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Liquid level gauge comparing moldulations of incident and reflected loser beams

  • US 5,194,747 A
  • Filed: 10/21/1991
  • Issued: 03/16/1993
  • Est. Priority Date: 10/21/1991
  • Status: Expired due to Fees
First Claim
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1. Apparatus for measuring the level of a light-reflective fluid boundary in a vessel relative to a reference level, wherein the vessel has an aperture in the top thereof, said apparatus comprising:

  • an optical unit mountable in the top of the vessel at the reference level;

    a control unit remote from said optical unit; and

    transmission means interconnecting said control unit and said optical unit;

    said control unit including modulation means for generating an output signal containing incident modulation information, said modulation means being coupled to said transmission means for applying said output signal to said optical unit;

    said optical unit including a housing having a window therein, and means fixedly securing said housing to the top of the vessel with said window in alignment with the aperture;

    said optical unit further including transmitter means disposed in said housing and coupled to said transmission means and responsive to said output signal for directing to the fluid boundary an incident light beam containing said incident modulation information, and receiver means disposed in said housing for receiving from the fluid boundary reflections of said incident beam and producing an input signal containing reflected modulation information, said receiver means being coupled to said transmission means for applying said input signal to said control unit;

    said control unit including processing means coupled to said transmission means and to said modulation means for comparing the incident modulation information to the reflected modulation information to produce a level signal indicative of the distance between the reference level and the fluid boundary.

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