Optical Image Formation Research Articles

Complexation of correlation-extreme navigation systems

The constantly increasing intensity of air traffic, due to the growth in the number of manned and unmanned aerial vehicles, as well as the increasingly frequent disruptions of radio navigation systems in recent years, require the development of new methods for increasing the accuracy and continuity of navigation support for flights. The use of correlation-extreme navigation systems (CENS), using digital terrain matrices (DEM) of the earth's surface, makes it possible to solve navigation problems when flying over many types of terrain. However, in the case of a multi-extreme correlation dependence, the problem of ambiguity in determining the location of the aircraft arises, which reduces the accuracy and continuity of the data generated by such a CENS. The aim of article to develop a method for integrating of airborne CENSs using DEM and optical images of the earth's surface to improve the accuracy and continuity of navigation determinations. A method has been developed for integrating CENS, built on the use of DEM and digital devices for the formation and processing of optical images, and allowing to increase the accuracy of classical correlation-extremal methods in the conditions of the emergence of multi-extremal correlation dependence. The paper examines the possibility of using digital devices for forming and processing images as part of the on-board equipment of an aircraft as a means of clarifying its current location when solving autonomous navigation problems, in particular, to correct deviations of the flight path of the aircraft from a given course.

Fantomnaya volokonnaya endoskopiya s neskol'kimi odnopiksel'nymi datchikami v ob\"ektnom kanale

We describe a new method for the formation of optical ghost images, in which radiation in the object arm is detected by several detectors. The advantage of the proposed method is demonstrated, which is the smaller number of illumination patterns required for reconstructing the object image as compared to traditional schemes of ghost imaging. We propose variants of algorithms for measurement reduction to the form relevant to the imaging of the object of investigation, which are aimed at improvement of the performance of the computing component of the endoscope. The fiber-optic version of ghost imaging considered here is suitable for investigating hard-to-reach abdomens and organs of human organism, which permit the introduction of a thin fiber-optic bundle, thus extending its applicability as compared to traditional optic endoscopic methods.

Human Brain Dynamics and Coordination Reflect the Task Difficulty of Optical Image Relational Reasoning.

Despite advances in neuroscience, the mechanisms by which human brain resolve optical image formation through relational reasoning remain unclear, particularly its relationships with task difficulty. Therefore, this study explores the underlying brain dynamics involved in optical image formation tasks at various difficulty levels, including those with a single convex lens and a single mirror. Compared to single convex lens relational reasoning with high task difficulty, the single mirror relational reasoning exhibited significantly higher response accuracy and shorter latency. As compared to single mirror tasks, single convex tasks exhibited greater frontal midline theta augmentation and right parietal alpha suppression during phase I and earlier phase II, and augmentation of frontal midline theta, right parietal-occipital alpha, and left mu alpha suppression during late phase II. Moreover, the frontal midline theta power in late phase II predicts the likelihood of solving single convex tasks the best, while the parietal alpha power in phase I is most predictive. In addition, frontal midline theta power exhibited stronger synchronization with right parietal alpha, right occipital alpha, and mu alpha power when solving single convex tasks than single mirror tasks. In summary, having stronger brain dynamics and coordination is vital for achieving optical image formation with greater difficulty.

Universal dictionaries for representation of turbulent atmosphere point spread functions

Dictionary methods have proved very useful in compressive sensing. Herein we show that, for dictionaries to represent the point spread functions (PSFs) of image formation in atmospheric turbulence, it is possible to construct dictionaries computationally. Computationally created dictionaries make unnecessary the exhaustive collection of PSF data, for arbitrarily large numbers of conditions of turbulence and optical image formation systems, while also reducing the overall number of dictionaries that need to be created and stored.

Formation of Optical Images with Synchrotron Radiation Flux of Relativistic Electrons in the X-Ray Generator "Nestor"

When setting up physical experiments involving the use of the polarization properties of synchrotron radiation (SR) or a monoenergetic photon beam, detailed calculation of the spectral angular distribution of SR and its polarization components is of interest. Consideration of the electron beam size shows that in real conditions the radiation propagating in the plane of the equilibrium orbit will not be completely polarized, and the shape and dimensions of the angular distribution of radiation will be distorted. The motion of electrons in the uniform magnetic field and SR of the beam of relativistic particles in the storage ring of "NESTOR" are considered. The effect of the size of the electron beam with the energy of E=225 MeV in the 6-dimensional space on the formation of images of the flux of quanta of SR is analyzed. It is shown that the main contribution to the formation of images is made by the two-dimensional distribution of particles along the vertical direction axis and vertical oscillations. A software simulation code has been developed, the use of which made it possible to simulate the process of optical image formations by the flux of SR quanta (Этого предложения нет в русской аннотации). The formation of images of the radiation of electrons with an energy of E=225 MeV with change in the longitudinal distance L to the registration plane is considered. It is determined that at small longitudinal distances the main contribution to the image is made by the vertical distribution of particles in the beam. With an increase in the basic distance L, the contribution of the distribution of particles over vertical oscillations increases, which becomes decisive for large L value. Numerical simulation of image formation has been carried out. For the base distance of 300 cm and beam parameters with the vertical root mean square size of 0.2 mm and a vertical root mean square size of 0.15 mrad, the family of angular distributions is presented in the form of two-dimensional histograms for wavelengths , , , where , is the critical wavelength of SR. The dimensions of the optical window are obtained, the size of which makes it possible to reliably register the entire flux of SR quanta for the indicated registration characteristics.

Diffraction Based Image Synthesis

In this paper, we explore the analysis of optical lens systems by using diffraction-based image synthesis. The resolution and strong contrast are the major characteristics of the image produced from the high-quality optical lens system. To check the image’s quality using the PSF, Image Simulation (IMS) method with a fast Fourier transform convolution algorithm. The Strehl ratio is a measure of the quality of optical image formation from the imaging system. It is well-defined as the ratio of peak focal irradiance to the diffraction-limited peak irradiance. The image quality assessment is done by code V up to scent percentage if the image quality is too good and the Strehl ratio is more. Image quality is worse than the Strehl ratio percentage is low. Finally compute with the sample optical lens system Strehl ratio between automatic optical lens design Strehl ratios in Code V.

Smartphone imaging technology and its applications

AbstractThanks to their portability, connectivity, and their image performance – which is constantly improving – smartphone cameras (SPCs) have been people’s loyal companions for quite a while now. In the past few years, multicamera systems have become well and truly established, alongside 3D acquisition systems such as time-of-flight (ToF) sensors. This article looks at the evolution and status of SPC imaging technology. After a brief assessment of the SPC market and supply chain, the camera system and optical image formation is described in more detail. Subsequently, the basic requirements and physical limitations of smartphone imaging are examined, and the optical design of state-of-the-art multicameras is reviewed alongside their optical technology and manufacturing process. The evolution of complementary metal oxide semiconductor (CMOS) image sensors and basic image processing is then briefly summarized. Advanced functions such as a zoom, shallow depth-of-field portrait mode, high dynamic range (HDR), and fast focusing are enabled by computational imaging. Optical image stabilization has greatly improved image performance, enabled as it is by built-in sensors such as a gyroscope and accelerometer. Finally, SPCs’ connection interface with telescopes, microscopes, and other auxiliary optical systems is reviewed.

Visibility Restoration: A Systematic Review and Meta-Analysis.

Image acquisition is a complex process that is affected by a wide variety of internal and environmental factors. Hence, visibility restoration is crucial for many high-level applications in photography and computer vision. This paper provides a systematic review and meta-analysis of visibility restoration algorithms with a focus on those that are pertinent to poor weather conditions. This paper starts with an introduction to optical image formation and then provides a comprehensive description of existing algorithms as well as a comparative evaluation. Subsequently, there is a thorough discussion on current difficulties that are worthy of a scientific effort. Moreover, this paper proposes a general framework for visibility restoration in hazy weather conditions while using haze-relevant features and maximum likelihood estimates. Finally, a discussion on the findings and future developments concludes this paper.

Learning Wavefront Coding for Extended Depth of Field Imaging.

Depth of field is an important factor of imaging systems that highly affects the quality of the acquired spatial information. Extended depth of field (EDoF) imaging is a challenging ill-posed problem and has been extensively addressed in the literature. We propose a computational imaging approach for EDoF, where we employ wavefront coding via a diffractive optical element (DOE) and we achieve deblurring through a convolutional neural network. Thanks to the end-to-end differentiable modeling of optical image formation and computational post-processing, we jointly optimize the optical design, i.e., DOE, and the deblurring through standard gradient descent methods. Based on the properties of the underlying refractive lens and the desired EDoF range, we provide an analytical expression for the search space of the DOE, which is instrumental in the convergence of the end-to-end network. We achieve superior EDoF imaging performance compared to the state of the art, where we demonstrate results with minimal artifacts in various scenarios, including deep 3D scenes and broadband imaging.

A general theory of far-field optical microscopy image formation and resolution limit using double-sided Feynman diagrams

Optical resolution of far-field optical microscopy is limited by the diffraction of light, while diverse light-matter interactions are used to push the limit. The image resolution limit depends on the type of optical microscopy; however, the current theoretical frameworks provide oversimplified pictures of image formation and resolution that only address individual types of microscopy and light-matter interactions. To compare the fundamental optical resolutions of all types of microscopy and to codify a unified image-formation theory, a new method that describes the influence of light-matter interactions on the resolution limit is required. Here, we develop an intuitive technique using double-sided Feynman diagrams that depict light-matter interactions to provide a bird’s-eye view of microscopy classification. This diagrammatic methodology also allows for the optical resolution calculation of all types of microscopy. We show a guidepost for understanding the potential resolution and limitation of all optical microscopy. This principle opens the door to study unexplored theoretical questions and lead to new applications.

Retinal Image Formation and Sampling in a Three-Dimensional World.

In this review, I develop an empirically based model of optical image formation by the human eye, followed by neural sampling by retinal ganglion cells, to demonstrate the perceptual effects of blur, aliasing, and distortion of visual space in the brain. The optical model takes account of ocular aberrations and their variation across the visual field, in addition to variations of defocus due to variation of target vergence in three-dimensional scenes. Neural sampling by retinal ganglion cells with receptive field size and spacing that increases with eccentricity is used to visualize the neural image carried by the optic nerve to the brain. Anatomical parameters are derived from psychophysical studies of sampling-limited visual resolution of sinusoidal interference fringes. Retinotopic projection of the neural image onto brainstem nuclei reveals features of the neural image in a perceptually uniform brain space where location and size of visual objects may be measured by counting neurons.

Realistic, Vectorial Modeling of the Detection Point Spread Function for Single Molecule and Brightfield Microscopy

In previous work, we presented a rigorous, vectorial theory for the illumination point spread function (PSF). Here, we extend this approach to model the detection PSF, which is responsible for optical image formation in virtually all microscopy applications, such as conventional widefield microscopy, confocal scanning microscopy, fluorescence correlation spectroscopy, single molecule imaging, and super-resolution microscopy. We cover the most general case of a single dipolar scatterer or emitter, such as a single fluorescent molecule, which is imaged by a microscope objective-tube lens combination. The dipole radiation passes through stratified media composed of up to three layers (sample medium, glass coverslip, and immersion medium). The theoretical model accounts for a high numerical aperture tube lens and microscope objective (corrected for refractive indices of coverslip/immersion medium and coverslip thickness), a finite detector or detection pinhole, and an optional Babinet-Soleil compensator and polarization analyzer in the detection path. The resulting equations are readily evaluated, and multiple application examples will be discussed, such as the influence of dipole orientation and polarization detection on the detection PSF.

Computational Super-Resolution Full-Parallax Three-Dimensional Light Field Display Based on Dual-Layer LCD Modulation

Due to physical limitation in resolution of display device, it is usually very difficult to achieve a high spatial resolution and a high angular resolution simultaneously for a three-dimensional (3D) light field display. Here, a computational super-resolution full-parallax 3D light field display is demonstrated, which can achieve both high spatial resolution and angular resolution. The proposed display consists of a specially designed backlight unit with controlled scattering angle, two cascadedly arranged LCDs with a resolution of 3840 × 2160, an aberration-suppressed compound lens array, and a holographic functional screen. The optical image formation processing of the display is analyzed and modeled as a whole process, and the superresolution light field synthesis method is presented. By co-designing the optical elements with computation processing, our proposed display architecture can improve the spatial resolution and angular resolution with a factor of 2× in both horizontal and vertical directions, comparing with these of the conventional light field display with single LCD and standard lens array. Finally, a super-resolution full-parallax 3D light field display with a designed spatial resolution of about 640 × 360 in a display area of 21.5 inches and an angular resolution of 166 × 166 in a viewing angle of 45 × 45 degrees is constructed, and an excellent 3D visual experience with improved image quality can be perceived.

Multi-Objective Adaptable Atmospheric Light and Depth Map Quantization Level Dehazing With CSA

Outdoor natural images captured in turbid weather are subject to produce low visibility which may cause fatal problem in computer vision applications. Single image visibility improvement is the most difficult of all model used in visibility improvement and mostly depends on restoration based optical image formation model. Existing dehazing techniques estimate atmospheric light (AL) and transmission by some prior information. In this work, we examined the strength of the Cuckoo Search Algorithm(CSA) in tuning a new multi-objective image performance function PCS for adaptable dehazing which estimates and balance between noise, contrast and geometrical information of image . Two parameters, AL and Otsu’s quantisation thresholding level in Depth Map (DM), are optimised with levy steps in search space of CSA to produce best dehazed image . GT O-Haze, DerainNet, Frida synthetic dataset have been used for evaluations and our method is compared with ten state-of-the art methods qualitatively and qualitatively for dehazing obtaining satisfactory results.

Analysis of the possibility of upscaling based on apodization for partially coherent optical systems in the presence of aberrations

The degree of coherence of radiation is an important characteristic on which the interference properties of light fields and, as a consequence, the resolution of optical systems depend. When propagating over long distances even in free space, initially completely coherent or incoherent radiation becomes partially coherent. This fact should be taken into account in the formation of optical images along with the influence of wave front aberrations. In this paper, we investigate the change in the resolution of the system for two near-point light sources depending on the degree of spatial coherence in the presence of different aberrations. The possibility of improving the resolution in the considered situations on the basis of the amplitude apodization of the optical system is also investigated.

X-ray Nondestructive Testing as an Essential Tool during Technology Design and Development of Modern Aircraft Materials

The X-ray nondestructive testing process is carried out by a system which includes an object of control (OC), source of radiation, detector, and operator. Under interaction of radiation with the OC, its radiation image is formed as an X-ray dose distribution in accordance with the OC properties. At this stage, useful information about the OC is formed, which is further partially lost, partially distorted, and veiled with a noise by conversion of a radiation image into an optical one. The optical image is analyzed by an operator, and the result of testing depends on his physical and emotional state. In this article, the step-by-step analysis of the entire radiation monitoring system is performed. The first stage is formation of a radiation image. For the theoretical estimate of the minimum defect size detected by the X-ray testing system, spatial-frequency spectrum analysis was used. The minimum sizes of a defect were established, for which the radiation image will be formed depending on the characteristics of the source of radiation and the OC. The second stage is the transformation of the radiation image into an optical one. We presented the simulation of this process and developed a model of how an operator recognizes the X-ray optical image and makes the decision about the OC condition. The optical image formation was studied and the choice criterion for the radiation energy was determined by using the digital radiography technique.

Research on remelting phenomena and metal joining of fused-coating additive manufacturing

Metal fused-coating is a novel additive manufacturing technology used to building complex components. In order to determine good metallurgical bonding between layers, a two-dimensional model was established to predict the temperature needed to promote the metallurgical bonding of multi-layer specimens. The temperature of the cladding process was tracked and measured by the thermal imaging system. The influence of heat transfer on the forming characteristics of the fusion track was studied systematically. In addition, the maximum remelting depth of the liquid-solid interface was evaluated and the interlaminar bonding state was further confirmed by the formation of three-dimensional samples and optical microscopy images. This work may help to develop metal fused-coating to the produce effective process control and performance prediction.

Realistic simulation and experiment reveals the importance of scatterer microstructure in optical coherence tomography image formation

Realistic simulation of image formation in optical coherence tomography, based on Maxwell’s equations, has recently been demonstrated for sample volumes of practical significance. Yet, there remains a limitation whereby reducing the size of cells used to construct a computational grid, thus allowing for a more realistic representation of scatterer microstructure, necessarily reduces the overall sample size that can be modelled. This is a significant problem since, as is well known, the microstructure of a scatterer significantly influences its scattering properties. Here we demonstrate that an optimized scatterer design can overcome this problem resulting in good agreement between simulated and experimental images for a structured phantom. This approach to OCT image simulation allows for image formation for biological tissues to be simulated with unprecedented realism.

Effect of Radiant Energy on the Formation of Optical Image in X-Ray Inspections

Digital radiography is currently a genuine alternative to the laborious and uneconomical method of X-ray diffraction in nondestructive testing. The processes of forming optical images on a radiographic film and on a flat-panel detector are different. The input action on a detector, whether a radiographic film or a digital transducer, is the so-called radiation image, the X-ray radiation generated by an X-ray tube and transmitted through a test object. The object attenuates radiation depending on its own thickness and material density. The main parameters of the radiation image are its contrast, definition, and signal-to-noise ratio (SNR). In order to achieve the most efficient conversion of the X-ray image into an optical one, one needs to choose the optimum combination of the listed parameters depending on which detector is being used. In this study, theoretical research and practical evaluation of its results have been carried out. Conditions have been determined for the best adaptation of a radiation image to the employed detector that ensure the prescribed quality indicators of the optical image of the test object. Results of the research that was carried out within the framework of scientific field 2.3 “Developing methods for automated nondestructive testing and the reliability of its results” (“Strategic directions of development of materials and technologies of their processing for a period of up to 2030”) are provided.

Size determination of microbubbles in optical microscopy: a best-case scenario

Microbubble-based ultrasound contrast agents are used in clinical settings to enhance backscattered ultrasound signals from blood during perfusion and blood flow measurements. The dynamics of microbubbles contained in ultrasound contrast agents are typically studied with a high-speed camera attached to a microscope. Such microbubbles, with resting diameters between 1 µm and 7 µm, are considered in optical focus if the bubble centers are in the focal plane of the objective lens. Nonetheless, when a three-dimensional object, a stack of infinitely thin two-dimensional layers, is imaged through a microscope, the image formed onto the charge coupled device element consists of contributions from all layers. If a bubble is larger than the depth of focus, the part of the bubble above the focal plane influences the image formation and therefore the bubble size measured. If a bubble is of a size in the order of the wavelengths of the light used, the system resolution and the segmentation method influence the bubble size measured. In this study, the projections of three dimensional microbubbles (hollow spheres) were computed with an ideal, weighted three-dimensional point spread function to find out under which circumstances the optical image formation leads to a significant deviation in measurement of the actual size. The artificial images were subjected to segmentation techniques for objectively comparing original microbubble sizes with measured microbubble sizes. Results showed that a systematic error was observed for objects in focus with radius ≤ 1.65µm. Also it was concluded that even though a three-dimensional object is in focus, there is discrepancy of up to 0.66% in size measurement. In addition, size measurement of an object for the same shift above and below focus could differ by up to 3.6%. Moreover, defocusing above 25% severely deviates size measurements while defocusing up to 90% could result in mean percentage error of up to 67.96.