Model examination of the crossover effect in two-layer light-sensitive system

The results of computer simulation of the effect of light scattering in a s ystem composed of two heterogenic light-sensitive layers coated on two side s of a transparent base are presented. It has been assumed that the modelle d system is irradiated with a directed X-ray beam, while the photographic e ffect is caused only by the light emitted by the fluorescent screens adjace nt to the light-sensitive layers and containing phosphors fluorescing due t o X-ray irradiation. The scattered light transpassing the base reaches the opposite light sensitive layer, thus damaging the sharpness of the details. This effect called crossover is disadvantageous in roentgenography. Qualit ative dependence of the modulation transfer function of the system on both its geometric and optical parameters was examined. It has been shown that w orsening of the image is the stronger the thinner the light-sensitive layer s and the weaker the light scattering by single silver halide crystals. Thi s result is surprising since in the case of single-layer light-sensitive sy stems not suffering from the crossover effect opposite effects are observed .