This PDF file contains the front matter associated with SPIE Proceedings Volume 12938, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

This paper describes some historical moments of Correlation Optics Conference, since 1991, the first conference which was organized in Chernivtsi National University, Ukraine. It was remembered the first persons, participants of the conference, noted interesting details of Correlation Optics organization, peculiarities of formation of the scientific groups due Correlation optics cooperation and its influence on the development of optics in Ukraine. Some outstanding technical results were presented, noted interesting facts that cover optical correlation diagnostics, interferometry and microscopy of rough surfaces, new applications of correlation optics in biology and medicine, nanooptics.

Present work includes a computer simulation of temperature- and pressure-induced spin transition phenomenon in a 2D spin crossover nanosystem. Modeling was carried out within a framework of an Ising-like model with the help of Monte Carlo technique based on metropolis algorithm. All the obtained results are in accordance with the experimental ones. For a fixed values of temperature, a reverse spin transition of the system was obtained. Brief review of possible practical application of such type of a system is presented.

A solution is proposed for the the front amplifier of the nuclear quadrupole resonance pulsed Fourier spectrometer, and its noise and signal characteristics are investigated using complex SPICE simulation of the electrical circuit diagram. The study made it possible to carefully analyze the main characteristics of the pre-amplifier and find out the possibilities of its application in the low-frequency region of the short-wave frequency range (2 MHz - 6 MHz), which is attractive for the possibility of identifying spin induction decay signals from explosive and narcotic substances. In particular, the optimal number of parallel-connected active elements of the input stage was investigated, which made it possible to reduce its own noise voltage to 12.8 nV/√Hz, and the modes of operation of the cascades of the entire circuit were determined, which made it possible to achieve a maximum gain of 74 dB at an input sensitivity of  10 V. The frequency characteristics of the amplifier were also studied, the analog bandpass filter and the elements of input and output impedance matching schemes were calculated.

Nuclear quadrupole resonance is one of the express and highly informative methods of experimental research and has a number of practical applications, in particular for pulse detection of explosive and narcotic substances in non-metallic containers, which include the 14N isotope. One of the key problems of equipment of this class is the need to use a specific radio frequency transmitter, which must correspond to the given signal and energy characteristics. The paper proposes an applied solution for the operating layout of such a device for a pulsed Fourier spectrometer of nuclear quadrupole resonance and considers the key aspects of battery power supply. Experimental studies have confirmed that the device provides amplification of excitation signals up to 1.2 kW in the frequency range 100 kHz - 10 MHz and up to 1.7 kW at the resonant frequency 14N - 4.65 MHz.

In this paper, a method of automated positioning of two photonic crystal fibers is proposed, which takes into account the angle of mutual rotation of the fibers around their longitudinal axis. This makes it possible to take into account the structure of the fiber mode field during the connection process and reduce optical signal losses due to the difference in mode fields. The developed algorithm and software implements the proposed method and allows you to automate the process of controlling the positioning of photonic crystal fibers according to the size and shape of the mode field, and also performs the calculations necessary for further analysis and finding the position of the maximum diameter of the mode field. Based on the obtained results, it is possible to ensure the correct mutual orientation of photonic crystal fibers with minimal introduced losses on the connections. The main advantage of the developed algorithm is its sensitivity, which allows recognizing even minor changes in the diameter of the mode field.

One of the newest stages in the improvement of unmanned aerial vehicles (UAVs) is the integration of such systems with artificial intelligence (AI), which, in turn, is not a novelty, but provides such systems with a further level of practical application. Having conducted a meta-analysis of the results of previous studies and available information on this topic, it was found that in the modern period, in addition to successful practical implementations of the integration of artificial intelligence with UAVs, there is already a certain classification of such processes according to the principles of optimal improvement of UAV capabilities and by areas of society. In addition to the publicly available and well-known information about the successful use of drones in the military and logistics sectors of human activity, UAVs successfully perform tasks in such sectors as agriculture, engineering, search, etc. The purpose of the article is to analyze, research, review and systematize existing information on the positive effectiveness and feasibility of using the principles, approaches and integration of unmanned aerial vehicles with AI technologies to improve the efficiency of solving the tasks of detecting landmines and minefields, which is a major humanitarian problem for civil society located in the territory where military conflicts are currently taking place or in the territories where military clashes or conflicts have occurred in the past.

The general concept of a non-dispersed optical infrared CO2 sensor is developed in this work. Its feature is simplicity, cheapness, and miniaturizes. An analysis of the modern component base is carried out with the selection of the necessary elements, such as an infrared emitter and a sensitive element. The performance characteristics of the sensor are considered based on a datasheet of an analog infrared photodiode AK9710ADF01. The sensor is built on the basis of a mid-IR quantum photodiode. An optical bandpass filter is used. The normal operating temperature range is from -40◦ to 90◦ . The element has a built-in optical filter designed for a wavelength of 4280 nm. For the interaction of the sensitive element with the microcontroller, it is applied a signal amplification scheme, based on OPAMP AK2920. The life time of photoinduced electrons, at which the device operates in BLIP mode, is determined. On the basis of these data, it is concluded that modern technologies for the production of photodiodes based on indium antimonide InSb provide the possibility of operation in the BLIP mode, while the speed of operation is acceptable for the operation of the photodiode as a gas sensor.

A new polarization-interference approach based on geometric phase for estimation of optically anisotropic media properties, is proposed. Linearly birefringent object is probed by linearly horizontally polarized incident beam, and the resulting polarization depends on the medium properties such as birefringence (phase retardation) and optical axis orientation. The modified Mach-Zehnder interferometer is used to obtain the polarization-interference pattern in two channels for determination the dynamic and geometric phase. The dynamic phase depends on the mean refractive index and allows to estimate the medium thickness, while the geometric phase is the function of medium polarization properties (birefringence and optical axis orientation). Thus, the dynamic and geometric phase values allow to estimate the medium optical properties, such as optical thickness, phase retardation and/or optical axis rotation.

Model of polarized light interaction with anisotropic biological medium, on the example of eye cornea, is given. The polarization of the object field, which occurs during propagation through a birefringent medium, in the case of a linearly polarized incident wave, is analyzed. A polarization-interference approach for determining the polarization characteristics of the medium is proposed, which consists in analyzing the change in polarization of the field that occurs during interference of the object and reference beams. The condition of compensation of the dynamic phase allows to obtain a polarization state, determined exclusively by the geometric phase of the object field, which contains information about the polarization properties of the medium. The geometric phase value was evaluated by the geodesic triangle on the Poincaré sphere, which made it possible to restore the orientation of the optical axis (collagen fibers) of the biological medium.

Method based on polarization-interference for determination the geometric and dynamic phase in a case of linearly birefringent, internally reflective media is proposed. The object is probed by horizontally polarized incident beam, and the resulting interference distribution consist of two components depending on medium orientation. The interference of horizontal components of object and reference field allows one to estimate the sum of dynamic and geometric phases, while the vertical components interference produce the dynamic phase. The proposed method allows one to estimate the geometric phase value in a case of only one input polarization state.

Carbon nanoparticles of about λ/10 in size and with the following optical properties: strong absorption and luminescence in the yellow-green region of the spectrum and weak absorption at the wavelength of He-Ne laser radiation, were proposed to use for diagnostics the distribution of optical flows in the speckle field obtained from polygraphic material, in particular glossy materials, the value of height inhomogeneity of which is proportional to the wavelength. The advantages and disadvantages of the existing roughness analysis methods of printing materials are analyzed. The scheme of the model experiment for study the movement of carbon particles in the speckle field is presented. Under the influence of gradient optical forces, carbon nanoparticles move in the optical field and are trapped by field singularities. The tracks of the movement of carbon nanoparticles under the action of the components of the resulting optical force until the moment of their capture by field singularities are experimentally demonstrated. It is shown that the concentration of particles and the intensity of luminescence differ significantly in areas with and without singularities.

Paper, matte and glossy materials (packaging materials) are one of the most common printing materials, particularly among those used in packaging. Glossy materials are characterized by height inhomogeneity of about 0.6 μm, which is comparable with the wavelength of the He-Ne laser that forms the speckle field. Obtaining amplitude-phase information for research of structurally heterogeneous packaging materials is an urgent task today. This study considers a model for analyzing the behavior of fluorescent carbon particles in a speckle field obtained from a glossy material. The application of the Hilbert transformation makes it possible to recover information about the phase distribution of the investigated optical field. To restore the phase information, the localization of carbon nanoparticles at the minimum intensity points with singularities and without singularities was used, with the addition of lost information to restore the phase map using the Hilbert transformation. Determining the location of carbon nanoparticles by fixing their luminescence significantly improves the overall picture of the phase restoration of the investigated object due to the high accuracy of reproducing the information about the localization of points of minimum intensity with singularities.

In this study, a new approach of surface analysis and restoration of the three-dimensional landscape of ultra-smooth surfaces is proposed. The use of carbon nanoparticles with a significant dipole moment and luminescence intensity is proposed for diagnosing the heights of surface inhomogeneities. To reproduce the profile of the studied surface, we use two successive stages of studying the surface. At the first stage, it is assumed that the electric field acts on a glass plate on which carbon nanoparticles are distributed. At the second stage, it is considered that the electric field acts on the plate, without nanoparticles. Significant luminescence of carbon nanoparticles allows visualization of the particles with subsequent reconstruction of the intensity distribution and reproduction of the surface structure according to the distribution of inhomogeneities.

This study examined the problems associated with the registration and visualisation of medical images. Scientific computing in the field of medicine was carried out and an intelligent system was developed to identify diseases based on these images. An approach to detecting affected tissue areas in medical images was proposed. To achieve this goal, a neural network was used, which was trained to identify masks of affected areas. The masks were identified by annotation, where polygons with affected tissues were highlighted. The objects under study were classified by disease type.

Control of the intensity of bactericidal radiation with a wavelength of 254 nm is an urgent task for medical UV radiometry. UV radiometers based on appropriate photodiodes are used to solve this problem. We have developed a mathematical model and design of a silicon-based photodiode with a thin epitaxial layer up to 2 μm thick and a 30 nm SnO2(F) layer that creates a barrier p-n junction. A study of the created structure was also conducted. The proposed design of the photodiode is implemented on the basis of standard planar technology, which is used in the manufacture of conventional silicon photodiodes. The photodiode is sensitive mainly in the ultraviolet range of the spectrum (200-400 nm). At the same time, it has a value of current monochromatic sensitivity at a wavelength of 254 nm at the level of 0.08 A/W. At the same time, the created photodiode has a certain level of sensitivity at wavelengths greater than 380 nm. But, according to spectral studies, the level of this sensitivity does not exceed 10% of the sensitivity at a wavelength of 254 nm. The photodiode works in photovoltaic mode. Therefore, the overall level of intrinsic noise of the photodiode has little effect on its sensitivity.

In the proposed study, a topical issue of modern electronics is considered - the creation of an algorithm for ensuring the stability of FSO technology against optical interference, and its solution is proposed using a photo-receiving device by optimizing the optical unit (photodiode - light filter) and creating an original design of a photo signal processing circuit that ensures the selection of a useful signal of a certain frequency modulation and compensation of background lighting. The created pair of optical filter - photodiode provides pulsed current monochromatic sensitivity of the photodiode at the level of 0.26 A/W at a wavelength of 980 nm and practically zero sensitivity at wavelengths shorter than 920 nm. The PRD design selects the useful signal in the frequency range of 3 kHz - 2 MHz and suppresses the frequencies of the background signal in the low frequency range from the constant component to 3 kHz. It compensates the background current up to 15 mA, which is equivalent to the power of light interference up to 15 mW. Further research should answer the questions regarding the reliability of the proposed PRD design and the optimization of its optical system. Practical application of PRD is carried out in construction, as well as in geodesy and control of atmospheric purity

A computer system for adjusting the «Brightness» and «Contrast» parameters of USB video cameras is developed, which consists of video cameras, computer and Python software. The settings of the video camera are performed by a computer program using an artificial neural network (ANN). A three-layer perceptron with learning by the method of backpropagation was used as an ANN. The inputs of the ANN are histograms of the brightness of the images, that read from the video camera. The ANN training dataset contained a series of images obtained at different values of the "Brightness" and "Contrast" parameters of the video camera. The settings of the video camera parameters are performed iteratively with a given step. An experimental test of the developed system for adjusting the "Brightness" and "Contrast" parameters of the video camera was performed, as a result of which the visual quality of the video stream was increased.

Geometric structure - a set of material objects (structures), built according to the functional idea of the product. There are two levels of this structure: external; internal. External structure - appearance, form of choice or External Geometric Structure (EGS). Otherwise, EGS is an artistic and design solution of the device. The internal structure is the assembled element base of the product in a geometrically limited space. According to the Vienna diagram, the external geometric structure is presented in the form of technical, aesthetic and ergonomic functions. In our consideration, we introduce the fourth component of the external structure - the protection function, which limits the space of the product and is provided with a casing (sheathing), which in special cases is called a hood - physical protection.

An optical image obtained using autonomous small-sized mobile optical systems (ASMOS) needs pre-processing. Modern ASMOS do not allow the use of on-board powerful computing facilities for primary processing. Such systems operate offline, without communication with a server. The limited computing power of a microcontroller (16 kB of flash memory) does not allow them to install a full-fledged operating system and JVM to use powerful neural networks. The object of this study is to provide primary processing of the optical image directly on ASMOS. The solution of this problem - recognition, coding, encryption, hashing of an optical image directly on ASMOS is provided by the technologies of cellular automata (CA). The implementation of new approaches based on CA to the main cryptographic directions is briefly considered: symmetric encryption, hashing, generation of pseudorandom series. The proposed systems were tested both by standard means of testing NIST STS cryptoresistance and by means of testing resource consumption of computing equipment (memory, speed) for various programming languages (Java, C#, C++, Assembler) .

Edge detection is an image processing technique used to identify and highlight the boundaries of different objects or regions in an image. In this paper, we propose a novel application for edge detection – adapting illustrations in both print and electronic publications to make them accessible to people with low vision. Normally, many illustrations can be problematic for people with low vision due to insufficient contrast, small details or densely packed visual elements. We showcase how with the help of several different edge detection algorithms these illustrations can be converted into clean, simplified lineart.

A wide range of consumables and equipment, high requirements for the quality of printed products, the use of triad and mixed inks in flexographic printing, lead to the need to carry out thorough incoming control of new raw materials and conduct test printing, obtain a reference print before starting the run. In this regard, the research of color formation in the "printing form-imprint" system when using new consumables for flexographic printing in the technological process is always an urgent task. Prints from a real order were selected for the study. Profiles printed on various non-sticky printed materials and samples of flexible packaging were used as test fragments. Visually and instrumentally, the stability of color reproduction during flexographic printing of flexible packaging and labels was investigated. The dependence of the saturation of CMYK and Pantone colors on the print on the printed materials used and the presence of a white substrate was determined. The pre-printing of non-woven material with white ink affects the subsequent color saturation indicators on the print and improves the color characteristics.

An intelligent web portal for analysing and forecasting the exchange rate of commodity money has been developed. The result of this research is a comprehensive system that allows for the analysis of the commodity money market, including price forecasting and risk assessment. The study identified the prophet method for predicting the exchange rate of a commodity unit and the monte carlo method for predicting the value of an investment portfolio with various assets. These methods allow us to reliably determine future trends based on the analysis of available data. To implement the web portal, we used the streamlit framework, which allows us to quickly develop interactive web applications using machine learning and data analysis tools. The scikit-learn library was used to work with machine learning, which has a wide range of tools for applying classical machine learning methods. The yfinance library was also used to retrieve financial data from the Yahoo Finance web service.

In some applications, including but not limited to synthetic-aperture radar (SAR) imagery and wireless communication, the Weibull distribution is more flexible than the exponential distribution for these purposes, because it fits particularly well at the heavy tail of the sea clutter. In this paper, we conduct a statistical analysis of Stokes parameters based on random polarization phasor sums. We provide a comprehensive analysis for the statistical properties of the Stokes parameters in stochastic electric field with a Weibull-distribution intensity. The presented statistics of the Weibull-distribution optical field will be useful to optical scattering from random birefringent medium and polarization speckle imaging, which can also be extended to deal with the characterization of the scattering matrix in radar polarimetry.

Optical fields with rich and well-developed spatio-temporal structure (e.g., ultra-short light pulses) contain a continuous spectrum of monochromatic constituents. However, some substantial features of such fields can be understood based on simplified models involving only two monochromatic paraxial components. We consider examples of such model beams which, in particular, enable a consistent analysis of the photon-probability distribution, its similarity and discrepancies with the energy distribution.

We considered the acousto-optic interaction of the optical and acoustic beams bearing spin and orbital angular momenta as well as vector beams of different polarization orders. The acousto-optic diffraction will be considered at the various conditions and geometries, i.e., tangential and collinear diffraction, diffraction in the presence of conical refraction, etc. As a result, the acousto-optic rules of the topological algebra of the strength of defects embedded into acoustic and optical beams have been demonstrated. The experimental results approved theoretical investigations of the acousto-optic interaction of singular acoustic and optical beams are presented.

Thermoelectric coolers (TECs) are widely used to ensure a stable operating temperature of IR detectors, which are the main component of most optical electronic devices. Cooling improves such parameters of IR detectors as sensitivity, detectability, speed, range of spectral sensitivity, reliability, etc. TECs provide cooling on a temperature level of up to 190 K. Modern research is carried out in the directions of expanding the temperature range of the TEC and of increasing its coefficient of performance. The paper considers the use of optimal control theory in the simulation of TEC, matched with the parameters of the photodetector. The methods make it possible to determine the most suitable thermoelectric materials, optimal structure and optimal operation mode of TEC. Examples of TEC simulation for IR detectors by means of optimal control methods are given.

The technology of quantum cryptography, based on the quantum properties of light, allows a random sequence of bits to be transmitted over an unprotected communication channel in such a way that an attacker's interference in the transmission process creates additional noise in the channel and is detected by legitimate users. One of the important elements of a quantum system is a single-photon detector. The closest to solving this problem is a device for recording single photons using avalanche photodiodes (APD) [1 - 6]. In this work, a scheme for amplifying current pulses flowing through a single-photon detector is proposed, using a charge-sensitive amplifier Amptek A250. The noise characteristics of the Amptek A250 amplifier are such that its contribution to detector noise is negligible. After amplification, the pulses are fed to the inputs of the comparators. The amplitude discrimination threshold of the first is selected above the level of the amplifier's own noise. The amplitude discrimination threshold of the second comparator is chosen so that the speed of pulse counting at the output of the first comparator is n times greater than at the output of the second comparator. From the outputs of the comparators, pulses are fed to the input of the microcontroller. When the microcontroller calculates a given number of N pulses, a corresponding signal for the DAC is formed at its output, which converts the digital signal into a control voltage for the power source of the avalanche photodiode. The developed device allows to increase the quantum efficiency of registration up to 48%.

The method of quantum communication using sideband-modulated emission allows for efficient integration of devices constructed on this principle into optical fiber communication lines due to a number of advantages, including the absence of complex distributed interference schemes, simplification of the phase alignment task of the transmitter and receiver modules, and a significant increase in spectral efficiency of the use of the optical fiber communication line [1, 2]. The development of low-loss quantum communication methods using sideband frequencies, the efficiency of which does not depend on uncontrolled polarization change in the communication channel, and the development of methods for high-speed generation of quantum states are important theoretical and practical tasks. A semiconductor frequency-tunable laser with a central wavelength of 1550 nm, a bandwidth of 1.5 MHz, and a tuning step of 0.005 nm was used as the radiation source. The signal attenuation in the filter band is 43 dB, which allows to apply a modulation index of 0.05 with a contribution of the central wavelength to the quantum bit error rate of not more than 0.1%. The error rate when using the compensation scheme does not exceed 0.5%. The losses in the receiving module are 6.4 dB, which consist of losses of each modulator, on the polarization beam splitter, mixer, filter, and optical connectors.

In the commercial production of products by digital printing, an urgent task is to ensure stable visual characteristics of the image, both on different types of paper and within the limits of the print run. An objective evaluation of the indexes of the prints of digital printing on various materials is carried out based on determining the optical characteristics of the prints, capture the image gradation, colour tone and brightness, uniformity of the distribution of the ink layer on the prints. To obtain predicted printing results, the preparation of original layouts is usually carried out taking into account the properties of the printed material and printing technology. In cases where the material is uncertain or changing, it is difficult to obtain the predicted optical indexes of prints. The paper is devoted to the study of the influence of the properties of printed materials and the characteristics of digital printing machines on the optical indexes of prints of digital printing. A method of conducting the printing process is proposed, including a set of recommendations for stabilizing the optical indexes of prints.

The article presents the results of foil embossing studies on synthetic paper. Based on the results of research, the influence of technological modes of foil embossing on the optical indicators of prints has been determined. According to the obtained results, the following regularities were found: at the heating temperature of the cliché in the range of 60-80 ºС, the transfer of the foil occurs unevenly, with indistinct torn contours, which is also characteristic of materials based on cellulose fibers; optimal reproduction of the image was obtained at temperatures of 95-120 ºС, embossing time 1 s; when the heating temperature increases above 130 ºС, the image is distorted, the material is significantly deformed, the color of the foil significantly changes, and the gloss changes, which primarily affects paper with a thickness of 200-300 microns.

Today, flexographic printing technology is dominant in packaging production. Therefore, the research on factors affecting the quality of imprints obtained by flexographic printing, in particular on film materials, is relevant. A comparison of the quality of flexographic imprints on PET obtained at different printing speeds was made. Control charts for the measured imprint indicators (optical density, raster dot compression, contrast, print stability) were constructed. In the process of analysis, some deviations from the standards were found, in particular optical density, which can be related to the change in viscosity of the ink in the process of increasing the printing speed. Using optical and electron microscopy, the influence of the parameters and cell structure of the anilox roller on the shape and size of the raster dots on the imprint was investigated. Based on microscopic studies of the surface and morphological structure of the substrates, the influence of the surface topography of the film materials on the densitometric and colourimetric indicators of the printed images was confirmed. The analysis of the phenomena of the interaction of ink with the film material during the imprint’s formation in the process of high-speed printing was carried out. Using the method of morphological analysis, the effectiveness of the interaction of the main influencing factors on the quality of printed images on packaging made of film materials was determined. A multi-level hierarchical model has been developed, which takes into account the factors affecting the quality of flexographic imprints during the production of packaging.

The results of diagnostic application of vector-parametric polarization mapping and polarization-interference phase scanning with digital holographic reconstruction of layer-wise polarization maps of azimuth and ellipticity of phase nonuniform object fields of soft tissue layers are presented for the differential diagnosis of necrotic and pathological changes in optically anisotropic polycrystalline components of myocardium - "ischemic heart disease (IHD) - acute coronary insufficiency (ACI)". All investigations within representative groups of histological sections were performed using circularly polarized laser beam illumination, ensuring azimuthal invariance and reliability of group polarization measurements. Integral and layer-wise maps, as well as histograms of distributions of random variables of azimuth and ellipticity of polarization in microscopic images of histological sections of human organ tissues with various types of pathology, are presented. Systematized tables of statistical moments of 1st-4th orders characterizing the maps of azimuth and ellipticity of polarization in microscopic images of histological sections of human organ tissues with various types of pathology are provided. A set of the most sensitive diagnostic markers, which are statistical parameters most responsive to changes in the polycrystalline structure of biological tissues, has been identified.

The paper proposes a method of radio frequency conversion of optical spectrum using an electro-optical modulator of moving mirror Fourier spectrometer, which allows to obtain high resolution with small movement of moving mirror Fourier spectrometer. The results of experimental measurements are presented.

The presented results are the outcomes of wavelet analysis of layered maps of polarization azimuth and ellipticity for diffuse images of biological tissues with the following pathologies: myocardium - "ischemic heart disease (IHD) - acute coronary insufficiency (ACI)". The coordinate maps and linear profiles of multiscale wavelet coefficients are provided, which characterize the coordinate distributions of azimuth and ellipticity values of the multiply scattered object field of optically thick layers of biological tissues with different morphological structures and pathological conditions in the phase cross-section 𝜃 = 𝜋⁄8, where the influence of the diffuse component is minimized. Tables of statistical moments of 1st to 4th orders are presented, which characterize the distributions of amplitude values of multiscale wavelet coefficients for maps of polarization azimuth and ellipticity of diffuse microscopic images, and diagnostic levels of differentiation accuracy for various pathological conditions are revealed.

Within the framework of a statistical approach, physical correlations were determined between the central statistical moments of the 1st to 4th orders characterizing integral and layer-specific maps of linear and circular birefringence and dichroism in dehydrated films of biological fluids, as well as different types of architecture of optically anisotropic polycrystalline structures. Regularities and statistical scenarios of transformation were established for holographically reconstructed layer-specific spatially non-uniform distributions of phase and amplitude anisotropy parameters (magnitude and position of extrema, ranges of histogram variation) in dehydrated films of polycrystalline biological fluids.

Methods for determining the angular orientation of objects using interferometric measurements of different-frequency signals reflected by corner reflectors of satellite systems are considered. Determining the angular orientation of objects is one of the most common ways to expand the functionality of the consumer equipment of satellite radio navigation systems. The proposed method provides the determination of the angular orientation of a distant object based on the results of the analysis of the frequency spectrum of the reflected signal. The method is implemented using corner reflectors consisting of mutually orthogonal plane-parallel plates of different optical thicknesses. Each face (plane-parallel plate) of the corner reflector forms a unique frequency spectrum of the reflected signal. The desired value of the angular orientation is determined based on the analysis of the frequency spectrum of the recorded reflected signal and the criterion of maximum similarity of the spectrum of a certain orientation of the corner reflector faces. With normal incidence of the probing beam on a plane-parallel plate of a corner reflector, only one frequency is present in the spectrum of the recorded signal. The appearance of only one frequency, determined by the optical thickness of the reflecting plate, serves as a criterion for the orthogonal orientation of the corner reflector and the distant object, respectively.

The development of the printing and packaging industry contributes to the emergence of new printing and finishing technologies. To ensure the quality of imprints, it is important to take into account the optical indicators of the substrates, such as colour, whiteness, shade, gloss, light transmission, and opacity. The objects of research were offset and flexographic imprints on paper, cardboard, and corrugated cardboard with different surface structure and composition. As a result, research has confirmed that the coated surfaces of substrates without optical brightener have a whiteness level of 70-76%, and with optical brightener - within 84-98%. Substrates containing wood pulp have a whiteness level of 72-82%. It has been studied that the values of the gloss index are closely related to the micro geometry of the surface - to smoothness. It was found that with an increase in the smoothness level, the imprint surface's gloss indicators also increased. The gloss of the matte coating of the substrate reaches 30%, and the glossy one reaches 75-80%. A study of the opacity index of imprints, which is very important in double-sided printing, was conducted. Studies have confirmed that as the mass of paper increases, its light transmission decreases. A comparison of optical indicators of imprints obtained by different printing technologies was made. A multi-level hierarchical model has been developed, which takes into account factors affecting the optical indicators of offset and flexographic imprints.

The processes of correcting the optical characteristics of multilayer interference filters and heterojunctions obtained by liquid epitaxy on the base of In₄Se₃, In₄(Se₃)_1-x(Te₃)_x and CdSb crystals were studied by laser modification of the film structure. The conditions for optimization of the properties of the created elements for use in the infrared range by laser action are determined.

The result of the paper and the quality depends on various interconnected mechanical, physical and chemical processes what are affected by material properties, reset technologies, equipment and the condition of the production premises in the Print industry especially in the printing processes. Due to the complicate technological processes different defects can appear during the printing process which reduces the quality of production and causes financial loss. One of the main leading Printing company of Latvia “Livonia Print” initiated to explore and find solutions – to reduce or eliminate the risk of GH. GH has not been sufficiently studied so far. Consequently, there is not much specialized, professional literature available. Research sample of printing is taken from a real order, album, and it was printed under real production conditions. The result of the research is to reduce or completely eliminate risk of GH occurrence in the production of high-class printed works (albums, catalogues, etc).

Fractal geometry with its ability of description difficult and irregular models found application in different scientific disciplines. In a field of production and polygraphic production protection understanding properties of paper with watermarks has crucial role in authentication and quality assurance. Fractal analysis gives powerful instrument for quantity description of difficult templates, which are created with watermarks on paper substrates, what gives ability to get vital information about its difficulty and uniqueness. This article is a complex research, which focuses on calculation of fractal dimension of paper surfaces with watermarks with the help of advanced methods of displaying and computational analysis. In the result we have interdependencies of fractal dimensions between measurements with different level of distance.

Surface topograms obtained by mechanical, laser, optical, and electron-microscopic profilometry are widely used to study the micro profile parameters. Experimentally obtained topograms are widely used to evaluate the quality of metallic and non-metallic surfaces for various purposes, including in printing technologies for quality control of finished printing products, in particular, those produced by the intaglio printing method. Laser topograms describe the micro profile with matrices of ordinates on a rectangular grid of large dimensions. At the same time, the problem of estimating micro profile parameters as a whole arises. Therefore, research aimed at developing integrated methods of micro profile analysis is relevant. One of the ways to solve this problem is to consider the anisotropy of the geometric characteristics of the micro profile in all directions. In this paper, the possibility of determining the integral characteristics of the micro profile based on the topogram of the surface using a mathematical apparatus based on hyperspectral analysis and tensor calculation methods is substantiated. The proposed methods are based on the introduction of a special tensor field, which determines the characteristic directions of the location of peaks and valleys of the micro profile. In particular, a multiple (two-dimensional) Fourier series is used to describe the microprofile. The coefficients are found by integrating the experimentally measured laser topogram of the microprofile smoothed by cubic splines, corrected by multiplication by a special form factor. The coefficients of the series represent the spectral (hyperspectral) characteristic of the micro profile.

The object of the study is the marks for people with visual impairments, which are embedded in banknotes of various countries to identify the denominations of banknotes. The subject of the study is to determine the impact of choosing the type of marks for people with visual impairments on the recognition and identification of banknote denominations by people with blindness or low vision. The main hypothesis of the study is based on the fact that people with blindness or low vision can not or can identify different types of marks for people with visual impairment differently. Therefore, the use of some types of marks for the visually impaired on banknotes may not be effective. The study is designed to solve the problem of inefficient use of various marks for people with visual impairments on banknotes, which leads to incorrect identification of banknote denominations by people with blindness or low vision. An analysis of the tactile recognition systems of banknotes of more than 180 countries was carried out, and the main types of marks for people with visual impairments were determined. A classification of marks for people with visual impairments by application method, design, and location has been developed. Testing of various types of marks for people with visual impairments was conducted on the level of tactile sensation of the mark and the accuracy of banknote denomination identification with the involvement of people with various visual impairments, including blind people. The technique has been adapted to people with visual impairments, including blind people, and improved using the principles of fuzzy logic. As a result, it was determined that the most effective systems for identifying banknote denominations are those based on determining the number of blocks of marks printed on a banknote and using blocks of marks of sufficiently large sizes

A complex technology of strengthening parts has been developed through the formation of a regular microrelief on the surface followed by chrome plating. The strengthening method was vibration rolling, which made it possible to obtain sinusoidal and hexagonal microrelief due to the correlation of processing modes. The conducted studies of the effect of complex processing of parts on quality have established the mechanism of obtaining minimum roughness. When using a vibrating tool with a radius of the deformable element R=2 mm, with a pressing force of Р=550 Н, the surface roughness is observed for a sinusoidal microrelief according to the arithmetic mean deviation Ra from 0.08 to 1.32 μm, for a hexagonal one - from 0.63 to 3, 2 μm, which is 7.5 times less without the use of strengthening methods. Due to this, it is possible to extend the operational properties, ensure the reliability of the application of complex technology followed by chrome plating. The parameters of the profile of the engraved strokes of the intaglio printing forms obtained by the method of direct laser engraving (DLE) were studied; it was found that the features of laser processing of the form material during DLE affects the roughness of the treated surfaces and creates inflows, which can affect the protective coating adhesion, the quality of the formation of the paint layer on the print, its tactile and colour properties. The studied engraved strokes differed in the designed profile, namely, the depth (60–100 μm) and the inclination angle of the stroke walls (45°; 90°). The research results give reasons to assert that all the engraved strokes of the samples have deviations from the given geometric profile (the stroke wall inclination decreases to 25°–30°), are asymmetrical, the protective PVD (Plate Vapor Deposition process) coating has insufficient adhesion to the main material of the form. The paper is devoted to the study of the effect of technological factors on geometric parameters and surface roughness.

The object of research is plastic cards. The subject of the study is to determine the effect of laser processing of the edge of plastic cards on the overall quality of the card, including the parameters of durability. The main hypothesis of the research is that the selection of optimal technological parameters of laser processing of the edge of plastic cards will lead to an improvement of their overall quality, in particular, will increase the properties of durability. The work analyzes the possible defects of plastic cards, identifies the most common defects that occur both during the production and during the operation of plastic cards. The work offers the technological processes of plastic card sample production, the methodology and the results of the study of the influence of laser processing parameters on the quality indicators of plastic cards, in particular characteristics of durability. Technological recommendations for improving the durability characteristics of plastic cards have been developed. In particular, the most optimal parameters for processing cards with a laser are given, which ensured high quality indicators, including durability of cards.

In this paper, we studied comparative distance detection using a Laser Rangefinder equipped with color detection and image processing techniques in air and water environments. The main objective of this study is to evaluate the performance and accuracy of the distance detection methods in these two mediums. Furthermore, color detection is employed in the air environment to identify objects within the captured images, followed by image processing techniques such as edge detection and contour analysis to calculate the distances between the objects and the Laser Range Finder. In the water environment, challenges arise due to the refractive properties of water, which can distort object appearances. To overcome this, we employ an underwater Laser Range Finder system, along with color detection and image processing methods adjusted for the refractive index of water. The findings show that the distance measurement in the air has a small error value of 0.63 %. Meanwhile, measuring distances in water has a high error value of 35.18 %. These results indicate that measurements in the air perform better than measurements in water. Water’s scattering and refractive properties caused significant deviations and higher error values. The light intensity fluctuations had minimal impact on measurements in water but were significant in water.

We report on an experimental study aimed to suppress the speckle structure produced by a coherent optical field. The technique proposed is based on the reduction of a laser output coherence utilizing enriching the emission spectrum lines. We achieved a temperature-controlled simultaneous emission of two components at 1.064 m and 1.066 m with nearly equal intensities in IR from diode-pumped Nd:YVO4 laser with intracavity second-harmonic generation The emission lines 532 nm, 532.6 nm and 533.1 nm were recorded in the second-harmonic output. The influence of the spectrum variation on the formation of a speckle field was checked. We succeeded to remove intensity zeroes and reduce the contrast (visibility) from 0.92 to 0.65 in a light scattered by a ground glass diffuser at the angle 35°. A simple consideration of the speckle field dumping mechanism is presented.

A method for recognizing images of broken window glass has been developed, the basis of which is the analysis of the orientation of the contours of glass cracks on a digital image. Contours in the images are highlighted by the fast-acting methods of Sobel or Canny. The obtained contours of the image depend slightly on the lighting conditions, which makes it possible to reliably detect cracks on the glass image. The orientation of image contours is determined based on the mD matrix of contour orientations, which records the sum of image contour values for each pixel within the dimensions of the matrix. For the matrix mD, discrete central moments and eccentricity SEC are calculated, which describes the degree of contour orientation. Based on the calculated eccentricity values, the presence of broken or unbroken glass in the image is determined. The program for recognizing the image of broken glass was developed in the Python language using the Google Colab cloud service. The initial images of the glass are read from video cameras or from graphic files. Contours are binarized using the Otsu method. Experimental testing of the developed program showed correct recognition of images of broken or unbroken glass. The developed program can be useful for monitoring the state of glass surfaces in vehicles and in various premises, for example, in educational institutions.

The article reveals the role of STEM education in today’s technological society and its impact on the development of students’ skills, necessary for building career in the modern world. The need to modernize methodological principles, educational content, and educational technologies is emphasized. Initial, basic, profile, higher/professional levels of STEM education development are described. The directions of STEM education in training of future specialists of engineering and pedagogical professions are highlighted. The STEM project “Spectroscope” was implemented to test innovative method of studying the phenomenon of light dispersion by means of robotics.

K−distribution plays a significant role in describing the statistics of the electromagnetic scattering. The influence of shape factor on the K−distribution is very significant because different shape factors in K-distributed sea clutter represent different actual scenarios. In this paper, we investigate the impact of different shape factors in the K−distributed sea clutter and provide the statistics of the Stokes parameters in electromagnetic scattering of the K−distribution under different shape factors.

The paper presents the economical design of the Optical Matrix to Vector Multiplier (OMVM) for optical education. This OMVM has a three-layer structure: input optical waveguides, a two-dimensional aperture array and output optical waveguides. It can be manufactured by students in university labs without expensive lithography equipment. The OMVM can be applied for hardware realization of artificial neural networks, integral transform calculators, optical signal processors, etc. The process of assembling, testing and implementation of the OMVMs helps students to improve knowledge and skills in optics, signal processing, artificial intelligence, and mathematics.

Using the transfer matrix method within the effective mass approximation and rectangular potentials model, the accurate analytical expression for the scattering S-matrix in an open multi-cascade resonant tunnel nanostructure was obtained. It made possible to develop the theory of spectral characteristics of quasi-stationary electron states in a multi-cascade element of a quantum cascade detector. Using the example of a nanostructure with GaAs wells and AlGaAs barriers, the peculiarities of the dependences of resonance energies and resonance widths of electron states on the number of cascades were investigated. It was established that in the N-cascade structure, the resonance bands are observed in spectrum, each of which is formed by the energies of N quasi-stationary states. If the number of cascades increases in the interval of small values, the widths of the energy bands become bigger and almost do not change at N≥20.

In this paper, the advancements in structured light beams recognition using speckle-based convolutional neural networks (CNNs) have been presented. Speckle fields, generated by the interference of multiple wavefronts diffracted and scattered through a diffuser, project a random distribution. The generated random distribution of phase and intensity correlates to the structured light beam of the corresponding speckle field. This unique distribution of phase and intensity offers an additional dimension for recognizing the encoded information in structured light. The CNNs are well-suited for harnessing this unique ability to recognize the speckle field by learning hidden patterns within data. One notable advantage of speckle-based recognition is their ability to identify structured light beams from a small portion of the speckle field, even in high noise environments. The diffractive nature of the speckle field enables off-axis recognition, showcasing its capability in information broadcasting employing structured light beams. This is a significant departure from direct-mode detection-based models to alignment-free speckle-based detection models, which are no longer constrained by the directionality of laser beams.

In experiments on 32 white nonlinear male rats weighing 0.16-0.18 kg on a hyposodium diet, the diagnostic possibilities of integrative correlation-optical study of the cortex, medullary area and papilla of the kidneys compared to the functional and biochemical state of the kidneys during the formation tubulo-interstitial syndrome on the 30th day of the polyuric stage of sublimate nephropathy. The formation of tubulo-interstitial syndrome showed the greatest increase in the average phase shift of the crystalline substance in the papilla of the kidneys in 7.44 times, in second place increased the excess orientation of the crystalline substance in the renal cortex by 6.73 times in third place asymmetry of phase shift medullary area of the kidneys 6.07 times, which were much more sensitive than the study of functional and biochemical state of the kidneys in the formation of tubulo-interstitial syndrome with inhibition of succinate dehydrogenase activity in the renal cortex of the kidneys 3.60 times, in second place was an increase in oxyproline in the renal cortex as a marker of collagenogenesis in2,03 times and in third place inhibition of fibrinolytic activity of urine by 1.84 times.

This article discusses the possibilities of measuring Particulate Matter using optical low-cost sensors. Depending on the sensor used, not only can there be problems with the positioning of the sensor with respect to the incoming sunlight, but it may also be possible to measure ultrafine particles. While PM2.5 and PM10 are commonly used to characterize air quality, in this paper we point out the need to pay more attention to smaller particles up to 0.1 µm in size (also referred to as ultrafine particulates) due to their highly negative effects on the human health. Attention is also paid to the correlation between particulate matter and meteorological factors like pressure, temperature, and humidity. However, the sudden change in Pearson’s correlation coefficient unveiled a need to look into the effect of the wind on particulate matter.

The presented results are from the multifractal analysis of the polarization-correlation maps of the modulus |𝑆𝐾₄ ¹²|(𝑚 × 𝑛) of the fourth parameter of the two-point Stokes vector in microscopic images of histological sections of biological tissues with fibrous (skin dermis) and parenchymal (spleen) architectural structures of the polycrystalline component.

The provided materials present the results of the diagnostic application of polarization-correlation cartography of microscopic images of the polycrystalline component of biological tissues for the differential diagnosis of benign (adenoma) and malignant (adenocarcinoma) prostate tumors. For microscopic images of histological sections of adenoma and adenocarcinoma biopsies, integral and layered maps, as well as histograms of the distributions of the following parameters are provided: 1. The modulus of the fourth parameter |𝑆𝐾4 12| of the polarization-correlation vector. 2. The argument of the fourth parameter 𝐴𝑟𝑔(𝑆4 12) of the polarization-correlation vector. Systematized tables contain the values of central statistical moments of the 1st to 4th order, which characterize the polarization-correlation, wavelet, and multifractal parameters of the polarization-correlation maps |𝑆𝐾4 12|(𝑚 × 𝑛) and 𝐴𝑟𝑔(𝑆4 12) (𝑚 × 𝑛). Additionally, a set of the most sensitive diagnostic markers has been determined, representing statistical parameters that are highly responsive to changes in the polycrystalline structure of biological samples.

The article is aimed at the development of a new multiparameter polarimetric approach for new methods of Mueller matrix polarization-phase tomography based on the differentiation of polarized and depolarized components and for reproducing the distributions of birefringence value, a set of solutions to the inverse problem - algorithms for polarization reproduction of the distributions of the phase parameters and linear and circular dichroism to determine objective criteria for early diagnosis and differentiation of pathology stages Modern public health is comprehensive in its goal, as it refers to measures aimed at both the entire community and individual health needs. A number of such measures are focused on improving the human environment, reducing risk factors that form a significant burden of disease and mortality among the population and stimulating those factors that, on the contrary, contribute to the promotion and preservation of health.

This report exposes some experimental results relating the mechanism of spectral sensitization of photosensitive microsystems “Core CaF₂ + dye + shell AgBr”. The studies were aimed at expanding their spectral sensitivity into the infrared (IR) region and reducing the effects of the dye self-desensitization.

The article is aimed at developing of a new multiparameter (statistical, correlation and fractal) laser polarimetric approach to the analysis of spatial (layered) distributions of the optical anisotropy parameters of multiple scattering biological fluids, finding of new methods of differential Mueller matrix mapping using algorithms of layered polarization-phase tomography based on differentiation of partial completely polarized and completely depolarized component of Mueller matrix to reconstruct the distributions of birefringence magnitude and linear and circular dichroism coefficients of polycrystalline networks of biological layers (polycrystalline films of plasma of donors and patients with diabetes).

The experimental methodologies of digital histology are presented, including: azimuthally-invariant polarization mapping of microscopic images of histological tissue sections of human internal organs; mapping of Mueller matrix invariants of linear and circular birefringence in histological tissue sections of human internal organs; polarization reconstruction of maps of linear and circular birefringence in histological tissue sections of human internal organs.

The basics for investigating histological brain tissue sections using polarization and differential Mueller matrix microscopy are provided. The structural and logical scheme, design, and examples of results for the Stokes polarimetric mapping technique of microscopic images of deceased brain tissue sections are presented, where orientation (OP) and phase (FP) parameters are determined. Furthermore, the structural and logical scheme, design, and examples of results for the azimuthally-invariant Mueller matrix mapping technique of histological brain tissue sections from deceased individuals are presented, where optical activity (MMI OA) and linear dichroism (MMI LD) maps are determined.

Results of computing unknown phase shift (UPS) errors between synthesized speckle fringe patterns (SFPs) using the population Pearson correlation coefficient (PPCC) are represented. It is shown that mean absolute error of UPS between normalized SFPs is very small over the entire range of phase shifts from 0 to 180 if the RMS height Sq of the 3D rough surface exceeds one seventh of the laser wavelength. These results indicate the possibility of using the PPCC to calculate the UPS in phase shifting digital speckle pattern interferometry.

Distributed computing has revolutionized the way complex mathematical calculations are performed. This article explores the application of distributed computing for the calculation of complex integrals which are widely used for numeric simulation of optic fields. Article discusses possible solutions for numeric simulation of optic fields involving distributed computing techniques, and highlights the advantages of this approach. By harnessing the power of distributed computing, researchers can tackle complex optical fields more efficiently than ever before

This article explores the innovative possibilities of Amazon Web Services (AWS) cloud computing for the calculation of complex optical fields. Complex optical fields are prevalent in various scientific and engineering applications, often posing significant computational challenges. By harnessing the scalability and resources of AWS, researchers and professionals can efficiently and cost-effectively address complex computations. This article discusses the advantages, possible solutions, and potential impact of utilizing AWS for tackling intricate mathematical problems.

The frequency band used in GSM network is mostly overload. For required network access traffic surface the channels inside the network are repeatedly used. It increases the negative interference processes. As a result the quality of service and the network capacity become lower. The effective optimisation methods decreases the interference influence and guarantees the comfort signal to noise ratio.

Many people are using their mobile or smartphone to store data and allow the user to access the internet and many online services. These situations are causing an intensification of cybercrimes, thus, to improve the security of the password required, the mobile phone came out with an alternative method, by using biometrics technology. This study firstly would be focusing on the implementation of typing patterns known as keystroke technique and secondly to conduct analysis to determine whether it is suitable to be implemented as an authentication technique by training and testing the dataset with several machine learning classifiers. From the seven classification techniques, three suitable classifiers have been identified and the results show that Random Forest with False Accepted Rate (FAR) of 0.2% and False Rejection Rate (FRR) of 5.31% had the best performance It can be concluded that keystroke technique has the potential to be a good method to authenticate a user with further research.

The paper presents the results of the research, based on the matrix method of optics of light-scattering media, influence of irradiation of polymer molecules of amphiphilic character on their optical-geometric and polarization characteristics. A comparative characterization of the regularities of the angular was carried out distribution of the normalized components of the scattering matrices of the unirradiated and irradiated polymer pellicle with high concentration of hard fixed bacteriorhodopsin molecules.

The calculation of the components of the light scattering matrices for the medium under study is based on measurements of the polarized intensities of the scattered beam at various states of polarization of the irradiating beam. To estimate the energy measurement error, we compared the experimentally determined values of the brightness coefficient of reference samples depending on the scattering angle with the data presented in the literature.

This paper introduces an automatic system for maintaining the zero interference band in interferometric measurements. It facilitates precise measurements of maximum (Imax) and minimum (Imin) intensities across the investigated area for interference pattern visibility. The system employs a piezoceramic modulator for interference fringe generation, synchronized detectors for simultaneous Imax and Imin registration, and automatic phase control to ensure phase coherency. This system enhances measurement accuracy and efficiency, finding applications in interferometric experiments involving phase-inhomogeneous objects and dispersive media.

Enhancement factor in wavefront shaping depends on the spatial resolution of a spatial light modulator (SLM) and on the modulation type. For a given resolution, phase modulation provides better enhancement than amplitude modulation, and thus is more preferable. In order to make wavefront shaping practical, it is important to provide the highest possible refresh rate of SLM. Liquid crystal SLMs are known for their outstanding phase modulation capabilities but their speed usually does not exceed a few hundred hertz. Meanwhile, digital micromirror devices (DMDs) can reach the refresh rates of 20 kHz that meets demands of practical applications. Although the refresh rate is high, this kind of the SLM can operate only in binary amplitude mode. In this paper we consider conversion of binary amplitude modulation into phase modulation by removal of zero spatial frequency from the modulated beam with respect to the application in wavefront shaping. We demonstrate experimentally increasing enhancement factor in 1.5 times (theoretically up to 2-fold). The advantage of considered method is its simplicity as it requires only a telescopic system and a simple spatial filter. In our case, it did not require any modification of the existing setup except the addition of the removable filter. Also, the considered method is suitable for any kind of spatial light modulator and is not limited to DMD. The obvious benefit of the modulation conversion is that we can use fewer modes to achieve the same enhancement factor and thus increase the focusing speed.

Optical methods for diagnosing various polycrystalline objects (layers of solid and soft matter) and visualizing their structure occupy a prominent place due to their high informativeness and the possibility of multifunctional (photometric, spectral, polarimetric, and correlation) monitoring of the investigated environment. However, there is currently no unified methodological approach to diagnose such structures. In studies of solid matter layers, methods of speckle optics, Fourier optics, correlation optics, and other branches of classical optics prevail. The main fundamental directions of such research are the results of theoretical and experimental studies of photon transport in soft matter layers, specifically biological tissues. Polarimetric research has formed a separate direction in the field of optical studies of biological tissues. The analysis of the polarization characteristics of scattered radiation allows obtaining qualitatively new results about the morphological and physiological state of biological tissues, including cataracts of the lens, glucose concentration in tissues of diabetic patients, and malignant changes.

The optical characteristics of digitally recorded holographic optical elements by the wavefront recording method are measured with a Shack-Hartmann wavefront sensor and their performances as an optical element are compared with those of a spherical mirror and an analog holographic optical element with use of the reconstructed wavefront by Zernike polynomial. The comparison shows that the digitally recorded holographic optical elements can work as a spherical mirror/lens, but it introduces wavefront aberration much more than the mirror and the analog holographic optical element.

The article presents the results of numerical modeling of the scattered optical field using a parabolic mirror. It is shown that the structure of the field at the focus depends on the physical dimensions of the mirror and the polarization of the incident beam. Specifically, the study investigates three polarization modes: linear, radial, and azimuthal. The research reveals that the structure of the optical field at the focus of the parabolic mirror exhibits intriguing characteristics, including a distinct minimum intensity region. This discovery opens up practical possibilities for the precise manipulation of nanosized particles. The findings have important implications for advancing optical technologies, particularly in fields where controlling and focusing light at nanoscale dimensions are essential, such as micro- and nanotechnology, biology, and medicine.

Application of fluorescent nanoparticles for optical flow diagnostics is an essential task, as they enable the determination of the locations of phase singularities and saddle points in the field by intensity extrema1-3 . The motion of such particles in an optical field is driven by optical forces (gradient and scattering forces) and Brownian forces. However, nanoparticles with sizes smaller than 100 nm are virtually not retained even by powerful light beams, as Brownian motion predominates over optical forces. Therefore, for the investigation of optical flows, we can utilize nanoparticles embedded within polymer spheres ranging from 0.5 to 10 µm in size, which do not quench fluorescence and allow for optical manipulation. These polymer nanoparticles can be obtained by introducing fluorescent quantum dots into polymer microspheres. They are referred to as encapsulated or hybrid nanoparticles^4,5 .

To conduct effective research on internal energy flows, we synthesized fluorescent carbon nanodots (CNDs) as test particles. The choice of synthesis methods and starting materials was based on relatively simple technologies. Structural and optical parameters of the CNDs were determined. To address the issue of capturing and retaining fluorescent nanoparticles smaller than 100 nm, we created polymer microspheres by introducing synthesized carbon quantum dots with high quantum yield into them.

The article proposes a new method for the formation of polychromatic edge dislocations with the aim of synthesizing radially and azimuthally polarized polychromatic beams. The proposed method is based on the use of computer-generated hologram technology. It has been shown that using this technology allows to obtain polychromatic edge dislocations with characteristics independent of the spectral composition of the radiation. The results of computer simulation and experimental investigation are presented, confirming the possibility of transforming smooth polychromatic beams into edge dislocations.

The purpose of the work is to demonstrate the effectiveness of optical diagnostics of cytological smears of the cervix for the presence of HPV using spectral-polarization methods. 30 cytological smears of the cervix with koilocytosis and 15 samples without koilocytosis were studied. Comparison of the obtained results with the viral load of HPV genomic equivalents in a smear-scraping by the PCR method, it was established that at wavelengths of 405-425 nm, less than 3 HE and 100 thousand cells correspond (clinically insignificant result). In contrast, at wavelengths of 425-440 nm corresponds to more than 5 HE per 100 thousand cells, which is a clinically significant variant (high carcinogenic risk). On the basis of the conducted research, it was established that the use of spectro-polarization research and the fluorescence method allows to increase the accuracy of the selection of patients for an expensive procedure - DNA diagnosis of HPV with a high carcinogenic risk by the standard PCR method.

The method of vascular segmentation is considered as one of the main approaches to the creation of automated retinal analysis tools. Improved retinal image analysis that can be used for segmented vascular tree to calculate vessel diameter and tortuosity, differentiation of veins and arteries together with measurement of arteriovenous ratio. The algorithm of segmentation of the retinal vessels based on fuzzy clustering of c-means and the method of setting the level is proposed. Morphological processes, CLAHE, and appropriate image filtering techniques were used to enhance the picture before fuzzy clustering of vascular pixels. A method of segmentation on publicly available datasets that uses common validation metrics in retinal vessel segmentation is proposed.

The purpose of the study: to conduct laser-spectrophotometric differential diagnosis of blood in postmenopausal patients with benign processes and endometrial cancer. It was analysed on this work the dependings of autocorrelation functionsK[S ( x)] i=_2;3;4 ∆ of coordinate distributions of the Stokes vector parameters polarization-inhomogeneous laser object fields of eksocervix native smears and cervical canal wall. It was revealed the behavior of power spectra distribution parameters Stokes vector ( , ) _1,2,3,4 S x y i= of object field cervix. Choice of statistical studies set points 1-4 orders polarized coherent radiation field, transformed as a result of interaction with the oncologic modified biological layers "epithelium - stroma" as a quantitative criterion polarimetric optical differentiation state of human biological tissues was proved. It is established that the increase in the value of birefringence layers of epithelial dysplasia in biological tissues and networks of collagen fibers with adenocarcinoma manifested in the growth of statistical significance since the 3rd order coordinate distributions of polarization of laser images smears and tissue sections cervix.

This work is devoted to the substantiation and selection of patients with ovarian tumor for the purpose of conducting expensive molecular genetic studies on genotyping. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5 - 25 microns) dry residue of plasma polarization and laser diagnostic technique of thin histological sections of biological tissues. Obtained results showed that the use of spectrophotometry in the range of 1000-3000 cm-1 allowed to establish quantitative parameters of the plasma absorption rate of blood of patients in the third group in different ranges, which would allow in the future to conduct an express analysis of the patient's condition (procedure screening) for further molecular-genetic typing on BRCA I and II.

An overview of the problem of contamination of water bodies with microplastics and methods of detection and identification of microplastics using optical technologies was carried out on the basis of general information in available Internet sources. Advantages and disadvantages of existing optical methods are determined. Features of the fluorescence spectrum of PE and PET micropastic samples when excited at a wavelength of 365 nm were determined experimentally. During the analysis of the spectra, radiation bands were found, which allow spectral identification of different types of microplastics. A comprehensive hardware solution for visualization of microplastics using a fluorescent probe-analyzer for remote monitoring of microplastics on the water surface and shoreline is proposed.

The use of optical vortices in fiber-optic communication lines is a promising direction, particularly for multiplexer creation. To generate an optical vortex and input/output it into/from the fiber, we utilized a biaxial crystal positioned between two parallel polarizers (a "sandwich" configuration). In our experiment, we employed a single-mode fiber and a He-Ne laser with a wavelength of 633 nm. For optical fiber communication, a similar approach involves using a multimode fiber with a core diameter of 20 μm, which allows the propagation of first and second-order vortices at a wavelength of 1550 nm. Based on the research results, the following conclusions can be drawn: a single singularity propagates better in the fiber than two simultaneously. This indicates that for a single singularity, the input beam apertures are better matched, whereas for two singularities, the input aperture is insufficient.

We have studied the formation of energy optical flows with phase singularities using a biaxial crystal during the propagation of light along its optical axes. We have expanded the theoretical foundations for forming a conoscope image in a biaxial crystal, as developed by Berry, to cover the case of arbitrary orientation of polarization elements. It has been shown that increasing the thickness of the crystal enhances the intensity gradient in the phase singularity, thereby enabling more reliable trapping and manipulation of nanoparticles. Reducing the scale of the phase singularity results in a sharper intensity distribution within the singularity, allowing for the capture of smaller nanoparticles.

Spin-crossover (SCO) materials exhibit thermal conversion from low to high-spin states. Hexagonal molecular nanoparticles are investigated in two dimensions with the two-state Ising-like model. Finite-size effects have been detected at finite temperature on the model. In this work, we employ Monte Carlo numerical simulation to examine an influence this effects on magnetic properties of an Ising-type hexagonal molecular lattice (sometimes called triangular lattice), specifically shaped as a finite hexagon. The influence of different parameters such as elastic coupling, crystal field, temperature on the studied system are investigated. Gradual and first-order transitions with thermally induced hysteresis phenomena have been observed.

We study the combustion of a vertical axisymmetric flame of a preliminarily prepared propane-butane mixture. Based on the optical observations, we claim the necessity to take into account the role of the ambient (secondary) air in the combustion process. We also suggest a mechanism for the formation of the flame front.

The paper presents an improved approach for the analysis of Kikuchi patterns. Calculation of the deformation state in different crystallographic directions are performed in terms of developed model. It is proposed to determine the deformation of local regions of synthetic diamond crystals based on the normalized intensity profiles of the Kikuchi band (εP) and the normalized parameters of the Fourier energy spectrum (εT) without using a reference image.

Chlorine doped CdTe single crystals (CdTe:Cl) were grown by the travelling heater method. The defect structure of the obtained single crystals was investigated using high-resolution X-ray diffractometry. The optimized models of dislocation systems based on the Thompson tetrahedron were constructed for CdTe:Cl single crystals. The analysis of the intensity distribution of diffracted X-rays as a function of reciprocal space coordinates and rocking curves was carried out using the kinematic theory of X-ray scattering in real crystals. The comparative analysis of experimental and theoretically predicted values of helical dislocation densities for CdTe:Cl crystals with perfect and mosaic structures were carried out. The dynamics of changes in concentrations and sizes of several types of interconnected dominant defects (spherical and disc-shaped clusters, dislocation loops) were studied with total integral reflectivity method. The generalized dynamic theory of X-ray diffraction in real crystals with randomly distributed microdefects of various types and a disturbed near-surface layer was used to interpret the experimental data.

The comparative analysis of experimental and theoretically predicted values of helical dislocation densities for CdTe:Cl and MoOx/CdTe:Cl crystals with perfect and mosaic structures were carried out. Two-fold increase in the dislocation concentration was found for MoOx/CdTe:Cl heterostructures as a result of compression deformations of the CdTe:Cl crystal lattice. The transitional deformed layer at the boundary between MoOx film and CdTe:Cl single crystal with a thickness of about 0.1 μm significantly affects the electrical and spectroscopic properties of the obtained systems as materials for γ-radiation detection. Typical square-root type of the reverse branch of current-voltage characteristics were measured for a heterostructures based on a perfect CdTe:Cl, when for MoOx/CdTe:Cl heterostructures based on a mosaic substrate, an atypical quasi-linear type of I(V) dependence is observed. The characteristics of the detectors are affected not only by the quality of the initial crystals, but also by the technology of their post-treatment.

In this study, we investigate changes in the surface plasmon resonance for silver nanoparticles during the light-induced synthesis. An unusual effect is observed during the dilution of light-irradiated samples of decahedral and prismatic nanoparticles. Continuous monitoring of extinction spectra during the synthesis shows that there is a slow movement of the extinction maximum to the short-wave region and stabilizes in 15 minutes. During the continuation of light irradiation, the peak again moves to the right. This can be a demonstration that during irradiation, Ag⁺ ions are sorbed on the surface, and upon dilution, ions are desorbed from the surface. We attribute this effect to the changes in charge distribution that lead to the decrease of the plasmon resonance frequency. The process is confirmed both for decahedra and prisms. The dynamism of this process is confirmed by the absence of the effect of dissolution on the formation of nanoseeds, as well as the growth of nanoparticles. Also, there is a simple relationship between the wavelength shift to the injected electron density for gold nanorods1 . Our goal is to figure out how the conduction electron density changes in case of observed shift for silver decahedra and prisms.

Sulfur nanoparticles were obtained in an aqueous solution of L-cysteine, sodium citrate, and sodium sulfide by using a hydrothermal method of synthesis. The luminescent optical properties of the nanoparticles were investigated using absorption spectroscopy and photoluminescence. Influence of the composition of the system components on the luminescent properties of nanoparticles was investigated. A series of syntheses was carried out changing the volume fractions of L-cysteine (Series 1) and sodium sulfide (Series 2) from 1 to 10 ml. It was noted that with an increase of L-cysteine content changes pH value from 7 to 5 and the presence of absorption maxima only in the range of 200-300 nm. Instead, an increase in the amount of sodium sulfide is accompanied by a change in the pH value from 7 to 12, and, the appearance of absorption maxima in the long-wavelength region. The presence of absorption maxima in the range of wavelengths from 200 to 700 nm in solutions of both series is likely due to the formation of polysulfide ions up to S4 2- in the Series 1 and up to S₈ ^2- in the Series 2 and to their subsequent oxidation into sulfur nanoparticles. The resulting colloidal systems with sulfur nanoparticles are stable over time and have photoluminescent properties, which makes them promising for further application in various fields, in particular, chemistry, medicine, and materials science.

An information system has been developed for the analysis of x-ray moiré images using artificial neural networks and wavelet filtering. Moiré images are obtained as a result of the action of a set of forces on the surface of the crystal. The analysis of the images consisted in solving the inverse problem, that is, in calculating the values of a set of forces based on the moiré image. To prevent retraining of the neural network, a control dataset of images was used. The input signals of the artificial neural network are moiré images after contour extraction, logarithmization, downscaling and wavelet filtering using Dobeshe wavelets. Due to such image processing, the training time of the neural network was reduced with a sufficiently low training error. The output signals of the neural network are the values of a set of forces that formed the moiré image. The training of an artificial neural network is performed by the method of backpropagation. The artificial neural network is implemented in the Python language in the Google Colab cloud platform. The results of testing the developed information system showed a high accuracy of calculating the values of a set of forces for simulated and experimental x-ray moiré images.

In this paper, we reviewed our recent work on the correlations of the Stokes parameters and their applications to diagnose random polarization in stochastic optical fields. With the aid of the ensemble-average van Cittert-Zernike theorem for the propagation of polar-coherence, we investigated the autocorrelation functions and power spectra of the Stokes parameters to expose the dependence of the polarization-related scale-size distributions. A generalized concept of the Stokes ensemble average coherence areas has been introduced to deal with the polarization-related average areas associated with polarization speckle. Noting the fact that the Stokes parameters cannot be measured at an ideal point, we also made investigation of the means and variances of the integrated Stokes parameters in polarization speckle after introduction of four parameters, i.e., the numbers of degrees of freedom for the Stokes detection. Furthermore, a new scheme of interferometry referred to as the Stokes Vector Interferometry has been proposed as an extension of intensity interferometry by taking the vector nature of electromagnetic field into account. Through the cross-covariance computations for the fluctuating Stokes parameters, the squared moduli of the generalized Stokes parameters are reconstructed for the first time.

Publisher's Note: This paper, originally published on 5 January 2024, was replaced with a corrected/revised version on 14 March 2024. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.

This paper, originally published on 5 January 2023, was replaced with a corrected/revised version on 19 April 2024. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.