Vol 54, No 2 (2018)

A method of fabrication of thick (~100 μm and more) resistive masks is described. These masks can be used for solving various engineering problems, e.g., for fabricating x-ray-absorbing topological patterns for LIGA masks, stamp microrelief, cast moulds, etc. Specific features of the contact photolithography method, which is used to design and fabricate the research device, are described. A source of exposure radiation in this device is a light-emitting diode. A possibility of obtaining individual elements of the resistive mask (in particular, with the lateral size ~5 μm, height of ~70 μm, and aspect ratio of ~14) and also the titanium stamp microrelief (with the height up to ~40 μm) generated by means of reactive ion-beam etching through the resistive mask, is experimentally demonstrated.

Results of the development and testing of a device for detecting and analyzing the diffraction pattern of computer-generated holograms are reported. It is demonstrated that this device allows characterization of the diffraction pattern of radiation reflected from the surface microrelief of the considered element or transmitted through it in the angular range of diffraction of the order of ±90° and 360° in terms of the azimuthal angle. A possibility of determining the periods, duty cycle, and angular orientation of diffraction structures and also the diffraction efficiency of all diffraction orders of the examined element is described. The device is designed for real-time monitoring of the microrelief depth and shape of computer-generated holograms in the course of their fabrication.

This paper describes a model of digital filtering of noisy contrasting images with minimum blur of brightness at the overfall boundary, which is based on smoothing out digital images with the help of the generalized method of least absolute values. The model requires variation of two parameters of the loss function as a function on the degree of contrast and noise level. The results are based on extensive computational experiments performed by the Monte Carlo statistical test method.

The characteristics of a piezo-optical transducer of a new design with high strain sensitivity at compact size have been studied.The original form of the photoelastic element provides a considerable increase in the stress in its working area at a given external force, resulting in an increase in the sensitivity of the transducer. The main characteristics of the transducer were measured using a specially designed device. The strain at a given applied force was calculated using a developed mathematical model of the transducer. As a result, the sensitivity to the relative strain was Δx/x=3 · 10⁻¹⁰, the dynamic range was at least four orders of magnitude higher and the gauge factor three orders of magnitude higher than those of strain-resistive gauges.

Multi-junction solar cells based on III–V compounds are the most efficient converters of solar energy to electricity and are widely used in space solar arrays and terrestrial photovoltaic modules with sunlight concentrators. All modern high-efficiency III–V solar cells are based on the long-developed triple-junction III–V GaInP/GaInAs/Ge heterostructure and have an almost limiting efficiency for a given architecture — 30 and 41.6% for space and terrestrial concentrated radiations, respectively. Currently, an increase in efficiency is achieved by converting from the 3-junction to the more efficient 4-, 5-, and even 6-junction III–V architectures: growth technologies and methods of post-growth treatment of structures have been developed, new materials with optimal bandgaps have been designed, and crystallographic parameters have been improved. In this review, we consider recent achievements and prospects for the main directions of research and improvement of architectures, technologies, and materials used in laboratories to develop solar cells with the best conversion efficiency: 35.8% for space, 38.8% for terrestrial, and 46.1% for concentrated sunlight. It is supposed that by 2020, the efficiency will approach 40% for direct space radiation and 50% for concentrated terrestrial solar radiation. This review considers the architecture and technologies of solar cells with record-breaking efficiency for terrestrial and space applications. It should be noted that in terrestrial power plants, the use of III–V SCs is economically advantageous in systems with sunlight concentrators.

In modern high-energy physics experiments, particular attention is paid to the global integration of information and computing resources into a unified system for efficient storage and processing of experimental data. Annually, the ATLAS experiment performed at the Large Hadron Collider at the European Organization for Nuclear Research (CERN) produces tens of petabytes raw data from the recording electronics and several petabytes of data from the simulation system. For processing and storage of such super-large volumes of data, the computing model of the ATLAS experiment is based on heterogeneous geographically distributed computing environment, which includes the worldwide LHC computing grid (WLCG) infrastructure and is able to meet the requirements of the experiment for processing huge data sets and provide a high degree of their accessibility (hundreds of petabytes). The paper considers the ATLAS grid information system (AGIS) used by the ATLAS collaboration to describe the topology and resources of the computing infrastructure, to configure and connect the high-level software systems of computer centers, to describe and store all possible parameters, control, configuration, and other auxiliary information required for the effective operation of the ATLAS distributed computing applications and services. The role of the AGIS system in the development of a unified description of the computing resources provided by grid sites, supercomputer centers, and cloud computing into a consistent information model for the ATLAS experiment is outlined. This approach has allowed the collaboration to extend the computing capabilities of the WLCG project and integrate the supercomputers and cloud computing platforms into the software components of the production and distributed analysis workload management system (PanDA, ATLAS).