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Asymmetric purge air system for cleaning a lens

  • US 4,836,689 A
  • Filed: 09/04/1987
  • Issued: 06/06/1989
  • Est. Priority Date: 02/27/1986
  • Status: Expired due to Fees
First Claim
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1. An instrument for sensing radiation representative of a parameter in a particle suspension and for providing an output indicative of the parameter, the instrument receiving a supply of pressurized fluid, comprising:

  • port means disposed on the instrument and opening to the parameter source for receiving the radiation;

    sensing means coupled to the port means for sensing the received radiation and for providing the output;

    window means disposed between the port means and the sensing means for transmitting the radiation therethrough and for shielding the sensing means from the particle suspension, the window means having a window surface with a central axis normal to the window surface, for transmitting radiation to the sensing means exposed to the suspension; and

    purge means disposed in the instrument for receiving the pressurized fluid and having openings arranged around the circumference of the window surface for directing flows of the pressurized fluid having an axially asymmetric flow pattern onto the window surface, generating an unstable flow pattern of the pressurized fluid on the window surface such that particles are removed from substantially all of the window surface.

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