Статьи журнала - Компьютерная оптика
Все статьи: 2572
Статья научная
This paper addresses neural network segmentation of a human olfactory bulb sample on X-ray phase-contrast tomographic reconstruction. The olfactory bulb plays a key role in the primary processing of olfactory information. It consists of several nested cell layers, the morphometric analysis of which has important diagnostic value. However, manual segmentation of the reconstructed volume is labor-intensive and requires high qualifications, which makes the development of automated segmentation methods crucial. X-ray phase-contrast tomography provides a high-resolution reconstruction of the olfactory bulb morphological structure. The resulting reconstructions are characterized by excessive morphological details and reconstruction artifacts. These features, combined with limited data volume, visual similarity of neighboring slices, and sparse ground truth, hinder the application of standard neural network-based segmentation approaches. This paper examines the characteristics of the data under consideration and suggests a training pipeline for a convolutional neural network, including inter-slice smoothing at the data preprocessing stage, alternative strategies for splitting the data into subsets, a set of augmentations, and training on sparse sampling. The proposed adaptations achieved a Dice score (micro) value of 0.93 on the test subset. An ablation study demonstrated that each of the above-mentioned modifications independently improves segmentation quality. The presented training pipeline can be applied to the segmentation of morphological structures on tomographic images in biomedical tasks with a limited dataset and non-standard ground truth.
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Статья научная
Our study aimed to develop a comprehensive system for discriminating between benign and malignant breast lesions on ultrasound images. The system integrated deep learning (DL) and conventional machine learning techniques. Our database consisted of 494 ultrasound images, comprising 231 benign and 263 malignant breast lesions. In the initial stage, we evaluated the performance of non-modified DL networks, including VGG-16, ResNet-18, and InceptionRes-NetV2. We assessed the results for the entire lesion as well as its inner and outer parts. For training the networks, we employed supervised transfer learning. In the second stage, we utilized a support vector machine (SVM) model for lesion classification. The features obtained from the modified DL networks, where we removed the last layers, were used for training and testing the SVM. In the final stage, we assessed the classification results using SVM, with a focus on selecting the most significant features obtained from the modified DL networks. We employed techniques such as ReliefF, FSCNCA, and LASSO for feature selection. Our three-step approach yielded impressive results, with an accuracy of 0.987, sensitivity of 0.989, and specificity of 0.983. These results significantly outperformed using only DL or DL+SVM without feature selection. Overall, our algorithm demonstrated sufficient accuracy in the clinical task of discriminating between benign and malignant breast lesions on ultrasound images.
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Статья научная
We propose and numerically verify a design of the photonic integrated circuit for in-plane generation of a 1st azimuthal order vortex mode in dielectric rectangular waveguides. Radiation is introduced into the proposed structure in a standard way through two grating couplers. Applying a mode coupling and specific phase shift, a field with the required amplitude-phase distribution is formed directly in the output waveguide. The geometric dimensions of the device are simulated and optimized to fit the technological parameters of the silicon-on-insulator platform.
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Design and optimization of high-contrast gratings for multispectral VCSEL-SOI laser sources
Статья научная
In the scope of a computational experiment, high-contrast gratings (HCG) formed on a silicon-on-insulator (SOI) platform within vertical-cavity surface-emitting lasers (VCSELs) were studied for multispectral laser sources. A simulation model for spectral characteristics calculation is proposed, which includes two heterogeneously integrated parts of the VCSEL: 1) the lower output mirror based on a HCG grating in the silicon layer of the SOI surrounded by air cavities to enhance the contrast of the HCG; 2) the semiconductor VCSEL structure with an air aperture for current and optical confinement. Comparative analysis results of the spectral characteristics of VCSEL-SOI structures for zeroth, first, and second-order modes, which can be excited in the air aperture of the VCSEL, are presented. It is demonstrated that the HCG, acting as one of the cavity mirrors, effectively discriminates the VCSEL higher-order modes. An algorithm for calculating HCG parameters that ensure the maximum reflectivity at a fixed thickness of the silicon layer of the SOI is developed.
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Статья научная
The paper proposes a new architecture for the photonic laboratory-on-a-chip sensing systems, where multiple sensors based on microring resonators (MRR) are fed by a MRR with low quality factor, working as a spectrum shaper. This architecture enables simultaneous intensity scanning of at least four MRR-based sensors on the silicon-on-insulator platform. We evaluated numerically the system’s sensitivity for various schemes of connecting the sensors and the spectrum shaper. The sensor’s sensitivity was 110 nm/RIU. The sensing system configuration largely determines its sensitivity, which reaches 1980 dB/RIU. The considered architecture may be useful for implementing fully integrated optical lab-on-a-chip structures, as well as distributed multichannel sensing systems.
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Design of a home video behavior recognition system based on visual privacy security mechanism
Статья научная
The rapid development of the Internet and advanced technology has brought great convenience to people’s lives; However, real-time video and other privacy information obtained from computers can be leaked, resulting in economic losses and not conducive to the construction of computer network security. In response to the above issues, this study introduces compressed perception theory and temporal adaptive modules to achieve visual shielding, and based on this, designs a home video behavior system based on visual privacy security mechanism. The research results show that in the comparison of measurement matrices at different levels, the Bernoulli random matrix has the highest recognition accuracy, with recognition accuracy rates of 100 %, 98.73 %, 98.76 %, and 85.62 % from the first layer to the fourth layer, respectively. In the recognition performance results of different video behavior recognition systems in the YouTube database, UCF Sports database, and Hollywood2 database, the average recognition accuracy of the proposed system is the highest in most cases, with 94.6 %, 73.5 %, and 77.1 %, respectively. In summary, the system proposed in the study can achieve accurate recognition of home video behavior after visual masking, and has good results in practical applications.
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Design of electro-optical flip-flop
Статья научная
The neuromorphic photonic circuits have the potential to generate a wide variety of devices or systems with specialized functions. In our previous work, we proposed an electro-optical architecture to form the logic gates. Electro-optical AND, OR, NAND, NOR, XOR and XNOR logic gates could be realized in the structure by tuning the parameters of the electro-optical devices. In this work, we design the electro-optical flip-flop with two electro-optical logic gates. The electro-optical logic gates are built by means of Multilayer Perceptron using directional couplers, phase modulators and optical amplifiers. The truth value of the input signal 0 or 1 is determined by the applied voltage, 0V or 1V, on the two phase modulators, respectively. We also assess the tolerance of the system by calculating the visibility of the output signals with 1% error due to the fabrication error of the optical components. The simulation results show that the minimum visibility of the logic gates and the flip-flop are 0.91 and 0.98, respectively indicating that the electro-optical flip-flop can be realized even with the fabrication errors.
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Design of lenses for the focusing into a line
Статья научная
A method for designing a curvilinear lens for focusing into a line is proposed. The obtained solutions represent a complex refracting surface in an analytical form expressed through the eikonal distribution along the line. The calculation of a 3-D lens focusing into a line-segment is reduced to a simple design of cylindrical profile with required function of ray-correspondence.
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Design, simulation, and fabrication of silicon-on-insulator MEMS vibratory decoupled gyroscope
Статья научная
This paper reports the design and fabrication of a 2-degree-of-freedom (DOF) decoupled vibratory gyroscope based on a silicon-on-insulator (SOI) MEMS process. The 2-DOF capacitive comb structure is deliberately designed to have a decoupled drive and sense mode oscillation to prevent the unstable operation due to mechanical coupling, resulting in a low zero rate out-put drift. It is well known that the closer are the drive and sense resonances, the higher is the angular rate resolution of the gyroscope. Generally, this is achieved by using symmetric suspensions, but it results in a reduced bandwidth. The proposed design has been configured to achieve a bandwidth of about 150 Hz, while ensuring the decoupled operation of the drive and sense modes. An analytical method has been employed to study the steady state response of the 2-DOF structure. FEM analysis has been carried out in CoventorWare® MEMS Design software and the simulation results show that the drive resonance occurs at 21.48 kHz and sense resonance at 21.63 kHz, which are in close agreement with the theoretical results. The structure is designed with a 15 µm thick device layer. Fabrication of the design is proposed using a two mask process based on Deep reactive-ion etching (DRIE) and sacrificial wet release etching on a SOI wafer. DRIE etching with an aspect ratio of 1:5 has been successfully carried out as desired and the results have been presented.
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Designing multilayer dielectric filter based on TiO2/SiO2 for fluorescence microscopy applications
Статья научная
This study presents a new construction design of a distributed Bragg reflector (DBR) filter and a Fabry-Pérot (FP) filter by using needle technique as a synthesis method. The optimized DBR and FP filters having a proper number of layers with controlling thickness TiO2/SiO2 are utilized to transmit only a certain narrow band of wavelengths while blocking the others. As a proof of concept, the filters are designed to selectively transmit only a very narrow band of wavelength at 780 nm which is the near infrared (NIR) fluorescent emission from Alexa Fluor 750 dye. The obtained results show that the optimized filters represent advanced spectral performance which can be used to improve the sensitivity and the imaging contrast in fluorescence microscopy.
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Determination of microrelief of the sample by singular beams superposition
Статья научная
In present paper we propose easy way to implement method of interfering vortices with opposite topological charge for the real time determination of the thickness and information about the surface of studied samples with the resolution up to 7 nanometers. The determination of the characteristics of the medial cross-section of submicron-objects becomes possible due to phase sensitivity of interfering singular beams to the slightest changes in the optical path difference between them. The dependence of rotational angle of resulting interference pattern in case of different sample thickness for two singular beams superposition is considered in detail.
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Determination of the beam waist position for the spin-orbit interaction effect observation
Статья научная
The spin angular momentum and the extrinsic orbital angular momentum of light are associated with the polarization of light and the light propagation trajectory, respectively. Those momenta are interdependent not only in an inhomogeneous or anisotropic medium but even in free space. This interaction is called the spin-orbit interaction of light. The effects of the spin-orbit interaction of light manifest themselves in a small transverse shift of the beam field longitudinal component from the beam propagation axis in the waist region under the circular polarization sign change. They can be observed both for Gaussian beams and for structured beams. The effects of the spin-orbit interaction of light should be taken into account when nanophotonics devices are created, but the detailed investigation of the effect had not been performed yet due to the low intensity noise image of the beam waist. Precise measurements of the focal waist centerline are needed to determine the transverse shift of the beam field longitudinal component of the asymmetric converging beam’s waist under the circular polarization sign change. We propose methods for determining the transverse and longitudinal positions of the beam waist. Computer image processing methods made it possible to obtain the value of the beam waist's transverse position with an accuracy of 0.1 mm. These methods will allow further testing of the shifts' theoretical predictions, the values of which are the order of 1 mm. The results obtained can also be used for laser processing of materials by polarized light and precise positioning of the beam's focal spot at a surface.
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Статья научная
In this paper, we propose an algorithm for the automatic construction (design) of a computational procedure for non-linear local processing of digital signals/images. The aim of this research is to work out an image processing algorithm with a predetermined computational complexity and achieve the best quality of processing on the existing data set, while avoiding a problem of retraining or doing with less training. To achieve this aim we use a local discrete wavelet transform for a preliminary image analysis and the hierarchical regression to construct a local image processing procedure on the basis of a training dataset. Moreover, we work out a method to decide whether the training process should be completed or continued. This method is based on the functional of full cross-validation control, which allows us to construct the processing procedure with a predetermined computational complexity and veracity, and with the best quality.
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Diamond focusators for far IR lasers
Статья научная
Recently a new technique has been proposed for laser-assisted generation of phase microrelief to manufacture diamond diffractive lenses for the far IR range. In the present paper the realization of diamond diffractive optical elements (DOEs) is considered, able to focus an incoming CO2 laser beam into certain pre-given focal domains. Exemplarily, two completely different DOEs for different tasks of laser beam focusing have been designed by different methods, manufactured and finally investigated by means of optical experiment and computer simulation. Measured intensity distributions in the DOEs' focal planes as well as measured diffraction efficiencies have been compared with related results of computer simulation, and have been found to be in good mutual concordance. Obtained first results indicate that technique of laser-assisted ablation can be effectively used for manufacturing of high quality diamond DOEs for laser beam focusing.
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Diffractive elements for imaging optics of mobile communication devices
Статья научная
An estimate of the permissible width of the working spectral range of optical systems with diffractive elements is given. It takes into account the interval of the angles of incidence of the radiation on the microstructure of the element and it proceeds from the requirement that there is no halo in the image that is visualized by the LCD monitor. It is shown that the design parameters of diffractive elements intended for mobile device cameras are quite achievable for today's technologies of mass production of plastic optics.
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Diffractive optical power of a square diaphragm
Статья научная
The concept of diffractive optical power is extended over the case of a square diaphragm and of the negative Fresnel numbers for the incident wave. The accurate interpolation formula for the image location is represented. It contains the additional factor describing the dependence of the optical power on the incident wave front curvature. The high precision of the approximation is the conclusive evidence for the correctness of the physical model for the focusing action of the diaphragms.
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Document image analysis and recognition: a survey
Статья научная
This paper analyzes the problems of document image recognition and the existing solutions. Document recognition algorithms have been studied for quite a long time, but despite this, currently, the topic is relevant and research continues, as evidenced by a large number of associated publications and reviews. However, most of these works and reviews are devoted to individual recognition tasks. In this review, the entire set of methods, approaches, and algorithms necessary for document recognition is considered. A preliminary systematization allowed us to distinguish groups of methods for extracting information from documents of different types: single-page and multi-page, with text and handwritten contents, with a fixed template and flexible structure, and digitalized via different ways: scanning, photographing, video recording. Here, we consider methods of document recognition and analysis applied to a wide range of tasks: identification and verification of identity, due diligence, machine learning algorithms, questionnaires, and audits. The groups of methods necessary for the recognition of a single page image are examined: the classical computer vision algorithms, i.e., keypoints, local feature descriptors, Fast Hough Transforms, image binarization, and modern neural network models for document boundary detection, document classification, document structure analysis, i.e., text blocks and tables localization, extraction and recognition of the details, post-processing of recognition results. The review provides a description of publicly available experimental data packages for training and testing recognition algorithms. Methods for optimizing the performance of document image analysis and recognition methods are described.
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EBS-YOLO: Foreign object detection algorithm for transmission lines based on improved Yolov10
Статья научная
When a foreign body touches a transmission line it may have serious consequences. If it is not handled in time it may lead to accidents such as short circuits and blackouts, affecting the normal operation of the power system and the stability of social life. In order to detect foreign objects on transmission lines, this paper proposes an EBS-YOLO method based on Yolov10. Firstly, in the structure of the backbone network, we adopt C2f-Efficient Multi-Scale-Conv plus (C2f-EMSCP) as the convolutional layer for feature extraction, replacing part of the C2f standard convolutional layer, and obtaining a richer feature representation by combining different scales of feature mapping. Secondly, a Bidirectional Feature Pyramid Network (BiFPN) is used, which enables the model to fuse features of different scales better. Then, the SEAMHead module with multi-head attention is utilized to augment the original features, enhance head detection, and reduce the effect of object occlusion. Finally, in order to solve the consistency problem between the predicted and real bounding boxes, the SIoU loss is used to replace the original CIoU loss in Yolov10. The experimental results show that EBS-YOLO achieves an average detection accuracy of 90.4 %, which is 4.1 % better than Yolov10, and Recall and Precision are improved by 5.3 % and 1.8 %, respectively. Compared with other methods, our EBS-YOLO has higher accuracy in detecting foreign objects on transmission lines.
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Статья научная
In this paper, attempts have been made to study the joint effects of apodization and aperture masking on the diffraction images of coherently illuminated straight edge. The Edge-Ringing, Edge-Shift and Edge-Eradient of the edge images have been evaluated for different values of apodization using edge masking of circular apertures. We have considered rotationally symmetric, aberrated coherent optical system. These investigations have lead to the use of certain pupil functions in conjunction with optimal apodizers to assess the quality of edge images. Any obstruction placed in the light path of an optical system prevents waves from a portion of the wavefront in reaching the focal zone. This results in the change in the light flux at every point of the diffraction pattern. This is in turn, depends on the shape and size of the obstruction.
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Efficiency of object identification for binary images
Статья научная
In this paper, a comparative analysis of the correlation-extreme method, the method of contour analysis and the method of stochastic gradient identification in the objects identification for a binary image is carried out. The results are obtained for a situation where possible deformations of an identified object with respect to a pattern can be reduced to a similarity model, that is, the pattern and the object may differ in scale, orientation angle, shift along the base axes, and additive noise. The identification of an object is understood as the recognition of its image with an estimate of the strain parameters relative to the template.
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