From: Bob Leif To: cyto-inbox Firstly, the compromise of employing a laser to both excite fluorescence and produce a very narrow beam for forward scatter is almost always skewed to enhance the measurement of fluorescence. Forward scatter really requires measurements within the forward lobe of the light scatter. This requires a laser beam with a very small divergence. Electronic cell volume is still the best way to measure cell volume. For non-spherical cells, The difference in vertical and horizontal light scattering can then be employed to determine the shape factor. "Apparatus and Method for Determination of Individual Red Blood Cell Shape" assigned to BeckmanCoulter, R. S. Frank, J. L. Wyatt, W. Gong, C. M. Rodriguez, and R. C. Leif. 5,798,827 (1998). -----Original Message----- From: David Lloyd [mailto:lloyddr@novell2.bham.ac.uk] Sent: Tuesday, August 03, 1999 5:58 AM To: cyto-inbox Subject: Very basic question Dear all Please excuse this very basic question, I would be very grateful for any wisdom you can give. It is generally accepted that "forward scatter = size" within certain limits; shape, refractive index etc. Does this knowledge come solely from the theoretical physics/optical properties of particles in laser beams, or is there any empirical evidence correlating fs with coulter volume (or any other size measurement)? I have looked for such evidence but have not been able to find any; perhaps it is further back in history than I can search. If anyone knows of any published empirical evidence I would be very grateful if you could share it with me. Thanks in advance David R Lloyd University of Birmingham England t; +44 (0)121 414 5264/7 e; D.R.Lloyd@bham.ac.uk http://www.bham.ac.uk/chemeng/actg/actghome
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