EMOSS: an epiillumination microscope objective slit-scan flow system.

An epiillumination microscope objective slit-scan flow system has been fabricated utilizing two dimensional slit scanning with hydrodynamic sample stream focussing. Low resolution (4 micron) analysis of cellular fluorescence is facilitated by the definition of a stabilized flow plane through hydrodynamic focussing. Coincidence of the region of stabilized flow with the focal plane of the microscope objective will allow for the collection and subsequent imaging of fluorescence from cells oriented along this plane. Two orthogonal slit-scan contours are generated as a cell traverses the excitation region. It is hoped that the need for a three dimensional system will be precluded by preferential orientation of the cells in the region of stabilized flow. Cellular fluorescence is collected by a high numerical aperture epiillumination optical system and imaged onto two orthogonal slits. Two photomultiplier tubes are used to detect fluorescence. It is anticipated that the epiillumination microscope objective slit-scan flow system will be used with a variety of fluorescent stains and markers, as well as extended to the research of light scattered by cells. (Steen, H.B., Cytometry 1:26-31, 1980.