Interference Fringes for the Detection of Airborne Particles
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
An airborne particle detector is described in which the air is passed through a spatially non-uniformly illuminated region (such as an interference fringe field) and scattered light is detected. Improved sensitivity and S/N ratio are possible by properly matching the characteristics of the detection scheme to the characteristics of the non-uniform illumination. Low-defect production of microelectronics requires an environment that is virtually free of particulate contaminants. There is a great need for a good method of detecting and measuring this type of contamination. We describe here a new class of instruments for the detection of airborne particles. In these devices (Fig. 1) the stream of air to be tested passes through an illuminated region having an irradiance which varies with position in some prescribed way.