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Photo-electric particle sensing system

  • US 4,422,761 A
  • Filed: 09/28/1981
  • Issued: 12/27/1983
  • Est. Priority Date: 09/28/1981
  • Status: Expired due to Fees
First Claim
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1. A photoelectric system for sensing light deflected from its direction of propagation by small particles in a fluid comprising a source of light, a photosensor having a light sensitive surface, two spaced light concentration zones and an inspection zone, means for directing the fluid to the inspection zone, a first of the said light concentration zones receiving light from the source of light, the said inspection zone being created by providing a first light concentrating reflecting surface so designed and arranged that it concentrates light from said first of the light concentration zones into the inspection zone and a second light concentrating reflecting surface so designed and arranged that it concentrates light deflected by particles at the inspection zone from the inspection zone toward a second of the light concentration zones, the said light sensitive surface being so placed that it intercepts light concentrated by the said second light concentrating reflecting surface toward the second of the light concentration zones, one of the said reflecting surfaces being located wholly outside a full cone having its apex at the inspection zone and the other of the said reflecting surfaces being located wholly inside the said full cone, the first light concentrating reflecting surface being of annular shape, whereby the space traversed by rays that the annular reflecting surface can reflect from one of the zones associated therewith to the other of the zones associated therewith encloses a free space not traversed by these rays and the second light concentrating reflecting surface is positioned between the two zones associated with the annular reflecting surface inside the said free space.

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