The diffraction method of measuring the diameters of erythrocytes

Abstract

Pijper (1, 2) has described a method of measuring the diameters of erythrocytes and similar circular bodies, by means of the diffraction spectra produced by them, under suitable conditions. The principle of the method is simple, and may be summed up as follows. A parallel beam of light is allowed to fall normally on the cell suspension and is then received, together with the light diffracted by the cells, by a lens. This lens converges the light and forms an image of the original light source at its principal focus. The diffracted light is also brought to a focus in the same plane as a series of circular spectra concentric with the central image of the source. The diameter of any given spectrum corresponding to a particular wave-length can be measured, and from this the mean diameter of all the cells producing the diffraction can be calculated.