Patent ID: 7053783

Claim:
A pathogen detector system, comprising: an outer housing having a sample area for containing environmental air; a light source on one side of the sample area for directing a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered; a beam blocking device on the opposite side of the sample area for blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light along a light path; a first photodetector positioned in the light path after the beam blocking device for detecting light directed by the beam blocking device onto the detector, and producing an output spectrum representing scattering intensity in which the size of each peak is proportional to particle size; a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light paths and a second photodetector positioned to detect light reflected from the reflector; a differential element responsive to said first and second photodetectors to provide a pulse signal having a scattering peak intensity; a pulse height discriminator using the scattering peak intensity to characterize particle size, such that the size distribution of airborne particles detected in the air sample at a given time is obtained; and an alarm unit connected to the pulse height discriminator for providing a warning signal if the number of particles within a predetermined pathogen size range of approximately 1 to 7 μm exceeds a predetermined normal level.