Computer Optics

12-25

Authors: Khonina S.N., Ustinov A.V.

We theoretically analyze sharp focusing of cylindrically polarized beams by a focusing system containing ring apertures and a vortex-phase optical element in the pupil. Analytic expressions for a field in the focal area for radially and the azimuthally polarized beams for one- and two-ring apertures are obtained. Asymptotic expressions for the focal field at a distance from the optical axis are also derived. It is shown that for a single vortex-phase narrow ring aperture, the field distribution in the focal area is proportional to the superposition of Bessel functions of different orders. The field is shown to possess the axial symmetry and be independent of the longitudinal coordinate. The structure of the interference field for radial and azimuthal polarization is investigated. With two narrow ring apertures in the pupil of the sharp-focus system, the interference pattern of two vector Bessel-type beams is formed in the focal area. If both ring apertures have the same vortex phase, the field in the focal area remains axis-symmetric, although becoming periodically dependent on the longitudinal coordinate. If each ring has a different-order vortex phase, the interference is more complex and leads to the formation of rotating beams. The three-dimensional structure in the focal area can be controlled by varying the polarization and phase distribution in each of the rings.

35-44

Authors: Kotlyar V.V., Stafeev S.S., Porfirev A.P.

We conduct the numerical and experimental study of sharp focusing of a linearly polarized asymmetric Bessel beam with topological charge n = 3 and a crescent-shaped transverse intensity pattern. Using the Debye integral, we show that in the focal plane of a high NA aplanatic lens (NA = 0.9 – 0.95) the intensity distribution is also crescent-shaped. Using the FDTD method it is shown that a binary zone plate with NA = 0.995 also forms a crescent-shaped focal spot that is rotated around the optical axis. An asymmetric Bessel beam was generated using a spatial light modulator (SLM) and focused using an immersion objective with NA = 1.25. A crescent-shaped intensity pattern formed in the focal plane was rotated by 90 degrees relative to the SLM-aided crescent.

52-57

Authors: Nalimov A.G., Kotlyar V.V.

We have carried out modeling of an image formation in hard x-ray coherent radiation using a Rayleigh-Sommerfeld integral. Combined zone plates have been used to form the image. The resolution of the combined zone plate was numerically shown to increase up to 10 times (equaling 20 nm) when compared with a traditional Fresnel zone plate without any changes of the outermost zone width (205 nm). The zone plate consisted of 6 areas operating in 1, 3, 5, 7, 9 and 11 diffraction orders. An efficiency improvement of 42% has been numerically achieved in contrast to a traditional Fresnel zone plate used in the third diffraction order. For the combined zone plate, the efficiency of 3.7 % has been achieved.

64-69

Authors: Murzin S.P., Balyakin V.B., Melnikov A.A., Vasiliev N.N., Lichtner P.I.

Laser surface microstructuring is applied to improve the tribological properties of materials. To increase potential practical applications, the expansion of the laser microstructuring functionalities through the use of more common laser systems with pulse durations in the millisecond range may show promise. For the first time it was shown that the tribological properties of the surface of the silicon carbide ceramic can be improved using a pulse-periodic laser treatment with millisecond pulses. Morphological changes of the surface under treatment after the exposure to pulse-periodic laser light were assessed. It was found that the pulse-periodic laser treatment with 0.5-ms pulses of energy 1.1 J led to the smoothing of recesses in the polished surface of the silicon carbide ceramic. Higher-energy laser treatment led to the formation of cracks on the material surface. The study of tribological properties of the resulting structures showed that following the laser treatment the mean value of the friction coefficient decreased by 15 %.

77-82

Authors: Anshakov G.P., Raschupkin A.V., Zhuravel Y.N.

The Resurs-P satellite enables one simultaneously to observe the underlying surface using both multi- and hyperspectral equipment. The multispectral images, thus obtained, have high spatial resolution but low spectral resolution. Hyperspectral images, on the contrary, have high spectral resolution but low spatial resolution. This article proposes a method of the hyper- and multispectral data fusion aimed at improving their information value.

87-93

Authors: Vorotnikova D.G., Golovashkin D.L.

We propose two variants of long vectors algorithms for solving grid equations of explicit difference schemes, allowing one to use the maximum number of CUDA cores even for a small dimension of the grid domain. The implementation of these algorithms is shown by the example of the heat conduction equation and the solution of Maxwell's equations. The comparison between the proposed algorithms implemented by means of the CUBLAS library and free software packages B-CALM and OpenCurrent is done.

101-108

Authors: Vizilter Yu.V., Gorbatsevich V.S., Zheltov S.Yu., Rubis A.Yu., Vorotnikov A.V.

In this paper, we present a new class of tree-structured morphological descriptors of image shape. The notion of a Haar-like function is formalized. It is demonstrated that Pytiev morphology of centered images can be described in terms of a Haar-like basis. The morphology of localized mosaic shapes and corresponding localized Haar-like wavelet systems are described. The formal way for generating a hierarchical structure of localized mosaic shapes and corresponding tree of localized Haar-like wavelets is reported. The notion of “morphlets” as Haar-like wavelets corresponding to the mosaic shape of some image is introduced. Some constructive schemes for the generation of morphlet-based image descriptors are considered.

119-124

Authors: Belim S.V., Kutlunin P.E.

The article suggests an algorithm of boundary extraction based on image clustering. In the process of clustering, the image is decomposed into simply connected regions based on pixel color. Edges of the regions are considered as the boundaries. The proposed approach allows obtaining welldefined boundaries without blurring. The algorithm is highly resistant to impulse noise.

136-142

Authors: Skidanov R.V.

The article briefly outlines the life and scientific activities of Professor Alexey Volkov, the chief researcher of the Image Processing Systems Institute of the RAS, Doctor of Engineering, a well-known specialist in the field of micro - and nanotechnologies.