Abstract: A gas flow measuring circuit includes at least one reference resistor and at least one variable resistor that varies in accordance with the characteristics of the flow of a gas and means for determination of the difference between the reference resistor and variable resistor, with at least one current loop arrangement including first current source means coupled in series with said reference resistor and second current source means coupled in series with said variable resistor wherein both resistors are connected to ground for providing an ideally constant current through the respective resistor to produce first voltages across the reference resistor and second voltages across the variable resistor, and voltage measuring means for measuring the voltage difference between said reference resistor and said variable resistor to produce a characteristic voltage difference representative of the characteristics of the gas.

Abstract: A method for operating an optical measuring system including a wavelength-tunable temperature-stabilized laser light source for measuring the concentration of a target gas in a measured gas, wherein an instantaneous base current IDC_ZG,act corresponding to a wavelength ?ZG of a target gas absorption line is set so that a wavelength distance ??DC defined during calibration between a target gas absorption line for a target gas and a reference gas absorption line for a reference gas is maintained. During operation, a temperature difference in the laser light source, defined in advance during calibration, between the operating points selected at the time of calibration of the reference gas, with a base current IDC_RG,cal, and the target gas, with a base current IDC_ZG,cal, is maintained by determining the required instantaneous base current IDC_ZG,act for the target gas, as a function of an instantaneous base current IDC_RG,act for the reference gas.

Abstract: A method for operating an optical measuring system for measuring the concentration of a gas component in a measured gas, based on wavelength modulation spectroscopy, wherein a laser light source is operated in a current-modulated manner with a base current IDC and a modulation current IAC and a laser beam of the wavelength ?0 having a wavelength modulation amplitude ??AC is emitted, and the wavelength modulation amplitude ??AC of the laser light is kept constant by way of variable setting of the current modulation amplitude ?IAC. The method provides for keeping a modulated power ?PAC at an internal resistor RI of the laser light source constant at the operating point so as to stabilize the wavelength modulation amplitude ??AC.

Abstract: A flow rate measuring unit, comprising a housing, which is composed of at least two housing parts that can be connected to one another and in which a flow passage extends, which branches off into a measuring channel branch and at least one bypass channel branch, wherein a substrate comprising a sensor system is disposed in the measuring channel branch. According to the invention, the flow passage includes a channel widening chamber in which an insert plate stack composed of at least two insert plates is disposed, which each include at least one plate-longitudinal recess extending in the longitudinal direction as the measuring channel branch and/or as the bypass channel branch. The insert plates are provided as insert parts for the channel widening chamber.

Abstract: A flow rate measuring unit, comprising a housing, which is composed of at least two housing parts that can be connected to one another and in which a flow passage extends, which branches off into a measuring channel branch and at least one bypass channel branch, wherein a substrate comprising a sensor system is disposed in the measuring channel branch. According to the invention, the flow passage includes a channel widening chamber in which an insert plate stack composed of at least two insert plates is disposed, which each include at least one plate-longitudinal recess extending in the longitudinal direction as the measuring channel branch and/or as the bypass channel branch. The insert plates are provided as insert parts for the channel widening chamber.

Abstract: An optical measuring system and a method for gas detection, the optical measuring system including a light emitter and at least one light detector arranged in at least one housing, wherein the light emitter emits a modulated main light beam with a mean wave length ?0 with a modulation span ??. At least one opto-mechanical component, e.g. a housing window including optically effective boundary surfaces, is arranged between the light emitter and the light detector and causes scatter light beams which interfere with the main light beam so that self-mixing occurs and/or etalons are caused. According to the invention the at least one opto-mechanical component is arranged relative to the light emitter and/or the light detector at an optimized distance L which is a function of the wave length ?0 and the modulation span ?? of the main light beam.

Abstract: This invention relates to a method that makes the measurement of a trace gas concentration invariant or at least less affected to pressure variations in the gas and atmospheric pressure changes. This method neither requires a pressure sensor nor a pressure calibration routine. Furthermore, the method can be applied to other gas species present in the background gas or to the background gas itself that cross-interfere with the target gas of interest. This allows removing any pressure dependency of cross-interference parameters of other gas species and/or the background gas. The new method for accurately measuring a gas concentration is based on optimizing the wavelength modulation amplitude of the laser to minimum pressure dependency.

Abstract: A flow sensor for measuring the flow of a gaseous or liquid medium with a sensor housing in which, between an inlet channel and an outlet channel, a flow channel extends that comprises a main channel and a measuring channel that is arranged parallel to the main channel. At least one main channel choke point is arranged in the main channel, and the measuring channel comprises a sensor element for measuring the flow. A measuring channel choke point in the measuring channel on the inlet and/or the outlet side, is arranged with the main channel choke point having at least one passage and the measuring channel choke point having a passage, both passages being of identical shape and extending parallel to each other in the flow direction.

Abstract: A sample stream of the gas to be analyzed is fed into a combustor. The combustor mixes the gas with ambient air to an over-stoichiometric oxygen content and combusts the sample gas completely. A respective TDLS analyzer measures the CO2 and/or H2O concentration of the combustor's flue gas. In case that the sample gas contains relevant concentrations of CO2 and/or H2O, a second TDLS CO2 and/or H2O analyzer may be added which measures the CO2 and/or or H2O concentration upstream of the combustor. The measurement of methane and ethane or other hydrocarbon and mixtures thereof is also possible. The method and device allows the measurement of the heating value and/or the total organic carbon of a natural gas with high temporal resolution.

Abstract: The invention relates to a laser diode structure, specifically for use in gas detection, with a hermetically sealed housing with electrical connections having a bottom and a window. A laser diode chip and a temperature control system for the laser diode chip are provided in the housing. A thermo element in the form of a Peltier element forms the temperature control system, and is connected via a lower flat surface to the bottom of the housing and via an upper flat surface to the laser diode chip, with a temperature-controlled beam shaping element as collimator provided between the laser diode chip and the window of the housing that acts on a laser beam emerging from a laser aperture of the laser diode chip before it passes through the window. The beam shaping element is in contact with the laser diode chip and is preferably connected via a boundary surface to the laser aperture with surface-to-surface contact or adhesively, or is made in one piece together with the laser aperture.

Abstract: An infrared radiation source for gas detection, with a thin layer infrared radiator that is arranged in the interior chamber of a protective housing that includes a support surface for the thin layer infrared radiator and an exit window for the infrared radiation arranged at a distance opposite the support surface. The thin layer infrared radiator includes a platinum layer and at least one structurally defined de-gassing canal with an entry opening and an exit opening that leads from the interior chamber of the protective housing to the outside. For non-critical applications, the de-gassing canal is not sealed. For critical applications, it may be sealed by a sealing membrane that is water impermeable, water vapor permeable and open for gas diffusion, with the sealing membrane preferably being semi-permeable.

Abstract: An TDLS gas sensor with a measuring pick-up to be arranged outside of the interior chamber of an incubator or a climate chamber of similar design, and with an absorption pick-up to be arranged inside the interior chamber, and also with a window separating the measuring area and absorption area for the atmospheric separation of the laser diode from the interior chamber of the incubator, with the window being arranged at an angle to the axis of the laser beam emitted by a laser diode, and with the optronic components being arranged in a block of material in the measuring pick-up, said block being made of thermally well-conducting material and serving as heat sink, and with a heating system for the window in the measuring pick-up. In addition, a process for measuring the moisture and the carbon dioxide concentration.

Abstract: Process and measuring equipment for improving the signal resolution in gas absorption spectroscopy, wherein the measuring equipment includes a laser light source, a light detector and a measuring chamber arranged in between, and furthermore a light source control unit and a light detector evaluation unit. To improve the signal resolution, the noise intensity of the measuring equipment is reduced by averaging over time the interfering signal portions caused by back-reflections, etalons respectively self-mixing effects. This is accomplished by a light modulator arranged downstream the laser light source that continuously periodically influences the optical path length of the light beam. Thereto the light modulator includes an optical element with an adjustable refractory index that continuously cyclically alters the phase of the laser light of the light beam.

Abstract: This invention relates to a method that makes the measurement of a trace gas concentration invariant or at least less affected to pressure variations in the gas and atmospheric pressure changes. This method neither requires a pressure sensor nor a pressure calibration routine. Furthermore, the method can be applied to other gas species present in the background gas or to the background gas itself that cross-interfere with the target gas of interest. This allows removing any pressure dependency of cross-interference parameters of other gas species and/or the background gas. The new method for accurately measuring a gas concentration is based on optimizing the wavelength modulation amplitude of the laser to minimum pressure dependency.