Patent ID: 7578973

Claim:
A device comprising: an impaction plate, a planar collection surface on the impaction plate, a spotting nozzle for directing an air stream towards the collection surface, the air stream passing through the spotting nozzle before impacting on the surface to form a spot of airborne particles on the collection surface, an analyzer configured to analyze the particles while the particles are retained on the collection surface and the impaction plate remains in the device, the analyzer comprising an optical detector that can analyze the particles as they remain on the collection surface, a surface regenerator for regenerating the collection surface such that particles collected before regenerating the collection surface are removed from the collection surface, and thus are substantially no longer present to contaminate a spot of particles collected after regenerating the collection surface, and a homing sensor, wherein the homing sensor is a mechanical structure configured to cyclically and automatically move the collection surface relative to the nozzle, the analyzer, and the surface regenerator, movement of the collection surface being controlled such that in each successive cycle a first portion of the collection surface will initially be adjacent to the nozzle, then adjacent to the analyzer, then adjacent to the surface regenerator, and then adjacent to the nozzle once again in a subsequent cycle, such that the analyzer and the surface regenerator are disposed proximate to the impaction plate during operation of the device.