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The advantages of correcting the refractive errors of the eye (nearsightedness and farsightedness) by introocular phakic (i.e., without removing the crystalline lens) lenses over the other types of correction are considered. A relation between the optical power of spectacle glasses and contact and phakic lenses is obtained and analyzed. New, more accurate approximate formulas for calculating the optical power of intraocular artificial lenses and phakic lenses are derived. It is shown that the deviation of calculations by the proposed formulas from the calculations by the formulas based on geometrical optics are much less than the deviation of calculations by the regressive formulas used in ophthalmic practice.

This paper presents a holographic interferometer configuration with inclined fixed mirrors based on a beam-splitting unit in which the convergence angle of the partial beams is tuned only by rotating the interferometer relative to the radiation source. The continuous range of tuning is close to the maximum possible (0-180º). The path lengths of the interfering beams are automatically aligned due to the mirror symmetry of the system. The position of the axis of rotation providing minimal aperture limitations in almost the entire range of tuning is determined. A comparison is made with an alternative configuration based on a beam-splitter cube.

Acetylene in transformer oil is an important feature gas, which can reflect early discharge faults. A tunable fiber laser photoacoustic (PA) spectrometer based on second harmonic modulation, with its fast response and good noise immunity, can be well applied to detect trace gases. In this work, the second harmonic PA measurement of the acetylene gas at the 1530.3709 nm transition line is demonstrated. An accurate analysis of acetylene in transformer oil gases is ensured by using an overcomplete-independent-component-analysis(ICA)-basis BSS model and a five-point-sampling method to improve the detection limit from 1.12 to 0.71 ppb. The experiment for detecting and analyzing acetylene in transformer oil gases shows that the discharge acetylene productivity can reach 303.72 ppb/s with a dynamic response time of less than 10 s, relative error of about 1.40%, and relevance coefficient up to 0.99946. At room temperature and atmospheric pressure, this can meet the demands of acetylene detection and analysis in early or ultra-early predictions of transformer discharge faults.

A kinetic diagram of Ge growth on Si is constructed by methods of fast electron diffraction and scanning electron microscopy. Activation energies of morphological transitions from twodimensional to three-dimensional growth and from hut-clusters to dome-type islands are determined. The curve of the 2D -3D transition has two segments that follow the Arrhenius law and refer to different mechanisms of two-dimensional growth: two-dimensional island mechanism in the temperature range of 300-525 ºC with the activation energy of −0.11 eV and step motion in the temperature range of 525-700 ºC with the activation energy of 0.15 eV. Transitions from hut-islands to dome-islands are also observed. The curve constructed for the hut-dome transition is approximated by two exponential segments that obey the Arrhenius law. The hut-dome transition activation energy is 0.11 eV in the temperature range of 350-550 ºC and 0.24 eV in the temperature range of 550-700 ºC. The maximum density of islands in the case of Ge growth on a Ge_x Si_{1 − x} layer reaches 4 · 10¹¹ cm⁻². An increase in the composition leads to an increase in the density of Ge islands owing to a decrease in the length of migration of Ge adatoms on the Ge_xSi_{1 − x} surface, as compared to the case of Ge growth on Si. The periodicity N, which is manifested as a (2 × N ) superstructure, decreases during the reconstruction from 14 to 8 with increasing Ge content in the Ge_xSi_{1 −x} layer. An increase in thickness or temperature leads to a decrease in periodicity and testifies to Ge segregation; in this case, stress relaxation occurs, which reduces the Ge diffisivity.

GaAs films on Si substrates miscut from the (001) plane by 6º in the [110] direction are grown by molecular beam epitaxy (MBE). GaAs films are grown both on the Si surface terminated by arsenic atoms and on thin pseudomorphic GaP/Si layers. The condition of formation of the As sublayer and the first monolayer of GaP on the Si surface is defined as the GaAs film orientation (001) or (00¯1). The processes of Si surface preparation and formation of the As sublayer and GaAs and GaP epitaxial layers are monitored by means of high-energy electron diffraction reflection (RHEED). The grown structures are investigated by methods of X-ray diffraction, atomic force microscopy (ATM), high-resolution transmission electron microscopy (HRTEM), and low-temperature luminescences. It is shown that the epitaxial film orientation affects both the surface morphology and its crystalline properties. Intense photoluminescence is obtained from the In_0.17Ga_0.83As quantum well structure grown on the GaAs/Si buffer layer.

Initial stages of ZnTe growth on GaAs(301) and Si(301) substrates by the method of molecular beam epitaxy are investigated by means of in situ one-wave ellipsometry. Layer-by-layer growth of the ZnTe film is observed on GaAs(301) substrates, whereas 3 D nucleation occurs during epitaxy on Si(301) substrates. Misfit dislocations (MDs) are inserted into the ZnTe film during the growth of the first monolayers. Owing to MDs, the film lattice turns with respect to the substrate lattice, which is confirmed by X-ray measurements. Threading segments of MDs in CdTe/ZnTe/GaAs(301) and CdTe/ZnTe/Si(301) heterostructures are subjected to etching. The etch dislocation pits are found to have different shapes, which testifies to different types of threading dislocations. In the case of layer-by-layer etching, the dislocation density is found to increase inward the CdTe film, which testifies to annihilation of dislocations in the course of growth of CdTe films. The dislocation annihilation rate is higher in films grown on GaAs(301) than in those grown on Si(301). A possible reason is the higher mobility of dislocations in CdTe films on GaAs(301) substrates.

The structure of extended defects introduced into Si by means of boron implantation followed by thermal annealing at T = 900 ºC is studied by the method of high-resolution transmission electron microscopy and computer modeling for different values of the implantation dosage (D) and concentration of boron atoms in substitutional positions B₀(C_B0) injected into the Si lattice before implantation. It is shown that the Frank dislocation loops of both interstitial (I) and vacancy (V) type at a ratio of 4 : 1 are observed in Si samples with D = 10¹⁶ cm⁻² up to C_B0 = 0.8 · 10²⁰ cm⁻³. The atomic structure of the I-type Frank dislocation loops is heavily deformed, which suggests segregation of finely dispersed boron in the defect plane. At the same time, the structure of the V-type Frank dislocation loops tends to be reconstructed due to interaction with self-interstitials. At C _B0 = 2.5 · 10²⁰ cm⁻³, the I-type Frank dislocation loops are found to transform to perfect dislocation loops, and boron precipitates with a high density appear in Si. Based on the results obtained, probable reasons for vacancy deficit formation in boron-implanted Si are discussed.

The molecular dynamics method is used to study the formation of Ge nanoislands on pit-patterned Si(100) substrates. For substrates with overlapping pits and pits in the shape of truncated inverted pyramids, the energy surface is calculated. On the basis of its analysis, the mechanism of nuclear surface diffusion on the pit-patterned surface is described. The specific energy of Ge/Si heterostructures with different morphology of nanoislands in pits is calculated. It is shown that the configuration with multiple nanoislands in a pit can be thermodynamically favorable.

Results of mathematical simulation of the hole spectrum and optical absorption in Si/Ge_xSi_{1 − x}/Si quantum wells formed on virtual Ge_ySi_{1 − y} substrates are presented. It is shown that the presence of elastic strains in such a system can significantly change the position of absorption lines in GeSi heterostructures. Selecting the quantum well and virtual substrate compositions can change the intersublevel absorption wavelength in the range from 6 to 12 µm for light polarized in the quantum well plane. When tensile strain is applied, the change in the hole transition intensity under the influence of the light polarized in the quantum well plane reaches a factor of 1.8. Compressive strain changes the intersubband transition intensity by a factor of 1.45.

Tools for optimizing the performance of parallel programs on multi-architectural distributed computing systems are considered. A method for optimizing the embedding of parallel MPIprogram into computing clusters with a hierarchical communication network structure is described. An adaptive approach to the delta optimization of restore points is proposed for effective fault-tolerant simulation on distributed computing systems.