Patent ID: 7847700

Claim:
A system for detecting particles in air, the system including: a light generator producing a collimated beam of light; a lens spreading said collimated beam of light; a sensing chamber, wherein said light generator and said lens are positioned on the periphery of said sensing chamber and spread said collimated beam of light to form a substantially planar beam of light to substantially fill a prescribed area of the interior of said sensing chamber; a light trap positioned in the interior of said sensing chamber, wherein said spread beam of light is received into said light trap and extinguished, wherein said light trap extends angularly around a substantial portion of the interior of said sensing chamber, wherein said light trap receives light that has been angularly diverted by said lens to an angle other than that described by said collimated beam of light; and a photon sensor placed within said sensing chamber to detect light scattered or reflected from airborne particles entering said chamber.