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    4.
    发明专利
    未知

    公开(公告)号：NO901793L

    公开(公告)日：1990-11-02

    申请号：NO901793

    申请日：1990-04-24

    Applicant: ROSEMOUNT ANALYTICAL INC

    Inventor： RYAN FREDERICK MERK ,  GOTTLIEB MILTON S

    IPC: G01N21/27 ,  G01J3/26 ,  G01J3/28 ,  G01N21/35 ,  G01N21/61

    Abstract: A remote gas measuring apparatus and method utilizes the optical absorption line characteristics to determine an amount of gas of interest as may exist in an area under study. The remote gas measuring apparatus includes a source of electromagnetic radiation (12) that can be projected toward the area in question and a light collecting arrangement (14). The light signal received is coupled to a fast light switch modulator (10) which modulates the light signal to a first frequency. A second modulating arrangement (40) modulates the light signal to a second frequency and includes a birefringent etalon device (42) having a periodic spacing equal to the periodicity of the absorption lines of the gas of interest. The second modulating means is further effective such that, when an electric field (48) is applied thereto the transmission spectra associated with the light signal is shifted between spectra which coincide with the absorption lines and spectra which fall between the absorption lines. The light signal from the etalon device is then conditioned and input to a detector configuration (56) which distinguishes between the light signal at the first frequency and the light signal at the second frequency in order to determine at least a quantity of the gas of interest.

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