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The electronic form of this document may be cited in the following style:
Human Genome Program, U.S. Department of Energy, DOE Human Genome Program Contractor-Grantee Workshop IV, 1994.

Abstracts scanned from text submitted for November 1994 DOE Human Genome Program Contractor-Grantee Workshop. Inaccuracies have not been corrected.

New Method For The Detection Of Right-Angle-Scattered Light In Flow Cytometry

Raymond Mariella Jr., D. Masquelier, Gerald Eveleth, and Richard Langlois
Human Genome Center, L-452, Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, California 94550.

We report a new physical configuration for the detection of right-angle-scattered (RAS) light in Flow Cytometry which greatly increases the signal-to-noise ratio, narrows the coefficient of variation for uniformly-sized latex spheres, and greatly eases the alignment requirements, too. The new technique views the scattered light which is trapped within the optical waveguide of the flow stream in air.

In previous Flow Cytometers, the RAS light has been viewed perpendicularly to the liquid flow, typically using a high-numerical-aperture (NA) microscope objective lens or fiber optic. Some of the difficulties associated with this approach are the very limited depth of field of high-NA optics, and the necessity to align precisely the exact focal point of the lens with the point where the excitation light source intersects the sample flow stream. Our invention uses the unconfined aqueous flow stream itself as a 0.75-NA optical waveguide. There is no "focal point" for this configuration. Alignment simply requires aligning the light source onto the flow stream; the liquid optical waveguide is then automatically "aligned". For the collection of elastically-scattered light, another advantage occurs: the background level of scattered light is extremely low when using the flow-stream waveguide (FSW), because the same physical properties which confine the desired light within the stream also keep random scattered light out, no obscuration bar is needed for the collection of RAS light.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract no.W-7405-ENG-48.