Yu. A. Mamaev

Poly(propylene glycols) as effective additives to the sol-gel process in fabrication of antireflection coatings onto silica glass

Possibility of obtaining mesoporous silicon dioxide antireflection coatings with low refractive index (1.20–1.277) by using additions of poly(propylene glycols) with various molecular masses in a sol-gel process was examined. It was demonstrated that the optimal concentration of poly(propylene glycols) in the sol, at which a sol-gel process followed by heating of a sample yields a transparent film with a maximum light transmission of 98.3–99.0%, depends on the average molecular mass of the additive.

Preparation of antireflection coatings from silicon dioxide on glass and quartz by the sol-gel method with oligoethers

Antireflection coatings with a low refractive index (1.18–1.23) have been prepared on silicate glass and optical quartz from mesoporous silicon dioxide synthesized by the sol-gel method in the presence of oligoethers. The optimum concentration of the oligoester in the sol is equal to 1.5–2.5 wt %. For the single-layer double-sided coating, the maximum transmission is equal to 99.0% for the silicate glass and 99.9% for quartz.

Optimization of the structure of an optical fiber polarizer with a metal film at a wavelength of 980 nm

The dependence of the extinction ratio of a 980-nm fiber polarizer with an Al film on the thickness of magnesium fluoride buffer layer has been experimentally and theoretically investigated. At the optimal thickness of the buffer layer, hb = 0.078 (normalized to the wavelength), extinction ratios of 23 and 41 dB were obtained for polarizers having fiber shell residual layers of 2.01 and 1.607 μm, respectively. The optimal thin-film structure is determined, which will make it possible to design polarizers with extinction ratios up to 100 dB.

Polarization dynamics of a fibre Fabry-Perot laser with feedback

Experimental results on the low-frequency polarization dynamics of a free-running Nd-doped optical fibre laser and a fibre laser with derivative feedback are presented. It is found that the power spectrum of each polarization mode reveals three relaxation peaks. Using the combined (negative and positive) derivative feedback it is possible to suppress noise in the region of the in-phase relaxation oscillations and to excite noise in the region of one of the two antiphase relaxation oscillations. The model developed of a class B laser with two orthogonal elliptically polarized modes is checked and explains the main experimental features of relaxation oscillation peaks.

Deposition of silicon dioxide antireflection coatings on glass by sol-gel method in the presence of Pluronic® F127 block-copolymer

Hydrolysis of tetraethoxysilane in the presence of Pluronic® F127 block-copolymer in a water-alcohol mixture was used to obtain sol-formulations from which antireflection coatings were deposited onto silicate glass by the dip-coating method and then calcined at high temperatures (200–500°C). Electron spectroscopy was used to study the dependence of the optical transmission of glass samples with a coating on the concentration of Pluronic® F127 in the starting sol, introduction of organic additives (toluene) into the sol, and calcination temperature of the glasses obtained. The refractive index and hardness of the film coatings were determined and their surface structure was assessed.

Hydrogeochemical features of water-rock interaction in Verkhnekamskiy Saliferous Basin

The hydrogeochemical features of water interaction with soluble minerals are considered in the case of salt strata in Solikamsk Depression in natural (the area of the anticipated Verchnekamskaya Hydropower Plant) and technogenically transformed (the area of Berezniki T.) environments. The preservation of rock and potash salt is shown to be possible only upon maintaining the hydrogeochemical groundwater regime that provides the stability of gypsum facially replaced by salt. The gypsum protects the latter from contact with highly aggressive groundwater and, thus, from intense dissolution.

Effect of Water Saturation on Elastic Characteristics of Alluvial Sands in Terms of the Nagim River Placer

The authors define elastic moduli of high-argillaceous alluvial sand with natural humidity content, compare the experimentally obtained and calculated moduli for sands saturated with water to 30%, and give recommendation on disintegration of high-argillaceous sand with high fine gold content.

Combined Measures on Providing Safety of Technogenic Objects Within the Mined Territories of Potassium Deposits in Perm Region, Russia

The paper covers a complex of protective measures providing safety during the construction and operation of potassium salt mines within the Solikamsk-Berezniki urban and industrial agglomeration in Perm region, Russia. At the municipal level, the protective measures imply the adoption of planning and administrative managerial decisions. At the local level, the programs of providing safety of mining works should be developed, the measures of engineering protection of engineering structures should be worked out, the monitoring network schemes should be substantiated, and the sets of special geological research should be performed. These works are aimed at minimizing risks of accidents and emergencies both at operating and projected objects.

Hydrogeomechanical Conditions of Karst Sinkhole Formation in the Area of Potassium Mines in Berezniki T., Perm Krai

The study area refers to the class of highly complex geotechnical conditions. Hazardous geological processes (HGP) are active here, including high seismicity up to 7 points MSK-64, karst, suffosion, subsidence and collapses of land surface, underflooding and flooding, erosion, ecological processes, etc. Large industrial plants with hazardous production and complex infrastructure are in operation here. One such plant is the First Berezniki Potassium Production Mine (BPPM-1), which have been operated since 1954. Its mine field extends below the industrial zone and the residential quarters of the town. An accident took place here in 2006, resulting in the inundation of the entire mined-out space with a volume of more than 80 million m3 and the formation of huge collapses of land surface in 2007, 2010, 2011, and 2015. The geological structure of a mine in the Verkhnekamskoe deposit of potassium salts is used as an example to discuss the effect of two leading groups of geological factors on the formation of karst sinkholes. Analysis is given to the hydrodynamic conditions and geomechanical structure of the above-salt rock stratum, whose synergy determines the diversity of models of possible development of deformations and collapses of land surface. The article gives the possible development schemes of land surface collapses above the mined-out space. The objective of the study is to assess and forecast the development of hazardous geological processes in the territory of Berezniki T. based on the geotechnical interpretation of the available materials of geological works, engineering surveys, and integral monitoring observations.

Use of adaptive nonlinear Zernike filter in phase-contrast technique for registration of weak absorption of the medium

The use of photothermal Zernike phase-contrast filter for measuring the absorption of the medium proposed. Results of numerical simulation are given. It is shown that the efficiency is comparable to the imaging scheme that uses linear filters, with a significant simplification of the process of its adjustment.