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Accepted papers to appear in an upcoming issue

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(CENTENNIAL) Light-field and holographic 3D displays

Masahiro Yamaguchi

Doc ID: 273844 Received 16 Aug 2016; Accepted 20 Oct 2016; Posted 20 Oct 2016  View: PDF

Abstract: A perfect 3D display that satisfies all depth cues in human vison is possible if a light-field can be reproduced exactlyas it appeared when it emerged from a real object,. The light-field can be generated based on either light-ray orwavefront reconstruction, with the latter known as holography. This article first provides an overview of theadvances of ray-based and wavefront-based 3D display technologies, including integral photography andholography, and the integration of those technologies with digital information systems. Hardcopy displays havealready been used in some applications, whereas electronic display of light-field is under active investigation. Next,a fundamental question in this technology field is addressed: what is the difference between ray-based andwavefront-based methods for light-field 3D display? In considering this question, it is of particular interest to lookat the technology of holographic stereogram. The phase information in holography contributes to the resolution ofa reconstructed image, especially for deep 3D images. Moreover, issues facing the electronic display system oflight-fields are discussed, including the resolution of the spatial light modulator, the computational techniques ofholography, and the speckle in holographic images.


Colin Sheppard

Doc ID: 273702 Received 12 Aug 2016; Accepted 19 Oct 2016; Posted 19 Oct 2016  View: PDF

Abstract: A deterministic Mueller matrix contains seven independent parameters. By writing the so-called c-vector (coherence vector) in parametric form, the Mueller matrix can also be written in parametric form, where the matrix elements automatically satisfy the known relationships between each other. Three of these parameters are also related to the so-called orientational parameters. The approach is generalized to express all 16 elements of a general Mueller matrix in terms of a scalar and five three-dimensional vectors. Many properties of a Mueller matrix can be written simply in terms of these vectors. Published experimental matrices are considered by this procedure.

Optical cryptosystem based on single-pixel encoding using the modified Gerchberg-Saxton algorithm with a cascaded structure

Wen Chen

Doc ID: 275309 Received 05 Sep 2016; Accepted 18 Oct 2016; Posted 18 Oct 2016  View: PDF

Abstract: In this paper, an optical cryptosystem is developed based on single-pixel encoding using the modified Gerchberg-Saxton algorithm with a cascaded structure. A series of random intensity-only patterns are pre-generated as principal security keys, and phase-only masks for optical encoding and decoding are generated by the modified Gerchberg-Saxton algorithm with a cascaded structure. Subsequently, a series of 1D intensity points, i.e., ciphertexts, are recorded by single-pixel detector, which may provide a potential for establishing low-cost and compact security systems. The phase-mask generation process can be flexibly designed by modifying Gerchberg-Saxton algorithm with a cascaded structure, hence high sensitivity and the large indirect space for phase can be guaranteed. It is also illustrated that high security can be achieved for the proposed single-pixel optical cryptosystem. The proposed method using a cascaded structure provides a novel alternative for single-pixel intensity-modulated optical security.

Spatio temporal blue noise coded aperture design for multi-shot compressive spectral imaging

Claudia Correa, Henry Fuentes, and Gonzalo Arce

Doc ID: 269176 Received 28 Jun 2016; Accepted 12 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: Multi-shot Coded Aperture Snapshot Spectral Imaging (CASSI) systems capture the spectral information of a scene using a small set of coded focal plane array (FPA) compressive measurements. Compressed sensing (CS) reconstruction algorithms are then used to reconstruct the underlying spectral 3D data cube. The only varying components in CASSI are the coded apertures whose structure is crucial inasmuch as they determine the minimum number of FPA measurements needed for correct image reconstruction and the corresponding attainable quality. Traditionally, the spatial structure of the coded aperture entries are selected at random leading to suboptimal reconstruction solutions. This work presents optimal structure design of the set of coded apertures by optimizing the concentration of measure of the multi-shot CASSI sensing matrix and its incoherence with respect to the sparse representation basis. First, the CASSI matrix system representation in terms of the ensemble of random projections is established. Then, the Restricted Isometry Property (RIP) of the CASSI projections is determined as a function of the coded aperture entries.The optimal coded aperture structures are designed under the criterion of satisfying the RIP with high probability, coined spatio temporal blue noise (BN) coded apertures. Furthermore, an algorithm that implements the BN ensembles is presented. Extensive simulations and a testbed implementation are developed to illustrate the improvements of the BN coded apertures over the traditionally used coded aperture structures, in terms of spectral image reconstruction PSNR and SSIM.

Inverse scattering for unbounded fractally corrugated surfaces

Lei Zhang

Doc ID: 272587 Received 28 Jul 2016; Accepted 12 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: The phaseless inverse scattering of optical or electromagnetic waves from unbounded fractally corrugated surfaces are taken into account. The main characteristics of this inverse scattering problem is that only the phaseless scattered field is measured and the incident field is tapered wave. In the previous recent works of the authors about the inverse scattering of rough surfaces, the cases of the Dirichlet boundary condition were considered ([18], [19]). Here we consider the inverse Neumann rough surface problems. The Fréchet derivatives of the scattered field with respect to the parameters of the surfaces are derived. Then a numerical method to identify the rough surfaces from the phaseless measurements of the scattered field at a fixed frequency is developed. Numerical examples are presented to show the validity and efficiency of the proposed method.

Method to determine the degrees of consistency in experimental datasets of perceptual color differences

Manuel Melgosa, Samuel Morillas, Rafael Huertas, and Luis Robledo

Doc ID: 273789 Received 15 Aug 2016; Accepted 12 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: We propose a fuzzy method to analyze datasets of perceptual color differences with two main objectives: to detect inconsistencies between couples of color pairs and to assign a degree of consistency to each color pair in a dataset. This method can be thought as the outcome of a previous one developed for a similar purpose [J. Mod. Optic. 56, 1447-1456, 2009], whose performance is compared with the proposed one. In this work, we present the results achieved using the dataset employed to develop the current CIE/ISO color-difference formula, CIEDE2000, but the method could be applied to any dataset. Specifically, in the mentioned dataset, we find that some couples of color pairs have contradictory information, which can interfere both in the successful development of future color-difference formulas as well as in checking the performance of current ones.

Near-core structure of a propagating optical vortex

Kedar Khare, Priyanka Lochab, and Paramasivam Senthilkumaran

Doc ID: 274803 Received 30 Aug 2016; Accepted 11 Oct 2016; Posted 11 Oct 2016  View: PDF

Abstract: We study the propagation of a charge-1 vortex beam using the angular spectrum method. While the vortex beams are commonly assumed to have a helical wavefront, it is well known that the phase of the vortex in the near-core region varies arbitrarily fast. In order to explain the wavefront behavior in the near-core region ideas such as evanescent fields or super-oscillatory functions have been used before. Our study using the angular spectrum method can inherently take into account the propagating as well as evanescent spatial frequencies and is able to provide the detailed wavefront structure as the vortex wavefront evolves. We report that the vortex wavefront shows a significant phase dip in the near-core region for all propagation distances and the phase contour lines in this region are seen to spiral around the core. While the radial extent of this phase dip is seen to expand on propagation the magnitude of the dip remains constant. Both propagating as well as evanescent components are seen to contribute to this phase dip which we attribute to the presence of the radial component in the propagation vector near the core. The angular spectrum method as used here, can be a valuable tool for probing the near core structure of optical vortices.

Propagation of the OAM mode carried by partially coherent modified Bessel-Gaussian beams in anisotropic non-Kolmogorov marine atmosphere

YiXin Zhang, Yun Zhu, Minyu Chen, and Ye Li

Doc ID: 272255 Received 22 Jul 2016; Accepted 10 Oct 2016; Posted 11 Oct 2016  View: PDF

Abstract: The effect of anisotropic non-Kolmogorov turbulence of the marine atmosphere on the propagation of orbital angular momentum (OAM) modes carried by partially coherent modified Bessel-Gaussian (PCMBG) beams is investigated. The analytic formula of the probability density of OAM modes is derived and used to explore the evolution of the received power of the OAM mode. We find that PCMBG beams with longer wavelength, lower quantum number of the OAM mode and lower spectral coherence of the source are more robust for the propagation of the OAM mode in turbulence. The influences of the source characteristics and turbulent properties on the received power of OAM mode are analyzed in depth.

Increase of resolution by use of microspheres related tocomplex Snell’s law

Yacob Ben-Aryeh

Doc ID: 269567 Received 14 Jul 2016; Accepted 09 Oct 2016; Posted 10 Oct 2016  View: PDF

Abstract: The increase of resolution by the use of microspheres is related to the use of evanescent waves satisfyingcomplex Snell’s law with complex trigonometric functions related to the incident and refracted angles, whilethe refractive indices are real. The evanescent waves are obtained in addition to initial propagating wavessatisfying the ordinary Snell’s law. The lateral spatial wave vectors of the evanescent waves which includeinformation on the object fine structures are converted at the microsphere surface to smaller wave vectors.Due to the reduction in the magnitudes of the spatial wave vectors of the evanescent waves they becomepropagating waves including the fine structures which are recovered in the image plane.

A compact formulation of the beam shape coefficients for elliptical Gaussian beam based on localized approximation

Jianqi Shen, Xiaowei Jia, and Haitao Yu

Doc ID: 274137 Received 22 Aug 2016; Accepted 09 Oct 2016; Posted 10 Oct 2016  View: PDF

Abstract: It has been proved that localized approximation (LA) is the most efficient way to evaluate the beam shape coefficients (BSCs) in generalized Lorenz-Mie theory (GLMT). The BSCs are usually expressed in the form of multiple summations of infinite series of terms, which is cumbersome to calculate and the infinite series is frequently slowly-convergent. In this paper, we present a compact expression of the BSCs for an elliptical Gaussian beam based on the localized approximation that is more convenient and efficient for numerical computations. A comparison with the integral localized approximation is made, showing the reliability, stability and the efficiency of the presented formulation.

Electromagnetic theory of optical coherence

Ari Tapio Friberg and Tero Setala

Doc ID: 275361 Received 07 Sep 2016; Accepted 05 Oct 2016; Posted 05 Oct 2016  View: PDF

Abstract: The coherence theory of random, vector-valued optical fields has been of great research interest in recent years. In this work we formulate the foundations of electromagnetic coherence theory both in the space--time and space--frequency domains, with particular emphasis on various types of optical interferometry. Analyzing statistically stationary, two-component (paraxial) electric fields in the classical and quantum-optical contexts we show fundamental connections between the conventional (polarization) Stokes parameters and the associated two-point (coherence) Stokes parameters. Measurement of the coherence and polarization properties of random vector beams by nanoparticle scattering and two-photon absorption is also addressed.

An optimal phase element for generating a perfect optical vortex

Alexey Porfirev, Victor Kotlyar, and Alexey Kovalev

Doc ID: 271983 Received 20 Jul 2016; Accepted 05 Oct 2016; Posted 06 Oct 2016  View: PDF

Abstract: We derived exact analytical relationships to describe the complex amplitude of a perfect optical vortex generated by means of three different optical elements, namely, (i) an amplitude-phase element with transmission function proportional to a Bessel function, (ii) an optimal phase element with transmission equal to the sign function of a Bessel function, and (iii) a spiral axicon. The doughnut intensity was shown to be highest when using an optimal phase element. The spiral-axicon-aided diffraction ring was found to be twice as wide as when generated using two other elements. Thus, the optimal filter was shown to be best suited for generating a perfect optical vortex. Simulation results were shown to corroborate theoretical predictions, with the experiment being in agreement with theory and simulation.

Upper bound of signal-relevant efficiency of constrained diffractive elementes

Antonie Verhoeven, Harald Aagedal, Frank Wyrowski, and Jari Turunen

Doc ID: 272048 Received 21 Jul 2016; Accepted 05 Oct 2016; Posted 06 Oct 2016  View: PDF

Abstract: We define the Signal-Relevant Efficiency (SRE) of a diffractive optical element as a measure of the proportion of the incident field power that ends up in the desired output signal. An upper bound for SRE is determined in the presence of arbitrary constraints imposed on the element, such as phase-dependent loss due to absorption within the microstructure and quantization of the surface profile. We apply the theory to the important class of diffractive elements that contain only one desired diffraction order (such as diffractive lenses) and derive the surface profile that provides the highest efficiency allowed by the constraints.

Implementation of multi-directional moiré computerized tomography: multi-directional affine calibration

Yang Song, Jia Wang, Ying Jin, Zhenyan Guo, Yunjing Ji, An-zhi He, and Zhen-hua Li

Doc ID: 272473 Received 26 Jul 2016; Accepted 04 Oct 2016; Posted 05 Oct 2016  View: PDF

Abstract: To realize three-dimensional (3D) instantaneous diagnoses for flow fields, many multi-directional Optical Computerized Tomographic (OCT) techniques based on laser interferometry have been proposed. Projections from different directions of these tomographic systems are captured simultaneously to reconstruct the test field. These projections are independent from each other. However, due to the inevitable errors from installation and difference between optical elements, projections will be imaged with different distortion and locate at different positions on sensors. Therefore, a multi-directional calibration should be performed to remap these projections to a unified coordinate before CT reconstruction. As far as we know, the multi-directional calibration problem for laser interferometric CT techniques has never been discussed in previous researches. In this paper, a six-directional moiré tomographic system is designed. Considering the projection characteristics of moiré deflectometry, a multi-directional affine calibration method is proposed to determine the extrinsic and intrinsic parameters of tomographic projections. With the calibration results, projections can be remapped to the unified coordinate and the 3D distributions of flow field can be reconstructed.

Biprism Distortion Modelling and Calibration for Single-lens Stereovision System

Beibei Qian and kahbin Lim

Doc ID: 262991 Received 16 May 2016; Accepted 30 Sep 2016; Posted 30 Sep 2016  View: PDF

Abstract: Biprism based single-lens stereovision system has several advantages over the conventional two-camera system, which makes it popular in the recent years. However, employing a biprism in front of the camera will induce additional unique distortion in the image, which cannot be adequately represented by the existing distortion models, and hence it is difficult to calibrate or correct. In this work, a parametric biprism distortion model aiming to correct this biprism distortion is developed and evaluated. The estimation of the model starts with a general bivariate polynomial and is then refined based on the distortion properties. These properties are determined by the geometrical analysis of the distortion formation in the system. This refined model is evaluated in two ways: distortion map data fitting and virtual camera calibration. Both simulation and actual experiments are carried out to show the feasibility of the proposed distortion model, and the improvements in calibration accuracy comparing with the existing distortion models.

Generalized Likelihood Ratio Test Change Detection With Optical Theorem Constraint

Jing Tu and Edwin Marengo

Doc ID: 269306 Received 27 Jun 2016; Accepted 29 Sep 2016; Posted 30 Sep 2016  View: PDF

Abstract: We demonstrate a new application of the optical theorem to enhance the detection, from noisy scattering data, of an unknown scatterer embedded in an unknown background medium. The proposed methodology is based on a generalized likelihood ratio test (GLRT) detector with an additional constraint that must be obeyed by the scattered field data if the scatterer is known to be passive, lossless, or active. The constraint in question is based on the classical optical theorem, which is used throughout the paper in its most general form applicable to arbitrary probing fields and background media. It relies on back- ground field information which is accessible in many practical applications. This also reveals, from a fundamental wave physics point of view, that background information is highly relevant in extra ways beyond the basic background suppression operation. This “optical theorem constraint” is discussed in a general Hilbert space framework that applies to a broad class of scattering systems. Particular forms of the optical theorem constraint are presented for special cases including spherical and cylindrical scanning systems for which it can be compactly expressed in the fundamental multipole representation. The pertinent change detection theory incorporating, via standard nonlinear programming, the physics-based optical theorem constraint, is elaborated in detail, and the successful detection performance of this new change detection method is illustrated with examples.

Impact of non-stationary optical illumination on image reconstruction in optoacoustic tomography

Mark Anastasio, Yang Lou, Alexander Oraevsky, and Kun Wang

Doc ID: 270394 Received 12 Jul 2016; Accepted 18 Sep 2016; Posted 19 Sep 2016  View: PDF

Abstract: Optoacoustic tomography (OAT), also known as photoacoustic tomography, is a rapidly emerging hybrid imaging technique that possesses great potential for a wide range of biomedical imaging applications. In OAT, a laser is employed to illuminate the tissue of interest and acoustic signals are produced via the pho- toacoustic effect. From these data, an estimate of the distribution of the absorbed optical energy density within the tissue is reconstructed, referred to as the object function. This quantity is defined, in part, by the distribution of light fluence within the tissue that is established by the laser source. When performing three-dimensional imaging of large objects, such as a female human breast, it can be difficult to achieve a relatively uniform coverage of light fluence within the volume of interest when the position of the laser source is fixed. To circumvent this, researchers have proposed illumination schemes in which the relative position of the laser source and ultrasound probe is fixed, and both are rotated together to acquire a to- mographic data set. A problem with this rotating-illumination scheme is that the tomographic data are inconsistent; namely, the acoustic data recorded at each tomographic view angle (i.e., probe position) are produced by a distinct object function. In this work, the impact of this data inconsistency on image re- construction accuracy is investigated systematically. This is accomplished by use of computer-simulation studies and application of mathematical results from the theory of microlocal analysis. These studies specify the set of image discontinuities that can be stably reconstructed with a non-stationary optical il- lumination set-up. The study also includes a comparison of the ability of iterative and analytic image reconstruction methods to mitigate artifacts attributable to the data inconsistency.

Maxwell Garnett approximation (advanced topics): tutorial

Vadim Markel

Doc ID: 273172 Received 05 Aug 2016; Accepted 18 Sep 2016; Posted 06 Oct 2016  View: PDF

Abstract: In the second part of this tutorial we consider several advanced topics related to the Maxwell Garnett approximation.

Adaptive Multi Focus Image Fusion Using Block Compressed Sensing With SPL Integration In Wavelet Domain

UNNI VS, Sai Subrahmanyam Gorthi, and Deepak Mishra

Doc ID: 267357 Received 24 Jun 2016; Accepted 23 Aug 2016; Posted 24 Aug 2016  View: PDF

Abstract: The need of image fusion in current image processing systems is increasing mainly due to the increased number and variety of image acquisition techniques. Image fusion is the process of combining substantial information from several sensors using mathematical techniques in order to create a single composite image that will be more comprehensive and thus, more useful for a human operator or other computer vision tasks. This paper presents a new approach to multi focus image fusion based on sparse signal representation. Block based compressive sensing integrated with a projection driven CS recovery that encourages sparsity in the wavelet domain is used as a method to get the focused image from a set of out of focus images. Compression is achieved during the image acquisition process using a Block Compressive Sensing (BCS) method. An adaptive thresholding technique within the Smoothed Projected Landweber (SPL) recovery process reconstructs high resolution focused image from low dimensional CS measurements of out of focus images. Discrete Wavelet Transform (DWT) and Dual Tree Complex Wavelet Transform (DTCWT) are used as the sparsifying basis for the proposed fusion. The main finding lies in the fact that sparsification enables better selection of the fusion coefficients and hence better fusion. Laplacian mixture model fit is done in the wavelet domain and estimation of the pdf parameters by expectation maximization lead us to the proper selection of the coefficients of the fused image. The proposed method is compared with the fusion scheme without employing PL scheme and observed that with fewer samples itself the proposed method outperforms the latter.

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