We introduce a partially coherent beam, called a multi-hyperbolic sine-correlated (MHSC) beam, by employing a multi-hyperbolic sine function to modulate the spectral degree of coherence. Based on the extended Huygens–Fresnel principle and second-order moments of the Wigner distribution function, we derive the analytical expressions for the spectral intensity, the root-mean-square (rms) angular width

The power spectrum of water optical turbulence is shown to vary with its average temperature $\langle T \rangle$ and average salinity concentration $\langle S \rangle$, as well as with light wavelength $\lambda$. This study explores such variations for $\langle T \rangle \in [{0{^ \circ}{\rm C},30{^ \circ}{\rm C}}]$, $\langle S \rangle \in [{0\;{\rm ppt},40\;{\rm ppt}}]$ covering most of the possible

Wave optics is usually thought to be more rigorous than geometrical optics to analyze integral imaging (II) systems. However, most of the previous wave-optics investigations are directed to a certain subsystem or do not sufficiently consider the finite aperture of microlens arrays (MLAs). Therefore, a diffraction-limited model of the entire II system, which consists of pickup, image processing, and

In this paper, we introduce a comprehensive study of the performance of intensity modulation (IM) techniques over gamma–gamma (GG) distributed free-space optical (FSO) channels. We derive closed-form expressions for the average bit error rate (BER) of thermal-noise-limited FSO systems adopting various IM techniques. The effect of atmospheric turbulence is studied. Comparisons are presented in terms

The paper describes a method using digital image processing in the detection of vaguely defined visual defects on objects symmetric with respect to a rotation axis. Automotive wheels and hubcaps, fans, turbines, symmetrical ceramic goods, merchandise, etc., are examples of such objects. The method uses the object’s surface symmetry to identify areas that do not meet the requirement for the symmetry

Adaptive optics (AO) is an established technique to measure and compensate for optical aberrations. One of its key components is the wavefront sensor (WFS), which is typically a Shack–Hartmann sensor (SH) capturing an image related to the aberrated wavefront. We propose an efficient implementation of the SH-WFS centroid extraction algorithm, tailored for edge computing. In the edge-computing paradigm

Phase-change materials are chalcogenide alloys used for nonvolatile memory applications due to their rapid and reversible structural transformation. ${{\rm In}_3}{{\rm SbTe}_2}$ is a promising candidate that exhibits transitions dependent on thermal conductivity. The minimum lattice thermal conductivity of amorphous ${{\rm In}_3}{{\rm SbTe}_2}$ is investigated by surface acoustic propagation. ${{\rm

In a previous paper we described an accurate method for tracking a Gaussian beam incident on a particular diffraction grating. In this paper we use the same method to track a fundamental Gaussian beam at microwave frequency incident upon rectangular and sinusoidal gratings for more general information about the interaction during the process. We extensively study how different parameters of the incident

We call a surface that appears undistorted when viewed in a curved mirror an eigensurface and the mirror an eigenmirror. Such pairs are described by a first-order nonlinear partial differential equation of the form ${a_0} + {a_1}{u_x} \,+ {a_2}{u_y} + {a_3}{u_x}{u_y} + {a_4}u_x^2 + {a_5}u_y^2 = 0$, where ${a_i} = {a_i}(x,y,u)$, which we call the anti-eikonal equation. We give examples of symbolic and

CMOS sensors employ a row-wise acquisition mechanism while imaging a scene, which can result in undesired motion artifacts known as rolling shutter (RS) distortions in the captured image. Existing single image RS rectification methods attempt to account for these distortions by using either algorithms tailored for a specific class of scenes that warrants information of intrinsic camera parameters or

We describe the details of an optical communication system using Gaussian vortex beams (GVBs). Our main focus will be on the detection strategy. The transmitter encodes the message symbols into the topological charges of the GVBs. Then the receiver implements a detection strategy based on the orthogonality of the GVBs. The graphical results obtained from the related theoretical derivation indicate

The stripe of the tropical freshwater fish “neon tetra” consists of many iridophores, in which tilted reflecting platelets are periodically arranged. The neon tetra has structural coloration and changes the color of a stripe in response to the surrounding conditions. The mechanism of the color change is thought to be controlling a slant angle of the platelets and changing the spacing between the platelets

JOSA A Editor-in-Chief P. Scott Carney and Feature Editor Johannes Courtial announce the recipient of the 2019 prize for the best paper published by an emerging researcher in the Journal.

Optical measurement and characterization are two of the pillars of metrology. The ability to measure precisely with high dynamic range and accuracy betters our understanding of nature and the universe. In this feature issue, we present a collection of articles that delves into the fundamental techniques used to advance the field.

Optical coherence tomography (OCT) is a high-resolution three-dimensional imaging technique that enables nondestructive measurements of surface and subsurface microstructures. Recent developments of OCT operating in the mid-infrared (MIR) range (around 4 µm) lifted fundamental scattering limitations and initiated applied material research in formerly inaccessible fields. The MIR spectral region, however

Ultrashort pulse lasers are emerging as an advanced tool of distance measurement, with their unique temporal and spectral characteristics being extended to diverse principles of absolute ranging and instrumentation. Here, a systematic methodology is presented for absolute ranging by means of the time-of-flight measurement of ultrashort light pulses using dual-comb asynchronous optical sampling. Based

High sensitivity of collimation testing equipment is desirable where collimated beams are used for precise and accurate measurements. Precision in the setting of collimation depends on the sensitivity of the testing equipment. In the present work, sensitivity to beam collimation of the recently reported holographic shearing interferometer (HSI) [J. Opt. 20, 055603 (2018) [CrossRef] ] is measured and

Confocal chromatic displacement sensors are versatile and precise sensors for measuring the distance to a single point. In order to obtain a 3D measurement device, this paper presents an integrated scanning sensor design that employs a tilting lens mechanism for manipulating the light path of the sensor. The optical implications of the design are analytically modeled and simulated. An experimental

This paper presents an on-machine surface defect detection system using light scattering and deep learning. A supervised deep learning model is used to mine the information related to defects from light scattering patterns. A convolutional neural network is trained on a large dataset of scattering patterns that are predicted by a rigorous forward scattering model. The model is valid for any surface

This paper reviews recent developments of non-contact three-dimensional (3D) surface metrology using an active structured optical probe. We focus primarily on those active non-contact 3D surface measurement techniques that could be applicable to the manufacturing industry. We discuss principles of each technology, and its advantageous characteristics as well as limitations. Towards the end, we discuss

We demonstrate an interference signal-processing method that extends the measurement range of dynamic displacement beyond half the wavelength of light without deteriorating the measurement accuracy in a phase-modulated optical interferometer. The measurement range extension is realized by the algorithm focusing on peak direction of the interference signal waveform. Deterioration of measurement accuracy

We have developed an inertially sensitive optomechanical laser by combining a vertical-external-cavity surface-emitting laser (VECSEL) with a monolithic fused silica resonator. By placing the external cavity mirror of the VECSEL onto the optomechanical resonator test mass, we create a sensor where external accelerations are directly transcribed onto the lasing frequency. We developed a proof-of-principle

Metal powder bed fusion (PBF) methods need in-process measurement methods to increase user confidence and encourage further adoption in high-value manufacturing sectors. In this paper, a novel measurement method for PBF systems is proposed that uses multi-view fringe projection to acquire high-resolution surface topography information of the powder bed. Measurements were made using a mock-up of a commercial

We establish the propagation model of orbital angular momentum (OAM) modes carried by hollow vortex Gaussian (hvG) beams propagating in anisotropic atmospheric turbulence. Effects of light source parameters and atmospheric conditions on the OAM mode propagation performance are investigated in detail. The findings indicate the hvG beam with a smaller OAM quantum number, a larger beam order, or a longer

We revisit the spectral coherence properties of far-field radiation emanating from an aperture in a blackbody cavity on the basis of Kirchhoff’s boundary conditions. We point out that the far zone cross-spectral density matrix derived earlier in the literature by separately propagating all three aperture-field components does not show transversality of the field at nonparaxial directions. This is not

We introduced a new class of a partially coherent source that can generate a field with a hollow rectangular profile, named the hollow rectangular multi-Gaussian Schell-mode source. The dependence of distribution of far-zone spectral density on the properties of the proposed source was analyzed. The results show that one can control the distribution properties of the far-zone intensity profile, including

The classical analogues of quantum correlations have been the subject of considerable interest in the past few years; however, all of these investigations consider the classical analogue of only pure quantum mechanical states. In this work, we study mixed classical light states and derive relations between the polarization coherence of the field and the (classical) entanglement between its degrees

Recently, a new form of laser beam, called the “centrosymmetric optical vortex” (CSOV), has been proposed. We employ the modified calculation method for studying the propagation of the CSOV beam, which is constructed via four canonical optical vortices with different topological charges. The speed of calculation is more convenient and faster than the usual means by using the diffraction integral directly

The paper presents a detailed theoretical analysis of characteristics of a rotationally symmetric lens system with one or two aspherical surfaces having corrected spherical aberration and reduced coma aberration for a given position of the object and the image. Formulas for surface shape optimization are derived, and the procedure for calculating the aspherical system is shown. The presented formulas

An exact reference wavefront for a single paraxial surface that provides two perpendicular remote image lines instead of a single focal point has not been provided in the recent literature. A naïve estimate would state that it may have a toric form. We provide a proof for the nonexistence of an exact toric reference wavefront for intermediate spaces in cross-cylindic symmetrical optical systems where

Our group recently showed that the Seidel primary ray aberration coefficients of an axis-symmetrical system can be accurately determined using the third-order Taylor series expansion of a skew ray ${\bar{\text{R}}_{\text{m}}}$ on an image plane. This finding inspires us to determine the third-order derivative matrix of ${\bar{\text{R}}_{\text{m}}}$ with respect to the vector ${\bar{\text{X}}_0}$ of

We investigate rotational diffusion of fluorescent molecules in angular potential wells, the excitation and subsequent emissions from these diffusing molecules, and the imaging of these emissions with high-NA aplanatic optical microscopes. Although dipole emissions only transmit six low-frequency angular components, we show that angular structured illumination can alias higher-frequency angular components

When encoding diffractive lenses onto a spatial light modulator (SLM), there is a Nyquist limit to the smallest focal length that can be formed. When this limit is surpassed, a two-dimensional array of lenslets is formed. There have been very few discussions on the performance of these lenslets. In this work, we focus on the phase distribution of these lenses in the array. We show that, for certain

Blackbody radiation inside a closed cavity is nothing other than the electromagnetic fields emitted from those atoms forming the cavity. In this work, these fields are calculated in the non-relativistic classical domain for the purpose of analyzing the distribution of the radiation inside the cavity in the low-frequency limit. Under the assumption that the cavity is a spherical one, the intensity of

The scattered intensity from large spheres with a real part of the refractive index of $n = 1.33,1.5,2.0$ is investigated as the radius $R$ and an imaginary part of the refractive index $\kappa$ are varied. It is shown that the product of $\kappa$ and the size parameter $kR$, $\kappa \textit{kR}$, is a universal parameter describing the quenching of the refraction phenomenon of the scattered light:

As a kind of typical self-accelerating laser beam, Airy beams have attracted much attention due to their fascinating properties and various potential applications. In this work, we carry out a full vector wave analysis of Airy beams upon reflection and refraction. A hybrid method based on the angular spectrum representation and vector potential in the Lorenz gauge is introduced to describe the vectorial

Conditions for the appearance of a modified Brewster or polarizing angle $\theta _P^\prime $ at which the magnitude of the reflection coefficient $|{\Gamma _p}|$ vanishes when both media have loss are derived. When these conditions are not satisfied, a pseudo-Brewster angle ${\theta _{\textit{PB}}}$ occurs at which $|{\Gamma _p}|$ is a minimum. Conditions are described under which previous expressions

The paper describes the results of finite-difference time-domain (FDTD) mathematical modeling of electromagnetic fields distortion near the surfaces of core-shell gold-based spherical gold nanoparticles (NPs). NPs were consistently functionalized by two shells of different thickness: a water shell, as a model substance for a drug, and an ${\rm SiO}_2$ shell, as a capsuling layer. The calculated field

We investigate localized plasmon-mode resonances in the scattering and absorption of transversely polarized light by bimetal core–shell nanowires made of silver and gold, in two possible combinations, using an analytical solution and experimental data for metal permittivities. In particular, the influence of the metal shell thickness and material on these resonances is studied. We show that, unlike

The Gouy phase, which describes how a field accumulates an additional phase shift around the focus compared to a spherical wave, is investigated for the strongly focused ${{\rm TM}_{01}}$ beam in free space. It is shown, using both analytical and numerical solutions, that when the effects of the edges of focusing optics are small, the complete variation of the on-axis Gouy phase of the longitudinal

This paper focuses on the two domain decomposition methods, the subdomain decomposition iterative method (SDIM) and the characteristics basis function method (CBFM), combined with adaptive cross approximation (ACA) to compute the normalized radar cross section (NRCS) from a perfectly conducting two-dimensional (2D) randomly rough surface. The 3D electromagnetic problem is solved from the electric field

Elastic properties of TaN films on (001)Si are investigated by surface Brillouin scattering (SBS). The velocity dispersion is obtained from Brillouin frequency shifts and surface acoustic wave phase velocities derived from measured SBS spectra. The observed Rayleigh surface acoustic and Sezawa waves indicate a soft on hard configuration. The elastic stiffnesses from the best fit of the calculated and

A contact-free inexpensive measurement system with an algorithm based on the integral form of video frames is proposed to estimate the respiration rate from an extracted respiration pattern. The proposed algorithm is applied and tested on 28 videos of sleeping-simulated positions, and the results are compared with the manual visual inspection values. With linear regression, the determination coefficient

Laser-induced fluorescence (LIF) combined with multivariate techniques has been used in identifying antimalarial herbal plants (AMHPs) based on their geographical origin. The AMHP samples were collected from four geographical origins (Abrafo, Jukwa, Nfuom, and Akotokyere) in the Cape Coast Metropolis, Ghana. LIF spectra data were recorded from the AMHP samples. Utilizing multivariate techniques, a

The fundamental physical phenomena occurring during the process of laser cutting are still only slightly understood, and thus the need to develop mathematical and numerical models to optimize the process parameters has become unavoidable for obtaining products with superior quality and for better use. It is in this context that we propose a new approach by building a model to study the laser cutting

Distribution of timing and frequency signals in a fast-changing world requires unprecedented levels of stability for characterization. Transfer of frequency references over long distance without introducing any additional instability is of urgent concern for optical clock development. Choice of optical transmitter is critical to achieving accurate and stable RF clocks for end users. In this paper,

This contribution reports on the observation of a strong light localization of Anderson type in 1D systems consisting of ship-shaped carbon nanotubes. Such a localization of infrared (IR) light was observed using Fourier transform infrared spectroscopy under attenuated total reflection geometry within the spectral range of 2–20 µm. Such an IR light localization manifests itself in the form of a significant

Structured light concerns the control of light in its spatial degrees of freedom (amplitude, phase, and polarization), and has proven instrumental in many applications. The creation of structured light usually involves the conversion of a Gaussian mode to a desired structure in a single step, while the detection is often the reverse process, both fundamentally lossy or imperfect. Here we show how to

This contribution reports on the optical properties of biosynthesised ${\rm{Eu}_2}{{\rm{O}}_3}$ nanoparticles bioengineered for the first time by a green and cost effective method using aqueous fruit extracts of Hyphaene thebaica as an effective chelating and capping agent. The morphological, structural, and optical properties of the samples annealed at 500°C were confirmed by using a high-resolution

We study the effects of increasing modulation instability and disorder on the onset times of rogue waves in waveguide arrays as described by the discrete unstable nonlinear Schrödinger equation (UNLSE). We analytically determine regions of instability, where rogue waves are likely to occur in the UNLSE, and then use numerical techniques to study the time evolution of these systems. Only for small modulation

In this paper, some generalizations of electromagnetic scattering problems by elementary shapes are presented. In particular, the aim of the paper is to provide solutions to the scattering problem by multiple objects with simple shapes, either in concentric configuration or arbitrarily distributed in the space. The vector harmonics, representing the fields, and their properties are applied in order

A handheld near-infrared optical scanner (NIROS) was recently developed to map for effective changes in oxy- and deoxyhemoglobin concentration in diabetic foot ulcers (DFUs) across weeks of treatment. Herein, a coregistration and image segmentation approach was implemented to overlay hemoglobin maps onto the white light images of ulcers. Validation studies demonstrated over 97% accuracy in coregistration

Linear canonical transformation (LCT) provides a generalized and elegant mathematical framework for analyzing the coherence properties of an electromagnetic (EM) beam propagating in quadratic phase systems (QPSs). It is shown that LCT may be used to analyze coherence properties such as generalized Stokes parameters and EM degree of coherence of a partially coherent EM beam propagating through a QPS

In this paper, a side-coupled liquid sensor and its array based on magneto-optical photonic crystal are proposed. The sensitivity and quality factor of a single magneto-optical photonic crystal sensor are 0.492 mm/RIU and 181,760, respectively. After arraying, the sensitivity of the single microcavity sensor can reach from 0.1 to 0.35 mm/RIU, and the corresponding quality factor can reach from ${{5}}

Passive imaging receivers that demultiplex an incoherent optical field into a set of orthogonal spatial modes prior to detection can surpass canonical diffraction limits on spatial resolution. However, these mode-sorting receivers exhibit sensitivity to contextual nuisance parameters (e.g., the centroid of a clustered or extended object), raising questions on their viability in realistic scenarios

This work presents the implementation, numerical examples, and experimental convergence study of first- and second-order optimization methods applied to one-dimensional periodic gratings. Through boundary integral equations and shape derivatives, the profile of a grating is optimized such that it maximizes the diffraction efficiency for given diffraction modes for transverse electric polarization.

The majority of spectrometers use reflective dispersion gratings with a metal-coated blazed grating profile for spectral decomposition. They achieve high diffraction efficiency at the design wavelength, which decays considerably in the adjacent longer and shorter wavelength ranges. We introduce a structured metal double-blazed grating with a high diffraction efficiency for a broadband spectral range

We present a new approach to coherent averaging in digital holography using singular value decomposition (SVD). Digital holography enables the extraction of phase information from intensity measurements. For this reason, SVD can be used to statistically determine the orthogonal vectors that align the complex-valued measurements from multiple frames and group common modes accounting for constant phase

Currently, valuable tickets are scanned and verified by embedding quick response (QR) codes, but few studies have embedded encrypted information into QR codes to prevent counterfeiting. In the existing literature on color image-based QR codes, there is room for improvement in image quality and anti-counterfeiting functions. We propose an optically decrypted microstructure overlapping image technology

Placido disk methods for corneal topography use a target with concentric rings in order to obtain measurements of the corneal surface, codifying the topography from the deformations of the rings’ image. Knowing exactly how the corneal surface departs from a rotational symmetric shape is difficult by using Placido rings. This is due to the fact that any ray deviations in the angular direction (sagittal