ON THE APPARENT RESPONSE OF PHOTOGRAPHIC-EMULSIONS ACCORDING TO LEAST-SQUARES DETERMINATIONS OF THE BLACKNESS CORRECTION FROM GAS ELECTRON-DIFFRACTION DATA

The single-hit assumption for the response of a photographic emulsion to electrons leads to a simple relationship between the exposure and the measured optical densities with the saturation density of the emulsion as the only parameter. With the inverse of this saturation density as a least-squares variable of the corresponding multiplicative 'blackness correction', this correction has been determined from data sets of gas electron diffraction plates of different exposures. For optical densities from our standard photometer procedure, the computed values of the saturation density are smaller than the real values for the plates used. The computed values increase with increasing optical density of the darkest plate applied and increase by reducing the amount of light scattered by the silver grains of the emulsion. Computer simulations indicate that relatively small changes in the direction of the specular optical densities would be necessary to obtain the agreement predicted by the single-hit assumption between the computed and the real saturation density. A good blackness correction for our standard procedures is easily obtained by least-squares calculations when plates of relatively high optical densities are included in the applied data set.