Dr. Ezekiel Bahar Profile

Dr. Ezekiel Bahar

Professor at Univ of Nebraska/Lincoln

SPIE Involvement:

Author

Publications (19)

Proceedings Article | 4 September 2008 Paper

Detection and identification of biological materials through their optical activity using the Mueller matrix

Ezekiel Bahar

Proceedings Volume 7029, 70290M (2008) https://doi.org/10.1117/12.796323

KEYWORDS: Chemical elements, Polarization, Organisms, Light scattering, Polarimetry, Biomedical optics, Electromagnetic radiation, Biological research, Optical components, Proteins

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SPIE Journal Paper | 1 September 2008

Description of versatile optical polarimetric scatterometer that measures all 16 elements of the Mueller matrix for reflection and transmission: application to measurements of scatter cross sections, ellipsometric parameters, optical activity, and the com

Ezekiel Bahar, Robert Kubik

OE, Vol. 47, Issue 09, 093603, (September 2008) https://doi.org/10.1117/12.10.1117/1.2979232

KEYWORDS: Chemical elements, Optical components, Optical activity, Polarimetry, Receivers, Polarization, Scatter measurement, Active optics, Dichroic materials, Solids

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Proceedings Article | 9 October 2007 Paper

Soil moisture content of composite rough surfaces based on a variational technique to distinguish between the larger and smaller scale surface spectral density functions

Ezekiel Bahar

Proceedings Volume 6742, 67420A (2007) https://doi.org/10.1117/12.730269

KEYWORDS: Modulation, Soil science, Polarization, Surface roughness, Composites, Reflection, Electro optical modeling, Remote sensing, Backscatter, Scattering

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The determination of soil moisture content is often based on the measurements of the ratio of the vertically and horizontally polarized cross sections for large angles of incidence, where the cross sections could be significantly different. Using the high frequency, physical optics model of the earth's surface, this ratio depends primarily on the Fresnel reflection coefficients for the two polarizations, while the impact of surface roughness factors out of the cross section ratio. Thus for highly conducting moisture saturated soils, this ratio approaches one. Using the low frequency, small height-small slope perturbation model of the earth's surface, the vertically and horizontally polarized cross sections are critically dependent on polarization for large angles of incidence, even for the perfectly conducting rough surfaces. However using the standard perturbation model, the ratios of the cross sections are also independent of the surface roughness. Applying the small perturbation approach to highly conducting rough surfaces, the ratio of the horizontally to vertically polarized cross sections approaches zero for grazing angles of incidence, for which the two cross sections differ significantly. There is ample experimental evidence that neither the physical optics nor the small perturbation models are adequate. The standard hybrid two scale physical optics-perturbation approach depends critically upon the decomposition of the composite surface into smaller and larger scale surfaces. The smaller scale surface is restricted to small Rayleigh roughness parameters, proportional to the mean square height, and the larger scale surface is restricted by the large radii of curvature criteria. Using a two scale full wave approach, the cross section are expressed as a weighted sum of a physical optics cross section for the larger scale surface, reduced by a factor equal to the square of the small scale surface characteristic function, and a cross section for the smaller scale surface that is modulated by the slopes of the larger scale surface. A variation technique is used to decompose the surface height spectral density function in a continuous, smooth manner into spectral density functions for the larger and smaller scale surfaces. It is shown that the corresponding polarization dependent rough surface cross sections are stationary over a wide range of the variation parameters. The ratio of the cross sections are dependent of the surface roughness, since the horizontally polarized cross sections are significantly dependent on modulation by the slopes of the larger scale surfaces, for large angles of incidence.

Proceedings Article | 28 September 2007 Paper

Fabrication and applications of negative refractive index matermaterials with chiral properties

Ezekiel Bahar, N. Ianno

Proceedings Volume 6638, 66380H (2007) https://doi.org/10.1117/12.729628

KEYWORDS: Refractive index, Reflection, Interfaces, Matrices, Metamaterials, Magnetism, Free space, Refraction, Reflectors, Wave propagation

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SPIE Journal Paper | 1 April 2007

Complex media characterized by chirality and negative refractive index: analysis and applications

Ezekiel Bahar, Natale Ianno

JNP, Vol. 1, Issue 01, 013509, (April 2007) https://doi.org/10.1117/12.10.1117/1.2736677

KEYWORDS: Reflection, Matrices, Interfaces, Wave propagation, Refractive index, Free space, Radio propagation, Waveguides, Lenses, Electromagnetic radiation

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Proceedings Article | 2 October 2006 Paper

Like and cross polarized reflections and transmission matrices for propagation across a chiral slab

Ezekiel Bahar

Proceedings Volume 6388, 63880S (2006) https://doi.org/10.1117/12.684698

KEYWORDS: Matrices, Lawrencium, Free space, Interfaces, Magnetism, Wave propagation, Reflection, Polarization, Biological detection systems, Composites

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Proceedings Article | 8 November 2005 Paper

Application of Mueller matrix and near fields measurements to detect and identify trace species in drugs and threat agents

Ezekiel Bahar

Proceedings Volume 5993, 59930G (2005) https://doi.org/10.1117/12.629022

KEYWORDS: Chemical elements, Scattering, Interfaces, Free space, Transform theory, Fourier transforms, Magnetism, Near field, Biological research, Maxwell's equations

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Proceedings Article | 4 March 2004 Paper

Near-field and far-field characterization of stratified chiral structures

Ezekiel Bahar, Paul Crittenden

Proceedings Volume 5270, (2004) https://doi.org/10.1117/12.516790

KEYWORDS: Interfaces, Electromagnetism, Magnetism, Scattering, Transform theory, Near field, Polarization, Agriculture, Fourier transforms, Maxwell's equations

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Proceedings Article | 9 July 2003 Paper

Electromagnetic scattering by stratified nanostructures with small-and large-scale periodic and random media and interface fluctuation: a full-wave approach

Ezekiel Bahar

Proceedings Volume 5218, (2003) https://doi.org/10.1117/12.503739

KEYWORDS: Interfaces, Scattering, Near field, Chemical elements, Waveguides, Electromagnetic scattering, Reflection, Nanostructures, Wave propagation, Magnetism

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The procedure followed in analyzing electromagnetic scattering by irregular layered structures, in which the heights of the interfaces as well as the medium parameters fluctuate laterally, is such that all the simplifying assumptions introduced in order to make the rigorous solutions to the problems more tractable, are made a posteriori rather than a prior. In this way the same analysis can be used to obtian the high frequency physical optics solutions that can be applied to structures with scales of roughness that are much larger than the wavelength as well as to obtain the low frequency small perturbation type solutions for structures with scales of roughness without introducing a wavelength. Thus this analysis can be applied to multiple scale structures without introducing an artificial scale parameter that dictates the solution to the problem. In addition the same analysis can be used to obtain the far field approximations suitable for structures with scales of roughness comparable and larger than the wavelength, as well as to obtain the near field approximations that are suitable for structures with subwavelength scales. The analysis accounts for evanescent as well as propagating waves, the lateral waves and the guided, surface waves of the irregular structures. To this end, a full wave approach that is based on the complete expansion of the fields as well as the imposition of exact boundary conditions at the rough interfaces is used in the analysis. Since these complete fields expansions do not necessarily converge uniformly at the irregular interface, careful mathematical procedures must be followed. It is shown that using the far field approximations, the solutions for the scattered fields are expressed as integrals over the spatial variables. On the other hand when the near field approximations are used, the scattered fields are expressed as integrals over the wave vector variables. This fulll wave analysis can also be applied to anisotropic media such as chiral materials.

Proceedings Article | 9 July 2003 Paper

Electromagnetic characterization of stratified chiral structures in nanotechnology

Paul Crittenden, Ezekiel Bahar

Proceedings Volume 5218, (2003) https://doi.org/10.1117/12.503744

KEYWORDS: Interfaces, Transform theory, Magnetism, Electromagnetism, Wave propagation, Scattering, Fourier transforms, Nanotechnology, Electromagnetic radiation, Reflection

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SPIE Journal Paper | 1 August 2002

Nanostructures with small and large scale periodic and random rough surfaces and lateral fluctuations in the permittivity and permeability-scattered near fields

Ezekiel Bahar

OE, Vol. 41, Issue 08, (August 2002) https://doi.org/10.1117/12.10.1117/1.1489050

KEYWORDS: Interfaces, Scattering, Nanostructures, Magnetism, Near field, Reflection, Electromagnetism, Wave propagation, Chemical elements, Waveguides

Proceedings Article | 5 December 2001 Paper

Near fields scattered by small- and large-scale rough surfaces and lateral fluctuations in the permittivity and permeability of nanostructures

Ezekiel Bahar

Proceedings Volume 4456, (2001) https://doi.org/10.1117/12.449525

KEYWORDS: Interfaces, Magnetism, Wave propagation, Scattering, Nanostructures, Electromagnetism, Near field, Radio propagation, Reflection, Waveguides

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Proceedings Article | 25 October 1999 Paper

One- and two-dimensionally rough-surface radar backscatter cross section based on a stationary two-scale full-wave approach

Ezekiel Bahar, Paul Crittenden

Proceedings Volume 3784, (1999) https://doi.org/10.1117/12.366701

KEYWORDS: Radar, Backscatter, Scattering, Numerical analysis, Composites, Chemical elements, Modulation, Electro optics, Polarization, Silicon

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Proceedings Article | 30 October 1998 Paper

High-frequency approximations of the full wave solutions to single and double scatter cross sections for two-dimensional random rough surfaces

Ezekiel Bahar, Magda El-Shenawee

Proceedings Volume 3426, (1998) https://doi.org/10.1117/12.328459

KEYWORDS: Backscatter, Scattering, Polarization, Radar, Electromagnetism, Receivers, Electro optics, Maxwell's equations, Geometrical optics, Numerical analysis

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The like and cross polarized single and double scattered fields are derived using a full wave approach. This approach is based on the complete expansion of the electromagnetic fields, the imposition of exact boundary conditions and the conversion of Maxwell's equations into generalized telegraphists equations for the scattered wave amplitudes. Thus, the zero order iterative solutions for the generalized telegraphists equations yield the primary electromagnetic (source) fields impressed upon the rough surface. The first and second order iterative solutions to the generalized telegropherts' equations yield the single and double scattered fields. This can be clearly demonstrated by taking the geometric optics limit of the full wave solutions. To obtain the corresponding like and cross polarized scatter cross sections, as in the case of scattering from one dimensional rough surfaces, it is necessary to account for contributions from the quasi parallel double scatter paths as well as the quasi antiparallel double scatter paths. However, for scattering from two dimensional rough surfaces, these paths are not restricted to the plane of incidence. The full wave solutions for the double scattered fields are expressed as six dimensional integrals, that account for the complete wave spectra of scattered fields and the coordinate variables at a pair of points on the rough surface. These expressions are used to obtain the multidimensional integrals for the like and cross polarized cross sections. To make these solutions tractable for computational purposes, a high frequency approximation of the full wave double scatter cross sections are expressed as four dimensional integrals involving scatter wave vector variables. These results can be evaluated in significantly less time than standard numerical solutions of the integral equations. Moreover, the physical interpretation of the results shed light on the impact, of different statistical parameters of the random rough surfaces, upon the backscatter enhancement.

Proceedings Article | 13 October 1998 Paper

Near fields and far fields excited by small- and large-scale fluctuations in the surface height, permittivity, and permeability of the medium

Ezekiel Bahar

Proceedings Volume 3467, (1998) https://doi.org/10.1117/12.326812

KEYWORDS: Scattering, Waveguides, Interfaces, Electromagnetism, Magnetism, Reflection, Near field, Near field optics, Maxwell's equations, Wave propagation

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Proceedings Article | 4 September 1998 Paper

Use of polarimetry to reduce the impact of clutter in the detection of mines buried in irregular stratified media

Ezekiel Bahar

Proceedings Volume 3392, (1998) https://doi.org/10.1117/12.324242

KEYWORDS: Interfaces, Scattering, Land mines, Reflection, Polarimetry, Electromagnetic scattering, Signal detection, Receivers, Coating, Electromagnetism

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Proceedings Article | 3 July 1998 Paper

Application of full wave analyses to electromagnetic scattering by multiple-scale anisotropic models of rough surfaces for industrial and climatic remote sensing

Ezekiel Bahar

Proceedings Volume 3382, (1998) https://doi.org/10.1117/12.312627

KEYWORDS: Scattering, Electromagnetic scattering, Chemical elements, Remote sensing, Electromagnetic radiation, Electromagnetism, Polarimetry, Polarization, Backscatter, Climatology

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Proceedings Article | 3 October 1997 Paper

Co- and cross-polarized fields scattered from irregular layered structures: full wave analysis

Ezekiel Bahar, Yuzhi Zhang

Proceedings Volume 3121, (1997) https://doi.org/10.1117/12.278965

KEYWORDS: Interfaces, Scattering, Coating, Medium wave, Matrices, Remote sensing, Californium, Polarimetry, Dielectrics, Thin film coatings

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Proceedings Article | 3 October 1997 Paper

Scattering from coated random rough surfaces characterized by the Mueller matrix

Yuzhi Zhang, Ezekiel Bahar

Proceedings Volume 3121, (1997) https://doi.org/10.1117/12.278964

KEYWORDS: Scattering, Coating, Chemical elements, Backscatter, Matrices, Remote sensing, Electromagnetic scattering, Electromagnetic radiation, Radar, Interfaces

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Showing 5 of 19 publications

Conference Committee Involvement (1)

Complex Mediums V: Light and Complexity

4 August 2004 | Denver, Colorado, United States

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