first analytical path and the second analytical path are less than two feet in length.

Abstract: A gas detector (100) for remote gas detection in a target region (106) comprises a light source (102) for emitting a light beam (110) into the target region and a light sensor (112) for sensing light returning therefrom. The light beam is wavelength-modulated around an absorption wavelength of the gas. A controller (108) is operatively connected to the light sensor for detecting a presence of the gas on a path of the light beam based on returning light sensed by the light sensor. An indicator (124) that is operatively connected to the controller indicates the presence of the gas. A scanning device (104) is arranged with respect to the light source so as to scan the light beam through the target region, and with respect to the light sensor so that the light sensor receives the returning light via the scanning device. The indicator cooperates with the scanning device to indicate a position of the gas in the target region.

Abstract: An apparatus and methods for measuring combustion parameters in the measurement zone of a gas turbine engine. The measurement zone is defined as being between an outer casing and an engine component having a reflecting surface inside the outer casing. The apparatus comprises a laser generating a transmitting beam of light of a select wavelength and a multimode transmitting fiber optically coupled to the laser. A transmitting optic is optically coupled to the multimode optical fiber for transmitting the beam into the measurement zone. The reflecting surface is configured to provide a Lambertian reflection. A receiving optic is positioned to receive the Lambertian reflection. Means are provided in operative association with the multimode transmitting fiber for averaging modal noise induced signal level variation of light propagating within the multimode transmitting fiber.

Abstract: A method of obtaining a fugitive emission flux measurement of airborne matter is provided. The method involves measuring the airborne matter along one or more than one measurement surface that spans the fugitive emission using two or more than two measurement beam paths where each of the two or more than two measurement beam paths are parallel to each other, or substantially parallel to each other, and determining a mass per unit length measurement for the measurement surface, determining a representative wind velocity at or near the one or more than one measurement surface, and calculating the fugitive emission flux of the airborne matter in mass per unit time using the mass per unit length determination and representative wind velocity.

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.

Abstract: Disclosed are a system and a method for monitoring unsaturated zone gas and near-surface atmosphere in real time by using an isotope analyzer. The system includes a near-surface atmosphere analyzer including a fixing member, a plurality of near-surface gas inlets, a plurality of gas transfer members communicating with the near-surface gas inlets, an analyzing member including an isotope analyzer, which analyzes an isotope of gas transferred through the gas transfer members, a channel connected to the gas transfer members and the analyzing member to select one gas transfer member and to supply gas transferred through the selected gas transfer member to the analyzing member, and a connection member connecting the channel to the analyzing member, a communication device transmitting components of the isotope output from the isotope analyzer, and a monitoring server outputting the components of the isotope transmitted from the communication device.

Abstract: Disclosed is a multi-band multiplexing intra-cavity gas sensing system and method. The system consists of a laser resonant cavity subsystem, a gas sensing subsystem and a detection-demodulation subsystem. The laser resonant cavity subsystem consists of the first beam splitter, two ways of gain paths composed of a pump light source, a wavelength division multiplexer, a rare earth doped fiber, an optical isolator and a tunable optical attenuator, a beam combiner and an F-P tunable optical filter. The gas sensing subsystem consists of a gas cell and an optical reflective mirror. The detection-demodulation subsystem consists of an optical coupler, the second beam splitter, two optical detectors, a data acquisition module and a computer. In this invention, different rare-earth doped fibers are multiplexing into one system, in order to cover more maser bands of different rare earth, which greatly expands the scanning range of wavelength, and is capable of detecting various gases simultaneously.