The automatic counting of red blood cells
E.H. Cooke-Yarborough, R E Whyard · British Journal of Applied Physics · 1954
The paper considers automatic blood cell counting apparatus in which the cells are scanned by mechanical oscillation of a microscope stage. It is shown how errors can arise from various sources and how these errors may be minimized by use of suitable electronic circuits, by careful choice of parameters and by adopting a novel shape of scanning aperture. Counting apparatus whose design follows these principles is described and the results are given of many experiments using this apparatus. These show that consistent results are obtainable which are largely independent of variations in light intensity, focus, cell size, amplifier and photocell sensitivity and of other variations likely to be encountered in practice.