Transformaiton of the diffraction patterns of screens into the diffraction patterns of additional screens in the course of scattering by a gas perturbation or by a particle in laser beam cuastic

摘要

The spatial distribution of the scattered-radiation energy duringfocusing, in atmospheric air, of the fourth-harmonic beam of a pulsedneodyminum laser (λ=264 nm) with an annular cross section wasstudied experimentally. Shortening of the UV scattered-radiation by afactor of 2-5, compared with the duration of the laser pulse, wasobserved. An interference structure of the scattered radiation,varying with increase in the laser-pulse energy, was recorded. Thediffraction rings and bands originating from screens were transformedinto analogous diffraction rings and bands from additional screens.This can be accounted for by the scattering of the laser beam on agas perturbation or on a particle in the caustic. Experiments wereperformed on the scattering of radiation with λ=0.63 μm onformations with an abrupt boundary, which confirmed the abovehypothesis.