Particle size detection device with noise cancellation

摘要

The detection device determines size from particle effected light scattering in a sensing region illuminated by a laser beam and receiving the particles in a medium, such as air. Background light from molecular scattering is reduced to a level that enables light scattered by particles having a size of about 0,1 micron to be sensed in a high background of molecular scattering such as for example, where molecular scattering can exceed the 0.1 micron particle's scattering by one hundred times. A linear array of detectors are positioned with respect to an imaging system, so that each detector monitors a different portion of the sensing region. An electrical output signal indicative of sensed particle presence within that portion monitored is provided. The output signals from the detectors are parallel processed. The output signals from detectors monitoring non-adjacent portion of the sensing region are combined at noise cancellation units.