Optical apparatus and method for sensing particulates
OwnerHermann E. Gerberinventor
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Abstract
The present invention relates to an apparatus and method of determining particulate integrated properties consisting of integrated volume concentration, integrated surface area concentration and aerosol extinction coefficient in the infrared portion of the light spectrum using a noncollimated light beam irradiating suspended particulates. A light trap is placed in front of the lens that collects the light scattered by the particulates. Two separate detectors are placed differently with respect to the noncollimated beam to measure the light scattered by the particulates. Variable transmission filters are placed in front of the detectors to correct for the distortions in the light scattered by the particulates due to the off-axis intensity of the noncollimated beam.
Claims7
A method for measuring integrated properties of suspended particulates consisting of the following steps:
- Irradiating particulates suspended in a noncollimated light beam with the light beam, measuring with a detector the light scattered by the particulates over a time interval sufficiently long that many particles contribute to the scattered light, correcting the distortion of the scattered light due to off-axis light intensity of the noncollimated beam by placing an inversion spatial filter in front of the scattered-light detector and at the focal point of the detector lens used for collecting light scattered from the particulates.
Apparatus for measuring integrated properties of suspended particulates consisting of the following parts:
- Light source coaxial with converging light beam falling into a light trap placed in front of the detector lens for collecting light scattered by the particulates, with inversion spatial filter located at the focal point of the detector lens, and with detector placed adjacent to the inversion spatial filter, the light trap, detector lens, spatial filter, and detector forming the first detector assembly wherein the particulates located in and irradiated by the convergent light beam scatter light into the first detector assembly, where the inversion filter corrects the distortion in the scattered light due to the off-axis light beam intensity, to yield directly particulate integrated properties as the detector output.
Dependencies are inferred from the claim text.