Patent ID: 7738099

Claim:
A particular detector system, comprising: a sampling area; a light source on one side of the sampling area for sending a substantially collimated beam of light through the sampling area; a beam blocking device on an opposite side of the sampling area having a non-transmissive region for blocking at least a portion of unscattered light emerging from the sampling area; a first optical detector positioned in the light path after the beam blocking device positioned to receive and detect a portion of forward scattered light scattered at various angles by particles of various sizes presence in the sampling area, and producing an output including information on a number and sizes of said particles; a second optical detector on the light source side of the sampling area positioned to receive and detect a portion of backward scattered light, and producing an output including information on a number of and fluorescence from said particles; and a first wavelength selective device positioned between the light source and the sampling area wherein backward scattered light emerging from within the sampling area is further directed by the first wavelength selective device to be received by the second optical detector.