diffraction ring

diffraction ring

[di′frak·shən ‚riŋ]
(optics)
Circular light pattern which appears to surround particles in a microscope field.
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Diffraction ring patterns of a slightly out-of-focus star on both sides of focus looked nearly identical, a sign that its objective is well-corrected.
These were indexed as corresponding to [Mo.sub.2]BC phase according to a simulation of the diffraction ring positions based on ICSD card number 613644.
For instance, the medium-range order (MRO) clusters less than 2 nm are frequently observed as indicated by the black circles, corresponding to the outer diffraction ring marked with white arrows shown in Figure 3(b).
1) Diffraction ring appearance, where the observer judged the seeing by the appearance and quality of the diffraction rings of highly magnified stellar images, using a small reflecting telescope.
Shortly thereafter, I began a collaboration with him in that effort, and introduced several improvements in the design of the instrument which included: (1) a reduction in the x-ray beam divergence and collimation diameter to 0.15 mm to minimize the effect of pressure gradients in the pressed sample; (2) an increase in the sample-to-film distance to include a range between 30 mm and 75 mm for improved accuracy in the measurement of diffraction ring diameters; (3) a corresponding increase in film-cassette diameter to 75 mm; (4) a modified entablature containing a wedge cutout to permit the recording of diffraction rings on film to 2[theta] [approximately equal to] 35[degrees].
Melt-crystallized isotropic polymers typically display a strong first-order diffraction ring and one or two higher-order rings of much lower intensity.
Once again, center Polaris in the eyepiece and switch to a high-power eyepiece, magnifying the view enough so that when the star is in focus you can see the Airy disk and the first diffraction ring. For the Airy disk and ring to be visible, the atmosphere must be steady and the telescope well acclimated to outdoor temperatures.
Furthermore, TEM bright-field image with the corresponding selected area electron diffraction (SAED) in Figure 3(b) indicates that except for diffraction halos, no sharp diffraction ring or spots can be observed.
The diffraction ring was clearly measured, and this revealed that the organo-clay nanoplatelets just after removing acetone (before starting the curing process), were intercalated and randomly oriented in DGEBA.
Each of its two tight pairs was cleanly split, with tiny Airy disks surrounded by a single diffraction ring and clear dark sky between the component stars.
Ideally, the outer diffraction ring should appear equally bright inside and outside of focus.
The origin of this diffraction ring in the heat-treated sample is not clear.