Vol 55, No 1 (2019)

The paper presents a mathematical tool based on the requirement of tautochronism in each of the diffraction orders of a harmonic kinoform lens, which was used as the basis to develop a method for calculating the lens microstructure. The method provides a limitation of the relative longitudinal chromatism of the lens to a given level. In addition, it allows obtaining the initial parameters necessary for the ray calculation and optimization of an optical system with a harmonic kinoform lens using well-known commercial optical design computer programs.

Diffusion burning of a hydrogen jet is studied by methods of the Hilbert optics. A diagnostic system based on the batch-produced IAB–463M device is implemented, which includes a specially developed Hilbert filtration module coupled with a light source. The influence of local turbulent perturbations (puff or slug) arising in the tube forming the jet on the dynamic structure and flame evolution is revealed. This phenomenon can be used to control the space-time structure of the flame.

The effect of the photo-response nonlinearity of a holographic material on the achievable diffraction efficiency of holograms has been studied. It has been shown that the interaction between the hologram form factor and the photo-response nonlinearity leads to an increase in diffraction efficiency compared to a linear photo-response. Numerical calculations for the photo-response nonlinearity corresponding to Reoxan phase holographic material are presented.

The mode structure of a four-layer optical waveguide consisting of an ion-exchanged channel waveguide in glass coated with a highly refractive nanoscale dielectric film has been studied. It has been found that varying the geometric dimensions of the film changes the polarization states of the second and third waveguide modes: the TM₀ mode is transformed into the TE₁ mode, and the TE₁ mode becomes the TM₀ mode. Based on this, a new method of designing a waveguide polarization converter has been proposed and experimentally confirmed.

A new terahertz (THz) imager based on THz-to-IR conversion has been proposed and studied. The THz-to-IR converter consists of an ultra-thin resonant THz absorber (meta-absorber) whose backside is coated with an emission layer with an emission factor close to unity. The absorption of THz radiation leads to converter heating, which is recorded by an IR camera from the emission layer side. The small thickness of the converter (more than 50 times smaller than the working wavelength of THz radiation) determines its low heat capacity, resulting in an increase in the sensitivity and operating speed of the imager. Optimization of the optics of the THz imager, making cuts in the converter structure to reduce the blooming and increase the response, and the IR image processing method increasing the signal-to-noise ratio, provided the sensitivity of the THz imager similar to the sensitivity of thermal detectors in the 8–12 μm IR range.

The problem of detection and estimation of spatial coordinates of moving objects by a passive scanning system of vision is solved. Algebraic and algorithmic approaches to determining the spatial coordinates and parameters of object motion are proposed. These approaches differ by taking into account the object velocities in searching for conjugate vectors of directions to the objects. The algorithms developed on the basis of these approaches show that the approach with allowance for motion parameters offers significant advantages of higher accuracy of coordinate estimation and higher probability of detecting all objects.

Mathematical bases of an integral operator for differentiating 2D images in order to increase their contrast are presented. Images are formed by an optic-electronic device under different background conditions. It is proven that the operator suppresses high-frequency components of images, generated by an applicative background and additive noise of the device. The universal property of the operator is determined, from which the known key differentiation operators are derived: gradient, Roberts, and Laplace operators. The results of contrasting real images by the proposed operator are presented.

This paper systematizes and generalizes data on the specific features, operation modes, and technical characteristics of world-class ground-based solar telescopes in order to obtain information required to develop and design an automated control systems for the large solar telescope included in the National Heliogeophysical Complex of the Russian Academy of Sciences.