A vectorial diffraction model is presented for the focusing of a Gaussian laser beam with a wavelength of 800 nm by a parabolic metallic mirror with a diameter of 15 mm and a focal length of 150 mm. The model is based on a rigorous calculation of the reflected electromagnetic field using s- and p-polarization basis functions, complex Fresnel coefficients, and the Kirchhoff–Rayleigh surface integral. The reflective coating is characterized by a complex refractive index n = 0.145 + 4.5i, corresponding to silver in the near-infrared spectral range. The incident beam has a waist radius of 3 mm at the mirror’s vertex plane. The field distribution in the focal plane is numerically computed on a 300×300 grid over a ±30 μm region. Focus quality is evaluated using three criteria: total intensity, radial intensity distribution, and the full width at half maximum (FWHM) of the focal spot. A focal spot with FWHM ≈ 8.56 μm is obtained, in close agreement with the theoretical diffraction-limited estimate. The results demonstrate that accounting for the vectorial nature of the field and the dissipative properties of the metal enables accurate prediction of polarization distortions and energy losses in practical mirror-based focusing systems.

Keywords: vectorial diffraction model, parabolic metallic mirror, Gaussian laser beam, Fresnel coefficients, complex refractive index

This article examines the problem of obtaining three-dimensional images of an object using digital holography. Several methods based on holographic interferometry exist: the offset source method, the immersion method, the dual-wavelength method, and the use of a low-coherence illumination source. Each of the methods discussed has its own advantages and disadvantages. In most cases, quantitative information about the relief parameters is required. However, the poor quality of topographic fringes and the problem of determining the sign during relief determination cause significant difficulties in volume determination. These problems can be overcome by using a simple method of determining the volume using two stereo images reconstructed from holograms and subsequent refinement using one of the methods for obtaining holographic topographic maps. This paper demonstrates a method for determining a three-dimensional image using two stereo images of an object reconstructed from digital holograms. long exposure and development time, which is usually done separately from the optical setup. In the case of holographic interferometry systems, it is necessary to provide for mounting the hologram back into the optical setup with sufficiently high accuracy. Therefore, digital holography methods have been developed to record holograms on photomatrices with limited resolution. These methods are based on the use of optical schemes at small angles (less than 5 degrees) between interfering beams. Recently, sensors with a single element size of 1.33 µm and 0.56 µm have appeared. This resolution makes it possible to return to registration schemes with angles between interfering beams of 30-60 degrees. This allows us to hope for the revival of holographic methods and methods of holographic interferometry at the modern level without the use of intermediate recording media.

Keywords: obtaining holograms and reconstructing images from them, digital holography, spatial resolution of holograms, stereo images, reconstruction of volumetric images

In this article, the focus shifts to an in-depth study of the effect of bending deformation on the change in the refractive index of the optical fiber core. The developed module will allow analyzing trends in this indicator, which will provide a more detailed understanding of the internal processes occurring in the fiber under the influence of deformation.

Keywords: mathematical modeling, optical fiber, bending deformation, modeling of deformed fiber behavior, software

A method for recording holograms using digital cameras with high spatial resolution is considered. To register holograms obtained in optical setups with an inclined reference beam, a high resolution of registration systems is required. To do this, it is necessary to use media with a resolution of 2000-4000 lines per mm. The use of photographic plates requires a fairly long exposure and development time, which is usually done separately from the optical setup. In the case of holographic interferometry systems, it is necessary to provide for mounting the hologram back into the optical setup with sufficiently high accuracy. Therefore, digital holography methods have been developed to record holograms on photomatrices with limited resolution. These methods are based on the use of optical schemes at small angles (less than 5 degrees) between interfering beams. Recently, sensors with a single element size of 1.33 µm and 0.56 µm have appeared. This resolution makes it possible to return to registration schemes with angles between interfering beams of 30-60 degrees. This allows us to hope for the revival of holographic methods and methods of holographic interferometry at the modern level without the use of intermediate recording media.

Keywords: digital holography, high spatial resolution photo matrix, tilted reference beam holography, Fourier transform

The article presents the development of a software tool for modeling the influence of physical processes occurring in a single-mode optical fiber as a result of bending deformation. Model of bending deformation of single-mode optical fiber is considered. Classical and refined models of deformation and their influence on the optical fiber params are given. The initial data required to implement the software tool is discussed in detail. The development of the modeling program was gradually considered. The specifics of the implemented program obtained during the computational experiment are indicated.

Keywords: mathematical modeling, optical fiber, bending deformation, modeling of deformed fiber behavior, computational experiment, software

The paper considers a model of a multi-aperture wave-front sensor for an active laser beam control system based on the iterative image reconstruction algorithms with limitations, particularly, on the Gerchberg-Saxton algorithm. The specifics of these algorithms is the presence of the so-called divergence factor which is characterized by obtaining “successful” and “unsuccessful” solutions, and may be clarified by stagnation conditions available (or by local extrema). The use of global optimization methods allows to avoid this constraint and to build quite an effective strategy for retrieving phase information. An experimental research was conducted to restore phase information using this method. For this purpose, a model of a seven-channel laser system with a different phase shift was developed.

Keywords: multichannel laser systems, wavefront sensor, Gerchberg-Saxton algorithm, physical modeling, image reconstruction, phase retrieval

A method for recording holograms using digital cameras with high spatial resolution is considered. To register holograms obtained in optical setups with an inclined reference beam, a high resolution of registration systems is required. To do this, it is necessary to use media with a resolution of 2000-4000 lines per mm. The use of photographic plates requires a fairly long exposure and development time, which is usually done separately from the optical setup. In the case of holographic interferometry systems, it is necessary to provide for mounting the hologram back into the optical setup with sufficiently high accuracy. Therefore, digital holography methods have been developed to record holograms on photomatrices with limited resolution. These methods are based on the use of optical schemes at small angles (less than 5 degrees) between interfering beams. Recently, sensors with a single element size of 1.33 µm and 0.56 µm have appeared. This resolution makes it possible to return to registration schemes with angles between interfering beams of 30-60 degrees. This allows us to hope for the revival of holographic methods and methods of holographic interferometry at the modern level without the use of intermediate recording media.

Keywords: holography, holographic interferometry, photomatrices with high spatial resolution, holography with an inclined reference beam, digital holography, Fourier transform

The article presents and substantiates the structure of the original combined pathospecific measuring device for the diagnosis of glaucoma, which will allow for a comprehensive analysis of the hydro- and hemodynamics of the eye and thereby improve the quality of glaucoma diagnosis. Based on this structure, a detailed metrological analysis of this installation as a means of biomedical measurements was given in the work. Brief conclusions on the work are given and prospects for the further development of the project are determined.

Keywords: combined pathospecific measuring device, tonometry, rheography, sphygmography

Methods for determining the position of the center of gravity and the static stability margin of an aircraft in flight are considered. Based on the analysis of the motion of an aircraft as a rigid body, possible methods for determining the position of the center of gravity are determined and their errors are calculated. Comparison of the errors of various methods made it possible to conclude that it is expedient to use a method based on the use of information on the fuel reserve.

Keywords: center of gravity, moments of inertia of the aircraft, free vibrations, fuel consumption