The development of electrically tunable liquid crystal (LC) lenses is perspective and promising for a wide range of applications, for example, for imaging system, pico projectors, optical zoom systems, ophthalmology applications and other. Of particular note is the development of polarization-independent LC lenses, as eliminates polarizers from application devices that reduce the efficiency of light transmission through optical systems. Alignment benzaldehyde photosensitive materials, capable of changing the pretilt angles of nematic LC from 90 to 0 ºС in a controlled manner under UV exposure are developed. The anisotropy of the benzaldehyde alignment layers is generated by a two-stage treatment consisting of uniform rubbing with a cloth and subsequent non-polarized UV exposure. Inhomogeneous UV exposure of uniformly rubbed alignment layers allows formation of refractive index gradient inside the LC cell. The concept of tunable polarization-independent self-aligned LC lens based on gradient pretilt angle alignment materials with different photosensitivity is demonstrated. Self-alignment of two polarization-dependent sub-lens is achieved due to a single UV exposure act of two alignment layers, which are located on the same piece of glass on both sides, forming one common optical axis for a polarization-independent LC lens. The independence of the polarization of LC lenses is achieved by setting the azimuthal rubbing direction of the alignment layers of two polarizationdependent LC lenses perpendicular to each other. The sub-lens cells have uniform cell gap and are independently controlled using low-voltage driving. Devices based on gradient benzaldehyde alignment materials can be used in many modern optical and photonic devices.

In a known display cell with the nematic liquid crystal (NLC) and interdigital electrodes on one of the glass substrates, the “In-Plane Switching” (IPS) mode is implemented, in which the NLC main optical axis reorients in a plane parallel to substrates, providing the most correct color reproduction at different angles view, up to 178 ° horizontally and vertically. Unfortunately, the creation of interdigital metal electrodes complicates and increases the technological process cost and causes a decrease in image contrast. At the same time, experimental results and calculations based on classical electro-optics of crystals indicate that electrooptical switching in the IPS mode is a natural and intrinsic feature of a conventional (with continuous electrodes) display cell with a planar-oriented layer of the ferroelectric liquid crystal (FLC), in which the effect of the deformed (by the electric field) helix FLC nanostructure is realized (DHF effect). In such a cell, the reorientation of the main optical axis under the influence of a weak electric field also occurs in the substrate plane if the FLC has a small pitch (about 100 nm or less) and a large tilt angle of molecules in the layer (about 38 ° or more). The dependences of the FLC cell light transmittance measured in this work, confirmed the achievement of the IPS electro-optical mode in the DHF FLC cell; moreover, the light modulation frequency was 1 kHz. Thus, while maintaining all the advantages of the IPS mode known in NLC, its implementation in FLC allows additionally obtaining technological advantages and multiple increase in modulation frequency.

The dependence of the helical pitch of a cholesteric liquid crystal based on a composite photosensitive chiral dopant (cChD) on the intensity of light irradiation was studied. The transmission spectra and the selective reflection spectra of cholesteric liquid crystal cells were measured. The concentration of the cChD additive is calculated, so that the peak of selective reflection and its rearrangement occurs in the visible range of the electromagnetic radiation spectrum (380-780 nm). The possibility of photo-control by shifting the peak of the selective reflection of the cChD additive was studied, when exposed to LEDs with wavelengths of 365 nm and 450 nm, while reducing or increasing the intensity, a change in the spiral pitch was observed. Depending on the light intensity, part of the molecules of the chiral additive containing the azo group underwent isomerization, i.e. molecules in the trans-form passed to the cis-form, which led to a spectral shift of the selective reflection peak. If a small intensity of the 365 nm LED was applied, then some of the molecules were forced to transition from the trans- to the cis-form, and then, when illuminated with a 450 nm LED, from the cisto the trans-form. After reversible rearrangement, the properties of cholesteric liquid crystal changes due to interaction with light, because under the influence of light, the equilibrium ratio of the trans- and cis-isomers of the molecules of the substance changed, which macroscopically changed the torsion force of the chiral additive. Using two LEDs of 365 nm and 450 nm with different emission spectra, a reversible control of the cChD selective reflection peak in the visible range was obtained. The maximum displacement occurred at approximately 145 nm.

The object of research is liquid crystal materials of the nematic and smectic types containing modified nanoparticles of detonation diamonds, partially reduced graphene and nanoclay. The purpose of the work is the development of new functional materials with improved physicochemical and electro-optical characteristics. During the study, methods for chemical modification of the surface of nanoparticles were developed; the mesomorphic, dielectric and electro-optical properties of nematic and ferroelectric compositions, doped with modified nanomaterials are studied. It has been established that the effect of modified nanodiamonds on the mesomorphic, dielectric, and electro-optical properties of liquid crystals is large and depends on the size of these particles and the type of grafted functional groups. Small-sized diamond nanoparticles do not significantly affect the properties of liquid crystals. At the same time, conglomerates based on nanodiamonds with a diameter of about 50–100 nm can increase or decrease the dielectric anisotropy and the response time of liquid crystals by 1,5–2,5 times, depending on the polarity of the functional groups. It has been experimentally shown that the addition of a small amount of graphene flakes to nematic and ferroelectric liquid crystals can significantly improve the electro-optical response time (up to 2 times depending on concentration). There is a decrease in threshold (by 7–30 %) and saturation voltages (by 11–31 %). For ferroelectric liquid crystals, the addition of graphene leads to an increase in the tilt angle and a spontaneous polarization.

The relation between numerical values of photometric characteristics (total luminous flux TLF, correlated color temperature CCT, color rendering index CRI) of white light emitting diodes (LED) and the variation of the spectral shape of their radiation during aging has been investigated. All the measurements were made on internationally adopted test methods, taking into account environmental conditions, electrical parameters and evaluated measurement uncertainty. Every piece of test and measurement equipment has actual verification or calibration with traceability to national and international references. It was demonstrated that in the luminescence spectra consisting of the “blue” band around 450 nm originating from the semiconductor heterostructure, and the broad “yellow” band from luminophor, the last band is nonelementary and consists of at least two bands: the “green” one around 530 nm and the “orange” one around 580 nm. The most unstable “green” band has the highest impact on photometric characteristics. As a consequence, further investigation should be performed on how instability of elementary bands and its quantity will link not only with photometric characteristics, but with production conditions and material properties of LED heterostructure and luminophor itself. In particular, for improvement of the color stability of white LED, the parameters of luminophor forming the “green” band should be stabilized. А unified method for accelerated testing of LED products and method for long-time lifetime prediction shall be developed, taking into account not only depreciation of TLF, but also shift of other photometric and spectral characteristics of white LED.

The possibilities of improving the quality of the topological pattern in the exposure of thick-film photoresists due to uniform irradiation with ultraviolet light-emitting diodes are investigated. The results of an experimental study of the developed LED ultraviolet photolithographic irradiator with a controlled exposure time are presented.

The article discusses the prospects of creating controlled field-effect cathodes based on arrays of columnar oxide niobium nanostructures for field emission displays. Geometrical models of field-emission cathodes and vacuum elements have been developed and investigated. The distribution of the electric field in the vacuum device at various distances between the cathode and the anode, the applied voltages between them, the shape and microgeometry of the cathodes were obtained. The optimal geometric parameters of nanostructured autoelectronic cathodes and matrices of these were calculated based on the simulation. The technological route has been developed for the production of autoelectronic cathode matrices based on arrays of niobium-oxide columnar nanostructures formed by electrochemical anodization of Al/Nb thin-film system. The samples of controlled arrays of autoelectronic cathodes were fabricated and the current-voltage characteristics with interelectrode gap of 2, 5 and 10 μm in various electric modes with change in the electric field strength from 3 to 85 V/μm were studied. At 2 μm gap between the anode and cathode, the emission occurs at minimum threshold voltages, but it is characterized by limited current values. The increasing in the interelectrode gap allows rising the emission currents, however, the threshold voltages increase. In the pulsed mode, the large emission currents are achieved. The threshold voltage of autoelectronic cathode matrices with interelectrode gap of 5 μm was 9.16 V, the maximum currents reached 350 μA at voltage of 22.5 V. In the pulsed mode, the emission arose at 11.06 V, the maximum current reached 1500 μA at 40 V.

The article observes different methods of coating the phosphor screens on the tritiated titanium matrices for creating the solid-state radioluminescent light sources (SRLS). Technology of SRLS is alternative to the existing technology of the gas-filled radioluminescent light sources. The main idea of SRLS is in bonding the working isotope (tritium) in the solid matrix and combining it with the phosphor. The key problem of SRLS is to provide the closest contact between the tritiated carrier matrix and phosphor screen. The basic requirements for the phosphor screens for SRLS would be the strength of fixation on the plate, uniformity and radiological and thermal stability. There have been made a comparison of various techniques of coating and fixing the phosphor screens by their effect on spectral and brightness characteristics of SRLS. The improved sol-gel technique of suspended sedimentation of phosphor screen from the potassium water glass binder solution was developed. The composition of the solution was established experimentally and we get the strong and uniform experimental prototypes of the glass coated phosphor screens of various thickness. The developed technology allows to deposit the strong and uniform phosphor coatings without using any additional dispersing agents. Screen thickness regulates by the amount of phosphor in the suspension. Also the optimal thickness of the phosphor screen, giving the maximum luminescence intensity was determined. The two laboratory prototypes of solid-state radioluminescent light sources were manufactured by coating the phosphor directly on the tritium β-source.

The aim of the work is to develop a new highly efficient light-emitting structure of microdisplays based on organic light-emitting diodes (OLED) for the modernization of the microdisplayes MDO 02 of the mass production. It is also intended to use the new OLED structure in subsequent developments of new series of microdisplays, including a green glow. Сomplete microdisplay element consists of а active matrix and OLED structure, which is a set of layers of low molecular weight organic materials. The active matrix of the microdisplay MDO 02 contains 800×3(RGB)×600 pixels for the full-color version and 800×600 pixels for the monochrome version. Microdisplay MDO 02 has the following characteristics: the nominal brightness of the full-color glow is 140 cd/m2, the monochrome glow is – 560 cd/m2, the unevenness of the brightness is not more than 15 %, the contrast in relative units is not less than 100:1, the power consumption is not more than 450 mW, the operating time on refusal not less than 5000 hours. To improve these characteristics, it is proposed to use OLED structure, including materials with thermally activated delayed fluorescence (TADF). Materials with TADF have a much simpler synthesis scheme, an expanded selection of starting components and do not need expensive rare and rare-earth metals, which are used for the synthesis of phosphorescent materials. A structure with high light (external quantum yield up to 26.2 %) and electrical parameters with the described dopant synthesis process was selected from a number of OLED structure. This structure consists of four organic layers: hole-injection, hole-transport, emission and electron-transport. As a dopant for the emission layer, material aICTRZs based on indocarbosol derivatives was used. The dopant aICTRZs was synthesized by us according to the proposed synthesis method. The characteristics of this structure were evaluated using an ITO / TAPC (30 nm) / TCTA (10 nm) / CBP (25 nm) / Bphen (30 nm) / LiF (0.5 nm) / Al (150 nm). Although the optical characteristics of such an LED did not reach the declared values, they showed quite good results. As a result, such an OLED structure can be used as an initial one and, with its further development, one can count on stable and high results of the optical and electrical characteristics of MDs.

The aim of the work is to develop vacuum technological equipment for deposition an interference antireflection coating with the evaporation of a hydrophobic protective layer in a single vacuum cycle. To deposition an interference antireflection coating, the method of magnetron reactive sputtering in the alternating current mode with a frequency of 20 kHz is used. This method allows using of a wide range of sputtered materials and obtains stable and high-quality coatings on various substrates. To determine the optical characteristics, a spectrophotometer was used, which evaluated the transmittance and reflection in the visible region of the spectrum of electromagnetic radiation. To check the physical characteristics of the hydrophobic coating, abrasion test of the coating with metal wool with a load of 1 kg/cm2 was used. The novelty of the presented method is the combination of the liquid-phase coating method together with physical deposition in a vacuum without interrupting the process. This method allows increasing productivity and yield of suitable parts since the number of operations at the multi-stage stage of production of the touch display is reduced. After the development and adjustment of the Aurora G5 linear vacuum equipment, a stable and reproducible process for producing hydrophobic anti-reflective coatings over large areas with high performance was obtained. An antireflection coating was obtained with an average reflection coefficient of less than 0.6 % in the wavelength range of 400 to 700 nm. The adhesion test showed grade 0 according to the ISO classification. The resulting coatings have high hardness >9 H and abrasion resistance >5000 cycles. The result of this development and research is the introduction of vacuum processing equipment in the manufacturing process for the manufacture of anti-reflective hydrophobic coatings on touch displays.

In the article MEMS technologies for display production and application presented. UV-LIGA and greyscale lithography based on SU-8 resist approaches were shown. Methods, technologies and structures of heterogeneous materials with soft magnetic properties, pros and cons are discussed. Unique specific parameters of soft magnetic composite material were achieved: magnetic induction of saturation – 2,1 Т, working frequency range – up to 1 MHz, permeability – up to 3000, total loss – 8 W/kg, Curie temperature – above 800 ºС. Electroplating allows deposition of soft magnetic alloys on the conductive substrate. Metals like Fe, Ni, Co with additives like B, P were used to get the best soft magnetic properties. Special codeposition process was developed to allow insertion of soft magnetic composite powder filaments into soft magnetic matrix formed during. It allows developing magnetic micromotors for display production. Simulation of the hybrid step micromotors was carried out in Ansys Maxwell 19. It was demonstrated that it is possible to get 10 mN m tourqe under 25 μm rotor-stator air gap. Only presented microtechnologies can provide such accuracy of the mciromotors elements. As for greyscale photolithography, special grey mask were developed and it was demonstrated the possibility to produce controllable real 3D relief on the SU-8 photoresist. Thus, microtechnologies should be integrated into display technology to provide cost effective production and advanced properties of final products.

The aim of the work was to study the optical properties of the one-dimensional photonic crystals from ultrathin alternating layers of titanium and silicon oxides with different order of alternating layers to form defective half-wave layers in the bulk of the photonic crystal. The layer thicknesses were optimized by the dispersion of the refractive index and it was shown that for the formation of 16-layer photonic crystal structure without a half-wave layer with a photonic band gap in the UV region, it is necessary to use layers of titanium dioxide and silicon oxide with a thickness of 28.3 and 53.2 nm, respectively. The structure of the 26-layer photonic crystal with a thickness of 2130 nm with two non-equidistant half-wave layers forming resonant transmission bands in the photonic band gap with peaks at 550 and 601 nm is proposed. Due to the dispersion of the refractive index, the ratio of the thicknesses of TiO2:SiO2 layers varies from 1:1.88 in the case of a 16-layer structure with a photonic band gap in the UV region to 1:1.5 in the case of a 26-layer structure with a photonic band gap in the visible range . The effect of a photonic crystal structure without half-wave layers on the emission spectrum of a liquid crystal display manufactured using IPS technology has been demonstrated in order to reduce the intensity of the blue component to increase the safety of the user's vision. The using of the photonic crystals with two half-wave defective layers allows to achieve complete separation of the spectrum components, which can be used to modify the spectra of large liquid crystal panels, their manufacture using AMOLED technology is a very difficult technological task even for leaders in this field.

This paper presents the study of the optical properties of multilayer periodic structures, such as Bragg reflector, with different synthesis conditions. Transmission, reflection, luminescence, luminescence excitation spectra and kinetics of luminescence are presented for the Bragg reflectors formed on quartz with 6 and 12 alternating layers BaTiO3:Eu/SiO2. The structures demonstrate photonic band gap and its long wavelength shift with increasing number of layers. Europium luminescence with the most intensive band at 615 nm is observed from the structures. A decrease in the luminescence intensity with increasing the number of pairs of the layers in the structure is observed.

The paper presents the results of a study of thin-film transistors based on the InGaZnO semiconductor compound (IGZO) for active-matrix displays addressing formed by magnetron plasma-chemical deposition. Their structural-morphological and electrophysical properties are investigated. Carrier mobility is analyzed using the Hall method. The effect of annealing in vacuum, an oxygen atmosphere, and a nitrogen atmosphere on the grain size of an IGZO film was investigated. The resulting layers are characterized by high mobility of charge carriers, which allows their use in the manufacture of new-generation LCD and OLED displays.

The results of research the surface of single-crystal silicon, glass, and stainless steel after processing in a plasma at atmospheric pressure are presented. It has been experimentally proved that after processing, the adhesive properties of the surface of materials are significantly improved.

Recently, problems of digital image sharpness determination are becoming more relevant and significant. The number of digital images used in many fields of science and technology is growing. Images obtained in various ways may have unsatisfactory quality; therefore, an important step in image processing and analysis algorithms is a quality control stage of the received data. Poor quality images can be automatically deleted. In this article we study the problem of the automatic sharpness evaluation of digital images. As a result of the scientific literature analysis, 28 functions were selected that are used to analyze the clarity of digital images by calculation local estimates. All the functions first calculate local estimates in the neighborhood of every pixel, and then use the arithmetic mean as a generalized quality index. Testing have demonstrated that many estimates of local sharpness of the image often have abnormal distribution of the data. Therefore, some modified versions of the studied functions were additionally evaluated, instead of the average of local estimates, we studied the Weibull distribution parameters (FORM, SCALE, MEAN weib, MEDIAN weib). We evaluated three variants of the correlation of quantitative sharpness assessments with the subjective assessments of human experts. Since distribution of local features is abnormal, Spearman and Kendall rank correlation coefficients were used. Correlation above 0.7 means good agreement between quantitative and visual estimates. The experiments were carried out on digital images of various quality and clarity: artificially blurred images and blurred during shooting. Summing up results of the experiments, we propose to use seven functions for automatic analysis of the digital image sharpness, which are fast calculated and better correlated with the subjective sharpness evaluation.

The paper discusses the work of the correlation algorithm for automatically tracking objects of interest in a two-channel optical-electronic system in a complex background-target environment and the presence of intentional interference. Conditions in which the contrast of the desired object in both channels is negligible but not equal to zero are considered difficult in the paper. Intentional interference refers to masking interference of natural and artificial origin, which helps to reduce the contrast of the object in both channels. By two-channel means an optical-electronic system, which includes channels of the visible and infrared ranges. It is believed that the multi-spectral images of both channels are reduced to a single time and scale, which allows them to be integrated using various methods. The purpose of this paper is to prove that the likelihood of disruption of automatic tracking is reduced when complexing the source images of the visible and infrared ranges, when the contrast of the desired object in both channels is negligible. For research the mathematical apparatus of the theory of random functions and simulation with subsequent statistical data processing are used. It is shown that the probability of disruption, characterized by the ratio of the correlation coefficients of two fragments of images, one of which contains the desired object, and the second not, depends on both the correlation coefficients and the values of their mean square deviations. The simulation shows that the breakdown of tracking occurs both when the mean square deviations of these correlation coefficients are equal, and at their different values, moreover, an increase in their difference increases the probability of a breakdown. The article shows that the likelihood of a breakdown in a two-channel optoelectronic system will decrease when using two channels, compared to working only in the visible or infrared channel. The obtained results substantiate the promise of using image complexing in multichannel systems of automatic tracking of objects in a complex background-target environment and the presence of deliberate interference.

The purpose of the work, the results of which are presented in this article was to study the possibilities and different options implementation of the modular approach to developing the content and organization of training. The relevance of such studies is due to the need to train highly qualified specialists in the operation, maintenance and repair of electric vehicles. This professional field is relatively new and actively developing in our country. Therefore, the system of training, retraining and advanced training of personnel for the electric vehicle industry and maintenance of electric vehicles should be flexible and dynamic. Vocational training should be organized in accordance with the changing requirements of the modern labour market. The paper shows the advantages of using modular educational technologies for the organization of professional education in this area. Taking into account the experience gained in the process of training students of the specialty "Industrial electronics" in IIT BSUIR, it is noted that the advantages of the modular approach are increasing many times in combination with the use of modern possibilities of infocommunication technologies and 3D-modeling for training, retraining and advanced training of specialists in electric vehicles. Based on the consideration of the concept of "Modules of labor competencies", developed by experts of the International labor organization, the structure of the modular curriculum for the study of displays, and the modern electric vehicle as a whole is proposed.

Electrical characteristics of the heterostructure titanium dioxide/silicon illuminated by the sun light were theoretically modeled. The modeling process includes consideration of generation of the charge carriers and their transport through the practically important heterostructure n-TiO2/p-Si. The current through the structure under small external bias up to 0.6 V was found to depend nonlinearly on the light wavelength. It is controlled by the movement of the electrons from silicon to the titanium dioxide. The highest current corresponds to the wavelengths of about 600 nm. The results obtained are explained by the difference in the absorption coefficients and reflectivity of titanium dioxide and silicon which determine generation of nonequilibrium charge carriers in the heterostructure n-TiO2/p-Si. It was demonstrated that under illumination of the unbiased heterostructure with the light of 500–600 nm the generated electrons freely move from the titanium dioxide to silicon while the movement of holes is blocked. It helps to concentrate electrons in the relatively thin nearsurface layer of titanium dioxide and use them for catalytic purification of water and air by oxidation of organic pollutants at its surface. The regularities observed are important in the detailed analysis of electronic processes at the surface of wide band gap semiconducting metal oxides and their practical application in photocatalytic processes.

In order to develop a technology for the growth of Al(Ga)N-based heterostructures, the effect of different molecular beam epitaxy growth conditions on the properties of AlN and AlGaN layers was studied. The optimal conditions for the growth of AlN buffer layers were established, which made it possible to achieve a root mean square roughness as small as 0.7 nm. It was shown that an increase of AlN layer thickness leads to a decrease of density of edge dislocations, while no explicit dependence of the screw dislocation density
on the layer thickness was observed. The minimal obtained dislocations density values for 1.25μm-thick AlN layer were nedges = 5.9×109 cm-2 and nscrew = 2.2×107 cm-2 for edge and screw dislocations respectively. As a result of optimization of the AlGaN growth temperature, a series of 0.15μm-thick layers was grown, which showed stimulated emission at wavelengths λ = 330 nm, 323 nm, 303 nm, and 297 nm with threshold power
densities of 0.7 MW/cm2, 1.1 MW/cm2, 1.4 MW/cm2 and 1.4 MW/cm2, respectively. The determined optimal epitaxy conditions for AlN and AlGaN layers were used to grow the AlGaN/GaN high electron mobility transistor structure on a sapphire substrate with two-dimensional electron gas, which had a mobility of 1950 cm2/(Vs) at a concentration of 1.15×1013 cm-2. The obtained results are important for creating of nitride-based
UV-emitting optoelectronic semiconductor devices, as well as high-power and high-frequency electronic devices.

Sapphire cutting is one of the largest markets in laser materials processing. Since sapphire is one of the hardest transparent materials its mechanical and optical properties made it the ideal choice for use in the production of various devices, such as LEDs and transistors, cover glasses of watches and mobile devices. Among existing laser- or diamond-based tools solutions, femtosecond laser scribing appear as a promising technology since this technology has the unique capacity to produce highly localized bulk modification owing to non-linear absorption. Sapphire cutting with solid-state lasers is well known for many years and has become a modern industrial process. However, achievable process speed and cut quality are still limited. The femtosecond laser scribing of sapphire was studied at wavelengths of 1040 and 520 nm, followed by wet etching in HNO3/HF solution to identify emerging defects. The morphology of the laser ablated sapphire surface was evaluated by scanning electron microscopy. It was shown that at the wavelength of 1040nm, the material was effectively removed from the surface; however, cracks on the surface were formed. The use of the second harmonic gave more accurate and deep cuts compared with the main frequency at the same conditions. At the wavelength of 520 nm, the cracks were formed anisotropically inside the volume of the material. Therefore, there is a potential application of the femtosecond laser scribing for the fabrication of sapphire-based devices.