scholarly journals John Frederick Nye. 26 February 1923—8 January 2019

2020 ◽  
Vol 69 ◽  
pp. 425-441
Author(s):  
Michael Berry
Keyword(s):  
Crystal Structures ◽  
Electromagnetic Fields ◽  
Linear Polarization ◽  
Geometrical Optics ◽  
Continuous Distributions ◽  
Water Flows ◽  
Phase Singularities ◽  
Scalar Waves

John Nye was an internationally renowned physicist who made fundamental contributions to the understanding of crystals, ice and light. He explored defects in crystal structures, in particular continuous distributions of dislocations. He explained the mechanics of the flow of glaciers: their advance and retreat, and how this depends on the underlying topography; and how water flows beneath and within them. He was a pioneer in the study of optical singularities on three levels: stable caustics in geometrical optics; phase singularities (wavefront dislocations) in scalar waves; and lines of circular and linear polarization in electromagnetic fields.

11.—High-Frequency Scattering in a Certain Stratified Medium. The Two-part Problem

1974 ◽  
Vol 72 (2) ◽  
pp. 149-178 ◽  
Author(s):  
W. G. C. Boyd
Keyword(s):  
High Frequency ◽  
Line Source ◽  
Geometrical Optics ◽  
Incident Field ◽  
Stratified Medium ◽  
Secondary Radiation ◽  
Shadow Region ◽  
Two Dimensional ◽  
Scalar Waves ◽  
Impedance Discontinuity

SynopsisThe propagation of scalar waves in a certain two-dimensional medium is considered. The incident field, which is due to the presence of a line source, is scattered by two coupled half-planes on each of which the impedance takes a constant value. The Wiener-Hopf technique is used to find a solution which is then examined asymptotically for high frequency. It is found that there is an illuminated region in which the solution is expressed in terms of geometrical optics rays, and a shadow region in which the solution is described by creeping modes. The point of impedance discontinuity may be regarded as producing secondary radiation. The nature of this secondary radiation is quite different according as the point of impedance discontinuity lies in the illuminated or shadow region of the geometrical optics field produced by the source.

scholarly journals Geometrical optics limit of stochastic electromagnetic fields

2008 ◽  
Vol 77 (4) ◽  
Author(s):  
Robert W. Schoonover ◽  
Adam M. Zysk ◽  
P. Scott Carney ◽  
John C. Schotland ◽  
Emil Wolf
Keyword(s):  
Electromagnetic Fields ◽  
Geometrical Optics

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

The Imaging of Crystal Structures and Crystal Defects

1978 ◽  
Vol 36 (3) ◽  
pp. 207-217
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscope ◽  
Crystal Structures ◽  
Phase Contrast ◽  
Crystal Defects ◽  
Atom Density ◽  
Lack Of Information ◽  
Spatial Frequencies

The problem of "understandinq" electron microscope imaqes becomes more acute as the resolution is improved. The naive interpretation of an imaqe as representinq the projection of an atom density becomes less and less appropriate. We are increasinqly forced to face the complexities of coherent imaqinq of what are essentially phase objects. Most electron microscopists are now aware that, for very thin weakly scatterinq objects such as thin unstained bioloqical specimens, hiqh resolution imaqes are best obtained near the optimum defocus, as prescribed by Scherzer, where the phase contrast imaqe qives a qood representation of the projected potential, apart from a lack of information on the lower spatial frequencies. But phase contrast imaqinq is never simple except in idealized limitinq cases.

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