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Spatio-spectral binary patterns based on multispectral filter arrays for texture classification

Sofiane Mihoubi, Olivier Losson, Benjamin Mathon, and Ludovic Macaire

Doc ID: 330378 Received 01 May 2018; Accepted 12 Jul 2018; Posted 13 Jul 2018  View: PDF

Abstract: To discriminate gray-level texture images, spatial texture descriptors can be extracted using the local binary pattern operator. This operator has been extended to color images at the expense of increased memory and computation requirements. Some authors propose to compute texture descriptors directly from raw images provided through a Bayer color filter array, which both avoids the demosaicing step and reduces the descriptor size. Recently, multispectral snapshot cameras have emerged to sample more than three wavelength bands using a multispectral filter array. Such cameras provide a raw image in which a single spectral channel value is available at each pixel. In this paper we design a local binary pattern operator that jointly extracts the spatial and spectral texture information directly from a raw image. Extensive experiments on a large dataset show that the proposed descriptor has both reduced computation cost and high discriminative power with regard to classical LBP descriptors applied to demosaiced images.

Binocular holographic three-dimensional display using a single spatial light modulator and a grating

Yanfeng Su, Zhijian Cai, Quan Liu, Lingyan Shi, Feng Zhou, and Jianhong Wu

Doc ID: 332451 Received 24 May 2018; Accepted 12 Jul 2018; Posted 13 Jul 2018  View: PDF

Abstract: In this paper, a binocular holographic three-dimensional (3D) display system by combining a single spatial light modulator (SLM) and a grating is proposed and implemented. A synthetic phase-only hologram of the left and right 3D perspective images of an object is calculated by the layer-based Fresnel diffraction method according to the depth information, and uploaded onto the SLM for holographic 3D reconstruction with correct depth cues. The grating is designed and fabricated to guide the reconstructed left and right 3D perspective images to the corresponding eye, respectively. Optical experiments demonstrate that the proposed system can successfully present binocular holographic 3D images with both of the accommodation effect and binocular parallax, which enables the observer free of the accommodation-vergence conflict and visual fatigue problem.

Near Infrared Polarimetric Imaging and ChangesAssociated with Normative Aging

Joel Papay and Ann Elsner

Doc ID: 325821 Received 12 Mar 2018; Accepted 10 Jul 2018; Posted 11 Jul 2018  View: PDF

Abstract: With aging, the human retina undergoes cell death and additional structural changes that can increase scatteredlight. We quantified the effect of normative aging on multiply scattered light returning from the human fundus. Asexpected, there was an increase of multiply scattered light associated with aging, and this is consistent with thehistological changes that occur in the fundus of individuals before developing age-related macular degeneration.This increase in scattered light with aging cannot be attributed to retinal reflectivity, anterior segment scatter, orpupil diameter.

Control of plasmon-polariton vortices on the surface of metal layer

Igor Dzedolik and Vladislav Pereskokov

Doc ID: 330629 Received 03 May 2018; Accepted 09 Jul 2018; Posted 10 Jul 2018  View: PDF

Abstract: Surface plasmon polaritons (SPPs) can be excited at the interface of metal layer and dielectric layer by various methods. If an inhomogeneity of permittivity with a curvilinear boundary is created in the metal layer by the external electric field, the incident SPPs and the reflected ones from this inhomogeneity interfere. A vortex lattice appears when such SPPs interfere, and the lattice configuration can be controlled by varying of the external electric field. Based on controlling of the SPP vortex lattice and reading out of the vortex localization, the plasmon logic gates “AND”, “OR” and “NOT” can be realized. These logic gates are the complete elemental base for logical operations in processors operating at optical frequencies.

Theoretical investigations of infrared optical wave MTF models in anisotropic marine turbulence

Linyan Cui, Wen Fei, and Bindang Xue

Doc ID: 330916 Received 03 May 2018; Accepted 09 Jul 2018; Posted 13 Jul 2018  View: PDF

Abstract: Previously derived marine turbulence modulation transfer function (MTF) adopts classical assumption of isotropic and Kolmogorov turbulence. However, more theoretical researches show that the marine turbulence demonstrates anisotropic non-Kolmogorov properties. In this study, new long exposure plane and spherical waves MTF models under anisotropic non-Kolmogorov marine turbulence will be investigated. Comparative analyses are performed for the new models and the existed ones which have been developed under the isotropic marine turbulence and the anisotropic terrestrial turbulence cases. It turns out that the anisotropic marine turbulence influences less on the electro-optical imaging system than the isotropic marine turbulence. Also, under the same turbulence strength condition, due to the humidity fluctuations of marine atmosphere, the anisotropic marine turbulence will reduce more severely the quality of electro-optical imaging system than the anisotropic terrestrial turbulence. Investigations conducted in this paper are beneficial to understand better the electro-optical imaging mechanism in marine atmospheric turbulence media.

Linear controllers error budget assessment forclassical adaptive optics systems

Rémy JUVENAL, Caroline Kulcsar, Henri-François Raynaud, and Jean-Marc Conan

Doc ID: 337904 Received 05 Jul 2018; Accepted 07 Jul 2018; Posted 11 Jul 2018  View: PDF

Abstract: Understanding limitations of Adaptive Optics (AO) systems is crucial when designing new systems. Inparticular, analyzing the potential of different controllers is of great interest for the upcoming AO systemsof the VLTs and ELTs. This paper thus details a complete error budget assessment formalism, basedon analytic formulas involving the disturbance temporal Power Spectral Density (PSD) and the controllertransfer function, and thus applicable to any linear controller. This formalism is presented here for thespecial case of classical AO systems, but can be extended to any closed or open-loop, single or multiconjugatedAO configuration. Special attention is paid to the “control-dependent” errors, the importanceof which is directly related to the type of control used in the AO system. The proposed method is appliedto a NAOS/VLT-type SCAO system, using disturbance PSD derived from a simulated turbulence trajectoryor estimated from WFS measurements, enabling to construct detailed error budgets for an integratorand different LQG controllers. Application to ELT-sized systems is discussed in the conclusion.

Beam wander of a partially coherent Airy beam inoceanic turbulence

wei wen, Ying Jin, Mingjun Hu, Mi Luo, Yang Luo, Xianwu Mi, Chenjuan Zou, Liwang Zhou, Chengfu Shu, Xixiang Zhu, Juxiang He, and Shengde Ouyang

Doc ID: 327875 Received 09 Apr 2018; Accepted 02 Jul 2018; Posted 03 Jul 2018  View: PDF

Abstract: The beam wander of a partially coherent Airy beam in oceanic turbulence is investigated with the help of theextended Huygens–Fresnel integral formula. Analytical expression for the second-order moment and the beamwander of a partially coherent Airy beam propagating in oceanic turbulence are derived. From the numericalresults which based on the analytical formula we find that increasing the dissipation rate of turbulent kineticenergy or decreasing the dissipation rate of mean-square temperature and relative strength of temperature andsalinity fluctuations of oceanic turbulence tend to decrease the wander effect of a partially coherent Airy beam.Moreover, it is found that increasing the transverse scale factor and wavelength or decreasing the coherent lengthand exponential truncation factor of a partially coherent Airy beam decrease the beam wander in oceanicturbulence. Our results will be useful in optical underwater communications and laser defence.

The optical performance of a dielectric-metal-dielectric anti-reflective absorber structure

Viacheslav Medvedev, Vladimir Gubarev, and Christopher Lee

Doc ID: 330718 Received 02 May 2018; Accepted 02 Jul 2018; Posted 03 Jul 2018  View: PDF

Abstract: The absorption of electromagnetic radiation by a planar structure, consisting of a three-layer dielectric-metal-dielectric coating on a metal back-reflector is analysed. The conditions for total absorption are derived. Our analysis shows that, in contrast with bi-layer structures, the calculated layer thicknesses are feasible to fabricate for any metal. The proposed absorber design is of potential use in infrared, terahertz and longer wavelength detectors and for radiant energy harvesting devices.

Three-dimensional single-pixel imaging of incoherent light with spatiotemporally modulated illumination

Jeffrey Field, Keith Wernsing, Jeffrey Squier, and Randy Bartels

Doc ID: 329037 Received 23 Apr 2018; Accepted 28 Jun 2018; Posted 28 Jun 2018  View: PDF

Abstract: We derive analytic expressions for the three-dimensional coherent transfer function (CTF) and coherent spread function (CSF) for coherent holographic image reconstruction by phase transfer (CHIRPT) microscopy with monochromatic and broadband illumination sources. The 3D CSF and CTF were used to simulate CHIRPT images, and the results show excellent agreement with experimental data. We include a ray-tracing model of the CHIRPT microscope to show that, in general, complicated aberration phases need not be applied to the formalism to predict imaging results in the laboratory. Finally, we show that the formalism presented here for computing the CSF/CTF pair in CHIRPT microscopy can be readily extended to other forms of single-pixel imaging, such as spatial-frequency-modulated imaging (SPIFI).

Scintillation and bit error rate analysis of partially coherent flat-topped array laser beam in maritime and terrestrial non-Kolmogorov atmospheric environment on slant path

SHOLE GOLMOHAMMADY, bijan ghafary, Masoud Yousefi, and AHMAD MASHAL

Doc ID: 330267 Received 02 May 2018; Accepted 28 Jun 2018; Posted 28 Jun 2018  View: PDF

Abstract: In this paper, on the basis of the extended Huygens–Fresnel principle, a semi analytical expression for describingon-axis scintillation index of a partially coherent flat-topped (PCFT) laser beam through non-Kolmogorov maritime and terrestrial atmospheric environment on slant path is derived; consequently, by using the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The effects of source factors (such as wavelength, order of flatness, and beam width) and the non- Kolmogorov turbulent atmosphere parameters (such as Kolmogorov inner scale, general spectral power-law exponent, the turbulence structure constant) on propagation behavior of scintillation index, and, hence, on BER, are studied in detail. Results indicate that, an increase in the average SNR causes a greater influence of the power-law exponent on BER. Also, it can be deduced that the mean bit error rate increases while the power-law exponent decreases. In addition, the scintillation index and BER as communication link parameters represent the fact that increasing the atmospheric refractive-index structure parameter on the ground and decreasing the inner scale of turbulence eddies causes an increase in theses parameters.

Solving large-scale general phase retrieval problemsvia a sequence of convex relaxations

R Doelman, Hieu Thao Nguyen, and Michel Verhaegen

Doc ID: 324747 Received 23 Feb 2018; Accepted 27 Jun 2018; Posted 27 Jun 2018  View: PDF

Abstract: We present a convex relaxation-based algorithm for large-scale general phase retrieval problems. Generalphase retrieval problems include i.a. the estimation of the phase of the optical field in the pupilplane based on intensity measurements of a point source recorded in the image (focal) plane. The nonconvexproblem of finding the complex field that generates the correct intensity is reformulated into arank constraint problem. The nuclear norm is used to obtain the convex relaxation of the phase retrievalproblem. A new iterative method, indicated as Convex Optimization-based Phase Retrieval (COPR), ispresented, with each iteration consisting of solving a convex problem. In the noise-free case and for aclass of phase retrieval problems the solutions of the minimization problems converge linearly or fastertowards a correct solution. Since the solutions to nuclear norm minimization problems can be computedusing semidefinite programming, and this tends to be an expensive optimization in terms of scalability,we provide a fast ADMM algorithm that exploits the problem structure. The performance of the COPRalgorithm is demonstrated in a realistic numerical simulation study, demonstrating its improvements inreliability and speed with respect to state-of-the-art methods.

Scattering matrix of arbitrarily shaped objects:Combining Finite Elements and Vector Partial Waves

Guillaume Demesy, Jean-Claude Auger, and Brian Stout

Doc ID: 324982 Received 27 Feb 2018; Accepted 26 Jun 2018; Posted 27 Jun 2018  View: PDF

Abstract: We demonstrate the interest of combining Finite Element calculations with the Vector Partial Wave formulation(used in T-matrix and Mie theory) in order to characterize the electromagnetic scattering properties of isolatedindividual scatterers. This method consists of individually feeding the finite element problem with incident VectorPartial Waves in order to numerically determine the T-matrix elements of the scatterer. For a sphere and anspheroid, we demonstrate that this method determines the scattering matrix to high accuracy. Recurrence relationsfor a fast determination of the vector partial waves are given explicitly, and an open-source code allowingthe retrieval of the presented numerical results is provided.

Evolution of near ground optical turbulence overconcrete runway throughout multiple days in summerand winter

Melissa Beason, JOSEPH COFFARO, Christopher Smith, Jonathan Spychalsky, Sara Belichki, Franklin Titus, Frank Sanzone, Bruce Berry, ROBERT CRABBS, Larry Andrews, and Ronald Phillips

Doc ID: 328510 Received 16 Apr 2018; Accepted 26 Jun 2018; Posted 27 Jun 2018  View: PDF

Abstract: Experimental data are presented which demonstrate the evolution of the anisotropy/isotropy of atmosphericstatistics throughout the course of four days (two winter, two summer) near the ground over a concrete runwayin Florida. In late January and early February of 2017, a 532 nm near-plane-wave beam was propagated oneand two kilometers at a height of 2 m above the runway and irradiance fluctuations were captured on a CCDarray. In August of 2017, a 532 nm Gaussian beam was propagated 100 m at a height of near 2 m andfluctuation data captured on a CCD array. Winter data was processed to calculate the covariance of intensityand summer data processed to calculate the scintillation index. The resulting contours indicated a consistentpattern of anisotropy early in the day evolving into isotropy midday and returning to anisotropy in lateafternoon. Accompanying atmospheric and wind data are presented throughout the measurement days.

Young’s interference experiment withelectromagnetic narrowband light

Henri Partanen, Bernhard Hoenders, Tero Setala, and Ari Tapio Friberg

Doc ID: 331742 Received 18 May 2018; Accepted 25 Jun 2018; Posted 26 Jun 2018  View: PDF

Abstract: We consider electromagnetic spectral spatial coherence of random stationary light beams of arbitrary spectralwidth. We demonstrate that the normalized spectral coherence (or two-point) Stokes parameters andthe electromagnetic spectral degree of coherence can be measured by narrowband filtering the light anddetecting the spectral density and the polarization-state fringes around the optical axis of Young’s interferometer.It is also shown that the normalized spectral polarization (or one-point) and coherence Stokesparameters are unaffected by filtering and that the filtered light is strictly cross-spectrally pure. We furtherprove theoretically and confirm experimentally that the (time-domain) electromagnetic degree of spatialcoherence of the filtered light at the pinholes does not increase when the passband of the filter is reduced.

3rd-order spherochromatism surface contribution andits intrinsic and induced aberration parts

Andrea Berner, Ewa Kasperkiewicz, Yueqian Zhang, and Herbert Gross

Doc ID: 326926 Received 27 Mar 2018; Accepted 21 Jun 2018; Posted 21 Jun 2018  View: PDF

Abstract: An investigation of the chromatic effects in refracting optical systems naturally shows that all of the five Seidelaberrations vary with wavelength, since they are all depending on the refractive index. In general, the colorvariation of spherical aberration is denoted as spherochromatism. Besides the chromatic variation of 1st-orderparaxial parameters, like focal length and magnification, described by axial and lateral color, alsospherochromatism can strongly affect the color correction of an optical system. However, in literature there is noexact analytical formula found, specifying this effect. Actually, also a general 3rd-order description based on thechromatic variation of Seidel’s surface contribution for spherical aberration has not been considered yet.Therefore, this paper deals with this mentioned analytical gap and provides a description of 3rd-order surfacecontribution for spherochromatism. Based on this, the result is analyzed and discussed concerning thedifferentiating between intrinsic and induced aberration parts. In case of spherochromatism, its 3rd-ordercontribution shows induced effects caused by prior summed up primary color aberrations of the system.

Vectorial aberrations of biconic surfaces

Yi Zhong and Herbert Gross

Doc ID: 328695 Received 18 Apr 2018; Accepted 21 Jun 2018; Posted 21 Jun 2018  View: PDF

Abstract: For non-rotationally symmetric systems, spherical surfaces provide non-sufficient effect in correcting aberrations. In anamorphic systems, biconic surfaces are used to provide different focal power in tangential and sagittal directions. The biconic surface shape is also used as the basic shape of freeform surface representation, which can decouple astigmatism and coma. In this paper, the biconic surface is expanded up to 4th order and decomposed into spherical part, astigmatism, aspherical part, secondary astigmatism and tetrafoil. The vectorial aberrations of the biconic surface are derived based on the extended Nodal aberration theory. When biconic surfaces are used in off-axis systems, it is beneficial due to the decoupling of astigmatism and coma. For instance, in initial system design of reflective systems, usually three mirrors are used. With biconic surfaces, it is possible to reduce the number of mirrors to two. This paper provides the insight of aberration analysis of biconic surfaces and the conversion of biconic surfaces into Zernike fringe freeform surfaces.

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