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Method and arrangement for measuring the optical absorptions of gaseous mixtures

  • US 4,998,017 A
  • Filed: 05/01/1989
  • Issued: 03/05/1991
  • Est. Priority Date: 05/01/1989
  • Status: Expired
First Claim
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1. An arrangement for measuring a gas of interest by its optical absorption characteristics, comprising:

  • a source of electromagnetic radiation;

    means for conditioning such electromagnetic radiation such that it passes through such gas of interest;

    means for electrically modulating such electromagnetic radiation that has passed through such gas of interest, said modulating means including a birefringent etalon having associated therewith, a periodic spacing equal to the periodicity of the absorption lines associated with such gas of interest;

    said modulating means being further effective for varying an electrical field applied to said birefringent etalon between first and second predetermined strengths such that the periodic transmission spectrum is shifted between spectra which coincide substantially with such absorption lines and spectra which fall between such absorption lines; and

    means for detecting at least the intensity of such periodic transmission spectra following passage through such gas of interest and determining therefrom at least an amount of such gas of interest present.

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