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To study specific features of stabilization of optical radiation in a turbulent atmosphere, a model of jitter of the image formed by radiation in the focal plane is created. The image is characterized by wavefront slopes. Approaches to modeling the wavefront slopes and methods for estimating the image formed by radiation in the focal plane of the recording device are outlined. Statistical studies include the calculation of the coordinates of the energy center of gravity of the focal spot by various algorithms depending on the parameters of a random phase screen that defines turbulent inhomogeneities, their intensities, and locations on the radiation propagation path. The results of experiments on stabilization of optical radiation on the stand of an adaptive optics system are presented.

The role of additional channels for the decay of an excited level on the formation of coherent states of the ground level in alkali metal atoms upon interaction with polarized radiation is studied theoretically. Using an example of ³⁹K, calculations show that these coherent states cannot be completely destroyed due to using additional decay channels.

A new method for estimating the bulk diffusion length L_dif of photogenerated charge carriers in the absorber material of mercury-cadmium-tellurium-based infrared focal plane arrays (MCT-based IR FPAs) is proposed. The method is based on the analysis of the modulation transfer function (MTF) of IR FPA detectors in normal operation and in operation with reduced gate voltage of input pixel field-effect transistors, when the built-in junction barriers of FPA diodes turn out to be reduced, and multiple re-emission of mutually induced microscopic currents of neighbor photodiodes takes place. The proposed mathematical model for the MTF of MCT-based FPAs assuming the capture of emitted electrons by the nearest FPA pixels provides an adequate description to the experimentally observed behavior of the diode-array MTF during the transition of FPA to the latter operation mode. This fact is illustrated in the article with the example of a 30-μm pitch FPA with ~10×10-μm diode sizes and 6-μm absorber-layer thickness. The coefficient of transfer of the injection current of a forward-biased photodiode to an adjacent pixel, which appears in the model, depends on the geometrical parameters of the diode array and on the length L_dif , and it can be used for determining this length.

The results of a study of remote temperature measurement systems of industrial electrical installations based on bolometric photodetector cameras are presented. A photodetector thermal imager camera of the FLIR system and a specialized radiometric thermal imager with internal temperature sensors and calibration shutters are considered. The best coating for calibration shutters with a minimum level of reflection of IR radiation from their surface has been determined (the integral reflection coefficient in the spectral range of 8-14 microns is no more than 5.8%). A mathematical description of the calibration process of the thermal imager camera of the FLIR system in a wide range of temperature changes of its components and the ambient medium is given. The requirements to the thermal imager camera for remote temperature diagnostics systems of industrial installations are analyzed.

The presence of an medium-range order in glassy materials, i.e., structural correlations on the nanometer scale, leads to fluctuations of elastic constants with the same characteristic correlation radius. The question of what is the characteristic amplitude of these fluctuations is of great interest both from the applied point of view and from the point of view of fundamental understanding of the structure and dynamics of glassy materials. In this study, we find the value of mean-square fluctuations of the shear modulus at the nanometer scale in salol (phenyl salicylate) molecular glass and its dependence on temperature during glass melting into a supercooled liquid. For this purpose, we use the theory of elasticity in a medium with spatial fluctuations of elastic constants in calculating the phonon free path using the perturbation theory. In addition, in the supercooled state of the material, we take into account the contribution of structure relaxation to phonon damping. Using the Ioffe-Regel criterion for the localization of transverse phonons, we find a relationship between the magnitude of shear modulus fluctuations and the frequency of the so-called boson peak caused by them in the spectrum of vibrational excitations of glasses. We determine this frequency from experimental data on the spectra of low-frequency inelastic light scattering in salol. A comparison with the theory makes it possible to find the temperature dependence of the rms fluctuations of the shear modulus at the nanometer scale. In addition, we compare this dependence with the temperature behavior of the Landau-Placzek parameter in salol. We also determine the temperature dependence of the radius of structural correlations in salol and glycerol and compare it with the temperature dependence of the size of the dynamic inhomogeneity.

The possibility of complete suppression of the instrumental error caused by inaccuracy of manufacturing of an angle-measuring structure, realized at an arbitrary form of the field of interaction of light radiation with the topology of the measuring structure is shown. This possibility is achieved by choosing a necessary structure of the encoder for which the principle of coherence of the complementary comb filters formed in the encoder is provided.

The system "movable electrode - nanometer gap - thin crystalline film of a material with a high value of dielectric permittivity - fixed electrode" is used to create high specific mechanical power microelectromechanical systems (MEMS). Two-dimensional electromechanical waves are found to arise in such a system. The occurrence of such excitations limits the maximum specific power of electromechanical converters - actuators, MEMS motors, and generators. On the other hand, this phenomenon opens up wide possibilities of using such structures.

In real conditions, the experimenter deals with input superconducting converters, whose design in biomagnetic systems depends on the research conditions, presence of magnetic shielding, available cryogenic support, required sensitivity to magnetic field induction, and technological capabilities of developers. It is impossible to compare the results of studies obtained for different biomagnetic systems. The paper considers the issues of describing the source of the magnetic field of the heart based on the spatial-frequency transformations of the 2-D model of the current dipole. The depth of occurrence, location and orientation of the current dipole on the value of magnetic field induction and its spectrum over the space of the magnetic field measurement grid of the heart are investigated.

The results of experimental studies of the deformation of a rail under the force of a moving railway transport are presented. The studies are carried out using a highly sensitive deformation sensor with a limit level of relative deformation of 2 · 10^-7 . The possibilities of optical strain measurement for solving the problem of monitoring the technical condition of the running gear of wagons and the upper structure of the track are analyzed.

The study of the photothermal effect during laser ablation of a 45 nm thick molybdenum oxide film is carried out. A hypothesis on the relationship of the thermal conductivity coefficient of the dielectric film with the limiting value of the photothermal effect is presented. It is shown that, with a thermal conductivity coefficient of more than 5 W / (m• K), the rate of temperature change decreases sharply at the beginning of heating the film, which, together with the peculiarity (singularity?) of the temperature distribution, can have a multidirectional effect on the width of the track being formed. It has been experimentally established that, under the action of continuous laser radiation in the 45 nm thick molybdenum oxide film, it is possible to form tracks with a width almost 2 times smaller than the effective diameter of the laser beam.