Comments on the Photon Echoes

The coherent light pulses obtained in the experiments of light echoes type [1] (as induction and echoes signals) and generated by the electric dipole system bring the information about the dynamical properties of the dipole system and are used for the registration of that information. As to the dynamics of the emitted photons them-selves at the present time the effects of pulse form changing [2] and self-induced transperancy [3] caused by the photon system interaction with the matter were taken into consideration only. In this work we discuss the memory effects of the system of photons itself spreading into the vacuum. The discussed effect is the method of the space-time coherence re-establishment of the laser radiation on the basis of application the effect which we called the photon echoes. The point of the method is in the plural reflection of electromagnetic radiation from the mirrors which gives the steady-state conditions of the electromagnetic wave spreading and is caused by diffraction. In itself the steady-state conditions of the electromagnetic wave spreading denote that the mutual intensity function J (n) (x 1 , x 2 ) is not dependent of the X 1 and x 2 coordinates if the n is sufficiently large (it is the factorisation condition of the mutual intensity function), and as it was shown in the work [4] the