Siemens Aktiengesellschaft

Airoptic Sp. Z O.o.

Pawel Kluczynski

Stefan Lundqvist

Rikard Larking

Per-Arne Thorsén

Jan Nygren

Tomas E Lock

Jack Margolis

A light beam generated by a light source having a wavelength corresponding to the ethanol absorption spectrum, preferably in the wavelength range of 3.28-3.52 &#x3bc;m or in one or more wavelength ranges 6.49-7.46 &#x3bc;m, 7.74-8.33 &#x3bc;m, 8.84-10.10 &#x3bc;m, 10.7-12.00 &#x3bc;m, is sent through a measuring space containing a sample of exhaled breath, and then the intensity of the light beam passing through the measuring space is measured. Based on the spectral analysis of the dependence of the light intensity to the alcohol concentration, the concentration of ethanol vapor is determined and the information about the level of the ethanol content is provided to a suitable display or device.

Method and apparatus for remote detection of alcohol vapor in the atmosphere

A method for reducing fringe interference of light created in a passive cavity defined by partially reflecting optical surfaces in a laser spectroscopy system, wherein the optical path length of the cavity is varied with a triangular back-and-forth movement (x). In accordance with the invention, the spectroscopic measurement is performed in successive measurement cycles with a time interval between each two successive measurement cycles, the triangular movement is performed such that the turning points of the triangular movement (x) are positioned in successive ones of the time intervals, and after each or at each n-th measurement cycle, the time position of the turning points is moved relative to the measurement cycle.

Method for reducing interference fringes by moving timing of triangular motion

An apparatus for reducing fringe interference of light created in the optical system of a laser spectroscopy system comprising an electromagnetic actuator for generating, along a laser path, physical translational vibration of an optical element of the optical system and a control device for controlling the amplitude and frequency of said vibration. The optical element is arranged on a cantilever body which is, at one end, attached to a base by a flexural pivot and, at the other free end, coupled to the electromagnetic actuator, and the control device includes a controller that controls the amplitude of the vibration and a vibration sensor attached to the cantilever body and providing the actual vibration value to the controller to improve fringe interference reduction, especially with longer wavelengths.

Apparatus for reducing fringe interference of light created in an optical system of a laser spectroscopy system

A method and system for measuring the concentration of a gas component in a measuring gas a provided. The wavelength of a light source is modulated with a modulation signal at a modulation frequency, while the wavelength is swept over an interaction feature of a sample. The intensity of the light source is further modulated at a wavelength outside the interaction feature with a burst signal, where an N-th harmonic of the burst frequency coincides with an M-th harmonic of the modulation frequency. The light is passed to the sample and thereafter to a detector. The detector output is demodulated at the M-th harmonic, and the demodulated detector output is normalized by calculating the ratio between a demodulated detector output portion derived from the light modulated with the modulation signal and another demodulated detector output portion derived from the light modulated with the burst signal.

Wavelength modulation spectroscopy method and system

There is described a method for measuring a concentration of a gas component in a measuring gas, wherein the light of a wavelength tunable light source is passed along a single optical path through a measuring volume containing the measuring gas and a reference cell containing a reference gas to a detector. The reference cell is selected to contain a selected isotope of the gas component to be measured in a known abundance ratio higher than the known natural-abundance isotope ratio of the gas component in the measuring volume; the light source is tuned to sweep the wavelength of the light over the absorption lines of the selected isotope and the remaining gas component; and the concentration of the gas component in the measuring volume is calculated from the ratio of the detector signals at the peaks of the absorption lines, based on Lambert's law and taking into account the known abundance isotope ratios.

Method for measuring the concentration of a gas component in a measuring gas

A method for reducing fringe interference of light created in a passive cavity defined by partially reflecting optical surfaces, wherein the optical path length of the cavity is varied with a Gaussian distribution, where the standard deviation is at least one-quarter of the light's wavelength.

Method and apparatus for reducing fringe interference of light

In spectroscopic devices the sections of an optical measuring path from a light source to a measuring volume containing a measuring gas and from there to a measuring detector are often sealed off from the ambient atmosphere and purged with a purge gas such as dry nitrogen to prevent penetration of atmospheric gas components, such as water vapor, which may interfere with the trace gas measurement. The moisture content in the nitrogen supply is usually in the range of a few ppm at the gas source and can increase dramatically at the measuring site depending on the length of the nitrogen pipe net and due to porosity of the pipe walls, leakage of seals and residual moisture trapped in so-called dead legs. In order to compensate interfering absorption of atmospheric gas components and other impurities in the purge gas the purge gas is collected after flushing the optical path sections, a portion of the light of the light source is transmitted along a second optical path to a compensation detector, the second optical path is flushed with the collected purge gas and the trace gas component in the measuring gas is determined based on a difference between the output of the measuring detector and the output of the compensation detector.

Method and apparatus for trace gas detection

A wavelength modulation spectroscopy method for measuring the concentration of a gas component is provided. A gas sample portion of the light is passed through a reference gas comprising the gas component in a constant concentration. Afterwards, the light is detected by a reference detector. Another portion of the light is passed through the gas sample and thereafter to a measuring detector. The light emitted by the light source is modulated with a frequency, while the wavelength is swept over a molecular absorption line of the gas component. Demodulation of the detector outputs is made at a higher harmonic. In order to compensate for variations of the modulation parameters of the light source in real time, a mathematical description of the demodulated reference detector output based on Fourier analysis of the modulated light and on a mathematical expression for the absorption line is provided.

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Västra Frölunda, Sweden

Pawel Kluczynski