Abstract: An energy content meter can spectroscopically quantify oxidation products after oxidation of a combustible mixture. The measured oxidation product concentrations or mole fractions can be converted to an energy content of the un-oxidized combustible mixture using a conversion factor that relates oxygen consumption during oxidation of the combustible mixture to the energy content of the combustible mixture.

Abstract: Scrubber media for reactive gases, that can include but are not necessarily limited to hydrogen chloride (HCl), hydrogen sulfide (H2S), hydrogen fluoride (HF), and ammonia (NH3), can include reactive particles, potentially as small as nano-scale, that can optionally be suspended on macro-scale carrier particles. Reactive gases can be converted to non-volatile compounds by being passed through a bed of such scrubber media. Such scrubber media can be used to remove reactive gases from gas mixtures. Potential applications include differential absorption spectroscopy, air pollutant emission controls, and the like. Methods of preparing scrubber media are also described.

Abstract: A differential absorption spectrum for a reactive gas in a gas mixture can be generated for sample absorption data by subtracting background absorption data set from the sample absorption data. The background absorption data can be characteristic of absorption characteristics of the background composition in a laser light scan range that includes a target wavelength. The differential absorption spectrum can be converted to a measured concentration of the reactive gas using calibration data. A determination can be made whether the background composition has substantially changed relative to the background absorption data, and new background absorption data can be used if the background composition has substantially changed. Related systems, apparatus, methods, and/or articles are also described.

Abstract: Moisture can be detected in a refrigerant background such as HFC (Hydrofluorocarbon) HFC-134A and HFC-152A and exampled by HFC-23, HFC-32, HFC-143A, HFC-125, HFC-245FA, HFC-227EA, and the like. The system can include a light source operating at any one of several wavelengths within the water absorption bands at wavelengths such as 1.4, 1.9 and 2.7 ?m and a detector that measures the transmitted light intensity through the HFC samples. In one variation, the light source is a tunable diode laser and the moisture level is determined by direct absorption and harmonic spectroscopy. Related techniques, apparatus, systems, and articles are also described.

Abstract: A differential absorption spectrum for a reactive gas in a gas mixture can be generated for sample absorption data by subtracting background absorption data set from the sample absorption data. The background absorption data can be characteristic of absorption characteristics of the background composition in a laser light scan range that includes a target wavelength. The differential absorption spectrum can be converted to a measured concentration of the reactive gas using calibration data. A determination can be made whether the background composition has substantially changed relative to the background absorption data, and new background absorption data can be used if the background composition has substantially changed. Related systems, apparatus, methods, and/or articles are also described.

Abstract: Low concentrations of water vapor within a background of one or more olefin gases may be detected and quantified using a differential absorption spectrometer. A dehydrated sample of the gas is used as a background sample whose absorption spectrum allows elimination of absorption features not due to water vapor in the gas. Absorption spectra may recorded using tunable diode lasers as the light source. These lasers may have a wavelength bandwidth that is narrower than the water vapor absorption feature used for the differential absorption spectral analysis.

Abstract: Thermodynamic properties of a natural gas stream can be determined in real time utilizing modeling algorithms in conjunction with one or more sensors for quantifying physical and chemical properties of the natural gas. Related techniques, apparatus, systems, and articles are also described.

Abstract: Concentrations of a target analyte in a gas mixture containing one or more background analytes having potentially interfering spectral absorption features can be calculated by compensating for background analyte absorption at a target wavelength used to quantify the target analyte. Absorption can be measured at a reference wavelength chosen to quantify the concentration of the background analyte. Using a background gas adjustment factor or function, the absorption measured at the reference wavelength can be used to calculate absorption due to the background analyte at the target wavelength and thereby compensate for this background absorption to more accurately calculate the target analyte concentration in real or near real time. Additional background analytes can optionally be compensated for by using one or more additional reference wavelengths.

Abstract: Low concentrations of complex gas mixture components may be detected and quantified using a gas-chromatograph to separate a gas mixture prior to analysis of one or more eluting components using an absorption spectrometer. Substantial reductions in analytical system complexity and improvements in reliability are achieved compared with other commonly used methods for analyzing such complex mixtures.

Abstract: A system includes a light source, a detector, at least one pressure sensor, and a control unit. The light source emits light at a wavelength substantially corresponding to an absorption line of a target gas. The detector is positioned to detect the intensity of light emitted from the light source that has passed through the target gas. The pressure sensor detects the pressure of the target gas. The control circuit is coupled to the detector and the light source to adjust the modulation amplitude of the light source based on the pressure detected by the at least one pressure sensor. Related systems, apparatus, methods, and/or articles are also described.

Abstract: A system and method are disclosed for the detection of water vapor in a natural gas background. The system includes a light source operating in a wavelength range such as, 1.877-1.901 ?m, 2.711-2.786 ?m, or 920-960 nm, passes through the natural gas to be detected by a detector. In one embodiment, the light source is a tunable diode laser and the moisture level is determined by harmonic spectroscopy. In other embodiments, a VCSEL laser is utilized.

Abstract: The method and system operate to maintain a widely tunable laser (WTL) at a selected transmission wavelength. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a transmission line for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector to determine the power of the beam. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift attributable to the etalon.

Abstract: A system and method are disclosed for the detection of water vapor in a natural gas background. The system includes a light source operating in a wavelength range such as, 1.877-1.901 ?m, 2.711-2.786 ?m, or 920-960 nm, passes through the natural gas to be detected by a detector. In one embodiment, the light source is a tunable diode laser and the moisture level is determined by harmonic spectroscopy. In other embodiments, a VCSEL laser is utilized.

Abstract: A system and method can detect ethylene oxide in a sample of gas, such as air. The system includes a light source operating at a wavelength where molecules typically found within air absorb light at a substantially lower level than ethylene oxide molecules. Exemplary wavelengths are in the range of approximately 1.6–2.2 ?m, and in particular at 1.6 ?m, 1.645 ?m, 1.692 ?m, 2.195 ?m, 2.2 ?m, 2.216 ?m, passes through the sample of gas to be detected by a detector. In one variation, the light source is a tunable diode laser or a VCSEL and the ethylene oxide level is determined using harmonic spectroscopy.

Abstract: A system and method are disclosed for the detection of water vapor in a natural gas background. The system includes a light source operating in a wavelength range such as, 1.877–1.901 ?m, 2.711–2.786 ?m, or 920–960 nm, passes through the natural gas to be detected by a detector. In one embodiment, the light source is a tunable diode laser and the moisture level is determined by harmonic spectroscopy. In other embodiments, a VCSEL laser is utilized.

Abstract: The method and system operate to maintain a widely tunable laser (WTL) at a selected transmission wavelength. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a transmission line for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector to determine the power of the beam. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift attributable to the etalon.

Abstract: A system and method are disclosed for the detection of ethylene oxide in a sample of gas, such as air. The system includes a light source operating at a wavelength where molecules typically found within air absorb light at a substantially lower level than ethylene oxide molecules. Exemplary wavelengths are in the range of approximately 1.6-2.2 &mgr;m, and in particular at 1.6 &mgr;m, 1.645 &mgr;m, 1.692 &mgr;m, 2.195 &mgr;m, 2.2 &mgr;m, 2.216 &mgr;m, passes through the sample of gas to be detected by a detector. In one embodiment, the light source is a tunable diode laser or a VCSEL and the ethylene oxide level is determined using harmonic spectroscopy.

Abstract: The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by a detector. Another portion of the beam is routed directly to another detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line.

Abstract: The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line.

Abstract: A semiconductor laser is provided having a cavity including a gain chip, a Mach-Zehnder wide tuning port, and a ring resonator mirror. Optical signals generated by the gain chip propagate through the Mach-Zehnder wide tuning port and into the ring resonator mirror where the optical signals are reflected back through the Mach-Zehnder wide tuning port to the gain chip. The ring resonator is configured to reflect only those optical signals back into the laser cavity having wavelengths within a set of sharp peaks and the laser cavity therefore can resonate only within one of the sharp peaks. The ring resonator mirror is heated to adjust its dimensions so as to maintain one of the sharp peaks at a selected emission wavelength. As optical signals reflected from the ring resonator pass through the Mach-Zehnder wide tuning port, the signals are split between two channels of differing lengths resulting in optical interference.