Andrzej Zardecki

Laser beam propagation in particulate media

In the small-angle approximation, the exact solution of an equation of radiative transfer is cast in a series form suitable for numerical computation. This is used to calculate the radiance produced by a cw laser beam. For the medium with Gaussian phase function, a convergent numerical procedure is described. Explicit results for the scattered radiance, obtained for a wide range of parameters, display the existence of three well-defined regions on the plots of radiance versus transverse distance. A comparison of the exact theory with two approximate approaches is carried out.

Noise transformation by optically bistable system

Abstract Numerical study of transmission of chaotic radiation by an absorptive bistable system is presented. It is found that in quasi-steady state the transmitted light shows enhanced intensity fluctuations.

The effect of occupation number fluctuations on partially developed speckle patterns

Abstract Within the random phase screen model, we discuss the contrast enhancing non gaussian fluctuations of thr partially developed speckle patterns. The occupation number fluctuations are simulated by assuming the number of the scattering centers to be distributed according to the Poisson law. Circularity conditions in the gaussian field limit are derived.

Generalized notion of the coherence area

Abstract The notion of a coherence area is introduced on the basis of photoelectron distribution analysis. In contrast with earlier results, the case of a source of arbitrary shape and intensity distribution is considered. A clear distinction is made between the number of degrees of freedom and the number of coherent elements.

Boltzmann–Langevin equation and light scattering by dilute gases

The Boltzmann–Langevin equation, which is the linear Boltzmann equation supplemented by a fluctuating force term, is used as a starting point to analyze the density correlation function in a dilute gas. By referring to the fluctuation–dissipation theorem, an equivalence of this approach and the conventional treatment based on the kinetic equation is established. For molecular gases, a quasi-classical description is employed, permitting one to incorporate internal degrees of freedom into the theory. With the help of Zwanzigs projection operator formalism, a new simple computational procedure is developed. Its versatility is illustrated by the explicit calculation of the scattered light spectrum from H2 and HD for two specific models.

Théorie Exacte de la Distribution de la Somme des Photoélectrons Emis en L Points

The statistical behavior of photoelectrons emitted at L points of a photocathode in partially coherent Gaussian light is considered. The exact formula for the cumulants and the factorial moment generating function is derived. An exact expression for the photocount distribution and for the factorial moments is obtained in the case when the detection time is much smaller than the coherence time. Two cases of interest which were treated earlier by the same authors are also considered. In particular, the case of two points of detection is of special interest because a physical meaning can be given to the difference of the normalized eigenvalues. Finally, both the exact and approximate theories are compared with the experimental photocount distribution for four different geometrical arrangements.