Behavior of heated particle gas and light-wave diffraction by phase screen in warm-ray model

On the basis of the analogy between the density evolution of a heated gas of noninteracting particles and the diffraction of monochromatic optical waves by a random phase screen, a formula is derived for the correlation function of intensity fluctuations behind the screen. A hypothesis on the statistical splitting of the geometric and diffraction means allows the multiplicity of the integral that determines this function to be reduced by half.