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Accepted papers to appear in an upcoming issue

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High Speed All-Optical DNA Local Sequence Alignment Based on 3D Artificial Neural Network

Ehsan Maleki, Hossein Babashah, Somayyeh Koohi, and Zahra Kavehvash

Doc ID: 287160 Received 21 Feb 2017; Accepted 26 May 2017; Posted 26 May 2017  View: PDF

Abstract: This paper presents an optical processing approach for exploring a large number of genome sequences. Specifically, we propose an optical correlator for global alignment and, an extended Moiré matching technique for local analysis of spatially coded DNAs, whose output is fed to a novel three-Dimensional Artificial Neural Network for local DNA alignment. All-optical implementation of the proposed 3D ANN is developed and its accuracy is verified in Zemax. Thanks to its parallel processing capability, the proposed structure performs local alignment of 4 million sequences of 150 base-pairs in a few seconds, much faster than its electrical counterparts, such as BLAST.

Automatic classification of atherosclerotic tissue in intravascular optical coherence tomography images

Ping Zhou, Tongjing Zhu, Chunliu He, and Zhiyong Li

Doc ID: 287894 Received 13 Apr 2017; Accepted 26 May 2017; Posted 26 May 2017  View: PDF

Abstract: Intravascular optical coherence tomography (IVOCT) has been successfully utilized for in vivo diagnostics of coronary plaques. However, classification of atherosclerotic tissues is mainly performed manually by experienced experts, which is time consuming and subjective. To overcome these limitations, an automatic method of segmentation and classification of IVOCT images is developed in this paper. The method is capable of detecting the plaque-contour between the fibrous and other components. Subsequently, the method classifies the tissues based on their texture features described by Fourier Transform and Discrete Wavelet Transform. The experimental results of 103 images show that an overall classification accuracy of over 80% in the indicator of depth and span angle is achieved in comparison to the manual results. The validation suggests that this method is objective, accurate, and automatic without any manual intervention. The proposed method is able to demonstrate the artery wall morphology successfully, which is valuable for the research of atherosclerotic disease.

Computational study of optical force between two nano-distant plasmonic sub-micro-wires

Masoud Rezvanijalal and Saba Fathollahi

Doc ID: 292328 Received 12 Apr 2017; Accepted 26 May 2017; Posted 26 May 2017  View: PDF

Abstract: In this paper, the optical force between two circular plasmonic wires of sub-micrometer diameter (0.3 μm) with nano-meter surface-to-surface distances (3-30 nm) interacting with radiation of a Complex Point Source (λ≈0.2 μm) is numerically studied. Calculations (which are based on the Muller Integral Equations and the Maxwell Stress Tensor) show that an attractive optical force with a number of distinct peaks is created in distances 3-10 nm. However, for plasmonic-dielectric and plasmonic-reflector double-wires the optical force has no such peaks. Comparisons reveal that the peaks are originated from the excitation of coupled Surface Plasmon Polariton in the gap region between the plasmonic wires.

Generalization of differential ray tracing

Jean-Baptiste Volatier, Alvaro Menduina-Fernandez, and Markus Erhard

Doc ID: 291574 Received 29 Mar 2017; Accepted 24 May 2017; Posted 24 May 2017  View: PDF

Abstract: Optical design relies on ray tracing to evaluate and optimize the performance ofoptical systems. Differential ray tracing, where the ray properties are calculated together with their derivatives has been shown to be of interest to improve accuracy and speed of common optical design tasks. We present in this paper an algorithm capable of performing differential ray tracing in the general case. This algorithm is not constrained by a specific optical system geometry such as rotational symmetry or restricted to a set of surface definitions (e. g. conics, polynomial aspheres).

General Refraction Problems with PhaseDiscontinuities on non flat metasurfaces

Cristian Gutierrez, Luca Pallucchini, and Eric Stachura

Doc ID: 292078 Received 04 Apr 2017; Accepted 24 May 2017; Posted 26 May 2017  View: PDF

Abstract: This paper provides a mathematical approach to study metasurfaces in non flat geometries. Analyticalconditions between the curvature of the surface and the set of refracted directions are introduced to guaranteethe existence of phase discontinuities. The approach contains both the near and far field cases.A starting point is the formulation of a vector Snell’s law in presence of abrupt discontinuities on theinterfaces.

Aberration analysis of AOTF-based spectral imaging systems

Vladislav Batshev, Alexander Machikhin, and Vitold Pozhar

Doc ID: 290572 Received 14 Mar 2017; Accepted 24 May 2017; Posted 24 May 2017  View: PDF

Abstract: Image aberrations caused by the acousto-optic (AO) anisotropic diffraction in uniaxial crystals are discussed. For their analysis, we propose a simplified ray-tracing model of AO crystal cell (AOC). With this approach, one can assign any configuration of AO interaction, any material and geometry of the crystal and then estimate all conventional ray aberrations: spherical, coma, astigmatism, distortion, etc. The optimization procedure is demonstrated by the aberration analysis of three principal spectral imaging schemes based on AO tunable filters (AOTFs). The developed approach promises a performance improvement of AOTF-based systems in high-quality spectral imaging and image processing.

Wavefront spacing and Gouy phase in strongly focused fields: the role of polarization

Jingcheng Zhang, Xiaoyan Pang, and Jun Ding

Doc ID: 290902 Received 17 Mar 2017; Accepted 23 May 2017; Posted 24 May 2017  View: PDF

Abstract: The wavefront spacings and the Gouy phases are investigated in the strongly focused fields with four differently polarized incident waves. It is shown that for such focused fields there are five kinds of wavefront spacings and Gouy phases corresponding to the different polarized axial field components. The four analytical and one numerical expressions are derived for these five kinds of wavefront spacings in the immediate neighborhood of the focus. Our results show that the polarization state, the semi-aperture angle and beam size influence the wavefront spacings and the Gouy phases in different ways. The difference between two very near wavefront spacings can be bigger than a half wavelength. It is also found that the axial field components with the polarization states orthogonal to that of the incident wave always have larger wavefront spacings.

The polarization-dependent effects of Airy beam due to the spin-orbit coupling

Hehe Li, Jingge Wang, Miaomiao Tang, and Xinzhong Li

Doc ID: 293164 Received 21 Apr 2017; Accepted 22 May 2017; Posted 22 May 2017  View: PDF

Abstract: We investigate the polarization-dependent effects when a circularly polarized Airy beam propagates in an inhomogeneous medium. It shows that there are some interesting polarization-dependent phenomena induced by the spin-orbit coupling: the circularly polarized Airy beam will follow a polarization-dependent trajectory in an inhomogeneous medium, and there are the polarization-dependent self-acceleration of the Airy beam in the linear-index inhomogeneous medium and the polarization-dependent rotation of the Airy beam in the quadratic-index inhomogeneous medium. These polarization-dependent phenomena are different from the manifestation of the "traditional" spin Hall effect of light beam which just displays the polarization-dependent transverse deflection of the beam.

Three-Dimensional Electromagnetic Imaging ofDielectric Targets by means of the MultiscalingInexact-Newton Method

Marco Salucci, Giacomo Oliveri, nicola anselmi, federico viani, alessandro fedeli, Matteo Pastorino, and Andrea Randazzo

Doc ID: 282666 Received 16 Dec 2016; Accepted 18 May 2017; Posted 19 May 2017  View: PDF

Abstract: A novel approach for three-dimensional electromagnetic imaging is presented. This technique is a combinationof an iterative multiscaling approach with an inexact-Newton method. The multiscaling procedureallows one to iteratively focus the region of interest on the detected target, whereas the inexact-Newtonmethod provides an efficient regularized solution of the nonlinear electromagnetic inverse scatteringproblem for each scaling step. The proposed method is validated against numerical data with differentconfiguration settings. A preliminary experimental validation is also reported.

Fast computer hologram generation by flexible-ratio adaptive point-spread spherical wave synthesis

Yutaka Mori and Yuto Arai

Doc ID: 287128 Received 23 Feb 2017; Accepted 15 May 2017; Posted 16 May 2017  View: PDF

Abstract: We propose a flexible-ratio adaptive point-spread spherical wave synthesis method for fast computergeneratedhologram (CGH) calculation. The conventional adaptive point-spread algorithm uses a fixedratio between the major and minor axes of the point source, whereas the proposed method uses flexibleratiosources, i.e., ellipses, for more effective calculation. Numerical simulation was conducted to validatethe proposed method. The results show that the proposed method has the potential to achieve fastercalculation compared to the calculation in conventional methods without significant image degradation.

Stochastic Calculus Analysis of Optical Time-of-Flight Range Imaging and Estimation of Radial Motion

Lee Streeter

Doc ID: 280668 Received 11 Nov 2016; Accepted 12 May 2017; Posted 12 May 2017  View: PDF

Abstract: Time-of-flight range imaging is analysed using stochastic calculus. Through a series of interpretations and simplifications, the stochastic model leads to two methods for estimating linear radial velocity: maxi- mum likelihood estimation on the transition probability distribution between measurements; and a new method based on analysing the measured correlation waveform and its first derivative. The methods are tested in a simulated motion experiment from (−40)—(+40) m/s, with data from a camera imaging an object on a translation stage. In tests maximum likelihood is slow and unreliable, but when it works it estimates the linear velocity with standard deviation of 1 m/s or better. In comparison the new method is fast and reliable but works in a reduced velocity range of (−20)—(−20) m/s with standard deviation ranging from 3.5 m/s to 10 m/s.

Wide Bandwidth, Millimeter-resolution InverseSynthetic Aperture Radar Imaging

Henry Everitt, Jonathan Richard, Martin Heimbeck, and L Autin

Doc ID: 282562 Received 09 Dec 2016; Accepted 12 May 2017; Posted 15 May 2017  View: PDF

Abstract: The combination of wide bandwidth W-band inverse synthetic aperture radar imagery and high fidelity numericalsimulations has been used to identify distinguishing signatures from simple metallic and dielectric targets. Targetsare located with millimeter-scale accuracy using super-resolution techniques, and Radon transformreconstructions of the returns from rotated targets approached the image quality of the complete data set in afraction of the time by sampling as few as ten angles. The limitations of shooting-and-bouncing ray simulations athigh frequencies are illustrated through a critical comparison of their predictions with the measured data andmethod of moments simulations, indicating the importance of accurately capturing the obfuscating role played bymultipath interference in complex targets.

Optimal configuration of static Mueller imagers for target detection

Francois Goudail, Matthieu Boffety, and stephane roussel

Doc ID: 287748 Received 01 Mar 2017; Accepted 07 May 2017; Posted 08 May 2017  View: PDF

Abstract: We investigate the target detection performance of static Mueller imagers that implement a fixed number of illumination and analysis polarization states. Using a maximin approach, we demonstrate that the optimal sets of measurement vectors consist in regular tetrahedra on the Poincar\'e sphere and that in this case, the obtained target/background contrast has a very simple expression. We then derive a universal lower bound on the contrast ratio between the best channel of a static imager and a fully adaptive one, and in a special case of practical interest, we demonstrate that this ratio is bounded and always larger than $1/9$. This is very important in practice since static imagers are much easier to build and operate. Our results show that they constitute a good alternative where ultimate contrast improvement is not necessary.

Illuminant estimation in multispectral imaging

Haris Ahmad Khan, Jean-Baptiste THOMAS, Jon Hardeberg, and Olivier Laligant

Doc ID: 282049 Received 05 Dec 2016; Accepted 05 May 2017; Posted 08 May 2017  View: PDF

Abstract: With the advancement in sensor technology, use of multispectral imaging is gaining wide popularity forcomputer vision applications. Multispectral imaging is used to achieve better discrimination between theradiance spectra, as compared to the color images. However, it is still sensitive to illumination changes.This study evaluates the potential evolution of illuminant estimation models from color to multispectralimaging. We first present a state of the art on computational color constancy and then extend a set ofalgorithms to use them in multispectral imaging. We investigate the influence of camera spectral sensitivitiesand number of channels. Experiments are performed on simulations over hyperspectral data. Theoutcomes indicate that extension of computational color constancy algorithms from color to spectral, givepromising results and may have the potential to lead towards efficient and stable representation acrossilluminants. However, it is highly dependant on spectral sensitivities and noise. We believe that the developmentof illuminant invariant multispectral imaging systems will be a key enabler for further use ofthis technology.

Color Opponency: A Tutorial

Steven Shevell and Paul Martin

Doc ID: 285192 Received 19 Jan 2017; Accepted 03 May 2017; Posted 08 May 2017  View: PDF

Abstract: In dialog, two color scientists introduce the topic of color opponency, as seen from theviewpoints of color appearance (psychophysics) and measurement of nerve cell responses(physiology). Points of difference, as well as points of convergence between theseviewpoints are explained. Key experiments from the psychophysical and physiologicalliterature are covered in detail to help readers from these two broad fields understandeach other's work.

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