Computer Optics

208-214

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

An optical microsensor of the laser light polarization state based on a metalens is proposed. Well-known polarization sensors based on metasurfaces usually transmit different types of polarization at different angles to the optical axis. The polarization sensor proposed in this work forms different patterns for different polarization types at the metalens focus. Specifically, the left-handed circular polarization at the focus forms a ring-shaped spot, the right-handed circular polarization - a round focal spot, and linear polarization forms an elliptical spot with two side lobes. Moreover, the angle of inclination of the elliptical focal spot corresponds to the angle of inclination of the initial E-vector of the linearly polarized beam. The simulation is consistent with theoretical predictions. A 30-μm metalens with a low aspect ratio, high numerical aperture, and short focal length equal to the incident wavelength 633 nm in a 120-nm thick thin film of amorphous silicon is designed, fabricated and characterized.

224-229

Authors: D.S. Zemtsov, A.K. Zemtsova, A.S. Smirnov, K.N. Garbuzov, R.S. Starikov, S.S. Kosolobov, V.P. Drachev

The paper describes results of the numerical simulation and experimental characterization of plasmonic gratings and waveguides in the optical range of 1520 – 1630 nm. Gold structures were coated with a 630-nm thick tetraethylorthosilicate layer to achieve higher coupling efficiency for plasmonic gratings using lensed optical probes. We experimentally demonstrated gold input/output plasmonic gratings with an efficiency of about – 3.8 ± 0.2 dB per grating. The measured loss of the plasmonic mode propagating over the surface of the gold waveguide was 0.14 ± 0.02 dB / μm. The work was carried out with the aim of studying integrated plasmonic structures for the development of a hybrid photonic-plasmonic integrated technology.

235-245

Authors: V.P. Kiryanov, N.A. Gurin

A brief review of methods for increasing the diffraction efficiency of optical elements synthesized by direct laser writing is done. It is noted that the previously proposed methods for recording the topology of similar elements using volumetric or surface contour masks do not provide an ultimate solution to a problem of increasing the diffraction efficiency. The performed model and physical experiments on the fabrication of structures of surface-relief phase optical elements by recording zone profiles using oblique laser beams show the fundamental possibility of forming steep side walls of the reverse zone slopes and the feasibility of developing this technology based on laser image generators.

251-261

Authors: Y.D. Vybornova

The article proposes a new method of copyright protection for deep neural networks. The main idea of the method is to embed digital watermarks into the protected model by retraining it on a unique set of pseudo-holographic images (pseudo-holograms). A pseudo-hologram is a two-dimensional sinusoidal signal that encodes a binary sequence of arbitrary length. By changing the phase of each sinusoid, it is possible to form various pseudo-hologram images based on a single bit sequence. The proposed approach to embedding is to generate a training sample in such a way that pseudo-holograms formed on the basis of one sequence fall into the same class. In this case, each class will correspond to different bit sequences. Verification of the digital watermark is carried out by applying various pseudo-holograms to the input of the model and checking whether the hidden sequence corresponds to a certain class. Experimental studies confirm the efficiency of the method and its compliance with all quality criteria established for the methods of neural network watermarking.

272-277

Authors: A.E. Zhdanov, A.Yu. Dolganov, D. Zanca, V.I. Borisov, E. Luchian, L.G. Dorosinsky

Electroretinography is a method of electrophysiological testing, which allows diagnosing diseases associated with disorders of the vascular structures of the retina. The classical analysis of the electroretinogram is based on assessing four parameters of the amplitude-time representation and often needs to be specified further using alternative diagnostic methods. This study proposes the use of an original physician decision support algorithm for diagnosing retinal dystrophy. The proposed algorithm is based on machine learning methods and uses parameters extracted from the wavelet scalogram of pediatric and adult electroretinogram signals. The study also uses a labeled database of pediatric and adult electroretinogram signals recorded using a computerized electrophysiological workstation EP-1000 (Tomey GmbH) at the IRTC Eye Microsurgery Ekaterinburg Center. The scientific novelty of this study consists in the development of special mathematical and algorithmic software for analyzing a procedure for extracting wavelet scalogram parameters of the electroretinogram signal using the cwt function of the PyWT. The basis function is a Gaussian wavelet of order 8. Also, the scientific novelty includes the development of an algorithm for analyzing electroretinogram signals that implements the classification of adult (pediatric) electroretinogram signals 19 (20) percent more accurately than classical analysis.

287-305

Authors: V.O. Yachnaya, V.R. Lutsiv, R.O. Malashin

Communication refers to a wide range of different behaviors and activities aimed at handing over information. The communication process includes verbal, paraverbal and non-verbal components, conveying the informational part of a message and its emotional part respectively. A complex analysis of all communication components makes it possible to evaluate not only the content, but also the situational context of what is being said, as well as to identify additional factors inherent in the mental and somatic state of the speaker. There are several methods of conveying a verbal message, among which are oral and gestural speech (such as the sign language and fingerspelling). Various forms of communication can be contained in multiple data transmission channels, such as audio or video channels. The review is concerned with video data analysis systems, as the audio channel is incapable of non-verbal components transmission that contribute supplemental details. The article analyzes databases of static and dynamic images and systems, developed to recognize the verbal component conveyed by oral and gestural speech, as well as systems that evaluate paraverbal and non-verbal components of communication. Challenges of designing such databases and systems are specified. Prospective directions in complex analysis of all communication components and its combinations for the most complete evaluation of messages are defined.

314-322

Authors: T.E. Shelkovnikova, S.F. Egorov, P.V. Gulyaev

We discuss the development of a technique for automatic generation of databases of images obtained with a scanning tunneling microscope. An analysis of state-of-the-art methods and means of automatic processing of images obtained from probe and electron microscopes is carried out. We proposed using generative-adversarial networks for generating images taken with a scanning tunneling microscope to form training databases of images. A process of training and comparison of deep convolutional generative adversarial network (DCGAN) architectures using the OpenCV and Keras libraries together with TensorFlow is described, with the best of them identified by computing the metrics IS, FID, and KID. The scaling of images obtained from DCGAN is performed using a method of fine tuning of a super-resolution generative adversarial neural network (SRGAN) and bilinear interpolation based on the Python programming language. An analysis of calculated quantitative metrics values shows that the best results of image generation are obtained using DCGAN96 and SRGAN. It is found that FID and KID metric values for SRGAN method are better than values for bilinear interpolation in all cases except for DCGAN32. All calculations are performed on a GTX GeForce 1070 video card. A method for automatic generation of a scanning tunneling microscope image database based on the stepwise application of DCGAN and SRGAN is developed. Results of generation and comparison of the original image, the one obtained with DCGAN96 and the enlarged image with SRGAN are presented.