Symmetrical double diffraction laser encoder

2018 ◽  
Author(s):  
Hung-Lin Hsieh ◽  
An-Jie Liang ◽  
Pei-Yun He
Keyword(s):  
Double Diffraction

Computer Indexing of Electron Diffraction Patterns Including the Effects of Lattice Symmetry

1977 ◽  
Vol 35 ◽  
pp. 22-23
Author(s):  
J. S. Lally ◽  
R. J. Lee
Keyword(s):  
Electron Diffraction ◽  
Zone Axis ◽  
Crystal Thickness ◽  
Double Diffraction ◽  
Automated Method ◽  
Lattice Symmetry ◽  
Intensity Calculations ◽  
Unknown Structure ◽  
Diffraction Patterns ◽  
Orientation Parameters

In the 50 year period since the discovery of electron diffraction from crystals there has been much theoretical effort devoted to the calculation of diffracted intensities as a function of crystal thickness, orientation, and structure. However, in many applications of electron diffraction what is required is a simple identification of an unknown structure when some of the shape and orientation parameters required for intensity calculations are not known. In these circumstances an automated method is needed to solve diffraction patterns obtained near crystal zone axis directions that includes the effects of systematic absences of reflections due to lattice symmetry effects and additional reflections due to double diffraction processes.Two programs have been developed to enable relatively inexperienced microscopists to identify unknown crystals from diffraction patterns. Before indexing any given electron diffraction pattern, a set of possible crystal structures must be selected for comparison against the unknown.

scholarly journals The s-dependence of double diffraction dissociation of protons at the CERN intersecting storage rings

1977 ◽  
Vol 72 (2) ◽  
pp. 261-264 ◽  
Author(s):  
G. Goggi ◽  
G.C. Mantovani ◽  
M. Cavalli-Sforza ◽  
C. Conta ◽  
M. Fraternali ◽  
...  
Keyword(s):  
Storage Rings ◽  
Double Diffraction ◽  
Diffraction Dissociation

scholarly journals Soft diffraction at LHC

2018 ◽  
Vol 172 ◽  
pp. 06005
Author(s):  
Jan Kašpar
Keyword(s):  
Elastic Scattering ◽  
Cross Section ◽  
Elastic Cross Section ◽  
Double Diffraction

This contribution reviews and compares various LHC results on soft diffraction, in particular elastic scattering, total, inelastic and elastic cross-section, single and double diffraction.

scholarly journals The Double Diffraction Model for LEED-Intensity Spectra of the Clean Pt(100) Surface

1977 ◽  
Vol 32 (1) ◽  
pp. 28-32 ◽  
Author(s):  
K. Heinz ◽  
P. Heilmann ◽  
K. Müller
Keyword(s):  
Surface Layer ◽  
Reciprocal Lattice ◽  
Normal Incidence ◽  
Second Order ◽  
Double Diffraction ◽  
Multiple Diffraction ◽  
Alternative Models ◽  
Diffraction Model

Abstract The intensity spectra of the superstructure diffraction spots of the clean platinum (100) surface are presented for normal or nearly normal incidence. Their gross features are interpreted in terms of multiple diffraction contributions. It is shown that most of the maxima in the spectra can be explained by double diffraction processes from an idealized pure hexagonal surface layer and quadratic bulk layers. Alternative models in which the surface layer exchanges already all occuring reciprocal lattice vectors would predict additional peaks which, however, do not arise. Therefore superstructure features of the surface layer are assumed to be of second order. Thus double dif­fraction involving only idealized hexagonal and quadratic structures seems to dominate the diffraction behaviour of clean Pt(100).

scholarly journals TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Moukrane Dehmas ◽  
Jacques Lacaze ◽  
Aliou Niang ◽  
Bernard Viguier
Keyword(s):  
Inconel 718 ◽  
Volume Fraction ◽  
Alloy 718 ◽  
Double Diffraction ◽  
X Ray Diffraction ◽  
Inconel 718 Alloy ◽  
X Ray ◽  
Delta Phase ◽  
Transmission Electron ◽  
Matrix Free

Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable Ni3Nb precipitation associated with a smaller volume fraction of Ni3Al precipitates. At very long ageing times at service temperature, decomposes to the stable Ni3Nb phase. This latter phase is also present above the solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

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