Abstract: An apparatus comprising a compact, folded path cell for optical gas detection and/or measurement utilising gas absorption spectroscopy. The apparatus includes a source of electromagnetic radiation, a gas sample cell containing reflective elements, and a detector of electromagnetic radiation. The source and detector are arranged between the reflective elements in an arrangement that reflects the radiation away from the source and detector until the reflected radiation has an adequate optical path length, and then reflects the radiation towards the detector. A spectroscopic analysis can be used to determine the presence and/or to measure at least one parameter of at least one gas species within a gas sample.

Abstract: An apparatus for optical gas detection and/or measurement in an absorption spectroscopy system comprising: a gas cell for containing a gas sample or calibration gas with at least one gas exchange port and at least one optical element for allowing transmission of electromagnetic radiation of a desired wavelength range in and out of the gas cell; and at least one source of converging, diverging or collimated electromagnetic radiation for transmitting electromagnetic radiation through a gas sample contained within the gas cell and towards at least one detector; said detector to monitor absorption of electromagnetic radiation for at least one absorption wavelength or wavelength range associated with at least one gas species, by detecting transmitted electromagnetic radiation that is not absorbed; at least one analyser for analysing an output signal from the at least one detector to measure a parameter of at least one gas species within the gas sample, characterised in that at least one dead volume within the spec

Abstract: An apparatus for use in absorption spectroscopy, comprising: at least one source of electromagnetic radiation for transmitting electromagnetic radiation along an optical path that passes through a gas measurement volume, towards at least one detector; at least one detector to detect the transmitted electromagnetic radiation after passing through the gas measurement volume and to provide an output signal indicative of the detected electromagnetic radiation; and an analyser connected to the at least one detector to receive the output signal and analyse the effects of absorption by at least one gas species within the gas measurement volume for at least one wavelength range of the transmitted electromagnetic radiation, thereby to detect or measure a parameter of the at least one gas species; wherein at least one source or detector comprises a Chip-on-Board (COB) component comprising a solid-state source and/or detector of electromagnetic radiation mounted onto a substrate in a COB configuration.

Abstract: Methods and apparatus for determination of the gas composition of a sample gas using glow discharge optical emission spectroscopy, in which the method comprises: generating one or more oscillating electromagnetic fields within a plasma cell to excite particles within the cell, to produce a glow discharge plasma in the plasma cell, and controlling the operating conditions for the plasma cell while flowing a gas mixture through the plasma cell to maintain glow discharge optical emissions from the plasma within a desired operating range; and monitoring one or more glow discharge optical emissions from the plasma in the plasma cell by measuring the optical emissions, or measuring a signal that correlates with the optical emissions, at twice the plasma excitation frequency; and processing the signal during each excitation cycle of the electromagnetic excitation, to determine the concentration of a gas within a gas mixture flowing through the plasma cell.

Abstract: A method and system for the suppression and/or modulation of absorption spectrum artifacts for the purpose of gas detection and concentration measurements using at least one magnetic, electric or electromagnetic field. A field applied selectively to at least one section of the system modulates absorption by influencing quantum energy state transitions of gas species.

Abstract: Provided are methods, apparatuses and systems for enhanced determination of the gas composition of a sample gas using glow discharge optical emission spectroscopy (GD-OES) for gas analysis.

Abstract: Provided are methods, apparatus and systems for stabilization of a glow discharge from a plasma. Also provided are methods, apparatus and systems for processing optical signals from a stabilised glow plasma with enhanced signal to noise recovery. A first method comprises: generating an electric field within a plasma cell using an alternating excitation voltage to excite particles within the cell, to produce a glow discharge from a plasma in the plasma cell in a resonant condition; monitoring, in each excitation cycle of the alternating excitation voltage, one or more signals that correlate with glow discharge optical emissions from the plasma in the plasma cell; and, in response to said monitoring, controlling one or more operating conditions for the plasma cell to maintain the glow discharge emissions from the plasma within a desired operating range in each excitation cycle of the alternating excitation voltage.

Abstract: A method and system for reducing the effect of distortions on the baseline signal in an absorption spectroscopy system used for the detection or measurement of chemical species in a medium, whereby one or more correlations or convolutions are performed on the signal using a kernel function. The shape of the kernel function is chosen to reduce the influence of the baseline distortions on the processed measurand determination. The kernel function may also be chosen to enhance the absorption signal.

Abstract: A method and system for reducing the effect of distortions on the baseline signal in an absorption spectroscopy system used for the detection or measurement of chemical species in a medium, whereby one or more correlations or convolutions are performed on the signal using a kernel function. The shape of the kernel function is chosen to reduce the influence of the baseline distortions on the processed measurand determination. The kernel function may also be chosen to enhance the absorption signal.

Abstract: A method and system for correcting the effect of intensity fluctuations of the transmitted light in an absorption spectroscopy system used for the detection or measurement of chemical species in a medium, whereby one or more modulation bursts are imposed onto a light beam that passes through the medium. This burst signal may be obtained by modulating the bias current of a tunable diode laser, and the modulation burst signal may be optimally at the second harmonic of the modulation frequency of a wavelength modulated beam to allow usage of the same signal path processing used for the spectroscopic detection of the measurand for a second harmonic detection system.

Abstract: A method and system for correcting the effect of intensity fluctuations of the transmitted light in an absorption spectroscopy system used for the detection or measurement of chemical species in a medium, whereby one or more modulation bursts are imposed onto a light beam that passes through the medium. This burst signal may be obtained by modulating the bias current of a tunable diode laser, and the modulation burst signal may be optimally at the second harmonic of the modulation frequency of a wavelength modulated beam to allow usage of the same signal path processing used for the spectroscopic detection of the measurand for a second harmonic detection system.

Abstract: Provided is a compact apparatus for measuring the flow rate of a fluid. The apparatus includes a heated measure element and a heated reference element which are in substantially the same thermal environment within a measure cell, except that the measure element is situated in the path of the cooling fluid flow and the reference element is sheltered from this direct fluid flow. These elements are arranged as parallel and concentric planar elements that are essentially identical to each other with matching thermal characteristics. The elements are electrically connected in a Wheatstone bridge arrangement. Thermal exchange between the reference and measure elements is used to optimise noise rejection due to common mode background thermal effects. Measured parameters from the bridge can be used to derive the fluid flow rate.

Abstract: Provided is a compact apparatus for measuring the flow rate of a fluid. The apparatus includes a heated measure element and a heated reference element which are in substantially the same thermal environment within a measure cell, except that the measure element is situated in the path of the cooling fluid flow and the reference element is sheltered from this direct fluid flow. These elements are arranged as parallel and concentric planar elements that are essentially identical to each other with matching thermal characteristics. The elements are electrically connected in a Wheatstone bridge arrangement. Thermal exchange between the reference and measure elements is used to optimise noise rejection due to common mode background thermal effects. Measured parameters from the bridge can be used to derive the fluid flow rate.

Abstract: A sensor for determining the thermal conductivity of a fluid comprising a sensing module located within a housing having inlet and outlet ports for a fluid under test, the sensing module comprising a reference base surface and a sensing element spaced therefrom and having measure and reference sections, and there being provided electrical power monitoring means for monitoring the power through the measure and reference sections in order to generate a signal indicative of the power difference due to thermal conductivity through the fluid. The sensing element is a thick film printed disc with measure and reference resistors printed on it. All changes in the fluid are common to both the measure and reference sections except for the thermal conductivity of the fluid itself.

Abstract: A sensor for determining the thermal conductivity of a fluid comprising a sensing module located within a housing having inlet and outlet ports for a fluid under test, the sensing module comprising a reference base surface and a sensing element spaced therefrom and having measure and reference sections, and there being provided electrical power monitoring means for monitoring the power through the measure and reference sections in order to generate a signal indicative of the power difference due to thermal conductivity through the fluid. The sensing element is a thick film printed disc with measure and reference resistors printed on it. All changes in the fluid are common to both the measure and reference sections except for the thermal conductivity of the fluid itself.