The growth features of trigonal La3Ga5SiO14 and Nd3Ga5SiO14 crystals and their solid solutions from the melt by Czochralski technique are studied. Optimal conditions are found and oriented (La1−xNdx)3 Ga5SiO14 single crystals are grown with 28 mm in diameter and 280 g by weight, of optical quality perfect to carry out excitation experiments on Nd3+ ion stimulated emission as well as investigations of acoustooptic and electromechanical properties of La3Ga5SiO14 crystals. Structural peculiarties and desorderness of La1−xNdx)3Ga5SiO14 crystals are considered. Crystal optics of La3Ga5SiO14 – linear dichroism and dispersion of refractive indexes (by a modified prism method), optical activity, and other optical characteristics are investigated. A comparison is made of some optical properties of La3Ga5SiO14 crystals and crystalline SiO2.

In this paper, a new method of spatial separation of several signals with different curvatures of the wave front is proposed. The method is based on the formation of a particular interference field structure of each signal in the location of the receiving antennas by means of a transmitting phased sparse linear array antenna. The peculiarity of the interference electromagnetic field consists in periodically repeating areas in which the amplitude of the useful signal is many times greater than the amplitudes of the other transmitted signals, which are electromagnetic interference. In addition, the electromagnetic interference signal in this area consists of practically two antiphase components. If in this area a reflective passive phased antenna array is placed, which will focus the useful signal while reflecting, it will be increased, and the interference signal will be significantly weakened. This method of signal separation allows simultaneous transmission of several signals in the same frequency band, in one direction and on one polarization, which increases the information transmission speed in communication systems.

This article presents research results of the signal-to-interference ratio dependence (S/I) on the spatial structure of the radiation field of a three-element linear sparse antenna array in communication systems with spatial signal separation. As a result of the research, it was stated that when the receiving linear antenna is located in the region of the zero order maximum of the field of the useful signal, the formation of the S/I ratio does not depend on whether the field distribution is considered on a straight line or on a circular arc. The location of the receiving antenna in the region of the first-order maximum of the field of the useful signal gives the best results in the formation of the S/I ratio if the field distribution is used on circular arc and not on a straight line.

The internal state of the material formed as a result of technological processing, indirectly affects the state of the material surface. A non-contact method of non-destructive control of the state of materials based on a visual analysis of the surface, requires high-quality images which can be obtained either using lens objectives or lenseless technologies. The results of studying image processing obtained by lensless technologies are presented. We used methods for modeling phase masks and image processing based on Gerchberg – Saxton iterative algorithms, adaptive-additive and phase mask rotation based algorithms. Materials such as granite, graphite, sand and carbon steel were analyzed. It is shown that the construction of cameras can provide significant reduction of their dimensions at the same or even improved characteristics. The images obtained using lensless technologies and the proposed methods of image processing also provide a significant increase in the accuracy of visual inspection of materials. The results obtained can be used in refining lensless technologies, improving the quality of images and reducing time of their processing.