Principle of relative phase spectrum measurement in SIP

2009 ◽  
Author(s):  
Rujun Chen ◽  
Zhanxiang He ◽  
Lanfang He ◽  
Xuejun Liu
Keyword(s):  
Relative Phase ◽  
Phase Spectrum ◽  
Spectrum Measurement

scholarly journals Dispersion Compensation Method for Lamb Waves Based on Measured Wavenumber

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
J. Li ◽  
Y. Han
Keyword(s):  
Steel Plate ◽  
Lamb Waves ◽  
Dispersion Compensation ◽  
Distance Estimation ◽  
Phase Spectrum ◽  
Compensation Method ◽  
Phase Compensation ◽  
Material Parameters ◽  
Spectrum Measurement

In this study, a delta wavenumber dispersion compensation (∆K-DC) method was developed and applied, not only with the theoretical wavenumber but also with the measured wavenumber. Dispersion compensation can be achieved by the following steps: relative wavenumber measurement, traveling distance estimation, phase compensation, and wave correction. The feasibility of ∆K-DC with the theoretical wavenumber and measured wavenumber was validated with a high-dispersive A0 mode in a 2 mm steel plate experiment. The results showed that phase spectrum measurement was an effective method to construct the wavenumber curve, the propagation distances estimated by SAP2 were very accurate, and the dispersive signals can be compensated perfectly by applying the phase compensation and wave correction methods for each wavepacket. The present results highlight the application of ∆K-DC on dispersion compensation without any material parameters of a waveguide.

Novel Phase Spectrum Measurement Method based on Stimulated Brillouin Scattering

2008 ◽  
Author(s):  
Asier Villafranca ◽  
Javier Lasobras ◽  
Francisco López ◽  
Rafael Alonso ◽  
Ignacio Garcés
Keyword(s):  
Measurement Method ◽  
Brillouin Scattering ◽  
Stimulated Brillouin Scattering ◽  
Phase Spectrum ◽  
Spectrum Measurement ◽  
Stimulated Brillouin

Friedel'S law breakdown and interpretation of stacking fault images in tetrahedral semiconductors

1987 ◽  
Vol 45 ◽  
pp. 318-319
Author(s):  
Rob. W. Glaisher ◽  
A.E.C. Spargo
Keyword(s):  
Relative Phase ◽  
Point Group ◽  
Binary Compound ◽  
Stacking Fault ◽  
Fold Axis ◽  
Atom Pair ◽  
Tetrahedral Semiconductors ◽  
Group Symmetries ◽  
Thin Crystal ◽  
Phase Differences

Images of <11> oriented crystals with diamond structure (i.e. C,Si,Ge) are dominated by white spot contrast which, depending on thickness and defocus, can correspond to either atom-pair columns or tunnel sites. Olsen and Spence have demonstrated a method for identifying the correspondence which involves the assumed structure of a stacking fault and the preservation of point-group symmetries by correctly aligned and stigmated images. For an intrinsic stacking fault, a two-fold axis lies on a row of atoms (not tunnels) and the contrast (black/white) of the atoms is that of the {111} fringe containing the two-fold axis. The breakdown of Friedel's law renders this technique unsuitable for the related, but non-centrosymmetric binary compound sphalerite materials (e.g. GaAs, InP, CdTe). Under dynamical scattering conditions, Bijvoet related reflections (e.g. (111)/(111)) rapidly acquire relative phase differences deviating markedly from thin-crystal (kinematic) values, which alter the apparent location of the symmetry elements needed to identify the defect.

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