| 摘要 |
Particles in a fluid sample are passed into a flow chamber 12, which has an inlet 20 and an outlet 22 and a passageway 24 having a cross-sectional area which may decrease substantially as the passageway extends from the inlet to a constriction 21, the cross-sectional area thereafter increasing from the constriction 21 to an imaging area 14. The thickness of the passage 24 in a direction which is parallel to the direction in which a microscope 16 is directed, may decrease substantially from the inlet 20 to the constriction 21. From the constriction 21, however, the thickness remains a constant T. The fluid sample is introduced into the flow chamber 12 at a distance L sufficiently far away from the imaging area 14 to be flowing in a laminar stream having a constant velocity profile at the imaging area 14. The working distance Wd of the microscope lens 30 is greater than one-half the outer thickness D of the flow chamber 12 at the imaging area 14. The focal depth Fd of the lens 30 is much less than the thickness D. The flow rates of the fluid sample and the sheath fluid are such that the fluid sample has a thickness t at the imaging area 14 which is less than or comparable to the focal depth Fd of the lens 30. <IMAGE> |
