Оptical wave fields measurement by digital holography methods

The solution of a wide range of research and application problems of modern science and technology is connected to the measurement of the wave field of optical radiation. The methods of digital holography allow not only to improve the accuracy of measurements of optical wave field parameters, but also to increase the compactness of devices without losing speed. Digital holography gives a push to the development of new approaches to the construction of devices such as a wave front sensor.The study was supported by the Ministry of Education and Science of the Russian Federation: agreement No. 14.577.21.0258 of September 26, 2017 (project identifier RFMEFI57717X0258)

The origin of paramagnetic magnetization in field-cooled YBa2Cu3O7 films

Temperature dependences of the magnetic moment have been measured in YBa_2Cu_3O_{7-\delta} thin films over a wide magnetic field range (5 <= H <= 10^4 Oe). In these films a paramagnetic signal known as the paramagnetic Meissner effect has been observed. The experimental data in the films, which have strong pinning and high critical current densities (J_c ~ 2 \times 10^6 A/cm^2 at 77 K), are quantitatively shown to be highly consistent with the theoretical model proposed by Koshelev and Larkin [Phys. Rev. B 52, 13559 (1995)]. This finding indicates that the origin of the paramagnetic effect is ultimately associated with nucleation and inhomogeneous spatial redistribution of magnetic vortices in a sample which is cooled down in a magnetic field. It is also shown that the distribution of vortices is extremely sensitive to the interplay of film properties and the real experimental conditions of the measurements.Comment: RevTex, 8 figure

RESEARCH OF ORAL MUCOSA REGENERATION AFTER FRACTIONAL TREATMENT BY DIODE LASER WITH 980 NM WAVELENGTH

Subject of Research. The paper presents the study of the oral mucosa reaction of experimental animals to fractional laser treatment by diode laser radiation with a wavelength of 980 nm.Methods. A single fractional laser treatment of oral mucosa was carried out in the experiment on Wistar laboratory rats at different exposure regimes: combinations of laser power from the range Р = 5-15 W, pulsewidth tp = 100-120 ms and the filling factor. The animals were taken out of the experiment immediately after exposure, on the 5th, 7th and 28th day after the treatment. For histological evaluation mucosal preparations were stained with hematoxylin and eosin, as well as aniline blue according to Masson. Thickness of mucosa layers and concentration of collagen fibers were defined as a result of computer processing of images of histological samples. Main Results. It was established that the mucous condition depends significantly on the laser treatment regime and the time elapsed since the fractional treatment. When exposed to pulsed laser radiation with P = 5 W, tp = 100 msor P = 7 W, tp = 120 ms,at the filling factor F = 200±50 microdamages/cm2 the mucous regeneration has been completed on the 28th day after treatment, and for the other studied regimes it continues. After regeneration the thickness of the epithelial layer of the oral mucosa is less, and the thickness of the submucosal layer with lamina propria of mucosaand concentration of collagen fibers in the mucosa correspond to control. Practical Relevance. The obtained results are promising for further research on the reconstruction of thinning oral mucosa

An algorithm for measuring wind speed based on sampling aerosol inhomogeneities

Разработан алгоритм на основе сэмплирования аэрозольных неоднородностей для обработки изображений в задаче лидарного измерения скорости ветра в атмосфере. Проверка разработанного алгоритма производилась с использованием синтезированных лидарных сигналов и на данных натурных измерений. Алгоритм обработки аэрозольных полей в координатах «дальность – время» позволяет существенно уменьшить погрешности лидарного времяпролётного метода измерения скорости ветра по сравнению с корреляционными методами измерения. A digital image processing algorithm based on sampling aerosol inhomogeneities was developed in the applied problem of laser remote sensing for measuring the velocity of wind. Tests of the developed algorithm were conducted for synthetic data from numerical simulations and data measured by a lidar. The algorithm developed performs processing of the field of aerosol backscattering coefficient in “RangeTime” coordinates and sufficiently increases the measurement accuracy in comparison with correlation methods