Home – Home – Jornals – Advanced Search

A monochromator capable of suppressing spurious laser radiation to a level required for low-frequency (<100 cm^-1) Raman spectroscopy is proposed. It has a high spectral resolution, contains a small number of optical elements, and can be easily included into the experimental optical scheme. The effect of using this monochromator in low-frequency Raman spectroscopy is illustrated by examples with test samples.

This paper presents a method for increasing the accuracy of operation of a circular laser system for writing large-diameter diffractive optical elements in a polar coordinate system and the results of its use. An algorithm for correcting positioning errors of a circular laser writing system developed art the Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences. Showing manufactured using High-precision diffractive optical elements developed by this method and the results of using these elements for testig the 6.5 m diameter aspheric mirror of the James Webb new space telescope are described.

Potential accuracy of methods of laser Doppler anemometry is determined for the single-particle scattering mode where the only disturbing factor is shot noise generated by the optical signal itself. The problem is solved by means of computer simulations with the maximum likelihood method. The initial parameters of simulations are chosen to be the number of real or virtual interference fringes in the measurement volume of the anemometer, the signal discretization frequency, and some typical values of the signal/shot noise ratio. The parameters to be estimated are the Doppler frequency as the basic parameter carrying information about the process velocity, the signal amplitude containing information about the size and concentration of scattering particles, and the instant when the particles arrive at the center of the measurement volume of the anemometer, which is needed for reconstruction of the examined flow velocity as a function of time. The estimates obtained in this study show that shot noise produces a minor effect (0.004-0.04 %) on the frequency determination accuracy in the entire range of chosen values of the initial parameters. For the signal amplitude and the instant when the particles arrive at the center of the measurement volume of the anemometer, the errors induced by shot noise are in the interval of 0.2-3.5 %; if the number of interference fringes is sufficiently large (more than 20), the errors do not exceed 0.2 % regardless of the shot noise level.

This paper describes the nonradiation (Fester) energy transfer between a dye J-aggregate and closely located nanoparticles possessing the properties of two-level systems. The dynamics of the process are described by deriving the equations that characterize the density matrix dynamics in a two-level medium and the evolution of exciton pulses in an extended quasi-one-dimensional dye J-aggregate. It is shown that effective controlled resonant transfer of the energy stored in the QD is implemented in the system and manifested in the amplification of the exciton pulses. In turn, there is a possibility of the reverse process of exciton energy transfer in partial inversion of two-level transitions of QDs. The results of this paper are confirmed by the experimental data from the literature.

This paper presents the results of measurement of the surface potential and the residence time of Rb and Na atoms on the surface of S-52 molybdenum glass. It is found that at temperatures below the glass transition temperature, the temperature dependence of the residence time of Rb atoms is well described by the Arrhenius formula. The surface potentials for Rb and Na are measured to be 0.67 and 1.37 eV, respectively. At temperatures above the glass transition temperature, the residence time of these atoms abnormally increases. This is due to the fact that during impact of an atom on the surface of molten glass, it can penetrate into the volume of the window and then return by diffusion and desorb from the surface. In this case, the residence time of the atom on the glass is determined by the diffusion time and can be very significant, despite the relatively low potential barrier at the surface and heat.

This paper describes the method for recovering digital holograms obtained at small angles between interfering wave fields. The technique for obtaining data on the phase of the wave front reflected from the object is under consideration.

A possibility of creating a capacitance accelerometer for measuring high- g accelerations (up to 10⁶ g and higher) is discussed. It is demonstrated that insertion of a thin electret film with a high surface potential into the gap between the electrodes ensures significant expansion of the frequency and amplitude ranges of acceleration measurements, whereas the size of the proposed device is smaller than that of available MEMS accelerometers for measuring high-$g$ accelerations. A mathematical model of an electret accelerometer for high- g accelerations is developed, and the main specific features of accelerometer operation are analyzed.

This paper describes the study of the surface morphology of BaF₂ epitaxial films grown by means of molecular beam epitaxy in various growth regimes on a CaF₂ Si(100) surface, which is performed by means of atomic force microscopy. The CaF₂ layers were obtained on a Si(100) substrate in a low-temperature growth regime (Ts = 500 ^oC). The technological regimes of growth of BaF₂ continuous films with a smooth surface on CaF₂/Si(100), suitable as buffer layers for the subsequent growth of PbSnTe layers or other semiconductors, such as A₄B₆, and solid solutions based on them.

The concept of «educational space» in recent years is one of the most used in the scientific literature. Nevertheless, today there is no methodological unity in the matter of its categorical definition. The author presents his understanding of the modern educational space as well as the criteria by which it can be characterized. The material of the research are normative documents and prognostic assessments belonging to key institutions responsible for the present and future of educational policy as well as the educational environment itself (mainly domestic ones). This approach allows us to identify the direction of changes in modern education as a socio-cultural complex of interactions and practices. To identify the characteristics and key features of the modern educational space, the author turns to the analysis of key trends in modern education. This allows, first, to determine the coordinate system in which the formation is located. It makes possible to determine the topological characteristics of the phenomenon being analyzed. Secondly, the systematic and large scale of modern education in all its forms (including the claim of «life-long education») allows us to draw a conclusion about the spatial nature of education as a phenomenon of social and political reality. The increase in the mass character of education is accompanied by an increase in the individual dimension of the educational process, which means the formation of a new type of relationship within the space of the reproduction of knowledge and innovations. An important factor in the process of transforming the educational space is also the widespread use of information and technology tools, which probably speeds up the process of introducing change. At the same time, geographical expansion (increase in coverage) of the educational space can be accompanied by a functional contraction and even the «withering away» of certain elements. The analysis of changing elements allows the author to distinguish unchanged (at least, relatively stable) features in the educational space. From the point of view of the content of education, we are talking about unification, the tendency to eliminate barriers, and non-dogmatism. The form of educational attitudes and practices remains the same, but the form itself can receive new content, according to some predictions. Finally, on the basis of the dynamics of the development of education, the author concludes that today we are seeing the formation of a fundamentally new educational space which is different from the Modern age. Under these circumstances, special attention should be paid to the axiological component of education as a necessary component of the future global educational space.

The processes of integration and differentiation in education and their results affect the social dimension of modern domestic education. Social integration and differentiation in education can manifest themselves as positive and negative trends. Social differentiation in education at the institutional level contributes to the coexistence of comprehensive education and author schools, providing an expansion of the range of opportunities to meet the educational needs of the younger generation. Nevertheless, differentiation also manifests itself in the reproduction of social inequality and professional stratification (division of professions into prestigious and non-prestigious, not completely corresponding to the real demand for representatives of non-prestigious spheres of employment in the eyes of citizens). At the level of the organization of the educational process, by means of introduction of tutoring, differentiation contributes to the individualization of education. However, such an individualized education can become elite and inaccessible for most citizens. Social integration serves the purposes of uniting the nation and acculturation of migrants in Russian society via the education system. Inclusive education of schoolchildren and students with disabilities and developmental peculiarities contributes to their socialization. The common content of education and similar educational trajectories of its subjects are also aimed at forming a single picture of the world in the citizens of the country and their consolidation. But social integration without taking into account the special educational needs of gifted students, students with disabilities or representatives of ethnic cultures narrows their choice and horizon of development. The author of the article finds empirical confirmation of these theses and proposes a way out of the current situation, which is possible with the successful implementation of the project «Open Education» by the Ministry of Education and the Government of the Russian Federation.