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We have calculated the light intensity distribution behind ruled halftone screens of the type used in the graphic arts industry. The resulting formulas, which are derived from the theory of partial coherence, include diffraction effects at both the lens aperture and the screen. Their form is that of rapidly converging summations rather than expressions requiring numerical integrations for their evaluation. The method of solution is general in that it treats arbitrarily shaped lens apertures and both straightline and crossline screens with either conventional absorbing or transparent phase rulings. Theoretical predictions for the phase screen and a variety of circular apertures, wavelengths, and screen spacings agree very well with the experimentally measured intensity patterns.

The photographic characteristics of photoactive pigment electrographic imaging systems are investigated by analysis of two model configurations. The results establish which physical parameters control the photographic characteristics. An analysis of electrophoretic display devices is also presented. The models give estimates for the ultimate performance of these systems and make it possible to correlate photographic measurements with related physical phenomena.

The optical properties of an electrophotographic film comprised of closely packed submicron selenium spheres embedded in a polymer matrix were investigated. In one case the spheres were arranged in a monolayer; in a second the particles were dispersed throughout the polymer matrix. The optical transmission of these structures was measured as a function of wavelength and particle size and compared with physical models based on Mie theory.