Effect of the state of the surface layers on the strength of materials for optoelectronic and sensors devices

The goal of this work is to determine the correlation of the strength of brittle amorphous nonmetallic materials with the defective surface layers and their physical properties. The defective surface layer of materials for optoelectronic and sensors devices consists of abundant structural near-surface defects, which are displaced under action of constant load and thermal fluctuations, reducing the elasticity of the surface layer. Microcreep processes in tested materials can be described by a general equation that is known as the logarithmic microcreep equation. The applicability of this equation for tested optical materials is indicative of the generality of microcreep processes in crystalline and amorphous hard materials. For each grade of polished optical glass, a minimal residual defective layer exists. The parameters of this layer are interrelated with the mechanical properties of glass, such as microhardness and optical strain coefficient, and thermophysical properties, such as thermal diffusivity, sintering temperature, and annealing temperature. The greater are the values of these properties, the less is the concentration of disrupted interatomic bonds. Based on the test results, the corresponding equation, using the parameter E⋅a¹/², for determining the strength of optical silicate glass and glassceramic has been proposed

Thermoresistant Nano-filled Glass-ceramics

AbstractIt is known that replacing microscopic particles by nano-particles in a composite formulation results in improved physical properties. The authors investigated the possibility adding of nanoparticles SiO2 and TiO2 in an amount of 10-30% in the slurry to produce glass-ceramics. Mechanical strength of the glass-ceramics parts greatly depends on micro-defects of surface and internal structures substantially connected with the factual quality of used production technology, mechanical and heat treatment. There is analyzed a special complex of the destructive and nondestructive methods of strength and quality control of glass-ceramics developed to guarantee the durability of structures used in the usual and extreme service conditions with the temperature up to 1000 ˚C. The methods based on the precise preproduction tests of specimens and real structural elements such as plates and shells were supplemented with the additional non-standard methods for effective use in the working environment which is typical for line production of super thermal-resistant glass-ceramic. As a result of the research found that the adding of nanoparticles in the slurry increases the density of the structure, improves the physical properties and provides high stability of glass-ceramics

Use of radiation from PC screen for non-destructive controlling the internal strains in transparent parts

It is known that the most widely used method to control internal strains is the optical polarization method. However, the sources of polarized radiation are the most problem issue of this method. There are some difficulties in using this method when testing large-scale optical parts, diameters of which exceed 500 mm. To choose an optical source suitable for solving these tasks, we have analyzed the design of liquidcrystal screens and ascertained the possibility to use their polarized radiation in tests of internal strains in optical parts of large dimensions. Adduced below are the results of investigations of internal strains in parts of sapphire and organic glass

Influence of elastic deformation on the residual ellipticity of polished optical materials

The elastic deformation of thin mirrors is widely used in systems of adaptive optics, however, there are no data upon investigations of influence of elastic deformations on parameters of reflected polarised light in the literature. Using the method of ellipsometry, the influence of elastic deformation on the residual ellipticity of polished samples made of optical materials was studied. The results obtained during the researches have shown that the application of elastic deformations leads to essential changes of the minimum ellipticity tgp of polished samples, which testifies to the necessity to take into account this circumstance for devices of adaptive optics, input windows, cryostats and other optical parts working with the changing temperature

Ellipsometric control of quality of polished MgF₂ optical ceramics

In this work, ellipsometric measurements were used to optimise the technology of machine working the polished parts made of MgF₂ optical ceramics. The ellipsometry is a high-performance contactless method to control quality of optical surfaces, which is used here due to a sharp response of light polarisation conditions to the properties and parameters of surface and subsurface layers in investigated reflective systems. It is shown that the highly productive technology of diamond polishing provides achievement of ellipsometric parameters at a level of conventional methods of polishing

Gauged Gravity via Spectral Asymptotics of non-Laplace type Operators

We construct invariant differential operators acting on sections of vector bundles of densities over a smooth manifold without using a Riemannian metric. The spectral invariants of such operators are invariant under both the diffeomorphisms and the gauge transformations and can be used to induce a new theory of gravitation. It can be viewed as a matrix generalization of Einstein general relativity that reproduces the standard Einstein theory in the weak deformation limit. Relations with various mathematical constructions such as Finsler geometry and Hodge-de Rham theory are discussed.Comment: Version accepted by J. High Energy Phys. Introduction and Discussion significantly expanded. References added and updated. (41 pages, LaTeX: JHEP3 class, no figures

Ions losses in multislit electromagnetic trap “Jupiter 2M”

The results of ions losses researches through magnetic slits and axial holes of a multislit electromagnetic trap “Jupiter 2M” are submitted. Plasma potential in the central area of a trap and potential depression in a ring magnetic slit are experimentally measured. The potential barriers to ions in ring magnetic slits are determined. It is shown, that the ions losses in the axial holes make no more than 4 % of total ions losses from the trap. The reason of low ions losses in axial holes is the additional forces arising at plasma interaction with crossed electrical and magnetic fields.В роботі представлені результати досліджень втрат іонів через магнітні щілини та осьові отвори багатощілинної електромагнітної пастки “Юпітер 2М”. Експериментально виміряні потенціал плазми в центральній області пастки та провисання потенціалу в кільцевих магнітних щілинах. Визначені потенційні бар’єри для іонів в кільцевих магнітних щілинах. Показано, що втрати іонів через осьові отвори не перевищують 4% загальних втрат іонів з пастки. Причиною малих втрат іонів через осьові отвори є додаткові сили, що виникають при взаємодії плазми з схрещеними електричним та магнітним полями.В работе представлены результаты исследования потерь ионов через магнитные щели и осевые отверстия многощелевой электромагнитной ловушки «Юпитер 2М». Экспериментально измерены потенциал плазмы в центральной области ловушки и провисание потенциала в кольцевых магнитных щелях. Определены потенциальные барьеры для ионов в кольцевых магнитных щелях. Показано, что потери ионов в осевые отверстия не превышают 4% общих потерь ионов из ловушки. Причиной малых потерь ионов через осевые отверстия являются дополнительные силы, которые возникают при взаимодействии плазмы со скрещенными электрическим и магнитным полями

Multislit electromagnetic trap “Jupiter F”

The construction of multislit electromagnetic trap “Jupiter F” with application of ferromagnetic materials to strengthening of a magnetic field, the results of calculations, and the results of experimental investigations of the magnetic field configuration are presented.Представлено конструкцію багатощілинної електромагнітної пастки “Юпітер Ф” з використанням феромагнітних матеріалів для підсилення магнітного поля, результати розрахунків та експериментальних досліджень конфігурації магнітного поля.Представлены конструкция многощелевой электромагнитной ловушки “Юпитер Ф” с применением ферромагнитных материалов для усиления магнитного поля, результаты расчетов и экспериментальных исследований конфигурации магнитного поля

Investigation of Al-ZERODUR interface by Raman and secondary ion mass spectroscopy

The interface of ZERODUR ceramics and thin aluminium film was investigated by Raman and secondary ion mass-spectroscopy techniques. Possible chemical reactions at the interface is briefly analyzed and compared with experimental data. Contributions of amorphous and crystalline phases of ZERODUR to Raman spectra are discussed. Keywords: ZERODUR ceramics, Raman spectra, secondary ion mass-spectroscopy. Manuscript received 19.04.05; accepted for publication 18.05.05

Semiclassical interferences and catastrophes in the ionization of Rydberg atoms by half-cycle pulses

A multi-dimensional semiclassical description of excitation of a Rydberg electron by half-cycle pulses is developed and applied to the study of energy- and angle-resolved ionization spectra. Characteristic novel phenomena observable in these spectra such as interference oscillations and semiclassical glory and rainbow scattering are discussed and related to the underlying classical dynamics of the Rydberg electron. Modifications to the predictions of the impulse approximation are examined that arise due to finite pulse durations