The numerical simulations of possibility of effective delivery of the speckled laser beam energy through the optical heterogeneous medium onto a target have been carried out. The calculations of speckled beam have been carried out within the framework of a numerical model of integration of the parabolic equation for the laser field amplitude taking into account the turbulence according to the phase screens model. Two approaches for pointing the speckled laser radiation onto the target in far field have been considered: the first approach is concerned with the preliminary scanning of the focal plane by the beam with the subsequent SPG correction of the beam position, and the second approach is the direct tip-tilts SPG correction without scanning. The probability estimation of the performance efficiency of the pointing system has been performed. It is shown that in both cases it is possible to direct the most intensive speckle of the laser beam onto the target with high probability.
The results of experimental works on creation of the closed-loop adaptive optical system intended for the tip-tilt wavefront correction have been described. The control unit with a high-speed microcontroller realizing the management by piezo-electrical stacked actuators of the tip-tilt corrector with the help of stochastic parallel gradient algorithm has been developed. The results of experiments on the dynamic wavefront tip-tilt correction at the system bandwidth of 2 kHz are reported. The basic characteristics of the closed-loop adaptive system are measured.
The numerical simulation has been carried out concerning the determination of needed number of adaptive mirror’s actuators for the correction of phase distortions accumulated by the laser beam under its propagation through an airway. For this purpose, a set of wavefronts of the laser radiation passed through the airway has been registered by a Shack-Hartmann wavefront sensor. The stacked actuators’ response functions of 107- and 203-element adaptive mirrors have been experimentally determined as well. The dynamic range of adaptive mirrors’ actuators has been considered in the calculations. It is established that the 203-element adaptive mirror is not suitable for correction of the registered aberrations due to the limited dynamic range. Meanwhile by means of 107-element adaptive mirror it is possible to obtain a corrected laser beam with the Strehl ratio St=0.65.
Method is explored of a focusing laser beam homogeneous quality receiving with a non-stationary plasma layer (DPPP) applying. The DPPP research is conducted on the Iskra-4 and Iskra-5 laser facilities aimed on its performance optimization. Irradiation inhomogeneity is received <8-10% at the reference time of an intensity distribution transposition -0.4 ps. It is shown, that the DPPP smoothing method raises the efficiency of radiation energy transfer to a laser target.
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