INFRARED SPECTROMETER
First Claim
1. An infrared, IR, spectrometer comprising:
- a first tunable IR laser for providing a first beam at a first wavelength;
a second tunable IR laser for providing a second beam at a second wavelength;
a first absorption cell arranged to receive both first and second beams;
a second absorption cell arranged to receive both first and second beams;
a first optical absorption detector arranged to detect said first wavelength; and
a second optical absorption detector arranged to detect said second wavelength.
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Accused Products
Abstract
Method and apparatus for detecting, by absorption spectroscopy, an isotopic ratio of a sample, by passing first and second laser beams of different frequencies through the sample. Two IR absorption cells are used, a first containing a reference gas of known isotopic ratio and the second containing a sample of unknown isotopic ratio. An interlacer or reflective chopper may be used so that as the laser frequencies are scanned the absorption of the sample cell and the reference cell are detected alternately. This ensures that the apparatus is continuously calibrated and rejects the baseline noise when phase sensitive detection is used.
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Citations
42 Claims
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1. An infrared, IR, spectrometer comprising:
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a first tunable IR laser for providing a first beam at a first wavelength; a second tunable IR laser for providing a second beam at a second wavelength; a first absorption cell arranged to receive both first and second beams; a second absorption cell arranged to receive both first and second beams; a first optical absorption detector arranged to detect said first wavelength; and a second optical absorption detector arranged to detect said second wavelength. - 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)
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25. An infrared, IR, spectrometer comprising:
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a first tunable IR laser for providing a first beam at a first wavelength; a second tunable IR laser for providing a second beam at a second wavelength; a first absorption cell arranged to receive both first and second beams; a second absorption cell arranged to receive both first and second beams; a first optical absorption detector arranged to detect said first wavelength; a second optical absorption detector arranged to detect said second wavelength; and an interlacer arranged such that said first and said second absorption cells are alternately switched from receiving said first and said second beams.
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26. A method of isotopic ratio determination comprising the steps of:
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(a) passing a first tunable IR laser beam through a first absorption cell; (b) passing a second tunable IR laser beam through a second absorption cell; (c) detecting the absorption due to a first sample contained within said first cell; and (d) detecting the absorption due to a second sample contained within said second cell such that the isotopic ratio of said second sample is determined. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method of selecting a pair of isotopic spectroscopic lines for a sample suitable for use in isotopic ratio determination comprising the step of:
(a) selecting a pair of isotopic spectroscopic lines of similar intensities such that a suitable pair of isotopic spectroscopic lines is selected. - View Dependent Claims (37, 38, 39, 40)
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41. A method for detecting an isotopic ratio of a sample comprising the steps of
(a) passing a first laser beam and a second laser beam of different frequencies through a sample; - and
(b) detecting the optical absorption due to the sample such that a first absorption line and a second absorption line are measured.
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42. A method for detecting an isotopic ratio of a sample by measuring the relative intensities of at least one of the following pairs of absorption lines:
- 3601.4210 cm−
1/2294.4811 cm−
1, 3599.7027 cm−
1/2295.8456 cm−
1, and 3597.9626 cm−
1/2297.1862 cm−
1.
- 3601.4210 cm−
Specification