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3 Optica Applicata

3 2001

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Model examination of the reflex-halation in single-layer light-sensitive system

Latacz L., Nowak P.

Optica Applicata

2001

Vol. 31, nr 2

499-506

The results of computer simulation of the effects of light scattering in a system composed of single silver halide light-sensitive layer coated on a transparent base are presented. The scattered light penetrating the base film can suffer from internal reflection from its lower surface and thus contributes to some loss of image sharpness. This effect, called reflex-halation, is very disadvantageous. The qualitative dependence of the MTF curve of the system on its geometric and optical parameters is examined. It has been shown, among others, that the deterioration of image quality is stronger for the thinner light-sensitive layer and is more elongated for the elementary scattering indicatrix of silver halide crystals. The result is similar to that obtained in the case of crossover effect, though in the presence of the antihalation layer the observed dependences are opposite to those just mentioned.

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

Latacz L., Nowak P.

Optica Applicata

2001

Vol. 31, nr 1

177-184

The results of computer simulation of the effect of light scattering in a system composed of two heterogenic light-sensitive layers coated on two sides of a transparent base are presented. It has been assumed that the modelled system is irradiated with a directed X-ray beam, while the photographic effect is caused only by the light emitted by the fluorescent screens adjacent to the light-sensitive layers and containing phosphors fluorescing due to 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. The qualitative dependence of the modulation transfer function of the system on both its geometric and optical parameters was examined. It has been shown that worsening of the image is the stronger the thinner the light-sensitive layers and the weaker the light scattering by single silver halide crystals. This result is surprising since in the case of single-layer light-sensitive systems not suffering from the crossover effect opposite effects are observed.

Model examination of application of fluorescent substance to silver halide light-sensitive layers

Latacz L., Nowak P.

Optica Applicata

2001

Vol. 31, nr 1

165-175

The results of computer simulation of the outcomes of scattering, fluorescence and absorption of actinic light inside the hypothetical light-sensitive layer containing the silver halide crystals and fluorescent substance are presented. It has been assumed that the modelled layer is exposed exclusively to the radiation of the wavelength belonging to the intrinsic sensitivity range of silver halide. The quantitative dependence of the effective light absorption by the silver halide on the fluorescent substance concentration, the layer thickness, quantum efficiency of fluorescence and the ratio of the absorption probability of a photon of wavelength belonging to the sensitized sensitivity range and the absorption probability of a photon of the wavelength from the intrinsic sensitivity range has been examined. Also, the dependence of the modulation transfer function curve on the above parameters has been studied. The results obtained indicate that under some circumstances an addition of fluorescent substance can enhance the photosensitivity of the layer and improve simultaneously the sharpness of the recorded image.