Integrating sphere aerosol particle detector
AssigneePacific Scientific Company
InventorHolger T. Sommer
Life of this patent
Estimating the term…
Abstract
An integrating sphere for detecting particles in an aerosol has a diffuse reflectant interior surface and a plurality of photodetectors. The aerosol passing through aligned ducts which are spaced at the center of the integrating sphere, and a beam of collimated light, such as a laser beam, projects transversely through the aerosol in the space. Particles in the aerosol scatter the light, and the scattered light is detected simultaneously by the photodetectors within the integrating sphere. A coincidence detection circuit is used to detect the number of times scattered light is simultaneously detected by the photodetectors and, thereby, count the number of particles in the aerosol.
Claims10
Apparatus for detecting particles in a gas stream comprising:
- an integrating sphere having an interior surface;
- means for conducing the gas stream through said integrating sphere;
- means for projecting a collimated light beam transversely through said gas stream in said integrating sphere, whereby the particles in the gas stream scatter light from said light beam;
- means for detecting light scattered from said light beam within said integrating sphere, said light detecting means comprising a plurality of photodetectors mounted on said integrating sphere,
- and coincidence detection means for detecting the simultaneous light detection by at least two of said photodetectors.
An apparatus for detecting particles in a gas stream comprising:
- an integrating sphere having an interior surface,
- means for conducting a gas stream through said integrating sphere;
- a laser for directing a laser beam across said integrating sphere through said gas stream in said integrating sphere, said laser having a brewster window at one end thereof positioned on one side of said integrating sphere and a mirror on the opposite side of said integrating sphere positioned to reflect the laser beam back through said brewster window into said laser, said brewster window and said mirror defining an external cavity for said laser, and means for detecting light scattered by particles in said gas stream from said laser beam within said integrating sphere.
Dependencies are inferred from the claim text.