Accepted papers to appear in an upcoming issue
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Broadband ultra-flattened dispersion, ultra-lowconfinement loss and large effective mode area in anoctagonal photonic quasi-crystal fiber
Exian Liu, Wei Tan, Bei Yan, Jianlan Xie, Rui Ge, and Jianjun Liu
Doc ID: 309974 Received 25 Oct 2017; Accepted 18 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: In this work, an octagonal Penrose-type photonic quasi-crystal fiber (PQF) with dual-cladding is proposed. Byoptimizing three geometric degrees of freedom, the PQF exhibits ultra-flattened near-zero dispersion of0.014±0.293 ps/nm/km, ultra-low order confinement loss of 10-4 dB/km, and large effective mode area over 16.2μm2, in a broadband of wavelength from 1.27 to 1.67 μm covering almost all optical communication bands. At thecommon communication wavelength 1.55 μm, completely opposite trends of the dispersion and the confinementloss varying with the air filling factor in inner cladding are demonstrated. In addition, the robustness of opticalproperties including dispersion, confinement loss and effective mode area in this PQF is discussed assuming adeviation ±3% of all air holes.
Improved photon-pair generation from transitionmetaldichalcogenide monolayers embedded in onedimensionalphotonic crystals
Doc ID: 312477 Received 03 Nov 2017; Accepted 18 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: We have theoretically investigated photon-pair generation from transition-metal dichalcogenide (TMDC)monolayers embedded in photonic crystals (PCs) by a rigorous quantum model of spontaneous parametric downconversion. The mean number of output photon-pairs and the signal-field energy spectrum have been elaborated.Two different structures are studied, one is a monolayer embedded in the defective PC and the other is a stackof layers in the dielectric multilayer structure. It is clearly shown that an obvious improvement of thegeneration rate of the correlated photon-pairs from the monolayer can be realized in these two structures andthe enhancement can reach as much as 14 orders of magnitude. Such an effective improvement utilizes theimproved field localization at the defect state or the band-edge state, the propagation of photons in the PCs andcoherent superposition, the similar phenomena can occur for other TMDC monolayers. These phenomena are verybeneficial for the design of optical devices.
Explaining Negative Refraction without NegativeRefractive Indices
Gregory Talalai, Timothy Garner, and Steven Weiss
Doc ID: 313030 Received 08 Nov 2017; Accepted 17 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: Negative refraction through a triangular prism may be explained without assigning a negative refractive index to theprism by using array theory. For the case of a beam incident upon the wedge, the array theory accurately predicts thebeam transmission angle through the prism and provides an estimate of the frequency interval at which negativerefraction occurs. The hypotenuse of the prism has a staircase shape because it is built of cubic unit cells. The largephase delay imparted by each unit cell, combined with the staircase shape of the hypotenuse, creates the necessaryconditions for negative refraction. Full-wave simulations using the finite-difference time-domain method show thatarray theory accurately predicts the beam transmission angle.
Contrast-dependent red-green balance shifts depend on S-Cone Activity
Tanner DeLawyer, Melissa Tayon, Chia-li Yu, and Steven Buck
Doc ID: 313243 Received 10 Nov 2017; Accepted 17 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: Previous research from our lab has established that red-green balanced yellow targets become greenish brown assurround luminance increases, while red-green balanced brown targets become reddish yellow as surroundluminance decreases. To help assess the generality and underlying processes of this contrast-dependent red-greenhue shift, we investigated red-green hue shifts for target stimuli that appeared achromatic or blue, as well asyellow/brown. Results confirmed that the red-green hue shift was largest for yellow/brown targets and wasprogressively reduced for achromatic and blue targets, as target excitation of S cones increased. The magnitude ofthe hue shift could be predicted by the S/(L+M) excitation of the target when bright white surrounds are used. Thehue shift also requires that the target and surround are presented to the same eye, consistent with processing inmonocular pathways. Increased S-cone excitation by the surround was associated with red-green hue shifts for alltargets equally. Thus, S-cone signals from bright white surrounds might play a role in the contrast-dependent redgreenhue shift, but the source of the variation of the magnitude of the hue shift with variations in target S-coneexcitation when presented on those surrounds is unknown.
Nondiffracting light beams carrying fractional orbital angular momentum
Zhenshan Yang, Xia Zhang, Chenglin Bai, and minghong wang
Doc ID: 308796 Received 13 Oct 2017; Accepted 17 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: We investigate a new class of nondiffracting optical beamscarrying fractional orbital angular momentum (FOAM Bessel beams), which canbe constructed by modifying the phase step of the spiral phase plate in asetup originally for the generation of traditional Bessel beams. The FOAMBessel beams have entirely stable vortex structures, and form an infinitenumber of orthogonal and complete subsets for monochromatic scalar light in free space. With the advantages of structural stability andorthogonality-completeness, the FOAM Bessel beams are expected to be usefulfor study and application in various fields of modern optics.
Chips In The Sunshine: Colour Constancy With Real vsSimulated Munsell Chips Under Illuminants AdjacentTo The Daylight Locus
jeremiah kelly, Ausra Daugirdiene, Kulikowski Janus, and Ian Murray
Doc ID: 309959 Received 02 Nov 2017; Accepted 16 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: Accurate colour judgements rely on a powerful cognitive component. Here we compare performance of colourconstancy under real and simulated conditions. Shifts in u’v’ colour plane induced by illuminant A (2750K) andIlluminant S (>20000K) were measured using asymmetric colour matching. A general linear model was used topredict performance from the following dependent variables; Chroma (“4” and “6”), Illuminant (“A” and ”S”),presentation mode (“Real” and “Monitor”) and Hue zone (“blue”, “green”, “yellow”, “red”, “purple”). There wasstrong overall effect. (F (7,264) =78.65 p<0.001). Post hoc analysis showed that performance was substantiallysuperior under real (chromatic constancy index, cCI = 0.76) compared with simulated (cCI =0.55) conditions.
Large group delay in a microwave metamaterial analog of electromagnetically induced reflectance
Doc ID: 313317 Received 13 Nov 2017; Accepted 16 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: Recently reported metamaterial (MM) analogues of electromagnetically induced reflectance (EIR) enable a unique route to endow classical optical structures with aspects of quantum optical systems. This method opens up many fascinating prospects on novel optical components, such as slow light units, highly sensitive sensors and nonlinear devices. Here we designed and simulated a microwave MM made from aluminum thin film to mimic the EIR system. High reflectance about 99% and also large delay-bandwidth product at reflection window about 243 are demonstrated, which mainly arise from the enhanced coupling between radiative and nonradiative elements. The interaction between the elements of the unit cell, induced directly or indirectly by the incident electromagnetic wave, leads to a reflection window, resembling the classical analog of EIR. This reflection window, caused by the coupling of radiative-nonradiative modes, can be continuously tuned in a broad frequency regime. The strong normal phase dispersion in the vicinity of this reflection window results in the slow light effect. This scheme provides an alternative way to achieve tunable slow light in a broad frequency band and can find important applications in active and reversibly tunable slow light devices.
Remote Controls illusion: Strange interactionsacross space cannot be explained by simple contrastfilters
Laysa Hedjar, Venice Cowardin, and Arthur G. Shapiro
Doc ID: 312626 Received 09 Nov 2017; Accepted 14 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: The visual system has separable visual encoding for luminance and for contrast modulation (Shapiro,2008); the two dimensions can be represented with a luminance contrast vs. luminance plane. Here we usea contrast asynchrony paradigm to explore contextual effects on luminance contrast modulation: twoidentical rectangular bars (0.5x2.5 deg) have luminance levels that modulate at 2 Hz; when one bar isplaced on a bright field and the other bar on a dark field, observers perceive the bars modulating inantiphase with each other and yet becoming light and dark at the same time. The antiphase perceptioncorresponds to the change in contrast between the bars and their surrounds (a change along the contrastaxis of the plane); the in-phase perception corresponds to the luminance modulation (a change along theluminance axis of the plane). We examine spatial interaction by adding bright rectangular (0.5x2.5 deg)flankers on both sides of the dark-field bar and dark flankers on both sides of the bright-field bar.Remarkably, flankers produce an in-phase appearance when separated from the bars by between 2' and 4'of visual angle, and produce antiphase appearance when they directly adjoin the bars or are separated bymore than 8'. To estimate the dimensions of the spatial interaction, we parametrically adjust the size of thegap between bars and flankers and the length of the flankers. We attempt to account for the results withmodels based on rectified difference of Gaussian (DoG) filters and with rectified oriented difference ofGaussian (ODoG) filters. The models can account for the results when the flankers are the same height asbars, but are unable to account for the effects of increasing the flanker length. The models thereforesuggest that the spatial interaction across distances requires more complex interactions of contrast filters.
Electroretinographical determination of human color vision
Avinash Aher, Cristiane Martins, Mirella Telles Salgueiro Barboni, Balazs Nagy, Einat Hauzman, Daniela Bonci, Dora Ventura, and Jan Kremers
Doc ID: 310208 Received 30 Oct 2017; Accepted 12 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: It has been demonstrated before that electroretinography (ERG) elicited by heterochromatically modulated stimulican be used for objective determination of color vision type. Color vision of trichromatic, deuteranopic andprotanopic participants was psychophysically assessed by the Cambridge Colour Test and confirmed genetically.ERG responses to red and green lights modulating in counter-phase at 12 and 36 Hz were recorded, while thefraction of red modulation was varied. At 36 Hz (and 2nd harmonics at 12 Hz), the responses were minimal at redfractions that differed significantly in protanopes. At 12 Hz (fundamental component) the responses of thetrichromats differed significantly to those of the dichromats. An improved protocol has shown that the threesubject groups can be separated with no overlap.
Photoreceptor-specific light adaptation of CriticalFlicker Frequency in Trichromat and DichromatObservers
Cord Huchzermeyer, Cristiane Martins, Balázs Nagy, Mirella Telles Salgueiro Barboni, Dora Ventura, Marcelo Costa, and Jan Kremers
Doc ID: 309565 Received 20 Oct 2017; Accepted 12 Jan 2018; Posted 19 Jan 2018 View: PDF
Abstract: The silent substitution paradigm offers possibilities to investigate and compare the temporal properties ofmechanisms driven by single photoreceptor types, including the critical flicker frequency (CFF), in which the stateof adaptation can be kept as invariant. We have: (1) measured CFFs using triple silent substitutions to isolate L-, MandS-cone as well as rod driven pathways under identical mean luminances and chromaticities; (2) repeated theCFF measurements at different mean luminances in order to validate the Ferry-Porter-law (stating that therelationship between CFF and the log retinal illuminance – log I – is linear); and (3) compared these CFF vs. log Ifunctionsfor L-, M-, S-cone-, and rod-isolating stimuli for five trichromats and four X-linked dichromats (twoprotanopes, two deuteranopes). We show that the effects of luminance on the CFFs with silent substitution arecomparable to those measured previously with chromatic stimuli. We found that M-cone-driven CFFs are smaller intrichromats than in protanopes. Furthermore, the slopes of the M-cone driven CFF vs log I-functions are smaller intrichromats. Possibly, the lacking L-cones are replaced by M-cones in these two protanopes and the CFF depends oncone density. Furthermore, we found that in trichromats, the slopes of the CFF-log I-functions are smaller for Mcone-than for L-cone-isolating stimuli. This contradicts the current interpretation of the CFF-log I-functions forchromatic stimuli, which states that CFF is mediated by the most strongly modulated photoreceptor type. Thus, thelarger slopes that were previously found with medium-wavelength chromatic stimuli compared with longwavelengthchromatic stimuli seem to be the result of an addition of signals from different photoreceptors and donot necessarily result from M-cones being inherently faster.
Tuning the resonance of polarization-degenerate cladding mode LP1,j in excessively tilted long period fiber grating for highly sensitive refractive index sensing
Zhihong Li, Jie Shen, Qiuping Ji, Yaoju Zhang, Xiukai Ruan, Yuxing Dai, and Zhennao Cai
Doc ID: 313853 Received 22 Nov 2017; Accepted 11 Jan 2018; Posted 11 Jan 2018 View: PDF
Abstract: This work presents a sensitive refractive index sensor based on the dual resonance of excessively tiltedlong period fiber grating (Ex-TLPFG). The Ex-TLPFG is tuned to couple the guided core mode with onlypolarization-degenerate cladding mode LP1,l which consists of TE/TM0,l and HE2,l vector modes. It isfound that the p-polarized LPp1,l mode exhibits a higher sensitivity than that of s-polarized LPs1,l mode. Anoptimized sensitivity as high as 12182.9 nm/RIU is achieved for p-polarized LPp1,2 mode at low refractiveindex region by tuning initial resonance condition. The sensing performance is also evaluated throughthe power measurement method for a single resonance band. It is demonstrated that the improved sensitivityin this work for diameter-reduced Ex-TLPFG is much higher than that for the conventional LPFGbased devices, which makes this sensing platform very attractive for a variety of index sensing applications.
A Kalman filter approach for uncertainty quantification in time-resolved laser-induced incandescence
Paul Hadwin, Timothy Sipkens, Kevin Thomson, Fengshan Liu, and Kyle Daun
Doc ID: 309168 Received 16 Oct 2017; Accepted 10 Jan 2018; Posted 11 Jan 2018 View: PDF
Abstract: Time-resolved laser-induced incandescence (TiRe-LII) data can be used to infer spatially- and temporallyresolvedvolume fractions and primary particle size distributions of soot-laden aerosols, but these estimatesare corrupted by measurement noise as well as uncertainties in the spectroscopic and heat transfersubmodels used to interpret the data. Estimates of the temperature, concentration, and size distributionof soot primary particles within a sample aerosol are typically made by nonlinear regression of modeledspectral incandescence decay, or effective temperature decay, to experimental data. In this work, we employnon-stationary Bayesian estimation techniques to infer aerosol properties from simulated and experimentalLII signals, specifically: the extended Kalman filter and Schmidt-Kalman filter. These techniquesexploit the time-varying nature of both the measurements and the models, and reveal how uncertaintyin the estimates computed from TiRe-LII data evolves over time. Both techniques perform better whencompared with standard deterministic estimates, however we demonstrate that the Schmidt-Kalman filterproduces more realistic uncertainty estimates.
Achieving a high mode count in the exactelectromagnetic simulation of diffractive opticalelements
Andre Junker and Karl-Heinz Brenner
Doc ID: 313631 Received 15 Nov 2017; Accepted 09 Jan 2018; Posted 11 Jan 2018 View: PDF
Abstract: The application of rigorous optical simulation algorithms, both in the modal as well as in the time domain,is known to be limited to the nanooptical scale due to severe computing time and memory constraints.This is true even for today’s high performance computers. To address this problem, we develop the FastRigorous Iterative Method (FRIM), an algorithm based on an iterative approach, which, under certainconditions, allows solving also large size problems approximation free. We achieve this in the case ofa modal representation by avoiding the computationally complex eigenmode decomposition. Thereby,the numerical cost is reduced from ON3to O (NlogN), enabling a simulation of structures like certaindiffractive optical elements with a significantly higher mode count than presently possible. Apart fromspeed, another major advantage of the iterative FRIM over standard modal methods is the possibility totrade runtime against accuracy.
Averaging colors of multicolor mosaics
Doc ID: 309463 Received 23 Oct 2017; Accepted 09 Jan 2018; Posted 10 Jan 2018 View: PDF
Abstract: The present study investigated how color information was summarized in multicolor mosaics. The mosaics werecomposed of small elements of 17 colors that roughly belonged to a single color category. We manipulated thedegree of color variation around the mean by varying the proportion of different color elements. Observersmatched 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 meantoward the most-saturated color, although hue of the matched color was almost the same as that of the colorimetricmean. These findings together suggested differential processing of hue and saturation. The deviation of thematched color decreased, but did not disappear, when the color variation was reduced. The analysis of color metricunderlying color averaging revealed differential color scaling in nearly orthogonal blue-orange and green-purpledirections, implying that the visual system does not solely rely on linear cone-opponent codes when summarizingcolor signals. The deviation itself was consistently found regardless of different color metrics tested. Therobustness of the deviation indicated an inherent bias of mean color judgments favoring highly saturated colors.
Semantic word impressions expressed by hue
Keizo Shinomori and Honami Komatsu
Doc ID: 312641 Received 02 Nov 2017; Accepted 08 Jan 2018; Posted 09 Jan 2018 View: PDF
Abstract: We investigated the possibility of whether impressions of semantic words showing complex concepts could bestably expressed by hues. Using a paired comparison method, we asked ten subjects to select from a pair of huesthe one that more suitably matched a word impression. We employed nine Japanese semantic words and usedtwelve hues from vivid tone in the Practical Color Co-ordinate System. As examples of the results, for the word"Vigorous" the most frequently selected color was yellow and the least selected was blue to purple; for "Tranquil"the most selected was yellow to green and the least selected was red. Principal component analysis of the selectiondata indicated that the cumulative contribution rate of the first two components was 94.6%, and in the twodimensionalspace of the components, all hues were distributed as hue-circle shape. In addition, comparison withadditional data of color impressions measured by a semantic differential method suggested that most semanticword impressions can be stably expressed by hue, but the impression of some words, such as “Magnificent” cannot.These results suggest that semantic word impression can be expressed reasonably well by color, and that hues aretreated as impressions from the hue circle, not from color categories.
Photonic Crystals: Role of Architecture and Disorder on Spectral Properties
Rupesh Verma, Romil Audkhasi, Krishna Thyagarajan, and Varsha Banerjee
Doc ID: 306939 Received 11 Sep 2017; Accepted 03 Jan 2018; Posted 08 Jan 2018 View: PDF
Abstract: Many of the present day optical devices use photonic crystals. These are multilayers of dielectric media which control the reflection and transmission of light falling on them. In this paper, we study the optical properties of periodic, fractal and aperiodic photonic crystals and compare them on the basis of their attributes. Our calculations of the band reflectivity and degree of robustness reveal novel features, e.g., fractal photonic crystals are found to reflect maximum amount of incident light. On the other hand, aperiodic photonic crystals have the largest immunity to disorder. We believe that such properties will be useful in a variety of applications in the field of optical communication.
The development of color vision discrimination during childhood: differences between blue-yellow, red-green and achromatic thresholds
Barbara Ling and Stephen Dain
Doc ID: 312529 Received 02 Nov 2017; Accepted 02 Jan 2018; Posted 03 Jan 2018 View: PDF
Abstract: Non-visual demands of tests affect vision test results in children. 150 children (79 female and 71 male, 5.3–12.7 years) were examined. Isoluminant blue, yellow, red, green and black & white thresholds were established with a four-alternative-forced-choice and pseudo 10-bit system with adaptive staircase and gaming elements. Where Threshold = b0+b1*age-1, b1 for RG = 6.26±1.90 (95% confidence limits), Achr = 3.96±1.07 and BY = 12.48±2.76 were significantly different. The non-color demands of the test are the same for RG, BY and Achr, so the later development of BY discrimination, especially, is not an artefact of the test.
Synchronization-based Clustering Algorithm forReconstruction of Multiple Reconstructed Targets inFluorescence Molecular Tomography
Zitong Wu, Xiaodong Wang, Jingjing Yu, Huangjian Yi, and Xiaowei He
Doc ID: 302083 Received 13 Jul 2017; Accepted 01 Jan 2018; Posted 03 Jan 2018 View: PDF
Abstract: Fluorescence molecular tomography (FMT) is an important in vivo molecular imaging technique and has beenwidely studied in preclinical research. Many methods perform well in reconstruction of single fluorescent targetbut may fail in reconstructing multiple targets because of the severe ill-poseness of FMT inverse problem. In thispaper original synchronization-inspired clustering algorithm (OSC) is introduced into FMT for resolving multipletargets from reconstruction result. Based on OSC, a synchronization-based clustering algorithm for FMT (SC-FMT)is developed to further improve location accuracy. Both algorithms utilize minimum spanning tree to automaticallyidentify the number of the reconstructed targets without prior information and human intervention. A serial ofnumerical simulation results demonstrate that SC-FMT and OSC can resolve multiple targets robustly andautomatically, which also show the potential of the proposed postprocessing algorithms in FMT reconstruction.
Stroboscopic effect: contrast threshold function anddependence on illumination level
Malgorzata Perz, Dragan Sekulovski, Ingrid vogels, and Ingrid Heynderickx
Doc ID: 308423 Received 06 Oct 2017; Accepted 28 Dec 2017; Posted 03 Jan 2018 View: PDF
Abstract: The Stroboscopic effect Visibility Measure (SVM) is a method used to quantify the stroboscopic effect visibilityin general illumination applications. SVM has been defined previously based on a limited numberof frequencies and participants. To validate and extend SVM, five perception experiments are presented,measuring the visibility threshold of light waveforms modulated at several frequencies, conducted intwo different labs. A power function is fitted through the aggregated results to develop a stroboscopiceffect contrast threshold function for a “standard observer”, which can be used to normalize SVM. An additionalexperiment shows the dependency on illumination level, extending the validity of SVM to otherapplications.
Paradoxical pupil constriction to isolated M-cone increments
Ian Murray, Jan Kremers, Declan McKeefry, and Neil Parry
Doc ID: 312400 Received 03 Nov 2017; Accepted 27 Dec 2017; Posted 03 Jan 2018 View: PDF
Abstract: M-cone onsets appear dimmer and elicit ERGs resembling the light offset response. We sought a corresponding anomalous pupillary light reflex (PLR) using a 4-primary ganzfeld as stimulator and pupillometer. Increments and decrements of white light were compared with M- and L-cone onsets and offsets. Luminance bias (LB) could be added to or subtracted from the cone-isolating stimuli. There was a normal PLR to L-cone increments but the pupil constricted to M-cone decrements. Changing LB produced a neutral point where on and off responses were balanced. The results reflect ERG and psychophysical studies. It may be linked to the antagonistic nature of the M-cone input to cone opponent mechanisms.
Human S-cone ERGs obtained by Silent Substitution Stimulation
John Maguire, Neil Parry, Jan Kremers, Ian Murray, and Declan McKeefry
Doc ID: 312491 Received 02 Nov 2017; Accepted 27 Dec 2017; Posted 03 Jan 2018 View: PDF
Abstract: We used triple silent substitution stimuli to characterize human S-cone ERGs in normal trichromats. S-cone ERGs were found to have different morphological features and temporal frequency response characteristics compared to ERGs derived from L-cone, M-cone and rod photoreceptors in normal participants. Furthermore, in two cases of retinal pathology, Blue Cone Monochromatism (BCM) and Enhanced S-cone Syndrome (ESCS), S-cone ERGs elicited by our stimuli were preserved and enhanced, respectively. The results from both normal and pathological retinae demonstrate that triple silent substitution stimuli can be used to generate ERGs that selectively that provide an assay of human S-cone function.
Age-related changes in ON and OFF responses toluminance increments and decrements
Keizo Shinomori, Athanasios Panorgias, and John Werner
Doc ID: 312637 Received 02 Nov 2017; Accepted 27 Dec 2017; Posted 03 Jan 2018 View: PDF
Abstract: Impulse response functions for an incremental luminous pulse (ON flash) or a decremental luminous pulse (OFFflash) were derived for twelve young (19-24 years old) and ten old (65-84 years old) observers. Thresholds weremeasured for two pulses separated by stimulus-onset-asynchronies from 13.3 to 186.7 ms. The pulses had a spatialGaussian shape and were presented as increments or decrements on a 15 cd/m2 equal-energy white background,having the same chromaticity as the pulse. A spatial 4-alternative forced-choice method was combined with astaircase procedure. Retinal illuminance was equated individually by heterochromatic flicker photometry andusing a 2.3 mm exit pupil in a Maxwellian-view optical system to reduce the effects of age-related changes andindividual variations in lens density and pupil size. Luminance ON- and OFF-impulse response functions calculatedfrom the threshold data revealed significant age-related changes in the response amplitude of both first excitatoryand first inhibitory phases. However, there were no significant changes in the time to the first peak or the secondpeak. These age-related changes in luminance varying ON- and OFF-IRFs, reflecting putative properties of themagnocellular pathway, are discussed in relation to motion detection and the balance of ON and OFF pathwaysacross the life span.
Security analysis of double-image encryptiontechnique based on an asymmetric algorithm
YI XIONG, Aohan He, and Chenggen Quan
Doc ID: 310073 Received 27 Oct 2017; Accepted 26 Dec 2017; Posted 03 Jan 2018 View: PDF
Abstract: In this paper, we evaluate the security of a double-image encryption technique based on an asymmetric algorithm.Compared with traditional cryptosystems based on phase-truncated Fourier transform (PTFT), the technique isable to improve the security of the encryption by combining a joint transform correlator (JTC); consequently, theencryption scheme is immune to some common attacks. We propose a special attack based on a phase retrievalalgorithm with median filtering and normalization operation to break the cryptosystem. Low key sensitivity of aposition parameter set has been found and an additional constraint is utilized to improve the attack to simplify theprocess and further decrease the computational time. Numerical simulation results show that the cryptosystem isvulnerable to the proposed special attack.
Optimized diffusion approximation
Vadim Markel, Ugo Tricoli, Callum Macdonald, and Anabela Da Silva
Doc ID: 308082 Received 27 Sep 2017; Accepted 22 Dec 2017; Posted 22 Dec 2017 View: PDF
Abstract: We show that the diffusion approximation to the radiative transport equation, which is commonly used inbiomedical optics to describe propagation of light in tissues, contains a previously unexplored adjustableparameter. This parameter is related to the rate of exponential decay of the reduced intensity. In the conventionaltheories, there are two distinct choices for this parameter. However, neither of these choicesare optimal. When the optimal value for the parameter is used, the resulting DA becomes much moreaccurate near the medium boundaries, e.g., at the depth of up to a few `, where ` is the transport meanfree path (typically, about 1mm in tissues). We refer to the new adjustable parameter as to the reduced extinctioncoefficient. The proposed technique can reduce the relative error of the predicted diffuse densityof the optical energy from about 30% to less than 1%. The optimized diffusion approximation can still beinaccurate very close to an interface or in some other physical situations. Still the proposed developmentextends the applicability range of the diffusion approximation significantly. This result can be useful,for instance, in tomographic imaging of relatively shallow (up to a few ` deep) layers of tissues in thereflection geometry.
Age and gender effects on perceptual colour scaling using triadic comparisons
David Bimler and Valerie Bonnardel
Doc ID: 312624 Received 03 Nov 2017; Accepted 20 Dec 2017; Posted 20 Dec 2017 View: PDF
Abstract: We examined age and gender as possible determinants of individual differences in triadic judgments of color dissimilarity. Seventy triads were constructed from 21 equal-lightness Munsell samples, at equal hue steps, forming a rough ellipse in the CIE-LAB plane, and presented to 51 males and 53 females (half young, half elderly adults) who indicated each triad’s “odd-one-out”. Principal Components Analysis, followed by MDS, revealed gender and age differences in judgment reliability, and localised gender differences in color similarity, perhaps involving the use of ‘color-circle’ propositional knowledge. Maximum-Likelihood MDS and inspection of specific triads allowed a more detailed description of these differences.
One-stop Measurement Model for Fast and Accurate Tensor Display Characterization
philip Surman, SHIZHENG WANG, Junsong Yuan, and Yuanjin Zheng
Doc ID: 303943 Received 02 Aug 2017; Accepted 19 Dec 2017; Posted 19 Dec 2017 View: PDF
Abstract: Many light field displays are fundamentally different to other displays in that they do not have quantizedpixels, quantized angular outputs or a physical screen position; this can make definitions and characterizationproblematic. We have determined that it is more appropriate the express the spatial resolutionin terms spatial cut-off frequency rather than a physical distance as in the case of a display with actualquantized pixels; this concept is then extended to encompass angular resolution. The technique exploitsthe fact that when spatial resolution of a sinusoidal grating pattern is halved, its contrast ratio is reducedby a known proportion. An improved model, based on an earlier design concept has been developed, cannot only be used to measure spatial and angular cut-off frequencies but can also enable comprehensivecharacterization of the display. This provides fast and simple measurement with good accuracy. It doesnot use special equipment or require time-consuming subjective evaluations. The result of using themodel to characterize images in a rapid and accurate manner validates the effectiveness of this technique.
On the depolarization in granular thin films: A Mueller-Matrix approach.
Bruno Gompf, Maximilian Gill, Martin Dressel, and Audrey Berrier
Doc ID: 303584 Received 27 Jul 2017; Accepted 18 Dec 2017; Posted 19 Dec 2017 View: PDF
Abstract: We describe a general method to disclose the information hidden in Mueller-matrices experimentally obtained from depolarizing samples. Although spectroscopic Mueller-matrix ellipsometry allows for a model-free characterization of inhomogeneous samples, i.e., independently from any assumption on the sample structure, the interpretation of the obtained results is often challenging. The proposed method combines three different decomposition techniques applied to the measured Mueller-matrices in transmission and reflection of granular thin films with different thicknesses and densities. We demonstrate that the comparative analysis of the respective differential-, product, and sum-decomposition of the Mueller-matrices, together with correlation effects and the visualization as Poincaré sphere, reveals the particular underlying physical processes of depolarization. As an example, we apply this method on granular BaS04 thin films. This method is general and can be applied to a wide variety of intrinsically inhomogeneous materials with applications in physics, industry, biology or medicine.
Amplitude and phase retrieval with simultaneousdiversity estimation using expectation-maximization
Joyce Fang and Dmitry Savransky
Doc ID: 300865 Received 07 Aug 2017; Accepted 17 Dec 2017; Posted 19 Dec 2017 View: PDF
Abstract: Iterative amplitude and phase retrieval algorithms have been proven to accurately reconstruct arbitrarywavefronts from multiple intensity measurements when system parameters are known exactly, given theability to induce phase diversity between images. Such sets of intensity images with phase diversity canbe generated by moving a lens in the optical system, but any position error on the lens will degeneratethe reconstruction result. We demonstrate the use of an expectation-maximization algorithm with Kalmansmoothing for recovering both the complex field and the lens position from a stack of intensity images.Our method successfully reduces the mean-squared-error of the estimated wavefront in comparison toan approach without position error estimation. We present and discuss the results of using a Kalmansmoother and nonlinear least-square optimization for the estimation of the moving lens position.
Cone and melanopsin contributions to human brightness estimation
Andrew Zele, Prakash Adhikari, Beatrix Feigl, and Dingcai Cao
Doc ID: 309510 Received 18 Oct 2017; Accepted 17 Dec 2017; Posted 19 Dec 2017 View: PDF
Abstract: We determined the contributions of cone and melanopsin luminance signaling to human brightness perception. The absolute brightness of four narrow-band primary lights presented in a full-field Ganzfeld were estimated in two conditions, either cone luminance equated (186.7 – 1,867.0 cd.m-2) or melanopsin luminance equated (31.6 – 316.3 melanopsin cd.m-2). We show that brightness estimations for each primary light follow an approximately linear increase with increasing cone- or melanopsin luminance (in log units), but are not equivalent for primary lights equated with either cone- or melanopsin luminance. Instead, brightness estimations result from a combined interaction between cone and melanopsin signaling. Analytical modeling with wavelength dependent coefficients signify that melanopsin luminance positively correlates with brightness magnitudes and the cone luminance has two contribution components, one that is additive to melanopsin luminance and a second that is negative, implicating an adaptation process. These results provide a new framework for evaluating the physiological basis of brightness perception and have direct practical applications for the development of energy efficient light sources.
Analysis of lateral binding force exerted on bi-sphere induced by Elliptic Gaussian beam
Bai Jing, Zhen-Sen Wu, Ge Chengxian, Zheng-Jun Li, Tan Qu, and Qingchao Shang
Doc ID: 301147 Received 28 Jun 2017; Accepted 16 Dec 2017; Posted 18 Dec 2017 View: PDF
Abstract: Based on the Generalized Lorentz Mie theory and the localized approximation of the beam shaped coefficients, we derived the expansions of incident elliptic Gaussian (EG) beam in terms of spherical vector wave functions (SVWFs). Utilizing Multiple Scattering (MS) equations and Electromagnetic Momentum (EM) theory, the lateral binding force (BF) exerted on bi-sphere induced by EG beam is calculated. Numerical effects of various parameters such as beam waist widths, beam polarization states, incident wavelengths, particle sizes and material losses are analyzed and compared with the results of circular Gaussian (CG) beam in detail. The observed dependence of the separation of optically bound particles on the incidence of EG beam is in agreement with earlier theoretical prediction. Accurate investigation of BF induced by EG beam could provide an effective test for further research on BF between more complex particles, which plays an important role in using optical manipulation on particle self-assembly.
Goos-Hänchen and Imbert-Fedorov shifts: relation with the irradiance moments of a beam
Miguel Angel Berbel, Alejandro Cunillera, and Rosario Martinez-Herrero
Doc ID: 309086 Received 12 Oct 2017; Accepted 13 Dec 2017; Posted 14 Dec 2017 View: PDF
Abstract: We present closed and simple expressions of the spatial and angular Goos-Hänchen and Imbert-Fedorovshifts in terms of the second order irradiance moments of a beam. Our results are applicable to a generaltotally polarized partially coherent beam. One of the main advantages of this formalism is that it canbe applied directly from the knowledge of the cross spectral density function and the polarization statewithout using any modal beam expansion. The obtained expressions allow to understand the relationshipbetween the global spatial characteristics of the incident beam and the experimented shifts in the reflectedbeam. Cosine-Gaussian Schell-model beams with rectangular symmetry are used to exemplify results.
Forward scattering of polarized light from birefringentturbid slab media: Monte Carlo simulation
Doc ID: 303251 Received 02 Aug 2017; Accepted 24 Nov 2017; Posted 11 Jan 2018 View: PDF
Abstract: The reduced effective Mueller matrices of forward scattering from birefringent turbid slab media were calculatedusing a Monte Carlo simulation and were factorized in two dimension by the Lu-Chipman polar decomposition. Fora slab medium with the birefringence axis parallel to the y axis, the polarization parameters have second- orfourth-order rotational symmetry. Especially, the absolute value of linear retardance || shows a characteristicvariation; it becomes maximal at the azimuths of 0 and 180 but minimal at 90 and 270. These features exactlyagree with the measurement results. However, when the birefringence axis is inclined to the slab surfaces, thepolarization parameters become non-symmetric with respect to the x-z plane, though they are symmetric or antisymmetricwith respect to the y-z plane. Moreover, as the inclination angle becomes larger than 45, the fast-axisorientation exhibits new centers of the radial pattern whose position becomes closer to the preexisting center. Thephoton trajectory in the medium may be approximated by a double scattering model in which the photonpenetrates forward into a depth, travels along the radial direction, and propagates forward to the front surface forexiting. The non-symmetry of the polarization parameters and the appearance of the second centers of the radialpattern suggest that the radial traveling of the photon may be oblique forward and that the obliqueness anglebecomes smaller as the photon exits at the distance farther away from the center.