Subject of study. A stand and a methodology for the analysis of sightline stabilization errors in optoelectronic surveillance systems were developed. Aim of study. The aim was to develop and construct stands for the analysis of sightline stabilization errors in optoelectronic surveillance systems under an independent simulation of angular sinusoidal oscillations and vibrations across specified frequency ranges, with the capability of positioning the surveillance system below the gimbal center. Method. The method involves experimental investigations of sightline stabilization errors in the channels of an optoelectronic system mounted on a common stabilized platform. Main results. A stand was successfully developed to simulate sinusoidal oscillations on the platform of the sightline stabilization system for the optical channels of optoelectronic surveillance systems. Using the developed oscillation and vibration stands, measurement setups were developed for studying, testing, and calibrating various sightline stabilization systems. Experimental studies on a two-axis stabilization system with a dual-gimbal suspension and gyrostabilized elevation and azimuth tracking drives showed that the sightline stabilization error in azimuth and elevation does not exceed 12 arcsec under angular oscillations in the frequency range of 0.1–5 Hz. Under random broadband vibrations in the frequency range of 1–2000 Hz, the error reaches 15 arcsec and increases by 45% at the resonance frequency of the structure.

By decision of the Editorial Board of Opticheskiĭ Zhurnal , Il’ya A. Levin, Tatiana Yu. Fisenko, Svetlana N. Khonina, and Vladimir E. Yashin are recognized as the Best Reviewers of 2024.

Subject of study. Technology for quantum key distribution in fiber-optic communication lines under the influence of electromagnetic fields generated by atmospheric discharges is studied. Aim of study. A test bench for testing experimental techniques to be used in studying the effect of atmospheric discharges on transmission of a quantum key via fiber-optic communication lines is developed. Method. The characteristics of a quantum communication channel upon exposure of a coil containing an optical fiber to a magnetic field from a pulsed current are experimentally studied. Main results. An experimental test bench has been created and methods have been developed to evaluate the influence of magnetic fields arising from atmospheric discharges (lightning) on the transmission speed of a quantum key in fiber-optic communication lines. It was shown that quantum key distribution blocks using the BB84 phase-encoding protocol continue to show operational stability when the optical cable is exposed to alternating magnetic fields of up to 1.2 mT. However, the very fact of exposure to magnetic fields above 0.8 mT can be detected by a systematic decrease in the quantum key transmission rate and an increase in the quantum bit error rate (QBER) by 0.5%–1%. Practical significance. The laboratory test bench and methods developed herein support magnetic-field testing of various optical cables used for transmission of qubits. Fiber-optic networks through which qubits are transmitted can serve as a distributed lightning sensor; an increase in the level of quantum errors and a decrease in quantum key generation rate will be observed in any segment of an optical network where a lightning discharge generates strong magnetic fields.

Subject of study. This study investigates the properties, conversion characteristics, and control functions of digital television cameras, as well as methods for their calibration. Aim of study. The aim is to develop and validate a methodology for using digital cameras in photometric and radiometric measurements. Method. The approach involves analytical and experimental studies of the conversion, threshold, and metrological characteristics of digital cameras. Main results. New approaches have been developed for the calibration and measurement of the spatial distribution of irradiance, radiant intensity, and luminance of radiation sources using digital cameras and personal computers for control. Practical significance. The proposed methodological framework has been successfully validated in practice, enabling the realization of a wide dynamic range and high spatial resolution in the measurement of photometric parameters (illuminance, luminous intensity, luminance) and radiometric parameters (irradiance, radiant intensity, radiance) of radiation sources and extended scenes.

Subject of study. The reflectance spectra of leaves and needles from woody vegetation were measured and analyzed within the spectral range of 1–2.4 µm. Aim of study. The study aims to explore the potential of hyperspectral measurements of forest-vegetation reflectance spectra (1–2.4 µm) for forestry applications in the Russian Federation. Method. Laboratory measurements were conducted on the reflectance spectra of leaves and needles from woody vegetation representative of the European part of the Russian Federation. The experimental setup included a spectrometer for capturing reflectance spectra within the 1–2.4 µm range. Specimens comprised green spruce, pine, birch, oak, maple, aspen, and linden, representing coniferous and deciduous vegetation. Measurements took place in summer (August) at a Bauman Moscow State Technical University branch in the Dmitrov district of Moscow. Main results. The results reveal that the reflectance spectra in the 1–2.4 µm range facilitate the differentiation between coniferous and deciduous tree species and the classification of forest vegetation. Reliable spectral separation between coniferous and deciduous species was observed in the ranges of 1.5–1.8 µm and 2.1–2.4 µm. Reflectance spectra in the range of 1–2.4 µm with a 10 nm resolution enabled effective classification of birch, oak, maple, linden, aspen, spruce, and pine, with at least 88% accuracy for each species. Practical significance. This research lays the groundwork for developing a spectral-reflectivity database of woody vegetation typical of forested regions in the Russian Federation. Hyperspectral data in the 1–2.4 µm range can support tree species identification, assess tree health, detect disease, monitor drying processes, and enhance remote forest inventory methods.

Subject of study. The study is focused on conical refractive axicons. Aim of study. The aim was to develop an easy-to-implement technique for inspecting axicons and verifying their geometrical parameters. Method. The intensity distribution of a Bessel beam was obtained using a lens projection system, and the resulting data were analyzed using digital image processing methods. Main results. A technique for geometrical characterization of axicons used in Bessel beam formation was developed and validated. Practical significance. The proposed technique for axicon characterization is straightforward to implement and allows the rapid determination of geometrical parameters and defect detection.

Subject of study. The study focuses on luminescent carbon nanoparticles, specifically carbon dots, based on citric acid, formamide, and various chiral molecules. Aim of study. The aim is to assess the influence of chiral molecules used in the synthesis of carbon dots on optical transitions in the long-wavelength spectral region and to investigate the mechanism underlying the circular dichroism signal of these nanoparticles. Method. Carbon dot samples were synthesized using two methods: (i) a one-step solvothermal synthesis of carbon dots from citric acid, formamide, and various chiral molecules and (ii) a two-step method involving the solvothermal synthesis of achiral carbon dots from citric acid and formamide, followed by surface treatment with L-cysteine. Absorption and luminescence spectroscopy methods were employed to study the chemical structure and optical properties of the carbon dots. The chiroptical properties of the obtained samples were analyzed using circular dichroism spectroscopy. Main results. The addition of various chiral molecules to a mixture of precursors during one-step synthesis enabled the fabrication of carbon dots with different chemical compositions, including variations in surface groups and types of emission centers in the spectral region of 350–700 nm. The use of L-phenylglycine and L-tryptophan in the one-step synthesis was shown to lead to the formation of nanoparticles with optical transitions in both short- and long-wavelength regions of the spectrum. The addition of L-glutathione during the one-step synthesis resulted in the formation of carbon dots with short-wavelength emission, while the addition of L-cysteine did not alter the emission characteristics of achiral carbon dots based on citric acid and formamide. The optical properties of the chiral carbon dots obtained using the two-step synthesis method with L-cysteine remained unchanged compared with those of the achiral carbon dots synthesized from citric acid and formamide. The circular dichroism spectra of all the samples showed a signal at ∼250nm, which was attributed to the derivatives of the chiral precursors attached to the surface of the nanoparticles, irrespective of the preparation method. Practical significance. Chiral carbon dots hold promise in biomedicine as sensors, luminescent biomarkers, and other applications due to their biocompatibility and non-toxicity. The results obtained in this work will serve as a foundation for the further fabrication and investigation of chiral carbon nanoparticles with long-wavelength luminescence.

Subject of study. The work studied the formation of germanium quantum dots on silicon with (100) crystallographic orientation under different growth regimes. Aim of study. The work is devoted to conducting experimental studies of the influence of growth mechanisms on the formation of germanium layers and quantum dots on a silicon (100) substrate for the production of optical elements based on silicon-germanium nanostructures. Methods. After pre-epitaxial cleaning of the Si substrate, germanium is synthesized on Si(100) through molecular beam epitaxy. The surface morphology is analyzed using reflection high-energy electron diffraction during synthesis and scanning electron microscopy after deposition. Main results. The work determines the temperature ranges at which the Si/Si(100) growth occurs due to the nucleation of islands, due to the movement of steps, and in combination. The effect of changing growth mechanisms on the size and density of Ge quantum dots on Si(100) is shown. Practical significance. The research results provide insight into the influence of growth mechanisms on the sizes of formed germanium quantum dots on silicon, which will make it possible to create nanophotonics and nanoelectronics elements with strictly specified parameters.

Subject of study. The study focuses on the plasma excited by a laser on a gas-jet Xe target. Aim of study. The aim was to achieve such a high emissivity of the Xe plasma at a wavelength of 11.2 nm that would meet the requirements of industrial lithography. In addition to the applied aspect, the work also has a diagnostic component, the purpose of which is to study the internal structure of the laser plasma and determine its internal parameters, such as temperature, concentration, and mean ion charge. Method. The paper contains a review of works devoted to the comprehensive investigation of the laser-produced plasma with a Xe gas-jet target. In the course of this research, several methods of measurements and plasma diagnostics were developed and tested, including multimirror Bragg spectrometry, probing the plasma with the same infrared laser radiation that creates it, and determination of mean ion charge of this nonequilibrium and short-lived laser-produced plasma using the measured absorption of the laser energy in the plasma and a database on cross-sections of ionization by electron impact. Main results. A multimirror Bragg spectrometry technique was developed and tested. This technique was then used to obtain quantitatively calibrated spectra of the laser-produced Xe plasma. An effective mode of irradiating the target with a wide, defocused laser beam has been found, which made it possible to achieve the coefficient of conversion of laser pulse energy into the energy of the narrow-band plasma radiation around λ=11.2nm, approximately equal to 4%. This value is currently a world record for plasmas of such a type. Additionally, an analytical method for determining the temperature and ion charge of the plasma based on experimental measurements was developed. Practical significance. The achieved conversion efficiency of the radiation source under consideration is sufficient for its application in high production industrial lithography. The use of the simple and “clean” radiation source with Xe plasma could eliminate a number of problems encountered in contemporary lithography with a wavelength of 13.5 nm and a source with targets of metallic tin.

Subject of study. The structure of plastic products manufactured using fused deposition modeling in the sub-terahertz range with varying parameters of 3D printing, such as the infill pattern and the infill density, is investigated. Aim of study. The influence of 3D printing parameters (such as the infill pattern and infill density percentage) on the optical characteristics of 3D printed plastic products is established to identify the possibilities of sub-terahertz imaging and non-destructive testing of plastic products and assess the necessity of accounting for these parameters in manufacturing terahertz optics elements. Method. Sub-terahertz imaging using a 300-GHz compact radiation source and a terahertz camera. The image resolution was improved by subpixel scanning. Main results. An overview of the applications of fused deposition modeling 3D printing in manufacturing terahertz optics elements is provided. It is noted that most previous studies do not provide comprehensive details of the printing parameters used. Images of plastic objects printed under various 3D printing parameters were captured and the differences in image characteristics were identified, showcasing the impact of the internal sub-wavelength structure on the optical properties of the products. The results indicate the potential to determine the infill density and type of filling pattern in plastic products. Practical significance. Sub-terahertz imaging with radiation from compact sources paired with terahertz cameras offers a promising and competitive alternative for non-destructive testing of 3D-printed plastic items. The necessity for a detailed description of 3D printing parameters to ensure reproducibility in scientific research, especially when designing optical elements for terahertz and sub-terahertz ranges, is emphasized.