Surface profile reconstruction using near-field data

1995 ◽  
Vol 116 (1-3) ◽  
pp. 20-24 ◽  
Author(s):  
Jean-Jacques Greffet ◽  
Anne Sentenac ◽  
Rémi Carminati
Keyword(s):  
Field Data ◽  
Near Field ◽  
Surface Profile ◽  
Profile Reconstruction

scholarly journals Imaging of bi-anisotropic periodic structures from electromagnetic near-field data

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dinh-Liem Nguyen ◽  
Trung Truong
Keyword(s):  
Inverse Scattering ◽  
Maxwell Equations ◽  
Field Data ◽  
Periodic Structures ◽  
Near Field ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Inverse Scattering Problem ◽  
Factorization Method ◽  
Unique Determination

AbstractThis paper is concerned with the inverse scattering problem for the three-dimensional Maxwell equations in bi-anisotropic periodic structures. The inverse scattering problem aims to determine the shape of bi-anisotropic periodic scatterers from electromagnetic near-field data at a fixed frequency. The factorization method is studied as an analytical and numerical tool for solving the inverse problem. We provide a rigorous justification of the factorization method which results in the unique determination and a fast imaging algorithm for the periodic scatterer. Numerical examples for imaging three-dimensional periodic structures are presented to examine the efficiency of the method.

USE OF RIGID REFLECTORS FOR THE VIRTUAL INCREASE OF FIELD DATA IN THE NEAR-FIELD ACOUSTICAL HOLOGRAPHY

2007 ◽  
Vol 15 (01) ◽  
pp. 49-61 ◽  
Author(s):  
SUNG-IL KIM ◽  
JEONG-GUON IH ◽  
JI-HOON JEONG
Keyword(s):  
Boundary Element Method ◽  
Transfer Matrix ◽  
Field Data ◽  
Near Field ◽  
Measurement Data ◽  
Source Reconstruction ◽  
Matrix Equations ◽  
Inverse Boundary ◽  
Additional Information ◽  
Acoustical Holography

This paper suggests the use of rigid reflectors to provide additional information for source reconstruction in near-field acoustical holography based on the inverse boundary element method. The additional field pressure and transfer matrix equations introduced provide a virtual increase in the measurement data without increasing the number of sensors or altering their arrangement, which could cost more than using reflectors. In order to validate this method, we successfully reconstruct a vibrating ellipse.

electromagnetic field at the particl e has to be computed numerically. An example of such a computation using a program based on [49] is given in Fig. 4. But not only doe s the Mie theory describe an enhancement of the laser intensity in the particles' near field, it also predicts that for certain values of the size parameter nd/X (d denoting the particle diameter, À the laser wavelength) the enhancement should be particularly efficient, resulting in a resonant intensity enhancement, the so-called "Mie-resonances". 3.2.2. Near-field induced substrate damage When inspecting contaminated samples by scanning electron microscopy (SEM) or atomic force microscopy (AFM ) after DLC using ns laser pulses, the consequences of the field enhancement process became obvious: all over the cleaned areas w e found substrate damages localized exactly at the former particle positions [35, 37-39]. These damages manifested as melting pools or even holes in the surface, typical examples can be seen in Fig. 5. The consequences for the laser cleaning process are obvious. The intensity enhancement reduces the maximum laser fluence that can be applied in the process. Usually in laser cleaning studies [19, 31 ] the laser fluence corresponding to the melting threshold of a bare surface is taken as the damage threshold fluence. Our experiments show clearly that this is an inadequate definition. Instead one must take into account the enhanced laser fluence underneath the particles, as it will be discussed in Section 4. Fro m the obtained AFM images we were able to analyse in detail the surface profile at the damaged sites. Here we found that for high field enhancement factors the silicon substrate was not only molten , but that some material was even ablated (see Sec. 4). The momentum transfer to the particles during the ablation process significantly contributes to the cleanin g process and hence local substrate ablation

2003 ◽  
pp. 327-330
Keyword(s):  
Laser Fluence ◽  
Near Field ◽  
Particle Diameter ◽  
Surface Profile ◽  
Field Enhancement ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Laser Wavelength ◽  
Laser Cleaning ◽  
Intensity Enhancement

scholarly journals Spectral near field data of LED systems for optical simulations

2019 ◽  
Author(s):  
Ingo Rotscholl ◽  
Klaus Trampert ◽  
Udo Krüger ◽  
Franz Schmidt
Keyword(s):  
Field Data ◽  
Near Field

Wavelet Transforms in Fractal-Based Form Tolerancing

1993 ◽  
Author(s):  
R. S. Srinivasan ◽  
Kristin L. Wood
Keyword(s):  
Wavelet Transforms ◽  
Design Research ◽  
Profile Analysis ◽  
Synthesis Method ◽  
Surface Profile ◽  
Synthesis Methods ◽  
Geometric Tolerancing ◽  
Analysis And Synthesis ◽  
Cost Implications ◽  
Profile Reconstruction

Abstract Tolerancing is a crucial problem for mechanical designers, as it has quality and cost implications on product design. Research in tolerancing has addressed specific areas of the problem. Building upon previous research, a unified approach for geometric tolerancing with fractal-based parameters has been recently proposed. This paper explores an alternative error profile analysis and synthesis method, based on wavelets, that maintains and extends the use of fractals for surface error abstraction. An overview of the theory of wavelets is provided, and the link between fractals and wavelets is established. Experimental data are used to illustrate the application of wavelet theory to surface profile reconstruction and synthesis. The synthesis methods are then implemented in the design of ball-bearing elements, demonstrating the utility of fractal-based tolerancing. Plans for further study and implementation conclude the paper.

Sign in / Sign up

Export Citation Format

Share Document