It has been shown that sectorial and zonary unhomogeneities of the crystal together with changing It has been shown that sectgriil in wth are among the main causes of appearance of the conditions in the tourse o temperature defectiveness and property crystallographic unhomogeneities in the volume of crystals grown. The method of structure direction luoul the large-size KDP and DKDP single rapid growing in the defined crystallites on the plain seed has been developed, which are applicable for production of wide aperture of such a harmonics frequency multipliers of laser emission into the secondlthird of growing allows to increase the coefficient of use of crystal material (KDP up to 40% and DKDP up to 70x) at production of nonlinear laser elements. High quality of the crystals grown has been confirmed by the results of investigation of structural perfection, optical homogeneity and bulk damage resistance threshold. c 2011 Elsevier