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Showing papers in "Journal of The Optical Society of America A-optics Image Science and Vision in 2022"


Journal ArticleDOI
TL;DR: In this article , a new type surface wave is found that propagates in a linearly graded-index and an intensity-dependent index layered structure characterized by an abrupt change in the dielectric constant.
Abstract: A new type surface wave is found that propagates in a linearly graded-index and an intensity-dependent index layered structure characterized by an abrupt change in the dielectric constant. The main surface wave characteristics are calculated analytically. The optical domain, the thickness of which increases with an increasing effective refractive index and decreases with an increasing characteristic distance, is formed. It is discovered that the characteristic distance of the graded-index medium and effective refractive index can control wave energy redistribution between the semiconductor layers.

12 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide a comprehensive analysis on the sampling of all Fresnel diffraction fields, including the complex amplitude, intensity, amplitude, and phase, from the perspective of phase space optics.
Abstract: Numerical calculation of Fresnel diffraction is widely used in optical applications where wave propagation is needed. Most cases for simulating Fresnel diffraction only consider sampling of complex amplitude fields, which lacks comprehensiveness when different diffraction fields are of interest. In this study, from the perspective of phase space optics, we provide systematical analysis on the sampling of all Fresnel diffraction fields, including the complex amplitude, intensity, amplitude, and phase. The space-bandwidth product of each field is illustrated with the aid of a phase space diagram, which is further demonstrated from a physical point of view. Such comprehensive sampling analysis could provide practical suggestions to the numerical calculations of various diffraction fields according to the requirements. Numerical experiments with discrete Fresnel diffraction are implemented to verify feasibility of the analyses.

6 citations


Journal ArticleDOI
TL;DR: A novel machine vision system for the detection of silicon-nitride-bearing roller surface defects that combines image segmentation and wavelet fusion to extract features from an image and uses a classifier based on the K-nearest neighbor for defect classification.
Abstract: Defect detection is a critical way to ensure quality for silicon-nitride-bearing rollers. To improve detection efficiency and precision for silicon-nitride-bearing roller surface defects, in this paper, a novel machine vision system for the detection of its surface defects is designed. This method combines image segmentation and wavelet fusion to extract features from an image. In turn, the features are used in a classifier based on the K-nearest neighbor for defect classification. The optimized image segmentation algorithm that is combined with wavelet fusion is the innovation of the proposed method. It is evaluated using different defect images acquired by the machine vision system. Our experiments show that the proposed machine vision system's precision in anomaly detection of the silicon-nitride-bearing roller surface can achieve 98.5%; further, its classification precision of various defects is greater than 91.5%. It has resulted in a solution for the automatic identification of the silicon-nitride-bearing roller surface defects.

5 citations


Journal ArticleDOI
TL;DR: In this paper , a two-sample estimator of the conversion gain was proposed and used to find approximate optimal sample size pairs that allow experimenters to achieve a predetermined measurement uncertainty with as little data as possible.
Abstract: Working from a model of Gaussian pixel noise, we present and unify over 25 years of developments in the statistical analysis of the photon transfer conversion gain measurement. We then study a two-sample estimator of the conversion gain that accounts for the general case of non-negligible dark noise. The moments of this estimator are ill-defined (their integral representations diverge), and so we propose a method for assigning pseudomoments, which are shown to agree with actual sample moments under mild conditions. A definition of optimal sample size pairs for this two-sample estimator is proposed and used to find approximate optimal sample size pairs that allow experimenters to achieve a predetermined measurement uncertainty with as little data as possible. The conditions under which these approximations hold are also discussed. Design and control of experiment procedures are developed and used to optimally estimate a per-pixel conversion gain map of a real image sensor. Experimental results show excellent agreement with theoretical predictions and are backed up with Monte Carlo simulation. The per-pixel conversion gain estimates are then applied in a demonstration of per-pixel read noise estimation of the same image sensor. The results of this work open the door to a comprehensive pixel-level adaptation of the photon transfer method.

3 citations


Journal ArticleDOI
TL;DR: In this paper , a deep learning approach for orbital angular momentum (OAM) mode classification is presented, where the intensity images of these speckle fields are fed to a convolutional neural network (CNN) for training a classification model that classifies modes with an accuracy > 99%.
Abstract: We present a speckle-based deep learning approach for orbital angular momentum (OAM) mode classification. In this method, we have simulated the speckle fields of the Laguerre-Gauss (LG), Hermite-Gauss (HG), and superposition modes by multiplying these modes with a random phase function and then taking the Fourier transform. The intensity images of these speckle fields are fed to a convolutional neural network (CNN) for training a classification model that classifies modes with an accuracy >99%. We have trained and tested our method against the influence of atmospheric turbulence by training the models with perturbed LG, HG, and superposition modes and found that models are still able to classify modes with an accuracy >98%. We have also trained and tested our model with experimental speckle images of LG modes generated by three different ground glasses. We have achieved a maximum accuracy of 96% for the most robust case, where the model is trained with all simulated and experimental data. The novelty of the technique is that one can do the mode classification just by using a small portion of the speckle fields because speckle grains contain the information about the original mode, thus eliminating the need for capturing the whole modal field, which is modal dependent.

2 citations


Journal ArticleDOI
TL;DR: In this article , a modal technique for modeling the behavior of spectrometers that allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces is presented.
Abstract: Modeling ultra-low-noise far-infrared grating spectrometers has become crucial for the next generation of far-infrared space observatories. Conventional techniques are awkward to apply because of the partially coherent form of the incident spectral field, and the few-mode response of the optics and detectors. We present a modal technique for modeling the behavior of spectrometers that allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces. We illustrate the technique by modeling the behavior of the long wavelength band of the proposed SAFARI instrument on the well-studied SPICA mission.

2 citations


Journal ArticleDOI
TL;DR: In this paper , Monte Carlo (MC) codes describing the transport of photons in anomalous media can be implemented, and the heart of the method involves suitably describing, in a "non-classical" manner, photon steps starting from fixed light sources or from boundaries separating regions of the medium with different optical properties.
Abstract: Anomalous radiative transfer (ART) theory represents a generalization of classical radiative transfer theory. The present tutorial aims to show how Monte Carlo (MC) codes describing the transport of photons in anomalous media can be implemented. We show that the heart of the method involves suitably describing, in a "non-classical" manner, photon steps starting from fixed light sources or from boundaries separating regions of the medium with different optical properties. To give a better sense of the importance of these particular photon step lengths, we also show numerically that the described approach is essential in preserving the invariance property for light propagation. An interesting byproduct of the MC method for ART is that it allows us to simplify the structure of "classical" MC codes, utilized, for example, in biomedical optics.

2 citations


Journal ArticleDOI
TL;DR: In this article , the authors describe how to generate random electromagnetic field instances or realizations consistent with a given or desired cross-spectral density matrix for use in wave optics simulations, assuming that the reader has knowledge of the fundamental principles of statistical optics and optical coherence theory.
Abstract: Numerous applications-including optical communications, directed energy, remote sensing, and optical tweezing-utilize the principles of statistical optics and optical coherence theory. Simulation of these phenomena is, therefore, critical in the design of new technologies for these and other such applications. For this reason, this tutorial describes how to generate random electromagnetic field instances or realizations consistent with a given or desired cross-spectral density matrix for use in wave optics simulations. This tutorial assumes that the reader has knowledge of the fundamental principles of statistical optics and optical coherence theory. An extensive reference list is provided where the necessary background information can be found. We begin this tutorial with a brief summary of the coherent-mode representation and the superposition rule of stochastic electromagnetic fields as these foundational ideas form the basis of all known synthesis techniques. We then present optical field expressions that apply these concepts before discussing proper sampling and discretization. We finally compare and contrast coherent-mode- and superposition-rule-based synthesis approaches, discussing the pros and cons of each. As an example, we simulate the synthesis and propagation of an electromagnetic partially coherent field from the literature. We compare simulated or sample statistics to theory to verify that we have successfully produced the desired field and are capturing its propagation behaviors. All computer programs, including detailed explanations of the source code, are provided with this tutorial. We conclude with a brief summary.

2 citations


Journal ArticleDOI
TL;DR: In this article , two designs with a multiplexed superluminescent diode for ultra-high-resolution spectral-domain polarization-sensitive optical coherence tomography (UHR-PS-OCT) are introduced.
Abstract: Two designs with a multiplexed superluminescent diode for ultra-high-resolution spectral-domain polarization-sensitive optical coherence tomography (UHR-PS-OCT) are introduced. In the first design, a Wollaston prism separates orthogonal polarization states next to each other on one linescan camera; the other design uses a beam displacer to separate orthogonal states onto two lines of a linescan camera with multiple rows of detectors. The coherence lengths measured with the two systems were 3.6 µm and 2.9 µm (n=1.38), respectively. Measurements were collected from the fovea of a healthy subject, a healthy subject with astigmatism, and a patient with central serous retinopathy (CSR). A single volumetric scan provides double pass retardance induced by the retinal nerve fiber layer birefringence (RNFL) and its birefringence, the cumulative double pass retardance induced by the Henle fiber layer, and the retardance that is induced by the retinal pigment epithelium-Bruch's membrane complex. The high axial resolution in UHR-PS-OCT is particularly helpful for the measurements of thin retinal tissue, such as the RNFL in the fovea, where birefringence values of around 1°/µm were found. Tilting of the retina due to a CSR or by off centering the imaging beam in the pupil causes an artificial increase in the double pass retardance induced by the RNFL and Henle fiber layer.

2 citations


Journal ArticleDOI
TL;DR: In this paper , a diffraction-based explanation of the reported phenomena is provided that yields a solid theoretical foundation for the prediction of experimental results and that clarifies many of the convoluted explanations found throughout the literature.
Abstract: The widespread concept of "generalized laws of reflection and refraction" that is commonly applied to wave propagation through metasurfaces is thoroughly explained on the foundation of diffraction theory. This allows definition of strict constraints to the applicability of these generalized laws and highlights the underlying physical effects. A diffraction-based explanation of the reported phenomena is provided that yields a solid theoretical foundation for the prediction of experimental results and that clarifies many of the convoluted explanations found throughout the literature.

2 citations


Journal ArticleDOI
TL;DR: In this article , the Gibbs-like oscillations that appear due to discrete "discontinuities" of the input images under unitary transformations have been examined, where some pixel color values may fall outside their required common numerical range [0, 1], between absence and saturation of the red, green, and blue formant colors we choose to represent the images.
Abstract: Unitary rotations of polychromatic images on finite two-dimensional pixellated screens provide invertibility, group composition, and thus conservation of information. Rotations have been applied on monochromatic image data sets, where we now examine closer the Gibbs-like oscillations that appear due to discrete "discontinuities" of the input images under unitary transformations. Extended to three-color images, we examine here the display of color at the pixels where, due to oscillations, some pixel color values may fall outside their required common numerical range [0,1], between absence and saturation of the red, green, and blue formant colors we choose to represent the images.

Journal ArticleDOI
TL;DR: In this article , the Mie scattering theory is combined with the polarization bidirectional reflection distribution function theory of a target with microfacet theory, and the Monte Carlo method is used to establish an underwater laser active-polarization imaging model.
Abstract: The polarization bidirectional reflection distribution function theory of a target is combined with microfacet theory, and the Monte Carlo method is used to establish an underwater laser active-polarization imaging model based on Mie scattering theory. The model presented herein can simulate imaging of an underwater target with a high degree of polarization, and the effects of optical thickness and target surface roughness on active underwater laser imaging results are demonstrated by the simulation image. Combined with histogram equalization and the traditional polarization differential imaging algorithm, an algorithm is presented herein that globally estimates the mutual information value between the target polarization degree and the correction factor of backscattered light polarization degree. The images received from the simulation test can be restored, and results show that the algorithm can restore the target image with a high degree of polarization to some extent. Finally, the correctness of the active underwater laser polarization imaging model and the feasibility of global estimation based on the polarization differential restoration algorithm are verified experimentally.

Journal ArticleDOI
TL;DR: This paper found that the pattern of human thresholds is not consistent with the ideal observer but is consistent with a suboptimal observer that performs partial whitening in spatial frequency and whitening (reliability-weighting) in space.
Abstract: Most studies of detection in complex backgrounds have measured and modeled human performance for statistically uniform (stationary) backgrounds. However, natural and medical images have statistical properties that vary over space. We measured detection of various target shapes presented in Gaussian 1/f noise backgrounds that were statistically uniform over space, and in ones that modulated in contrast over space. We find that the pattern of human thresholds is not consistent with the ideal observer but is consistent with a suboptimal observer that performs partial whitening in spatial frequency and whitening (reliability-weighting) in space, and has a small level of intrinsic position uncertainty.

Journal ArticleDOI
TL;DR: In this article , the power spectrum model for natural water turbulence is extended from weak to moderate-to-strong regimes with the help of the spatial filtering approach, and expressions for the scintillation index (SI) are obtained, and based on its signal to noise ratio and bit error rate of the underwater wireless optical communication (UWOC) system with the on-off-keying modulation and gamma-gamma irradiance distribution model, the analysis is performed.
Abstract: The recently introduced power spectrum model for natural water turbulence, i.e., that at any average temperature, average salinity, and stratification [J. Opt. Soc. Am. A37, 1614 (2020)JOAOD61084-752910.1364/JOSAA.399150], is extended from weak to moderate-to-strong regimes with the help of the spatial filtering approach. Based on the extended spectrum, the expressions for the scintillation index (SI) are obtained, and based on its signal-to-noise ratio and bit error rate of the underwater wireless optical communication (UWOC) system with the on-off-keying modulation and gamma-gamma irradiance distribution model, the analysis is performed. The obtained results are compared with those derived from the widely used Nikishov and Nikishov spectrum. It is shown that the natural water turbulence results in the SI for plane (spherical) waves attaining higher maxima values at shorter propagation distances, about 20 m (40 m) with respect to 30 m (50 m) of Nikishovs turbulence. Therefore, it predicts a stronger degradation of the UWOC system performance in weak and moderate turbulence regimes.

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors proposed three-dimensional (3D) photon counting integral imaging by using multi-level decomposition such as discrete wavelet transform to improve the visual quality and measurement accuracy under photon-starved conditions.
Abstract: In this paper, we propose three-dimensional (3D) photon counting integral imaging by using multi-level decomposition such as discrete wavelet transform to improve the visual quality and measurement accuracy under photon-starved conditions. Conventional 3D integral imaging can visualize 3D objects and acquire their depth information. However, the amount of irradiated light on the object causes the degradation of visual quality for 3D images under photon-starved conditions. To visualize 3D objects, photon counting integral imaging has been utilized. It can detect photons from 3D scenes by using a computational photon counting model, which is modelled by the Poisson random process. However, photons occur not only from objects but also in areas where objects do not exist. Moreover, photon fluctuation may occur in the scene through shot noise. Since these noise photons are measurement errors, it may decrease the image quality and accuracy. In contrast, our proposed method uses 2D discrete wavelet transform, which can emphasize the object photons effectively. Finally, our proposed method can enhance the visual quality of 3D images and provide more accurate depth information under photon-starved conditions. To prove the feasibility of our proposed method, we implement the optical experiment and calculate various image quality metrics.

Journal ArticleDOI
TL;DR: In this paper , a neurobiological color vision model was proposed to predict spectral locations and variability of the irreducible unique hues-red, green, blue, and yellow.
Abstract: The irreducible unique hues-red, green, blue, and yellow-remain one of the great mysteries of vision science. Attempts to create a physiologically parsimonious model that can predict the spectral locations of the unique hues all rely on at least one post hoc adjustment to produce appropriate loci for unique green and unique red, and struggle to explain the non-linearity of the Blue/Yellow system. We propose a neurobiological color vision model that overcomes these challenges by using physiological cone ratios, cone-opponent normalization to equal-energy white, and a simple adaptation mechanism to produce color-opponent mechanisms that accurately predict the spectral locations and variability of the unique hues.

Journal ArticleDOI
TL;DR: In this article , a unified method for three-dimensional reconstruction of objects from transmission images collected at multiple illumination directions is described, which may be applicable to experimental conditions relevant to absorption-based, phase contrast, or diffraction imaging using x rays, electrons, and other forms of penetrating radiation or matter waves.
Abstract: A unified method for three-dimensional reconstruction of objects from transmission images collected at multiple illumination directions is described. The method may be applicable to experimental conditions relevant to absorption-based, phase-contrast, or diffraction imaging using x rays, electrons, and other forms of penetrating radiation or matter waves. Both the phase retrieval (also known as contrast transfer function correction) and the effect of Ewald sphere curvature (in the cases with a shallow depth of field and significant in-object diffraction) are incorporated in the proposed algorithm and can be taken into account. Multiple scattering is not treated explicitly but can be mitigated as a result of angular averaging that constitutes an essential feature of the method. The corresponding numerical algorithm is based on three-dimensional gridding which allows for fast computational implementation, including a straightforward parallelization. The algorithm can be used with any scanning geometry involving plane-wave illumination. A software code implementing the proposed algorithm has been developed, tested on simulated and experimental image data, and made publicly available.

Journal ArticleDOI
TL;DR: In this paper , a rigorous model has been proposed to qualify fluorescence scattering through the Mueller matrix viewpoint in terms of absorption/excitation, emission, and the process in between them.
Abstract: A rigorous model has been proposed to qualify fluorescence scattering through the Mueller matrix viewpoint in terms of absorption/excitation, emission, and the process in between them. The process in between the excitation and emission processes of fluorescence, irrespective of the scattering directions, has been modeled as a depolarization process. The absorption/excitation of the fluorophore molecules gets revealed through the first-row elements while the emission of fluorescence has been observed through the first column elements of the fluorescence Mueller matrix. Information of the transitions between the molecular ground and excited states gets encoded into the diagonal elements following the photon selection rule. The other off-diagonal elements of the fluorescence Mueller matrix also exhibit very small nonzero values due to the anisotropic absorption and phase changes that the ground state of the fluorophore molecules imposes on the incident polarized beam while parallelly governing the emitted beam. The comparison of the current model with the earlier model has been discussed in a detailed way. The modeling of the in-between process as the depolarizing one enables us to qualify the fluorescence detected linear and circular dichroism and luminescence and very effectively overcomes the shortcomings in the earlier model.

Journal ArticleDOI
TL;DR: In this paper , analytically individual autofocusing luminal and superluminal localized waves are presented that can attain high-intensity peaks and spatiotemporal localization at prespecified positions along the path of their propagation.
Abstract: Highly focused space-time wavepackets in free space have already been achieved by means of suitable superpositions of nondiffracting and almost undistorted spatiotemporally localized pulses. Here, we present analytically individual autofocusing luminal and superluminal localized waves that can attain high-intensity peaks and spatiotemporal localization at prespecified positions along the path of their propagation.

Journal ArticleDOI
TL;DR: In this article , an analysis of finite-energy Airy beams is presented from a flux trajectory perspective with the purpose of better understanding the mechanisms that make infinite and finite energy beams exhibit different behaviors.
Abstract: Airy beams are solutions to the paraxial Helmholtz equation known for exhibiting shape invariance along their self-accelerated propagation in free space. These two properties are associated with the fact that they are not square integrable, that is, they carry infinite energy. To circumvent this drawback, families of so-called finite-energy Airy-type beams have been proposed in the literature and, in some cases, also implemented in the laboratory. Here an analysis of the propagation of this type of structured light beam is presented from a flux trajectory perspective with the purpose of better understanding the mechanisms that make infinite and finite energy beams exhibit different behaviors. As is shown, while the foremost part of the beam can be clearly and unambiguously associated with the well-known accelerating term, the rear part of the beam corresponds to a nearly homogeneous distribution of flow trajectories, particularly for long propagation distances. This is shown to be related to an effective transfer of trajectories between adjacent lobes (gradually, from the fore part of the beam to its rear part), which leads to smearing out the transverse flow along the rear part of the beam. This is in sharp contrast to the situation found in ideal Airy beams, where trajectories belonging to a given lobe of the intensity distribution remain the same all along the propagation. The analysis is supplemented with an also trajectory-based description of Young's experiment performed with finite-energy Airy beams to provide a dynamical understanding of the autofocusing phenomenon observed with circular Airy beams.

Journal ArticleDOI
TL;DR: In this paper , the authors compare direct measurements of cavity and mirror losses in the Caltech 40 m gravitational-wave detector prototype interferometer with numerical estimates obtained from semi-analytic intra-cavity wavefront simulations using mirror surface profile maps.
Abstract: Optical losses degrade the sensitivity of laser interferometric instruments. They reduce the number of signal photons and introduce technical noise associated with diffuse light. In quantum-enhanced metrology, they break the entanglement between correlated photons. Such decoherence is one of the primary obstacles in achieving high levels of quantum noise reduction in precision metrology. In this work, we compare direct measurements of cavity and mirror losses in the Caltech 40 m gravitational-wave detector prototype interferometer with numerical estimates obtained from semi-analytic intra-cavity wavefront simulations using mirror surface profile maps. We show a unified approach to estimating the total loss in optical cavities (such as the LIGO gravitational detectors) that will lead towards the engineering of systems with minimum decoherence for quantum-enhanced precision metrology.

Journal ArticleDOI
TL;DR: In this paper , a method for high-resolution, three-dimensional reconstruction of internal structures of objects from planar transmission images is proposed, which can be used with any form of radiation or matter waves, provided that the depth of field is smaller than the thickness of the sample.
Abstract: A method is proposed for high-resolution, three-dimensional reconstruction of internal structures of objects from planar transmission images. The described approach can be used with any form of radiation or matter waves, in principle, provided that the depth of field is smaller than the thickness of the sample. The physical optics basis for the method is elucidated, and the reconstruction algorithm is presented in detail. A simulated example demonstrates an application of the method to three-dimensional electron transmission imaging of a nanoparticle under realistic radiation dose and spatial resolution constraints. It is envisaged that the method can be applicable in high-resolution transmission electron microscopy, soft x-ray microscopy, ultrasound imaging, and other areas.

Journal ArticleDOI
TL;DR: In this paper , a scalar approximation that accounts for the polarization of the incident field is proposed. But the scalar wave equation is not suitable for the case of light-sample interaction.
Abstract: Replacing Maxwell equations by a scalar wave equation is often used in computational imaging to simulate the light-sample interaction. It significantly reduces the computational burden but provides field maps that are insensitive to the polarization of the incident field, provided the latter is constant throughout the sample. Here, we develop a scalar approximation that accounts for the polarization of the incident field. Comparisons with rigorous simulations show that this approach is more accurate than the classical scalar approximation with similar computational cost.

Journal ArticleDOI
TL;DR: In this paper , the authors combine two-dimensional freeform reflector design with a scattering surface modeled using microfacets, i.e., small, specular, surfaces representing surface roughness.
Abstract: We combine two-dimensional freeform reflector design with a scattering surface modeled using microfacets, i.e., small, specular, surfaces representing surface roughness. The model resulted in a convolution integral for the scattered light intensity distribution, which yields an inverse specular problem after deconvolution. Thus, the shape of a reflector with a scattering surface may be computed using deconvolution, followed by solving the typical inverse problem of specular reflector design. We found that the presence of surface scattering resulted in a few percentage difference in terms of reflector radius, depending on the amount of scattering in the system.

Journal ArticleDOI
TL;DR: This paper analyzes the optimization process of the objective function of the multi-class GAN (Mc-GAN), which can generate high-quality images and reduce training time, and it can be used for data augmentation in object recognition.
Abstract: The current generative adversarial network (GAN) is limited in the application of data augmentation in object recognition. The training of the GAN is unstable, and the generated image quality is poor. Methods such as progressive growing of GANs and multi-scale gradient GAN solve these problems. The packed GAN (PacGAN) solves the problem of mode collapse during training. However, these methods can generate only one type of image at a time, and the training time is long. To solve the above problems, this paper proposes the multi-class GAN (Mc-GAN). It uses an augmented discriminator to train multiple generators at the same time. Through iterative training, the discriminator can accurately judge the output of each generator and guide it to generate the corresponding image. This paper analyzes the optimization process of the objective function of Mc-GAN. Experiments show that the method can generate high-quality images and reduce training time, and it can be used for data augmentation in object recognition. It effectively improves the practicality of GAN.

Journal ArticleDOI
TL;DR: In this article , a system and method that record spatio-temporal scene information and location of the center of visual attention in ecological environments is presented and evaluated, which can be used to determine accommodation and vergence cues of the human visual system continuously within habitual environments, including everyday applications (e.g., use of hand-held devices).
Abstract: This paper presents and evaluates a system and method that record spatiotemporal scene information and location of the center of visual attention, i.e., spatiotemporal point of regard (PoR) in ecological environments. A primary research application of the proposed system and method is for enhancing current 2D visual attention models. Current eye-tracking approaches collapse a scene's depth structures to a 2D image, omitting visual cues that trigger important functions of the human visual system (e.g., accommodation and vergence). We combined head-mounted eye-tracking with a miniature time-of-flight camera to produce a system that could be used to estimate the spatiotemporal location of the PoR-the point of highest visual attention-within 3D scene layouts. Maintaining calibration accuracy is a primary challenge for gaze mapping; hence, we measured accuracy repeatedly by matching the PoR to fixated targets arranged within a range of working distances in depth. Accuracy was estimated as the deviation from estimated PoR relative to known locations of scene targets. We found that estimates of 3D PoR had an overall accuracy of approximately 2° omnidirectional mean average error (OMAE) with variation over a 1 h recording maintained within 3.6° OMAE. This method can be used to determine accommodation and vergence cues of the human visual system continuously within habitual environments, including everyday applications (e.g., use of hand-held devices).

Journal ArticleDOI
TL;DR: In this article , the authors study visual sensitivity to image statistics in three families of textures that include multiple gray levels and correlations in two spatial dimensions, and build a computational model, fully constrained by prior studies of sensitivity to uncorrelated textures and black-and-white textures with spatial correlations.
Abstract: Analysis of visual texture is important for many key steps in early vision. We study visual sensitivity to image statistics in three families of textures that include multiple gray levels and correlations in two spatial dimensions. Sensitivities to positive and negative correlations are approximately independent of correlation sign, and signals from different kinds of correlations combine quadratically. We build a computational model, fully constrained by prior studies of sensitivity to uncorrelated textures and black-and-white textures with spatial correlations. The model accounts for many features of the new data, including sign-independence, quadratic combination, and the dependence on gray-level distribution.

Journal ArticleDOI
TL;DR: In this article , an optimized controlling light method of a binocular holographic three-dimensional (3D) display system based on the holographic optical element (HOE) is proposed.
Abstract: Due to the limited pixel pitch of the spatial light modulator (SLM), the field of view (FOV) is insufficient to meet binocular observation needs. Here, an optimized controlling light method of a binocular holographic three-dimensional (3D) display system based on the holographic optical element (HOE) is proposed. The synthetic phase-only hologram uploaded onto the SLM is generated with the layer-based angular spectrum diffraction theory, and two different reference waves are introduced to separate the left view and the right view of the 3D scene. The HOE with directional controlling light parameters is employed to guide binocular information into the left-eye and the right-eye viewing zones simultaneously. Optical experiments verify that the proposed system can achieve binocular holographic augmented reality 3D effect successfully with real physical depth, which can eliminate the accommodation-vergence conflict and visual fatigue problem. For each perspective, the FOV is 8.7° when the focal length of the HOE is 10 cm. The width of the viewing zone is 2.3 cm when the viewing distance is 25 cm.

Journal ArticleDOI
TL;DR: In this article , the dynamics of a dielectric microparticle in air using a lensed counter-propagating dual-beam trap was studied experimentally and by numerical simulations.
Abstract: Orbital dynamics of a dielectric microparticle in air using a lensed counter-propagating dual-beam trap was studied experimentally and by numerical simulations. Relationships between the dynamic parameters, trap geometry, and optical power were examined both experimentally and computationally. We found that this scheme can provide narrow bandwidth (δν/ν≈10-3) detection that is at least two orders of magnitude below typical values attainable with previously studied geometries. We predict that this characteristic makes the approach suitable for ultrasensitive in-situ detection of particle mass changes. In our experimental conditions, silica microspheres orbited on trajectories spanning tens of µm, at frequencies of up to ∼2kHz, at atmospheric pressure. With the help of simulations, we briefly discuss how the dual-beam lensed orbital trap approach can be further enhanced to gain unmatched capabilities to measure changes in the physical parameters associated with a particle interacting with its surrounding medium.

Journal ArticleDOI
TL;DR: A method is presented to design a stigmatic lens with a user-defined apodization pupil function that is required by Richards-Wolf diffraction integrals to compute non-paraxial diffraction patterns.
Abstract: Here we present a method to design a stigmatic lens with a user-defined apodization pupil function. The motive is that the apodization pupil function is required by Richards-Wolf diffraction integrals to compute non-paraxial diffraction patterns. Then, the user-defined apodization pupil function can be chosen such that the focus spot obtained by the stigmatic lens is smaller. The mentioned method is based on numerically solving a non-linear differential equation.