Dual parameter flow photometric apparatus and method

Claim 1

Photometric apparatus for measuring scattering and fluorescence exhibited by appropriately stained biological cells in a solution in response to illumination thereof with high intensity light and for discriminating said fluorescence from spurious fluorescence in the solution carrying the cells, said apparatus comprising: means for producing a high intensity light beam; means for passing said cells through said beam to cause said cells to scatter light in said beam and to fluoresce in response to illumination from said beam, wherein the cells pass one by one through said beam and wherein said beam is focused on said cells as a spot having a diameter of from 40 Mu to 60 Mu ; means for detecting at least a portion of said scattered light and at least a portion of said fluoresced light and for producing simultaneous first and second electrical signals representative of said detected portions, wherein said detecting means comprises means for receiving said fluoresced light at approximately a 90* angle from the direction of said light beam and means for receiving said scattered light within a range of from about 0.6* to about 1.8* to the longitudinal axis of said light beam; and means for normalizing said signals and for comparing said signals to one another to produce an output signal representative of coincident portions of the signals.