Relationships Between Sensitometric and Optical Properties of Photographic Emulsion Layers with Particular Reference to the Wave-Length Variation of Sensitivity^*

* Communication No, 2029H from the Kodak Research Laboratories.

Abstract

The influence of light scatter within an emulsion layer on its speed in terms of incident exposure, and of the diminution of intensity through the layer on H. and D. curve shape are discussed. The various considerations are combined in an expression for the wave-length variation of sensitivity of a non-optically sensitized emulsion. There are three wave-length dependent terms in the expression:

(a) The grain absorption factor, which is directly proportional to the product of the absorption coefficient, k, of the silver halide and the thickness of the grain, if the product is small.

(b) The factor by which intensity is increased in the top single-grain-layer of the multilayer owing to scatter. This is $$\{1+\frac{R\left(1+r\right)}{\left(1-r\right)}\}$$ where is the external reflection factor of the emulsion, and r the internal reflection factor for diffuse radiation.

(c) The exposure wastage due to self-absorption in the multilayer. For production of half-saturation density this factor is lO_∆12, where ∆ is the unexposed emulsion density.

Following the same principles the wave-length variation of sensitometric characteristics of an emulsion coating in the optically sensitized region can be deduced, given the wave-length variation in shape and location against the incident exposure axis of the H. and D. curve of a single-grain-layer of the emulsion.

The validity of the separate terms, and hence of the theory as a whole, is demonstrated by published data or the results of experiments specially devised and carried out for this purpose.

Notes

* Communication No, 2029H from the Kodak Research Laboratories.