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Accepted papers to appear in an upcoming issue

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The analytical expressions of the imaging andabberation coefficients of a general form surface

Liu Yang, Jin qi, and Zhu Bin

Doc ID: 302589 Received 19 Jul 2017; Accepted 21 Sep 2017; Posted 22 Sep 2017  View: PDF

Abstract: A theoretical development is presented in this paper for describing and understanding the imaging and aberrationsof a general form surface. The development is based on the Taylor expansion of an arbitrary ray trace fromthe object reference plane to the image reference plane, which is called the base mapping of the general formsurface in this paper. The base mapping is expressed as two Taylor series of the object and pupil coordinatesand the imaging and aberration coefficients in the third order scope, are derived and presented as analyticalexpressions relevant to the optic parameters, invoking no approximations. The situation that with tilted objectand observing plane is also considered and the mapping from a tilted object to a tilted observing plane is derivedvia simple mathematical manipulations based on the base mapping.

Polarized optical scattering by inhomogeneities and surface roughness in an anisotropic thin film

Thomas Germer, Katelynn Sharma, Thomas Brown, and James Oliver

Doc ID: 302460 Received 14 Jul 2017; Accepted 20 Sep 2017; Posted 20 Sep 2017  View: PDF

Abstract: We extend the theory of Kassam et al. [J. Opt. Soc. Am. A 12, 2009–2021 (1995)] for scattering by oblique columnar structure thin films to include the induced form birefringence and the propagation of radiation in those films. We generalize the 4 × 4 matrix theory of Berreman [J. Opt. Soc. Am. 62, 502–510 (1972)] to include arbitrary sources in the layer, which are necessary to determine the Green function for the inhomogeneous wave equation. We further extend first-order vector perturbation theory for scattering by roughness in the smooth surface limit, when the layer is anisotropic. Scattering by an inhomogeneous medium is approximated by a distorted Born approximation, where effective medium theory is used to determine the effective properties of the medium and strong fluctuation theory is used to determine the inhomogeneous sources. In this manner, we develop a model for scattering by inhomogeneous films, with anisotropic correlation functions. The results are compared to Mueller matrix bidirectional scattering distribution function (BSDF) measurements for a glancing angle deposition (GLAD) film. While the results are applied to the GLAD film example, the development of the theory is general enough that it can guide simulations for scattering in other anisotropic thin films.

High-resolution coherent X-ray diffraction imaging of metal coated polymer microspheres

Eirik Torbjørn Skjønsfjell, David Kleiven, Nilseh Patil, Yuriy Chushkin, Federico Zontone, Alain Gibaud, and Dag Breiby

Doc ID: 302542 Received 18 Jul 2017; Accepted 19 Sep 2017; Posted 19 Sep 2017  View: PDF

Abstract: Coherent X-ray Diffraction Imaging (CXDI) is becoming an important 3D quantitative microscopy technique, allowing structural investigation of a wide range of delicate mesoscale samples that cannot be imaged by other techniques like electron microscopy. Here we report high-resolution 3D CXDI performed on spherical microcomposites consisting of a polymer core coated with a triple layer of nickel-gold-silica. These composites are of high interest to the microelectronics industry, where they are applied in conducting adhesives as fine-pitch electrical contacts – which requires an exceptional degree of uniformity and reproducibility. Experimental techniques that can assess the state of the composites non-destructively, preferably also while embedded in electronic chips, are thus in high demand. We demonstrate that using CXDI, all four different material components of the composite could be identified, with radii matching well to the nominal specifications of the manufacturer. Moreover, CXDI provided detailed maps of the layer thicknesses, roughnesses and defects such as holes, thus also facilitating cross-layer correlations. The size of the voxels in the reconstruction, given by the experimental geometry, was 16 nm. The effective resolution was estimated to be about 26 nm, yet still enabling even the thinnest coating layer to be resolved. We discuss critically the influence of the weak phase approximation and the projection approximation on the reconstructed electron density estimates, demonstrating that the latter has to be employed. We conclude that CXDI has excellent potential as a metrology tool for microscale composites.

Effect of Eddy Diffusivity Ratio on Underwater OpticalScintillation Index

Mohammed elamassie, Murat Uysal, Yahya Baykal, Mohamed Abdallah, and Khalid Qaraqe

Doc ID: 298243 Received 16 Jun 2017; Accepted 17 Sep 2017; Posted 18 Sep 2017  View: PDF

Abstract: The performance of underwater optical wireless communication systems is severely affected by the turbulence that occurs due to the fluctuations in the index of refraction. Most of the previous studies assume a simplifying, yet inaccurate, assumption in turbulence spectrum model that eddy diffusivity ratio is equal to unity. It is however well known that eddy diffusivity of temperature and salt are different from each other in most underwater environments. In this paper, we obtain a simplified spatial power spectrum model of turbulent fluctuations of the sea-water refraction index as an explicit function of eddy diffusivity ratio. Using the derived model, we obtain the scintillation index of optical plane and spherical waves and investigate the effect of eddy diffusivity ratio.

Simulation of generation and dynamics of polarization singularities with circular Airy beams

Dong Ye, Xinyu Peng, Muchun Zhou, Yu Xin, and MinMin Song

Doc ID: 300766 Received 22 Jun 2017; Accepted 15 Sep 2017; Posted 15 Sep 2017  View: PDF

Abstract: The generation and dynamics of polarization singularities have been under research for years, while the focusing property of the topological configuration has not been explored too much. In this article, we simulated the generation of low-order polarization singularities with circular Airy beam, and explore the focusing property of the synthetic light field during propagation due to the autofocusing of the component. Our work may provide a method to research the focusing properties of the polarization singularity configuration, which may help to develop its application prospect.

Infrared and Visible Image Fusion Based on Total Variation and Augmented Lagrangian

Hanqi Guo, Ma Yong, Xiaoguang Mei, and Jiayi Ma

Doc ID: 302050 Received 11 Jul 2017; Accepted 14 Sep 2017; Posted 15 Sep 2017  View: PDF

Abstract: This paper proposes a new algorithm for infrared and visible image fusion based on gradient transfer which achieves fusion by preserving the intensity of infrared image and then transferring gradients in the corresponding visible one to the final result. The gradient transfer suffers from the problems of low dynamic range and detail lost because it ignores the intensity from visible image. The new algorithm solves these problems by providing additive intensity from the visible image to balance the intensity between the infrared image and the visible one. It formulates the fusion task as an l1-l1-TV minimization problem and then employs variable splitting and augmented Lagrangian to convert the unconstrained problem to a constrained one which can be solved in the framework of alternating direction method of multiplier. Experiments demonstrate that the new algorithm achieves better fusion results with high computation efficiency in both qualitative and quantitative tests than gradient transfer and most state-ofthe-art methods.

A special ciphertext only attack to double randomphase encryption by plaintext shifting with specklecorrelation

Shuming Jiao, Guowei Li, Changyuan Zhou, Wenbin Zou, and Xia Li

Doc ID: 303300 Received 25 Jul 2017; Accepted 12 Sep 2017; Posted 12 Sep 2017  View: PDF

Abstract: In this paper, a special ciphertext only attack (COA) scenario to the traditional double random phase encoding(DPRE) technique is proposed based on plaintext shifting. We assume the attacker can illegally manipulate theDRPE system to gain multiple ciphertexts from randomly shifted versions of the same plaintext. The plaintextimage can be recovered when our proposed scenario is combined with speckle correlation attacking methodproposed in previous work. Simulation results demonstrate our proposed scheme can successfully crack theDRPE system even when the speckle correlation method alone fails to work in conventional single ciphertextscenario due to the small size of plaintext image. The work in this paper reveals a severe security flaw of DRPEsystems when minor position shifting of the plaintext occurs.

Electromagnetic energy stored in inhomogeneous scattering systems

Tiago Arruda, F Pinheiro, and Alexandre Martinez

Doc ID: 297263 Received 02 Jun 2017; Accepted 11 Sep 2017; Posted 11 Sep 2017  View: PDF

Abstract: We analytically study the time-averaged electromagnetic energy stored inside scatterers containing inclusions of arbitrary shapes. Assuming the low density of inclusions, we derive the expression for the energy-transport velocity through disordered media without relying on the radiative transfer equation. Moreover, this expression is independent of the shape of scatterers. In addition, we obtain a relation between the dwell and absorption times associated with inclusions by considering the relationship between internal energy and absorption cross-section. An approximation for the electromagnetic energy stored inside a disordered medium in terms of the transport mean free path and the packing fraction is also derived. This expression suggests that the enhanced electromagnetic energy within the host medium is achieved for inclusions exhibiting negative scattering asymmetry parameters. As a result, disordered media with enhanced backscattering is expected to exhibit large quality factors.

Orthotropic elastic moduli of biological tissuesfrom ultrasound assisted diffusing-wavespectroscopy

R. Vasu, Dibbyan Mazumder, Gurudas Kar, Debasish Roy, and Rajan Kanhirodan

Doc ID: 297533 Received 06 Jun 2017; Accepted 07 Sep 2017; Posted 08 Sep 2017  View: PDF

Abstract: We obtain vibro-acoustic (VA) spectral signatures of a remotely palpated region in tissue or tissuelikeobjects through diffusing-wave spectroscopy (DWS) measurements. Remote application of forceis through focused ultrasound and the spectral signatures correspond to vibrational modes of thefocal volume (also called the ROI) excited through ultrasound forcing. In DWS, one recovers the timeevolution of mean-square displacement (MSD) of Brownian particles from the measured decay ofintensity autocorrelation of light, adapted also to local particles pertaining only to the ROI. Weobserve that the plateau of the MSD vs. time curve has noisy fluctuations when ultrasound is applied,which disappear when forcing is removed. It is shown that the spectrum of fluctuations containspeaks corresponding to some of the modes of vibration of the ROI. This enables us to measure thevibrational modes carried by VA waves. We also show recovery of components of the orthotropicelastic tensor pertaining to the material of the ROI from the measured vibrational modes. We firstrecover the elastic constants for agar slabs which are verified to be isotropic. Thereafter, we repeatthe exercise on fat recovered from pork back tissue, which, from these measurements, is seen to beorthotropic. We validate some of our present measurements through independent runs in arheometer. The present work is the first step taken, to the best of our knowledge, to characterizebiological tissue on the basis of anisotropic elasticity property, which may potentially aid in thediagnosis and tracking of the progress of cancer in soft-tissue organs.

Analytical theory of real-argument Laguerre-Gaussian beams beyond the paraxial approximation

Ilia Vovk, Nikita Tepliakov, Mikhail Leonov, Alexander Baranov, Anatoly Fedorov, and Ivan Rukhlenko

Doc ID: 303379 Received 28 Jul 2017; Accepted 07 Sep 2017; Posted 08 Sep 2017  View: PDF

Abstract: We study the propagation of real-argument Laguerre-Gaussian beams beyond the paraxial approximation using the perturbation corrections to the complex-argument Laguerre-Gaussian beams derived earlier by Takenaka et al. [J. Opt. Soc. Am. A 2, 826 (1985)]. Each higher-order correction to the amplitude of the real-argument beam (l, m) is represented as a superposition of the same-order corrections to the amplitudes of the complex-argument beams (l, q) with q = 0, 1, 2, ..., m. We derive explicit expressions for the electric and magnetic fields of transversely and longitudinally polarized real-argument beams and calculate the chirality densities of these beams up to the fourth order of the smallness parameter. For the first time to the best of our knowledge, we show that essentially achiral Gaussian beams (corresponding to l = m = 0) possess nonzero chirality density due to the wavefront curvature. The obtained corrections to the paraxial beams may prove useful for precise laser beam shaping and in studies of optomechanical forces.

Polarization properties of composited vector Laguerre-Guassian beams during propagation

Jue Wang, Lin Wang, Yu Xin, and MinMin Song

Doc ID: 294841 Received 05 May 2017; Accepted 06 Sep 2017; Posted 08 Sep 2017  View: PDF

Abstract: We use analytical and numerical techniques to study the superposition of two vector Laguerre-Guassian (LG) beams. Vector LG beams contain rich polarization information and have many interesting features of intensity and polarization. The composited electric field shows inhomogeneous polarization distribution and we find out the distribution law for the singular points obtained. The number and position of singular points are calculated and confirmed by numerical methods. We also study the fundamental cases for nonconcentric composited vector LG beams and find out difference distribution laws of several types of singular points in all the possible combinations.

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