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Journal of the Optical Society of America. A, Optics, Image Science, and Vision

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https://www.readbyqxmd.com/read/29726496/temporal-modes-of-stationary-and-pulsed-quasistationary-electromagnetic-beams
#1
Lutful Ahad, Jari Turunen, Ari T Friberg, Tero Setälä
We present a novel time-domain coherent-mode representation for random, stationary electromagnetic beams. We subsequently introduce random, quasistationary pulsed electromagnetic beams and develop an analogous (pseudo) mode decomposition for them as well. The former decomposition is valid provided the time window in which the field is considered is much longer than the coherence time, while the latter requires the field to vanish outside the window. For stationary beams, the theory is demonstrated by an example illustrating the role of polarization in the representation...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726495/optical-constants-and-electrochromic-characteristics-of-h-x-moo-3-and-li-x-moo-3-bronzes
#2
Zahid Hussain
Ellipsometric concentration dependent data of Zx MoO3 (Z=H+ , Li+ ) bronze thin films are interpreted from different prospects to unravel a detailed account of electrochromic characteristics. From the linear parts of the electronic energy loss functions (-1/ϵ), and from the dips in the optical density data, it is very difficult to decide about crystallographic phase shifts in these bronzes, simply because of the difficulty of the structural determination of these microcrystalline materials. MoO3 bronze thin films are found to have high electrochromic efficiency, and therefore require higher charge density, and less substoichiometry, to obtain the same contrast ratio as observed in tungsten bronze thin films...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726494/what-is-a-troland
#3
Larry N Thibos, Norberto Lopez-Gil, Arthur Bradley
Trolands are a widely used measure of retinal illuminance in vision science and visual optics, but disagreements exist for the definition and interpretation of this photometric unit. The purpose of this communication is to resolve the confusion by providing a sound conceptual basis for interpreting trolands as a measure of angular flux density incident upon the retina. Using a simplified optical analysis, we show that the troland value of an extended source is the intensity in micro-candelas of an equivalent point source located at the eye's posterior nodal point that produces the same illuminance in the retinal image as does the extended source...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726493/optimization-model-for-multiplicative-noise-and-blur-removal-based-on-gaussian-curvature-regularization
#4
Fuquan Ren, Roberta Rui Zhou
In this paper, we focus on the restoration of images that are simultaneously blurred and corrupted by multiplicative noise. First, we introduce a variational restoration model consisting of the convex data-fitting term and the Gaussian curvature of the image as a regularizer to remove multiplicative Gamma noise because it is able to eliminate staircase effects while preserving sharp edges, textures, and other fine structures of the image. We then propose computing the minimizers of our restoration functionals by applying the augmented Lagrange multiplier method with splitting techniques...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726492/inverse-source-in-the-near-field-the-case-of-a-strip-current
#5
Raffaele Solimene, Maria Antonia Maisto, Rocco Pierri
In this paper, we consider an inverse source problem in the near zone for a prototype configuration where the field radiated by a bounded strip magnetic current is observed over a rectilinear and parallel (to the source) observation domain. The study focuses on how the achievable performance depends on the configuration's geometric parameters and the noise. In particular, we succeed in working out an approximation for the singular spectrum of the pertinent radiation operator that allows us to obtain analytical estimations for the resolution, the number of degrees of freedom, and the information content...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726491/unified-description-of-three-dimensional-optical-diffraction-microscopy-from-transmission-microscopy-to-optical-coherence-tomography-tutorial
#6
Anne Sentenac, Jerome Mertz
In this tutorial, we present a general model linking the data provided by any optical diffraction microscope to the sample permittivity. Our analysis is applicable to essentially all microscope configurations, in transmission or reflection mode, using scanning or full-field illumination, with or without interferometric measurements. We include also a generalization of our analysis to vector fields.
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726490/tunable-optical-properties-of-plasmonic-au-al-2-o-3-nanocomposite-thin-films-analyzed-by-spectroscopic-ellipsometry-accounting-surface-characteristics
#7
Jyoti Jaiswal, Satyendra Mourya, Gaurav Malik, Ramesh Chandra
In the present work, we have fabricated plasmonic gold/alumina nanocomposite (Au/Al2 O3 NC) thin films on a glass substrate at room temperature by RF magnetron co-sputtering. The influence of the film thickness (∼10-40  nm) on the optical and other physical properties of the samples was investigated and correlated with the structural and compositional properties. The X-ray diffractometer measurement revealed the formation of Au nanoparticles with average crystallite size (5-9.2 nm) embedded in an amorphous Al2 O3 matrix...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726489/normative-best-corrected-values-of-the-visual-image-quality-metric-vsx-as-a-function-of-age-and-pupil-size
#8
Gareth D Hastings, Jason D Marsack, Larry N Thibos, Raymond A Applegate
The visual image quality metric the visual Strehl ratio (VSX) combines a comprehensive description of the optics of an eye (wavefront error) with an estimate of the photopic neural processing of the visual system, and has been shown to be predictive of subjective best focus and well correlated with change in visual performance. Best-corrected visual image quality was determined for 146 eyes, and the quantitative relation of VSX, age, and pupil size is presented, including 95% confidence interval norms for age groups between 20 and 80 years and pupil diameters from 3 to 7 mm...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726488/fractal-spiral-zone-plates
#9
Ziwen Ji, Huaping Zang, Chunzhen Fan, Junqiao Wang, Chenglong Zheng, Lai Wei, Chuanke Wang, Leifeng Cao
We present diffractive optical elements with an extended depth of focus, namely, fractal spiral zone plates (FSZPs), which combine a fractal structure and spiral zone plates (SZPs) to generate a sequence of coaxial vortices in the focal volume along the propagation direction. The axial irradiance of the FSZPs is examined both experimentally and in a simulation and is compared with that of SZPs and that of fractal zone plates. The focusing properties of the FSZPs with different parameters are investigated, and a potential application to edge-enhancement images is also shown...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726487/how-accurately-do-different-computer-based-texture-characterization-methods-predict-material-surface-coarseness-a-guideline-for-effective-online-inspection
#10
Sajjad Ghodrati, Saeideh Gorji Kandi, Mohsen Mohseni
The growing industrialization has emphasized the need for high-performance computer-based inspection methods. Here, we investigated the performance of four major computer-based texture characterization methods in the prediction of visually perceived and actual surface coarseness of real materials. Gray level co-occurrence matrix (GLCM), distance-dependent edge frequency (DDEF), fractal dimension (FD), and histogram skewness (SK) were used as the methods. A novel collection of real materials consisting of 20 sandpapers with high, medium, and low coarseness levels was employed...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726486/turbulence-effects-on-fluctuations-of-the-aperture-averaged-orbital-angular-momentum
#11
Mikhail Charnotskii
A complete asymptotic theory for the aperture-averaged orbital angular momentum (OAM) variance is developed for both weak and strong fluctuation conditions, based on the asymptotic expansions of the Feynman path-integral solution for the fourth-order coherence function of a spherical wave propagating through a random inhomogeneous medium. We show that the OAM fluctuation averaging is very different for circular-symmetric and non-circular-symmetric apertures. Aperture averaging of the OAM fluctuations does not obey the standard "square root" law, and the weak/strong fluctuation conditions for the aperture-averaged OAM are not defined solely by the values of the scintillation index of the incident wave...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726485/flat-bands-of-optical-dielectric-beats
#12
Gandhi Alagappan, Ching Eng Png
When we combine two periodic dielectric functions of slightly different spatial frequencies, we have spatial dielectric beats, which are periodic supercells in the longer spatial scale. This paper investigates these dielectric beats by solving the one-dimensional Maxwell's equation using a slowly varying envelope approximation. We show that the Maxwell's equation reduces to a three-term recurrence relation, leading to a tridiagonal eigenvalue problem with a dense number of eigenmodes with ultrasmall dispersions...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726484/radial-angular-entanglement-in-laguerre-gaussian-mode-superpositions
#13
S Asokan, J Solomon Ivan
Classical optic entanglement between the radial and angular degrees of freedom in Laguerre-Gaussian mode superpositions is explored within the framework of symmetric first-order optical systems. The Gouy phase picked by a Laguerre-Gaussian mode on free propagation is seen to be of consequence to the radial-angular entanglement in the mode superpositions. We illustrate examples of mode superpositions for which radial-angular entanglement is preserved on passage through symmetric first-order optical systems. An indicator of radial-angular entanglement in two-mode Laguerre-Gaussian superpositions is demonstrated to be a robust free space signaler in the presence of atmospheric turbulence, through examples...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726483/four-mirror-flat-field-anastigmat-aplanat-telescopes-with-simple-closed-form-solutions
#14
Rajesh Govindan
A four-mirror anastigmat aplanat telescope can be constructed using a Gregorian-form Mersenne afocal telescope as a feeder for a concentric spherical Schwarzschild objective. A flat image field can be obtained by adjusting the ratio of the radii of the mirrors. With the tertiary at the image of the aperture stop (the primary) the primary's conic K1 can be varied, using the tertiary's conic K3 to cancel the primary's spherical aberration without affecting the system's coma or astigmatism. For a spherical primary, the tertiary is an oblate ellipsoid (K3 >0)...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726482/effect-of-interaction-between-the-internal-cavity-and-external-cavity-on-beam-properties-in-a-spectrally-beam-combined-system
#15
Zhen Wu, Takashi Ito, Hidefumi Akiyama, Bin Zhang
A high-power beam can be achieved in spectrally beam combined systems due to the interaction between internal and external cavities. In order to investigate effects of the coupled cavity on the combined beam, we started with the derivation of the equivalent reflectance and transmittance of the external cavity based on a multilayer dielectric grating (MDG). Then, photons in active regions of diode lasers with/without feedback were calculated by utilizing Lang-Kobayashi rate equations. The results indicate that the lens and the MDG have an obvious impact on both the reflectance and transmittance of the external cavity, which determine whether the photons of a laser with feedback are larger or smaller than those without feedback...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29726481/calibrating-reconstruction-radius-in-a-multi-single-element-ultrasound-transducer-based-photoacoustic-computed-tomography-system
#16
Sandeep Kumar Kalva, Zhe Zhi Hui, Manojit Pramanik
In a circular scanning photoacoustic computed tomography (PAT/PACT) system, a single-element ultrasound transducer (SUT) (rotates in full 360° around the sample) or a full-ring array transducer is used to acquire the photoacoustic (PA) data from the target object. SUT takes several minutes to acquire the PA data, whereas the full-ring array transducer takes only few seconds. Hence, for real-time imaging, full-ring circular array transducers are preferred. However, these are custom built, very expensive, and not available readily on the market, whereas SUTs are cheap and easily available...
May 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29603986/averaging-colors-of-multicolor-mosaics
#17
Eiji Kimura
The present study investigated how color information was summarized in multicolor mosaics. The mosaics were composed of small elements of 17 colors that roughly belonged to a single color category. We manipulated the degree of color variation around the mean by varying the proportion of different color elements. Observers matched the mean color of the multicolor mosaic by adjusting the color of a spatially uniform matching stimulus. Results showed that when the color variation was large, the matched color deviated from the colorimetric mean toward the most-saturated color, although the hue of the matched color was almost the same as that of the colorimetric mean...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29603985/discrimination-of-spectral-reflectance-under-environmental-illumination
#18
Takuma Morimoto, Hannah E Smithson
Color constancy is the ability to recover a stable perceptual estimate of surface reflectance, regardless of the lighting environment. However, we know little about how observers make judgments of the surface color of glossy objects, particularly in complex lighting environments that introduce complex spatial patterns of chromatic variation across an object's surface. To address this question, we measured thresholds for reflectance discrimination using computer-rendered stimuli under environmental illumination...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29603984/a-mathematical-approach-to-best-luminance-maps
#19
Ali Alsam, Hans Jakob Rivertz
An algorithm to calculate the best global mapping from color to grayscale is presented. We assert that the best mapping minimizes the difference between the multi-channel local tensor and the tensor of the resultant mono-chromatic image. To minimize the objective function, we represent the grayscale image as a weighted sum of the RGB channels, three channels and their second-order polynomial and three channels and their root polynomial. The optimization searches for the best weights to combine the linear, polynomial, and root polynomial functions...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29603983/accuracy-enhanced-and-synthetic-wavelength-adjustable-optical-metrology-via-spectrally-resolved-digital-holography
#20
D Claus, G Pedrini, D Buchta, W Osten
This paper demonstrates the usefulness of spectrally resolved digital holography for dual-wavelength optical metrology. Based on the large degree of phase information available, multiple de-correlated dual-wavelength phase maps can be generated, which, when averaged, result in a signal-to-noise-ratio improvement. Compared with single-wavelength averaging, no further post-processing of the reconstructed dual-wavelength phase map is required. Moreover, the constraint imposed on the wavelength stability, as experienced in the conventional dual-wavelength method, can be relaxed, and the corresponding synthetic wavelength is adapted to the object under investigation...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
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