×

Method and instrumentation for determining absorption and morphology of individual airborne particles

  • US 7,126,687 B2
  • Filed: 06/19/2003
  • Issued: 10/24/2006
  • Est. Priority Date: 08/09/1999
  • Status: Expired due to Fees
First Claim
Patent Images

1. An apparatus for determining absorption and shape characteristics of individual airborne particles comprising:

  • an aerosol concentrator to draw air containing particles of interest and deliver a significant fraction of the desired particles in an outlet flow to a nozzle;

    a nozzle, coupled to said aerosol concentrator, producing an aerodynamically focused aerosol jet, thereby providing a second stage of aerosol concentration, in a particle sample volume;

    a first trigger laser emitting a beam of wavelength λ

    1 and focused in a trigger region through which particles flow on their way to a detection region;

    a second trigger laser emitting a beam of wavelength λ

    2 aimed in a direction approximately orthogonal to the direction of the first trigger laser and focused in the trigger region, the trigger region being defined by the intersection of the beams of the first and second trigger lasers;

    a first wavelength-selective photodetector sensitive to light scattered from the individual airborne particles in the trigger region and emitting a first output signal in response to light of wavelength λ

    1;

    a second wavelength-selective photodetector sensitive to light scattered from particles in the trigger region and emitting a second output signal in response to light of wavelength λ

    2;

    at least one probe laser configured to emit a pulse of light focused on the particle sample volume, the particle sample volume being slightly downstream of the trigger volume, and triggered by the logically ANDed first and second output signals of the first and second wavelength-selective photodetectors, to emit the pulse of light;

    an ellipsoidal mirror, having a first and second focal plane, where the particle sample volume substantially coincides with the first focal plane, where the ellipsoidal mirror is deployed to collect and focus the light scattered by individual airborne particles;

    a multi-element detector for measuring the spatial distribution of light scattered by individual airborne particles;

    a spatial filter placed at the second focal point of the ellipsoidal mirror to block stray light from entering the multi-element detector;

    a means for transforming the measured spatial distribution of light scattered by individual airborne particles into an angular scattering of light scattered from the individual airborne particles; and

    a means of determining characteristics of light absorption and morphology of the individual airborne particles from the angular scattering of light.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×