The results of correction to microscopically determined particle sizes of, among others, the smallest of nearly monodispersed polystyrene latex particles (Latex A1) were reported, according to the optical diffraction correction theory, on the basis of the correction applicable to transparent ( phase) spherical particles (1, 2). Also, as an illustrative test example, the smallest observed particle diameters, shown in Table on page 211, were corrected, considering these as opaque (for the sake of comparison with the treatment for transparent phase particles), using the tabulations and graphs of Smith (3). The latter results were shown in parentheses Table (columns 4 and 9 in reduced units, and columns 5 and 10 in usual units) and also were plotted in Fig. on page 217.
In the oil-immersion optical microscope assembly used for photomicrography of the polystyrene latices, the degree of coherence of the illumination was calculated to be ρ = 0.40 (page 210), whereas the numerical calculations of the case treated by Smith (3) correspond to ρ = 1.0. Evidently, the figures shown in parentheses in Table , the histogram shown in Fig. , and the corresponding discussion on pages 216-217 require correction, because this discrepancy in ρ values was inadvertently overlooked. It is presumed that if the actual experimental value of ρ = 0.40 were used in the theoretical calculations (presuming that these were available, treating the particles as opaque), the image contrast would decrease somewhat, because ρ = 0.40 implies a more coherent illumination (4) than is the case for ρ = 1.0. Consequently, the corrected OM size would show somewhat more deviation with respect to the true TEM size. Pending detailed calculations, it is estimated that this deviation would be within 20% of the reported corrected OM size values.