speckle

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speckle

(spĕk′əl)
n.
A speck or small spot, as a natural dot of color on skin, plumage, or foliage.

speck′le v.

speckle

A grainy distortion (a kind of “noise”) in an ultrasonographic image.
References in periodicals archive ?
We are going to call this magnitude the "space contrast" (SC) of the speckle pattern.
At the beginning the paint is "fresh" (just-applied), and therefore the observed speckle pattern presents a high local activity.
On the other hand, when the paint is completely "dry," the speckle diagram does not reveal any activity and all N images are identical and equivalent to a single speckle pattern with maximum contrast (that is, the statistical independence condition between the patterns is not fulfilled).
Then, a new image, named the "Temporary History of the Speckle Pattern (THSP)," is constructed by setting, side by side, the chosen column of the first image, the same column of the second image, and so on, 512 times.
So, when a phenomenon shows low temporal activity, time variations of the speckle pattern are slow and small.
Briers (12) theoretically studied the concepts of space and time contrast in a case where the dynamic speckle pattern was produced by a mixture of moving and stationary scatterers.
13) In this case, a set of N images is recorded by using an optical system, so a Fraunhofer speckle pattern is formed.
When applying the spray paint, we observed that the contrast was low because the speckle pattern was blurred.
The same idea applies to the speckle pattern created by laser light bouncing from a microscopically rough surface, such as a sheet of white paper or a wall coated with white paint.
But researchers who study optical effects are now turning to solid-state physics for fresh ideas, and in doing so they have found that recent theories about electrical conductivity in microscopic wires provide surprising new information about laser speckle patterns.
Indeed, just by observing shifts in speckle patterns, researchers can actually detect changes in the direction of an incoming laser beam.