Method and an arrangement for initiating radiation absorption measurements of gaseous media
First Claim
1. An apparatus for analyzing a gas mixture for one or more gas components that may be present in the gas mixture, the analysis of the one or more gas components being carried out on the basis of radiation absorption properties, said apparatus comprising:
- a radiation source for providing a radiation beam;
a measuring chamber (6) for receiving a gas mixture, said measuring chamber having at least one radiation transmissive window (7a,7b) for the radiation of said radiation source, radiation from said radiation source passing through the gas mixture in said measuring chamber;
a first detector (1) for receiving radiation that has passed through said measuring chamber;
a first optical interference band pass filter (3) interposed in front of said detector along a path of said radiation beam, said first filter having a surface to which is applied radiation that has passed through said measuring chamber, said first filter having a radiation wavelength transmission band (λ
1) for transmitting radiation of the transmission band wavelength through the filter to said first detector, said surface reflecting radiation having wavelengths outside said radiation wavelength transmission band, said first filter being movable to a plurality of positions inclined with respect to the radiation beam for altering said radiation wavelength transmission band of said first filter, movement of said first filter causing movement of the radiation reflected from said surface; and
a second detector (2) positioned with respect to said first filter for receiving radiation reflected from said surface when said first filter is moved to a given one of said plurality of positions of said first filter.
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Accused Products
Abstract
The invention relates to an arrangement in an apparatus for analyzing, on the basis of radiation absorption properties, one or more gas component included in a gaseous medium from an origin, like exhaled air from a person. The apparatus comprises a radiation source (10); a measuring chamber (8) provided with radiation transmissive windows (7a, 7b) for receiving a gas mixture (6) from at least the gaseous medium (G1); a first detector (1), which receives the radiation passed through the gas mixture; and between the radiation source and the detector a first optical interference filter (3), which has a first radiation transmission wavelength band and which is tiltable (P) relative to the passing radiation (R) beam. The arrangement further comprises a second detector (2) directed towards a radiation input surface (5b) of the first interference filter, said second detector receiving momentarily a portion of said radiation (R) as reflected from said radiation input surface (5b) of the first interference filter (3) during the tilt (P) movement.
16 Citations
41 Claims
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1. An apparatus for analyzing a gas mixture for one or more gas components that may be present in the gas mixture, the analysis of the one or more gas components being carried out on the basis of radiation absorption properties, said apparatus comprising:
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a radiation source for providing a radiation beam;
a measuring chamber (6) for receiving a gas mixture, said measuring chamber having at least one radiation transmissive window (7a,7b) for the radiation of said radiation source, radiation from said radiation source passing through the gas mixture in said measuring chamber;
a first detector (1) for receiving radiation that has passed through said measuring chamber;
a first optical interference band pass filter (3) interposed in front of said detector along a path of said radiation beam, said first filter having a surface to which is applied radiation that has passed through said measuring chamber, said first filter having a radiation wavelength transmission band (λ
1) for transmitting radiation of the transmission band wavelength through the filter to said first detector, said surface reflecting radiation having wavelengths outside said radiation wavelength transmission band, said first filter being movable to a plurality of positions inclined with respect to the radiation beam for altering said radiation wavelength transmission band of said first filter, movement of said first filter causing movement of the radiation reflected from said surface; and
a second detector (2) positioned with respect to said first filter for receiving radiation reflected from said surface when said first filter is moved to a given one of said plurality of positions of said first filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 33, 34, 35, 36)
providing a sample of a calibrating gas mixture;
passing said radiation through the calibrating gas mixture; and
detecting an intensity of the radiation transmitted through the first filter and an intensity of the radiation reflected from the first filter at the given inclined position of the first filter.
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34. A method according to claim 33 further comprising the step of determining a first relationship between the transmitted radiation intensity and the reflected radiation intensity for the calibrating gas mixture sample.
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35. A method according to claim 34 further comprising the steps of:
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determining a second relationship between the transmitted radiation intensity and the reflected radiation intensity for the reference gas mixture sample;
comparing the second relationship with the first relationship to determine a characteristic of the reference gas mixture; and
controlling the carrying out of the steps of the method in accordance with the comparison of the first relationship and the second relationship.
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36. A method according to claim 35 further defined as one for analyzing the respiratory air, of a person for alcohol and as allowing measuring for a concentration of alcohol in the respiratory air of the person if the difference between the first relationship and the second relationship is smaller than a predetermined value.
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26. An apparatus for analyzing the breathing gases of a person for alcohol, the analysis being carried out on the basis of infra red radiation absorption properties, said apparatus comprising:
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a radiation source for providing an infra red radiation beam;
a measuring chamber (6) for selectively receiving the breathing gases of a person or ambient air, said measuring chamber having at least one radiation transmissive window (7a,7b) for the radiation of said radiation source, radiation from said radiation source passing through the contents of said measuring chamber;
a first detector (1) for receiving radiation that has passed through said measuring chamber;
a first optical interference band pass filter (3) interposed in front of said detector along a path of said radiation beam, said first filter having a surface to which is applied radiation that has passed through said measuring chamber, said first filter having a radiation wavelength transmission band (λ
1) for transmitting radiation of the transmission band wavelength through the filter to said first detector, said surface reflecting radiation having wavelengths outside said radiation wavelength transmission band, said first filter being movable to a plurality of positions inclined with respect to the radiation beam for altering said radiation wavelength transmission band of said first filter, movement of said first filter causing movement of the radiation reflected from said surface;
a second detector (2) positioned with respect to said first filter for receiving radiation reflected from said surface when said first filter is moved to a given one of said plurality of positions of said first filter;
means coupled to said first detector for analyzing the breathing gases for alcohol on the basis of radiation received by said first detector when said first filter is in a plurality of positions; and
comparison means coupled to said first and second detectors for establishing a relationship between the transmitted radiation received by said first detector and the reflected radiation received by said second detector at said given one of said plurality of positions of said first filter when ambient air is in said measuring chamber for determining the suitability of ambient air as a reference gas mixture.
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27. A method for analyzing a gas mixture for one or more gas components that may be present in the gas mixture, the analysis of the one or more gas components being carried out on the basis of radiation absorption properties, said method comprising steps of:
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providing a sample of a reference gas mixture;
passing a beam of radiation through the sample for absorption by the reference gas mixture;
applying the radiation passed through the reference gas mixture sample to a first optical interference bandpass filter, which has a first radiation wavelength transmission band;
placing the first filter in a given inclined position with respect to the beam of radiation;
allowing a portion of the radiation having wavelengths outside the first radiation wavelength transmission band to reflect from the first filter;
detecting an intensity of the radiation transmitted through the first filter and detecting an intensity of the radiation reflected from the first filter to determine a characteristic of the reference gas mixture;
providing a sample of the gas mixture to be analyzed;
passing the radiation through the gas mixture sample for absorption by the gas mixture to be analyzed;
applying the radiation passed through the gas mixture sample to be analyzed to the first filter;
moving the first filter to a plurality of inclined positions to provide wavelength shifting of the first radiation wavelength transmission band; and
detecting the intensity of the radiation passed through said gas mixture sample and transmitted through the first filter at the plurality of the inclined positions to analyze the one or more components of the gas mixture. - View Dependent Claims (28, 29, 30, 31, 32)
selecting the first radiation wavelength transmission band of the first filter so as to include an absorption peak of a gas mixture component which is to be analyzed; and
selecting the second radiation wavelength transmission band of the second optical interference filter deviating from the absorption peaks of the gas components to be analyzed.
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30. A method according to claim 29 further defined as one for analyzing the gas mixture for alcohol and wherein the first transmission band is selected to be in a range of 10 μ
- m and the second transmission band is selected to be in a range of 10.6 μ
m.
- m and the second transmission band is selected to be in a range of 10.6 μ
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31. A method according to claim 30 further defined as analyzing the respiratory air of a person for alcohol.
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32. A method according to claim 29 further defined as one for analyzing a gas mixture for alcohol and wherein the first transmission band is selected to be in a range of 3.5 μ
- m and the second transmission band is selected to be in a range of 3.7 μ
m.
- m and the second transmission band is selected to be in a range of 3.7 μ
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37. A method for analyzing a gas mixture for one or more gas components that may be present in the gas mixture, said process comprising the steps of:
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providing a sample of the gas mixture;
passing a beam of radiation through the sample for absorption by the gas mixture;
applying the radiation passed through the gas mixture sample to a radiation input surface of a first optical interference bandpass filter which has a first radiation wavelength transmission band;
moving the first filter to a plurality of positions that are inclined with respect to the beam of radiation to provide a wavelength shifting of the first radiation wavelength transmission band;
allowing a portion of the radiation having wavelengths outside the first radiation wavelength transmission band to reflect from the radiation input surface;
detecting an inclined position of the first filter for which specular reflection of said radiation to a second detector directed towards the radiation input surface of the first optical interference filter occurs; and
calculating, for the inclined position of the first filter, a center wavelength of the first radiation wavelength transmission band. - View Dependent Claims (38, 39, 40, 41)
providing a sample of a reference gas mixture;
passing said radiation through the reference gas sample;
detecting an intensity of the radiation transmitted through the first filter and an intensity of the radiation reflected from the first filter at least one of inclined position of the first filter; and
determining a first relationship between the transmitted radiation intensity and the reflected radiation intensity indicative of a characteristic of the reference gas mixture.
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40. A method according to claim 39, further comprising, prior to providing a sample of said reference gas mixture, the steps of:
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providing a sample of a calibrating gas mixture;
passing said radiation through the calibrating gas sample;
detecting an intensity of the radiation transmitted through the first filter and an intensity of the radiation reflected from the first filter at least one inclined position of the first filter; and
determining a second relationship between said transmitted radiation intensity and said reflected radiation intensity.
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41. A method according to claim 40, further comprising the steps of:
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comparing said first relationship and said second relationship; and
controlling the carrying out of the steps of the method in accordance with the comparison of the first relationship and the second relationship.
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Specification