Object wave field extraction in off-axis holography by clipping its frequency components

2020 ◽  
Vol 59 (13) ◽  
pp. D43 ◽  
Author(s):  
Nicómedes Leal-León ◽  
Modesto Medina-Melendrez ◽  
J. M. Flores-Moreno ◽  
Josué Álvarez-Lares
Keyword(s):  
Wave Field ◽  
Object Wave ◽  
Frequency Components

Study of the structure of the object wave field reconstructed by a phase vector hologram

1984 ◽  
Vol 41 (6) ◽  
pp. 1419-1425
Author(s):  
V. M. Serdyuk ◽  
A. P. Khapalyuk
Keyword(s):  
Wave Field ◽  
Object Wave ◽  
Phase Vector

Reconstruction and Prediction of Short-Crested Seas Based on the Application of a 3D-FFT on Synthetic Waves: Part 1 — Reconstruction

2012 ◽  
Author(s):  
Peter Naaijen ◽  
Elise Blondel-Couprie
Keyword(s):  
Wave Field ◽  
Domain Size ◽  
Offshore Structures ◽  
Propagation Model ◽  
Wave Measurements ◽  
Measurement Domain ◽  
Frequency Components ◽  
Spatio Temporal ◽  
Domain Description ◽  
Temporal Measurement

This article explores the feasibility of using a 3-dimensional Fast Fourier Transform (3D FFT) to obtain a frequency domain description of a spatio temporal measured short crested wave field. As 3D FFT is also the basic technique behind wave measurements by navigational X-band radars, the frequency components obtained by these radars could be used as initialization of a wave propagation model, enabling deterministic prediction of wave elevation on board of ships / offshore structures. Different methods are presented to use the dispersion relation to filter wave components obtained by the 3D FFT. The effect on the accuracy of data windowing and temporal measurement domain size are explored by simulations with linear synthetic wave data: It is investigated how well a synthetic wave field reconstructs after inverse transforming the filtered frequency components obtained by 3D FFT. A second paper [1] will consider the prediction outside the measurement domain by using the filtered 3D FFT components.

Spherically-arranged piecewise planar hologram for capturing a diffracted object wave field in 360 degree

2013 ◽  
Author(s):  
Seungtaik Oh ◽  
Hoyong Seo ◽  
Chi-Young Hwang ◽  
Beom-Ryeol Lee ◽  
Wookho Son
Keyword(s):  
Wave Field ◽  
Object Wave

Object Wave Determination by Single-Sideband Methods

1973 ◽  
Vol 31 ◽  
pp. 266-267
Author(s):  
Kenneth H. Downing ◽  
Benjamin M. Siegel
Keyword(s):  
Phase Shift ◽  
Carbon Films ◽  
Object Wave ◽  
Electron Wave ◽  
Phase Object ◽  
Heavy Atoms ◽  
Single Sideband ◽  
Thin Carbon ◽  
Additional Phase Shift ◽  
Additional Phase

Under the “weak phase object” approximation, the component of the electron wave scattered by an object is phase shifted by π/2 with respect to the unscattered component. This phase shift has been confirmed for thin carbon films by many experiments dealing with image contrast and the contrast transfer theory. There is also an additional phase shift which is a function of the atomic number of the scattering atom. This shift is negligible for light atoms such as carbon, but becomes significant for heavy atoms as used for stains for biological specimens. The light elements are imaged as phase objects, while those atoms scattering with a larger phase shift may be imaged as amplitude objects. There is a great deal of interest in determining the complete object wave, i.e., both the phase and amplitude components of the electron wave leaving the object.

Electron holography in materials science

1991 ◽  
Vol 49 ◽  
pp. 670-671
Author(s):  
Hannes Lichte ◽  
Edgar Voelkl
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Materials Science ◽  
Fourier Spectrum ◽  
Object Wave ◽  
Electron Holography ◽  
Reconstruction Procedure ◽  
Numerical Reconstruction ◽  
Transmission Electron ◽  
Unique Interpretation

The object wave o(x,y) = a(x,y)exp(iφ(x,y)) at the exit face of the specimen is described by two real functions, i.e. amplitude a(x,y) and phase φ(x,y). In stead of o(x,y), however, in conventional transmission electron microscopy one records only the real intensity I(x,y) of the image wave b(x,y) loosing the image phase. In addition, referred to the object wave, b(x,y) is heavily distorted by the aberrations of the microscope giving rise to loss of resolution. Dealing with strong objects, a unique interpretation of the micrograph in terms of amplitude and phase of the object is not possible. According to Gabor, holography helps in that it records the image wave completely by both amplitude and phase. Subsequently, by means of a numerical reconstruction procedure, b(x,y) is deconvoluted from aberrations to retrieve o(x,y). Likewise, the Fourier spectrum of the object wave is at hand. Without the restrictions sketched above, the investigation of the object can be performed by different reconstruction procedures on one hologram. The holograms were taken by means of a Philips EM420-FEG with an electron biprism at 100 kV.

Imaging of ferroelectric domain walls by electron holography

1992 ◽  
Vol 50 (1) ◽  
pp. 246-247
Author(s):  
Xiao Zhang
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Object Wave ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Quantitative Measurements ◽  
Resolution Imaging ◽  
Electron Microscopes

Electron holography has recently been available to modern electron microscopy labs with the development of field emission electron microscopes. The unique advantage of recording both amplitude and phase of the object wave makes electron holography a effective tool to study electron optical phase objects. The visibility of the phase shifts of the object wave makes it possible to directly image the distributions of an electric or a magnetic field at high resolution. This work presents preliminary results of first high resolution imaging of ferroelectric domain walls by electron holography in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls.

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