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Apparatus and method for the analysis of particle characteristics using monotonically scattered light

  • US 5,471,299 A
  • Filed: 07/29/1994
  • Issued: 11/28/1995
  • Est. Priority Date: 02/21/1992
  • Status: Expired due to Term
First Claim
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1. Apparatus for analysis of individual particle characteristics from an aerosol or other suspension of particles in a particle stream, said apparatus including:

  • a scattering chamber including an optical system having an ellipsoidal reflector with an orifice therein leading to a rear chamber;

    a monochromatic light source adapted to transmit a collimated beam of light along a main axis of the reflector;

    means for directing said particle stream in a stream of finite thickness containing said particles through the beam of light at substantially a main focus of the reflector;

    an optical system comprising a means for collecting scattered light from a solid angle of at least 3π

    around a region where the particle stream crosses the light beam;

    a detector having a two dimensional array of a multitude of sensors for forming an image from light scattered from a particle in the particle stream and collected by the optical system;

    and a data processor for comparing parameters of the image with parameters stored in a memory to determine a characteristic of the particle;

    the detector is associated with an imaging screen positioned behind a secondary focus of the reflector said optical system, said light source, and said means for directing, in combination, comprising a means for providing monotonically ordered scattered rays of light at said imaging screen such that, whatever part of the finite thickness of the particle stream occupied by the particle when it passes through the beam of light, rays of light scattered from the particle and imaged thereon by the optical system are monotonically ordered with respect to the angle of scattering of the rays from the particle so that the image recorded on the imaging screen is substantially independent of position of the particle in the particle stream.

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