Patent ID: 7972559

Claim:
A particle analyzing apparatus comprising: a capillary tube having a first end portion, a second opposite end portion, and a predetermined internal cross-sectional area, said first end portion being adapted to be suspended for immersion into a sample fluid containing particles to be analyzed; one or more holders for holding one or more sample fluids, said one or more holders being movable relative to the first end portion of the capillary tube; a source of light; an optical system configured to receive and focus the light from said source to form and direct a rectangular beam through the capillary tube to define an analyzing region in the capillary tube; a pump connected to the second end portion of the capillary tube, said pump being adapted to draw a volume of a sample fluid through the first end portion into the capillary tube and passing through said analyzing region; at least one first detector for detecting fluorescent light emitted by particles excited by said beam in said analyzing region; a valve coupled to the pump, the second end portion of the capillary tube and a waste dump, wherein when the valve is closed, the pump draws the sample fluid from the first end portion through said capillary tube, and when the valve is opened the pump discharges the fluid sample previously drawn through the capillary tube to the waste dump; wherein the pump is coupled to the waste dump via a conduct which has a diameter substantially greater than a diameter of the capillary tube.