X-ray luminescence computed tomography (XLCT) has become an emerging hybrid molecular imaging technology with high detection sensitivity and low cost. However, the inverse problem of reconstruction has severe ill-posed consequences. The original regularization algorithm needs to take much time to solve the problem. To reduce the cost of time, a three-term conjugate gradient (TTCG) algorithm is proposed

Simultaneous contrast enhancement and speckle suppression in optical coherence tomography (OCT) are of great significance to medical diagnosis. In this paper, we propose a selective weighted variational enhancement (SWVE) model to enhance the structural parts of OCT images, and then present a shape-preserving fourth-order-oriented partial differential equations (SP-FOOPDE) algorithm to suppress speckle

Optical diffraction tomography (ODT) is a label-free and noninvasive technique for biological imaging. However, ODT is only applicable to weakly scattering objects. To extend ODT to the multiple-scattering regime, more advanced inversion algorithms have been developed, including optimization-based ODT (Opti-ODT) and iterative ODT (iODT). In this paper, we propose a combined strategy, namely, an iODT

According to singular optics, the phase and intensity that characterize structured electromagnetic beams can be understood in terms of concepts that involve subspaces where they or their derivatives exhibit a particular behavior, such as giving rise to extreme values or not being well defined. Caustics are a paradigmatic example of the former, while helical dislocation lines exemplify the latter. In

Comparisons between machine learning and optimal transport-based approaches in classifying images are made in underwater orbital angular momentum (OAM) communications. A model is derived that justifies optimal transport for use in attenuated water environments. OAM pattern demultiplexing is performed using optimal transport and deep neural networks and compared to each other. Additionally, some of

The performance of terahertz (THz) detectors based on two-dimensional electron gas (2DEG) with the aid of a subwavelength gratings coupler depends critically on the amplitude difference of an electric field with positive and negative scattering orders. An efficient method was proposed to enhance the current response of the AlGaN/GaN material in the frequency range from 0 to 5 THz under oblique incidence

The effect of pressure (up to 10 GPa) on the electronic and optical properties of bromine-substituted cesium lead iodide (${{\rm CsPbI}_3}$), as one promising inorganic halide perovskite, is investigated using modified Backe–Johnson (mBJ) potential for the first time to our knowledge. The lattice parameters, electronic bandgap, and imaginary and real parts of the dielectric function, along with the

Incoherent digital holography (IDH) enables passive 3D imaging through the self-interference of incoherent light. IDH imaging properties are dictated by the numerical aperture and optical layout in a complex manner [Opt. Express 27, 33634 (2019) [CrossRef] ]. We develop an IDH simulation model to provide insight into its basic operation and imaging properties. The simulation is based on the scalar

It is well known that natural images possess statistical regularities that can be captured by bandpass decomposition and divisive normalization processes that approximate early neural processing in the human visual system. We expand on these studies and present new findings on the properties of space-time natural statistics that are inherent in motion pictures. Our model relies on the concept of temporal

Minimization of the on-axis scintillation index of sinusoidal Gaussian beams is investigated by using the modified Rytov method in weak atmospheric turbulence for uplink/downlink of aerial vehicle-satellite laser communications. Among the focused cosh-Gaussian (cosh-G), cos-Gaussian (cos-G), annular, and Gaussian beams, a suitable displacement parameter for a cosh-G beam is determined that will minimize

The Fourier modal method (FMM) is certainly one of the most popular and general methods for the modeling of diffraction gratings. However, for non-lamellar gratings it is associated with a staircase approximation of the profile, leading to poor convergence rate for metallic gratings in TM polarization. One way to overcome this weakness of the FMM is the use of the fast Fourier factorization (FFF) first

In this work, we describe analytically the diffraction of some important beams due to a circular obstacle. In order to obtain the desired results, we deal with the wave equation in paraxial approximation together with the diffraction Fresnel integral and apply the analytical method proposed by Zamboni-Rached et al. [Appl. Opt. 51, 3370–3379 (2012) [CrossRef] ]. As a byproduct of our method, we notice

We present a method for designing lenses with two aspherical surfaces having minimal Fresnel losses among the class of stigmatic lenses. Minimization of Fresnel losses is achieved by ensuring equal ray deviation angles on the lens surfaces. Calculation of lenses with minimal Fresnel losses is reduced to solving an explicit ordinary differential equation. Simple analytical approximations are also obtained

We propose a new method for training convolutional neural networks (CNNs) and use it to classify glaucoma from fundus images. This method integrates reinforcement learning along with supervised learning and uses it for transfer learning. The training method uses hill climbing techniques via two different climber types, namely, “random movement” and “random detection,” integrated with a supervised learning

Imaging in the natural scene under ill lighting conditions (e.g., low light, back-lit, over-exposed front-lit, and any combinations of them) suffers from both over- and under-exposure at the same time, whereas processing of such images often results in over- and under-enhancement. A single small image sensor can hardly provide satisfactory quality for ill lighting conditions with ordinary optical lenses

We present a preliminary experimental demonstration of an acousto-optic frequency shifted (AOFS) comb laser-based micro-Doppler detection system for moving object identification. The AOFS comb laser was constructed by successively frequency shifting a single-frequency seed laser at 1063.8 nm using an acousto-optic modulator in an amplified fiber loop, which resulted in a stable pulse output with a

Intrinsic image decomposition aims to factorize an image into albedo (reflectance) and shading (illumination) sub-components. Being ill posed and under-constrained, it is a very challenging computer vision problem. There are infinite pairs of reflectance and shading images that can reconstruct the same input. To address the problem, Intrinsic Images in the Wild by Bell et al. provides an optimization

In this study, multilayer graphene metamaterials comprising graphene blocks and graphene ribbon are proposed to realize dynamic plasmon-induced transparence (PIT). By changing the position between the graphene blocks, PIT phenomenon will occur in different terahertz bands. Furthermore, PIT with a transparent window width of 1 THz has been realized. In addition, the PIT shows redshifts or blueshifts

All-optical switch and multiple logic gates have been demonstrated using a hybrid-cavity semiconductor laser composed of a square microcavity and a Fabry–Perot cavity experimentally. In this paper, two-section tri-mode rate equations with optical injection terms are proposed and applied to study all-optical logic gates of NOT, NOR, and NAND operations utilizing the hybrid-cavity laser. Steady-state

The van de Hulst formula provides an expression for the effective refractive index or effective propagation constant of a suspension of particles of arbitrary shape, size, and refractive index in an optically homogeneous medium. However, its validity for biological matter, which often consists of very dense suspensions of cells, is unclear because existing derivations of the formula or similar results

We consider how vectorial aspects (polarization) of light propagation can be implemented and their origin within a Feynman path integral approach. A key part of this scheme is in generalizing the standard optical path length integral from a scalar to a matrix quantity. Reparametrization invariance along the rays allows a covariant formulation where propagation can take place along a general curve.

We report on an analytic model of a laser-controlled thermally deformable mirror. The model shows the spatial low pass behavior of such a mirror system regarding the intensity distribution that controls the temperature distribution and the optical phase difference distribution of the deformable mirror. The model is validated using the data of measurements described by Schmid and Mahnke [J. Opt. Soc

In this paper, the equations for the transfer matrix method of one-dimensional cylindrical magnetized plasma photonic crystals are proposed, and its nonreciprocal properties based on the Thue–Morse sequence are also studied. By adding the influence of the magnetic field into Maxwell’s equations in the cylindrical coordinate system, the transmission matrix equation of cylindrical wave propagation in

A short pulse propagating through a medium consisting of randomly distributed scatterers, large compared to the wavelength, is expected to develop an “early-time diffusion” (ETD) behavior: a sharply rising structure in the time-resolved intensity, immediately following the coherent (ballistic) component. Since the ETD signal is attenuated at a rate substantially lower than the coherent wave, it offers

We present a method for designing lenses with two aspherical surfaces having minimal Fresnel losses among the class of stigmatic lenses. Minimization of Fresnel losses is achieved by ensuring equal ray deviation angles on the lens surfaces. Calculation of lenses with minimal Fresnel losses is reduced to solving an explicit ordinary differential equation. Simple analytical approximations are also obtained

JOSA A Editor-in-Chief P. Scott Carney, Feature Editor Johannes Courtial, and members of the 2020 Emerging Researcher Best Paper Prize Committee announce the recipient of the 2020 prize for the best paper published by an emerging researcher in the Journal.

An introduction to the Hilbert spaces that are endowed with a reproducing kernel is presented on using the mathematical tools of Fourier optics and coherence theory. After giving the basic definition of such spaces, some examples are worked out to show how the inner product can take different forms depending on the particular function space one works with. The basic rule to build a reproducing kernel

General first-order optical systems—represented by a four-dimensional real symplectic group—can be realized using thin lenses and free propagation transformations. It is shown that such systems can be realized using four units of free propagation transformation and nine thin rotated cylindrical lenses (or equivalently, four thin rotated astigmatic lenses and a thin rotated cylindrical lens). If these

Holography is a long-established technique to encode an object’s spatial information into a lower-dimensional representation. We investigate the role of the illumination’s spatial coherence properties in the success of such an imaging system through point spread function and Fourier domain analysis. Incoherent illumination is shown to result in more robust imaging performance free of diffraction artifacts

This paper aims at presenting the complexity of the process of image target-based color correction (CC). We present issues encountered from acquisition to rendering using colorimetric traditional tools. Target-based CC can be seen as an optimization problem. We have tested SAT and HUE adaptive fine tuning (SHAFT) an automated framework for target-based CC. A key element of SHAFT is an iterative CIEDE2000

The imaging performance of tomographic deconvolution phase microscopy can be described in terms of the phase optical transfer function (POTF) which, in turn, depends on the illumination profile. To facilitate the optimization of the illumination profile, an analytical calculation method based on polynomial fitting is developed to describe the POTF for general nonuniform axially symmetric illumination

We propose a new method for band structure calculation of photonic crystals. It can treat arbitrarily frequency-dependent, lossy or lossless materials. The band structure problem is first formulated as the eigenvalue problem of an operator function. Finite elements are then used for discretization. Finally, the spectral indicator method is employed to compute the eigenvalues. Numerical examples in

The metaplectic transform (MT), a generalization of the Fourier transform sometimes called the linear canonical transform, is a tool used ubiquitously in modern optics, for example, when calculating the transformations of light beams in paraxial optical systems. The MT is also an essential ingredient of the geometrical-optics modeling of caustics that we recently proposed. In particular, this application

In previous studies, the receivers in indoor visible light communication (VLC) were usually fixed. However, in reality, the receivers in VLC have random locations and orientations. Therefore, it is important to consider these random factors for performance analysis in VLC. In this paper, we consider a typical VLC system with a fixed transmitter and a random receiver. Two types of receivers are investigated:

A new scaling law model for propagation of optical beams through atmospheric turbulence is presented and compared to a common scalar stochastic waveoptics technique. This methodology tracks the evolution of the important beam wavefront and phasefront parameters of a propagating Gaussian-shaped laser field as it moves through atmospheric turbulence, assuming a conservation of power. As with other scaling

We study the propagation of superpositions of Airy beams and show that, by adequately choosing the parameters in the superposition, effects as opposite as autofocusing and quasi-adiffractional propagation may be obtained. We also give a simple analytical expression for free propagation of any initial field, based on so-called number states (eigenstates of the quantum harmonic oscillator), that allows

An analytical tool capable of easily calculating a new aspheric intraocular lens (IOL) (shape factor, aspherization) chosen to be designed as “aberration free” in terms of spherical aberration and/or coma is reported. In terms of retinal image quality, the theoretical performances given by the new proposed IOLs compare well with commercial IOLs.

The results show that the larger the real part of the wave number is, the farther the transmission of PCVBs with hollow distribution will be. The expression of partially coherent vortex beams passing through a gain/absorption medium is derived in this paper based on the generalized Huygens–Fresnel principle. The influences of the refractive index (related to the real part of the wave number) and the

We present an intuitive and efficient method for modeling light propagation in layered isotropic and anisotropic media, which we call the Iterated Ray Method. Considering a single layer sandwiched between semi-infinite layers, the infinite reflected and transmitted rays are summed to obtain effective Fresnel coefficients for the center layer. Thus, the system can be represented as two semi-infinite

When a small particle is located near an interface, its electric dipole moment can be induced by laser irradiation. Since the laser light reflects at the interface, this leads to an interference pattern, and the dipole moment is determined by this total field. In addition, the dipole radiation emitted by the particle reflects at the interface, and this field adds to the external field. In this fashion

Based on Maxwell’s stress tensor and the generalized Lorenz–Mie theory, a theoretical approach is introduced to study the radiation force exerted on a uniaxial anisotropic sphere illuminated by dual counter-propagating (CP) Gaussian beams. The beams propagate with arbitrary direction and are expanded in terms of the spherical vector wave functions (SVWFs) in a particle coordinate system using the coordinate

We theoretically show how, using a cylindrical lens, a Gaussian beam with a finite number of parallel zero-intensity lines (edge dislocations) is transformed into a vortex beam that carries orbital angular momentum (OAM) and topological charge (TC). Remarkably, while the original beam is assumed to carry a non-zero OAM and have no TC, the latter is shown to appear during free-space propagation. Considering

The physical additivity of optical-see-through (OST) augmented reality (AR), where display and the real-world overlay with each other, impacts its color appearance. We explored this unique dynamic by looking at the effect of background correlated color temperature (CCT) on AR color appearance with a color matching experiment between a prototype OST-AR RGB system and daylight spectrum reproduction.

This erratum corrects the relative error plots and references in our paper [J. Opt. Soc. Am. A 31, 301 (2014) [CrossRef] ].

The results show that the larger the real part of the wave number is, the farther the transmission of PCVBs with hollow distribution will be. The expression of partially coherent vortex beams passing through a gain/absorption medium is derived in this paper based on the generalized Huygens–Fresnel principle. The influences of the refractive index (related to the real part of the wave number) and the

This paper aims at presenting the complexity of the process of image target-based color correction (CC). We present issues encountered from acquisition to rendering using colorimetric traditional tools. Target-based CC can be seen as an optimization problem. We have tested SAT and HUE adaptive fine tuning (SHAFT) an automated framework for target-based CC. A key element of SHAFT is an iterative CIEDE2000

The recently introduced power spectrum of the refractive index fluctuations of the natural oceanic water turbulence is applied to an underwater communication system in the presence of adaptive optics corrections. The effects of the average temperature (0–30°C), the average salinity (0–40 ppt), the temperature–salinity gradient ratio (0–400°C/ppt), and the wavelength of the source (400–700 nm) on such

Reconstruction of a stable and good quality solution from noisy single-shot Fourier intensity data is a challenging problem for phase retrieval algorithms. We examine behavior of the solution provided by the hybrid input–output (HIO) algorithm for noisy data, from the perspective of the complexity guidance methodology that was introduced by us in an earlier paper [J. Opt. Soc. Am. A 36, 202 (2019)

The diffraction grating is a classic and important optical element, and its design usually traverses the whole parameter space to search for an optimal solution, which is time consuming and inefficient. In order to specify the optimization direction of the grating to obtain clearer physical images and to improve the design efficiency, a new blazing model based on the total internal reflection (TIR)

Graphene is now a crucial component of many device designs in electronics and optics. Just like the noble metals, this single layer of carbon atoms in a honeycomb lattice can support surface plasmons, which are central to several sensing technologies in the mid-infrared regime. As with classical metal plasmons, periodic corrugations in the graphene sheet itself can be used to launch these surface waves;

The recently proposed omnidirectional depth segmentation method (ODSM) has advantages over traditional depth segmentation in terms of robustness and computational costs. However, this method uses at least six fringe patterns and changes their sequences multiple times to perform depth segmentation, which limits its segmentation speed and increases computational complexity. This paper proposes a fast

Registration of 3D lidar point clouds with optical images is critical in the combination of multisource data. Geometric misalignment originally exists in the pose data between lidar point clouds and optical images. To improve the accuracy of the initial pose and the applicability of the integration of 3D points and image data, we develop a simple but efficient registration method. We first extract

A refined model of an extreme ultraviolet (EUV) mask stack consisting of the Mo/Si multilayer coated by a Ru protective layer and a TaBN/TaBO absorber layer was developed to facilitate accurate simulations of EUV mask performance for high-NA EUV photo-lithography (EUVL) imaging. The model is derived by combined analysis of the measured EUV and x ray reflectivity of an industry-representative mask blank

In this paper, we concentrate on dense estimation of disparities between fish-eye images without corrections. Because of the distortions, fish-eye images cannot be processed directly utilizing the classical adaptive support weight (ASW) method for perspective images. To address this problem, we propose a modified hemispherical ASW method in a hemispherical framework. First, 3D epipolar curves are calculated

A zoom camera can change its focal length and track moving objects with an adjustable resolution. To extract precise geometric information for the tracked objects, a zoom camera requires an accurate calibration method. High-precision camera calibration methods, however, usually require a number of control points that are not guaranteed in some practical situations. Most zoom cameras suffer radial distortion

Phase-space analysis has been widely used in the past for the study of optical resonant systems. While it is usually employed to analyze the far-field behavior of resonant systems, we focus here on its applicability to coupling problems. By looking at the phase-space description of both the resonant mode and the exciting source, it is possible to understand the coupling mechanisms as well as to gain

This work presents a mid-fusion pipeline that can increase the detection performance of a convolutional neural network (RetinaNet) by including polarimetric images even though the network is trained on a large-scale database containing RGB and monochromatic images (Microsoft COCO). Here, the average precision (AP) for each object class quantifies performance. The goal of this work is to evaluate the

In this work, the theoretical study of the interaction of terahertz (THz) waves with graphene embedded into two different semi-infinite metamaterials was carried out. To model the graphene, the effective surface conductivity approach based on the Kubo formalism was used. In addition, two types of metamaterials, i.e., double-positive (DPS) and double-negative (DNG), were studied in the THz regime. The

Standard circularly polarized Airy light-sheets are synthesized by combining two dephased TE and TM wave fields, polarized in the transverse directions of wave propagation, respectively. Somewhat counterintuitively, the present analysis theoretically demonstrates the existence of unconventional circularly polarized Airy light-sheets, where one of the individual dephased wave fields is polarized along

Optical coatings formed from amorphous oxide thin films have many applications in precision measurements. The Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo use coatings of ${\rm{Si}}{{\rm{O}}_2}$ (silica) and ${\rm{Ti}}{{\rm{O}}_2}:{\rm{T}}{{\rm{a}}_2}{{\rm{O}}_5}$ (titania-doped tantala) and post-deposition annealing to 500°C to achieve low thermal noise and