Computer Optics

5-11

Authors: A.A. Kovalev, V.V. Kotlyar, S.G. Zaskanov, D.S. Kalinkina

We studied a generalization of the family of Laguerre-Gaussian (LG) laser modes with asymmetrical intensity distribution. As the asymmetrical LG beam is propagating in a homogeneous medium, the asymmetry of its main (central) bright ring reduces, while the contrast of the rest rings increases. The number of bright rings coincides with that of a standard (symmetrical) LG mode. Using the expansion of the complex amplitude into the angular spectrum of plane waves, we calculated analytically the power of the asymmetrical LG beams and projection of their orbital angular momentum (OAM) on the optical axis. It is found that the normalized OAM (OAM per photon) is completely determined by the topological charge and the ratios between the shifts and the waist radius. We also found the conditions under which the normalized OAM coincides with the topological charge (as is the case for the optical vortices).

19-25

Authors: V.V. Ivakhnik, M.V. Savelyev

The spatial selectivity of the degenerate four-wave radiation converter in a transparent twocomponent medium based on the electrostriction and Dufour effect has been analyzed as a function of the rotation and divergence of pump waves. Expressions connecting most efficiently the converted spatial frequency bandwidth with the rotation angle and divergence of pump waves has been obtained.

31-35

Authors: D.A. Anchikov, A.A. Krents, N.E. Molevich, A.V. Pakhomov

In this paper we investigated the spatio-temporal instabilities of stationary lasing in broadarea class-B lasers. Conditions for the onset of filamentary instability and its spatio-temporal characteristics were obtained analytically. The lasing stabilization capabilities through varying laser parameters were considered. We have also shown that effective suppression of unstable field components may be achieved by external optical injection into the cavity.

45-50

Authors: A.V.Gornostay, S.B. Odinokov

We discuss the computation of parameters of a diffractive beam splitter that uses a diffractive optical element synthesized in a bichromated gelatine to split a white incident laser beam into three different-wavelength beams.

57-63

Authors: V.S. Nikitin, E.I. Semyonov, A.V. Solostin, V.G. Sharov, S.V. Chayka

We conducted a theoretical study of the development of optical signal dividers for twodimensional arrays of VCSEL-lasers and PIN photodiodes used in transceivers of full duplex ‘Smartlink connections’ with the constituent components fabricated by 3D printing. A multichannel optical signal divider for full duplex ‘Smartlink connections’ that can be fabricated using 3D printing technologies, such as SLA (Stereolithography) and FDM (Fused Deposition Modeling), was designed.

73-79

Authors: A.Yu. Rubis, M.A. Lebedev, Yu.V. Vizilter, O.V. Vygolov

In this paper a technique of morphological comparative filtering based on image guided contrasting is proposed. Also, a technique of image background normalization based on guided contrasting via an image pyramid and the corresponding сhange detection algorithm is presented. The approach is tested on a public change detection benchmark dataset.

87-98

Authors: V.A. Fedoseev

The paper presents a new model for a unified description of information hiding systems including both steganographic and watermarking systems. The model is based on considering three possible representations of the information being embedded: a binary vector, a digital signal, and a feature matrix. Some examples of the model usage are discussed.

112-120

Authors: V.G. Chafonova, I.V. Gazeeva, G.V. Tihomirova

In this article, we propose a method for automatically controlling and correcting the scale and rotation mismatch of stereo pairs using digital image processing. The algorithm of this method is implemented using Matlab. The control of the mentioned parameters is based on the use of special feature detectors, statistical analysis methods and trigonometric relations. The correction is performed with the use of affine transformations.