<title>Scattering effects from residual optical fabrication errors</title>

For the aimed redefinition of the SI-unit kilogram the international Avogadro group is to measure the amount of substance of a silicon sphere with a relative uncertainty of better than 2 x 10-8. Up to now 3.0 x 10-8 is reached, mainly caused by the 2.7 x 10-8 uncertainty of the volume determination. Which itself is essentially affected by the uncertainty of wave front distortion caused by optical fabrication errors and possible misalignment. To gain more information on how the wave front distortion influences the result a new interferometer with improved optics and rather large changes in the etalon is built up. A comparison of the measurements of one sphere taken with two different interferometers gives direct access to this information. Additionally a ray tracing software is being developed to simulate the alignment and measurement processes. Following the alignment steps the resulting positioning uncertainties of each element can be simulated and elements which contribute mainly to the uncertainty can be identified. This gives evidence where an improvement of the alignment techniques is most effective and necessary. With the additional use of Monte Carlo method based calculations the influence on the measurement results can be determined.

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Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010008701x ◽

1991 ◽

Vol 49 ◽

pp. 540-541

Author(s):

Kenneth H. Downing ◽

Hu Meisheng ◽

Hans-Rudolf Went ◽

Michael A. O'Keefe

Keyword(s):

High Resolution ◽

Three Dimensional ◽

High Resolution Electron Microscopy ◽

Atomic Resolution ◽

Dimensional Structure ◽

Structure Information ◽

Resolution Electron ◽

Scattering Effects ◽

High Resolution Images ◽

Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

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Dynamical Scattering in Electron Diffraction of wet Protein Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000167 ◽

1980 ◽

Vol 38 ◽

pp. 42-43

Author(s):

B. B. Chang ◽

D. F. Parsons

Keyword(s):

Electron Diffraction ◽

Scattering Theory ◽

Protein Crystals ◽

Electron Diffraction Data ◽

Specimen Thickness ◽

Major Question ◽

X Ray ◽

Scattering Effects ◽

Diffraction Patterns ◽

Acceleration Voltage

The significance of dynamical scattering effects remains the major question in the structural analysis by electron diffraction of protein crystals preserved in the hydrated state. In the few cases (single layers of purple membrane and 400-600 Å thick catalase crystals examined at 100 kV acceleration voltage) where electron-diffraction patterns were used quantitatively, dynamical scattering effects were considered unimportant on the basis of a comparison with x-ray intensities. The kinematical treatment is usually justified by the thinness of the crystal. A theoretical investigation by Ho et al. using Cowley-Moodie multislice formulation of dynamical scattering theory and cytochrome b5as the test object2 suggests that kinematical analysis of electron diffraction data with 100-keV electrons would not likely be valid for specimen thickness of 300 Å or more. We have chosen to work with electron diffraction patterns obtained from actual wet protein crystals (rat hemoglobin crystals of thickness range 1000 to 2500 Å) at 200 and 1000 kV and to analyze these for dynamical effects.

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MULTIPLE SCATTERING EFFECTS IN THE COBALT K-EDGE EXAFS OF METAL CARBONYL COMPLEXES

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19868110 ◽

1986 ◽

Vol 47 (C8) ◽

pp. C8-589-C8-592

Author(s):

N. BINSTED ◽

S. L. COOK ◽

J. EVANS ◽

R. J. PRICE ◽

G. N. GREAVES

Keyword(s):

Multiple Scattering ◽

Metal Carbonyl ◽

Carbonyl Complexes ◽

Metal Carbonyl Complexes ◽

Scattering Effects ◽

Multiple Scattering Effects

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Scattering effects of solar panel on Space Station Space-To-Ground (SGS) antenna performance

10.2514/6.1992-1941 ◽

1992 ◽

Cited By ~ 2

Author(s):

SHIAN HWU ◽

LARRY JOHNSON ◽

JON FOURNET ◽

ROBERT PANNETON ◽

DONALD EGGERS ◽

...

Keyword(s):

Space Station ◽

Solar Panel ◽

Antenna Performance ◽

Scattering Effects

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Multiple Scattering Effects of an Ensemble of Irregularly Shaped Particles.

10.21236/ada175420 ◽

1986 ◽

Author(s):

Cavour Yeh

Keyword(s):

Multiple Scattering ◽

Scattering Effects ◽

Multiple Scattering Effects

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A critical review of optical switches

Journal of Optical Communications ◽

10.1515/joc-2020-0284 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ompal Singh ◽

Rajeev Paulus

Keyword(s):

Future Generation ◽

Optical Switches ◽

Literature Survey ◽

Optical Packet Switching ◽

Optical Fabrication ◽

Optical Components ◽

Detailed Review ◽

Switch Architectures ◽

Packet Switch ◽

Large Speed

Abstract Optical packet switching has gained lot of popularity in last a few years due to its advantages like, large speed, more bandwidth and very less crosstalk. But due to immature optical fabrication and designing technology OPS is still beyond reality. However, many of the optical components are commercialized and some of them are still in laboratory. Thus, for optical switches which are considered as future generation routers, many switch architectures are proposed by using different sets of optical components. This paper presents a detailed review of notable switch designs in past 20 years, and also presents a comprehensive literature survey of the notable papers related to optical packet switch designs.

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