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Journal of the Optical Society of America A

Journal of the Optical Society of America A



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Early Posting

Accepted papers to appear in an upcoming issue

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Analysis of Scattering from Complex Dielectric Objects using the Generalized Method of Moments

  • Jie Li, Dan Dault, Naveen Nair, and Balasubramaniam Shanker
  • received 05/22/2014; accepted 09/03/2014; posted 09/04/2014; Doc. ID 212430
  • [full text: PDF (867) KB)]
  • Abstract: Integral equation based analysis of scattering from dielectric objects has been a topic of research for many decades. Different integral equation formulations, discretization methods, and comparative data of their relative advantages have been well studied. Traditional discretization methods typically rely on a tight coupling between the underlying geometry discretization and the approximation function space that is defined on this discretization. As a result, it is difficult to stitch together different approximation spaces or non-conformal domains or match basis sets to local physics. Furthermore, the basis sets most commonly used in discretizing dielectric boundary integral operators impose limits on the variety of integral equation formulations that can be employed. We recently presented a methodology \cite{Nair2011} that overcomes several of these bottlenecks. In the present paper, we introduce several extensions to these concepts for dielectric scattering problems. Specifically, we present a method that (i) uses mixed higher order local geometric descriptions, and (ii) mixes multiple basis sets defined on this geometry including higher order polynomials and classical Rao-Wilton-Glisson (RWG) functions. Furthermore, we provide a unified description of different integral equation formulations that can be used for analysis of scattering from dielectric objects and show that the present approach admits a larger range of formulations than existing methods. A number of results demonstrating the efficiency of the method (in terms of accuracy and capability) together with applicability to different formulations are presented.

Keywords (OCIS):

  • (000.4430) General : Numerical approximation and analysis
  • (290.0290) Scattering : Scattering
  • (050.1755) Diffraction and gratings : Computational electromagnetic methods

Vector Scattering from One Dimensional Periodic Perfectly Conducting Surface: TM Polarization

  • Qi Huang, Tian-lin Dong, Boyuan Chen, Qingxia Li, Jiasheng Tian, and Ping Chen
  • received 06/03/2014; accepted 09/02/2014; posted 09/03/2014; Doc. ID 213361
  • [full text: PDF (562) KB)]
  • Abstract: Abstract- Based on the Rayleigh hypothesis and the Floquet’s theorem, a vector method for studying electromagnetic wave scattering from one-dimensional periodic conducting surface with tapered transverse magnetic (TM) wave incidence is presented. The new formulation opens a new wide range of applications of the method, concerning not only gratings used in TM polarization but also conical diffraction, crossed gratings, two-dimensional problem, photonic band gaps, nonlinear optics, etc. The numerical results are consistent with the T-matrix method in the particular case when the plane of incidence is perpendicular to the generators of the surface. For the general case when the plane of incidence is not perpendicular to generators of the surface, the proposed method obtains significant results which reveal cross-polarized and anisotropic characteristics in the scattering while the energy balance is kept satisfactory. This straight forward approach is much more efficient than the T-matrix, thus suitable to be extended to other more involved periodic scattering problems.

Keywords (OCIS):

  • (050.0050) Diffraction and gratings : Diffraction and gratings
  • (050.1960) Diffraction and gratings : Diffraction theory
  • (290.5870) Scattering : Scattering, Rayleigh
  • (050.1755) Diffraction and gratings : Computational electromagnetic methods
  • (290.5825) Scattering : Scattering theory

Localized input fields in the rigorous coupled-wave analysis

  • Maximilian Auer and Karl-Heinz Brenner
  • received 06/11/2014; accepted 09/02/2014; posted 09/04/2014; Doc. ID 213842
  • [full text: PDF (953) KB)]
  • Abstract: We introduce a new treatment for localized input fields in the coupled wave theory. Therefore, a combination of the angular spectrum decomposition (ASD) and a cyclic formulation of the rigorous coupled-wave analysis (RCWA) is used, which does not require the computation of several standard RCWA calculations. The cyclic approach especially concerns the definition of the convolution matrix of the permittivity and enables the processing of multiple input plane waves in a single RCWA calculation. At the same time it ensures physically meaningful simulation results for finite truncation limits and thus inherently conserves energy. By adapting the 3D-RCWA algorithm to efficiently simulate the effects of localized and arbitrarily polarized input fields to three-dimensional volume gratings, various advanced diffraction problems like fiber coupling, the influence of distorted plane waves or the effects of focused beams on diffraction gratings can be investigated. Therefore, the impact of this work should concern many fields of application.

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (090.7330) Holography : Volume gratings
  • (230.7370) Optical devices : Waveguides
  • (070.7345) Fourier optics and signal processing : Wave propagation


Analysis of the polarizability of an array of spherical metallic inclusions in a dielectric host sphere

  • Fabio Mangini, Nicola Tedeschi, Fabrizio Frezza, and Ari Sihvola
  • received 07/23/2014; accepted 08/29/2014; posted 09/16/2014; Doc. ID 217372
  • [full text: PDF (853) KB)]
  • Abstract: The polarizability of an array of metallic spheres embedded in a dielectric host sphere is obtained by means of a quasi-static analysis of the electromagnetic interaction. The proposed model is validated through comparisons with the results obtained with a Finite-Element based software. A parametric study of the polarizability as a function of the number of inclusions, their radii and their positions is presented. An analysis of the plasmon resonances of the particle as a function of the same parameters is performed.

Keywords (OCIS):

  • (260.5430) Physical optics : Polarization
  • (260.5740) Physical optics : Resonance
  • (260.2065) Physical optics : Effective medium theory
  • (160.3918) Materials : Metamaterials

Human gesture recognition using 3D Integral Imaging

  • Pedro Latorre-Carmona, V. Traver, Eva Salvador-Balaguer, Filiberto Pla, and Bahram Javidi
  • received 05/02/2014; accepted 08/25/2014; posted 09/03/2014; Doc. ID 211272
  • [full text: PDF (3379) KB)]
  • Abstract: Three-dimensional Integral Imaging allows one to reconstruct a 3D scene, including range information, and provides sectional re-focused imaging of 3D objects at different ranges. This paper explores the potential use of 3D passive sensing Integral Imaging for human gesture recognition tasks from sequences of reconstructed 3D video scenes. As a preliminary testbed, the 3D Integral Imaging sensing is implemented using an array of cameras with the appropriate algorithms for 3D scene reconstruction. Recognition experiments are performed by acquiring 3D video scenes of multiple hand gestures performed by ten people. We analyze the capability and performance of gesture recognition using 3D Integral Imaging representations at given distances and compare its performance with the use of standard 2D single-camera videos. To the best of our knowledge, this is the first report on using 3D Integral Imaging for human gesture recognition.

Keywords (OCIS):

  • (100.5010) Image processing : Pattern recognition
  • (100.6890) Image processing : Three-dimensional image processing
  • (110.6880) Imaging systems : Three-dimensional image acquisition
  • (150.6910) Machine vision : Three-dimensional sensing

Radiologist Experience Effects on Contrast Detection

  • David Leong, Louise Rainford, Tamara Haygood, Gary Whitman, William Geiser, Tanya Stephens, Paul Davis, and Patrick Brennan
  • received 02/12/2014; accepted 08/10/2014; posted 09/05/2014; Doc. ID 206197
  • [full text: PDF (1141) KB)]
  • Abstract: Current literature shows that reader experience does not affect detection tasks, when the object does not require medical training to detect. However the research was never sufficiently detailed to examine if the contrast detection threshold is also the same for radiologists versus non-radiologists. Previously contrast threshold research was performed predominantly on non-radiologists, therefore any differences could lead to over- or under-estimation of the performance capabilities of radiologists. Fourteen readers, evenly divided between radiologists and non-radiologists, read a set of 150 mammogram-like images. The study was performed with the location of the objects known and unknown, requiring two separate readings. No difference in the contrast detection threshold between reader groups for either the location-unknown (+3) or location-known (+2) images was seen. The standard deviation for the location-unknown condition had no difference (p 0.91). But for the location-known condition, a significant difference (p 0.0009) was seen between radiologists and non-radiologists. No difference in contrast detection based on reader experience was observed, but decreased variance was seen with radiologists in the location-known condition.

Keywords (OCIS):

  • (120.2040) Instrumentation, measurement, and metrology : Displays
  • (330.1800) Vision, color, and visual optics : Vision - contrast sensitivity
  • (330.1880) Vision, color, and visual optics : Detection
  • (330.7310) Vision, color, and visual optics : Vision


(CV) Independence and interaction of luminance and chromatic contributions to spatial hyperacuity performance

  • Bonnie Cooper and Barry Lee
  • received 09/30/2013; accepted 02/02/2014; posted 02/03/2014; Doc. ID 198653
  • [full text: PDF (1336) KB)]
  • Abstract: Here we test interactions of luminance and chromatic input to spatial hyperacuity mechanisms. First, we tested alignment with matching or mismatching (contrast polarity or modality) grating pairs that were adjusted to detection threshold. Thresholds with mismatched pairs were significantly elevated. Second, we determined alignment acuity as a function of luminance or chromatic contrast alone or in the presence of contrast pedestals. For in-phase pedestal conditions, performance followed the envelope of the more sensitive mechanism. However, polarity reversals revealed an asymmetric effect for luminance and chromatic conditions. This suggests that luminance can overrule chromatic mechanisms in hyperacuity; we interpret these findings in the context of spatial mechanisms.

Keywords (OCIS):

  • (330.1720) Vision, color, and visual optics : Color vision
  • (330.5510) Vision, color, and visual optics : Psychophysics
  • (330.6100) Vision, color, and visual optics : Spatial discrimination

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