Related Experiment Video
Updated: Jul 6, 2026
07:51
Dielectric RheoSANS — Simultaneous Interrogation of Impedance, Rheology and Small Angle Neutron Scattering of Complex Fluids
Published on: April 10, 2017
Three-dimensional reconstruction of dielectric objects by the coupled-dipole method
1Departamento de Física, Av Universitária syn, Campus Universitário km 03-BR 116, 44031-460 Feira de Santana BA, Brazil.
Applied Optics
|March 14, 2008
Summary
This study introduces an electromagnetic scattering inversion technique using the coupled-dipole method and optimization for dielectric object imaging. The method effectively reconstructs refractive indices even with noisy scattered electric field data.
Area of Science:
- Electromagnetics
- Computational Physics
- Materials Science
Background:
- Electromagnetic scattering is crucial for characterizing materials.
- Imaging dielectric objects with dimensions near the incident wavelength presents challenges.
- Robust inversion methods are needed for real-world applications with imperfect data.
Purpose of the Study:
- To develop and demonstrate an inversion procedure for electromagnetic scattering.
- To enable imaging of dielectric objects using the coupled-dipole method.
- To assess the method's efficiency with corrupted scattered electric field data.
Main Methods:
- Utilized the coupled-dipole method combined with an optimization algorithm.
- Applied the inversion procedure to dielectric objects comparable in size to the incident wavelength.
- Tested the method's performance with scattered electric field data corrupted by Gaussian noise.
Main Results:
- Successfully demonstrated an inversion procedure for electromagnetic scattering.
- Showcased the method's capability for imaging dielectric objects.
- Confirmed the efficiency of the coupled-dipole method with noisy scattered field data.
Conclusions:
- The coupled-dipole method combined with optimization provides an effective inversion technique for electromagnetic scattering.
- This approach is feasible for imaging dielectric objects, even with corrupted data.
- The method can recover the medium's refractive index using both conventional matrix and iterative inversion.
Related Concept Videos
01:31Dielectric Polarization in a Capacitor
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
01:29Potential Due to a Polarized Object
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
01:30Electric Dipoles and Dipole Moment
Consider two charges of equal magnitude but opposite signs. If they cannot be separated by an external electric field, the system is called a permanent dipole. For example, the water molecule is a dipole, making it a good solvent.
Theoretically, studying electric dipoles leads to understanding why the resultant electric forces around us are weak. Since electric forces are strong, remnant net charges are rare. Hence, the interaction between dipoles helps us understand electrical interactions in...
Theoretically, studying electric dipoles leads to understanding why the resultant electric forces around us are weak. Since electric forces are strong, remnant net charges are rare. Hence, the interaction between dipoles helps us understand electrical interactions in...
01:27Electrostatic Boundary Conditions in Dielectrics
When an electric field passes from one homogeneous medium to another, crossing the boundary between the two mediums imparts a discontinuity in the electric field. This results in electrostatic boundary conditions that depend on the type of mediums the field propagates through.
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity.
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity.
01:28Induced Electric Dipoles
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
01:26Susceptibility, Permittivity and Dielectric Constant
When placed in an external electric field, a dielectric material gets polarized. The charge density in the dielectric material is given by the sum of the bound and free charge densities, while the total charge density can also be written in terms of the total electric field. The bound charge density can be measured in terms of polarization, leading to the relationship between electric displacement and polarization.