speckle interferometry


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speckle interferometry

A technique whereby the limit to the resolution of a telescope, imposed not by its design but by atmospheric turbulence (see seeing), may be considerably improved: factors of 50 have been reported. A typical stellar image has, at best, a diameter given by that of the diffraction-limited Airy disk; atmospheric turbulence however causes small continuous erratic movements in image position on a long-exposure photograph, producing a final blurred image enlarged many times. In optical speckle interferometry and its more recent infrared counterpart, many short exposures (10–20 milliseconds) of the object are taken in rapid succession. These freeze the effects of turbulence so that the individual ‘speckles' making up the overall image are distortion-free stellar images: those of supergiants are relatively large, those of binary stars are double. Substantial differences between the speckles of the many short exposures require the application of statistical analysis to the images. This leads to a range of information, including the separation and other properties of close binary stars, often hitherto unresolvable. In addition reconstructions have been achieved of the disks of supergiants, such as Betelgeuse; apparent diameters can thus be measured and large-scale surface details discerned. Very small areas of the Sun have also been studied.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

speckle interferometry

[′spek·əl ‚in·tər·fə′räm·ə·trē]
(optics)
The use of speckle patterns in the study of object displacements, vibration, and distortion, and in obtaining diffraction-limited images of stellar objects.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
performed a series of studies on temporal phase evaluation through speckle interferometry for out-of-plane deformation [36], in-plane deformation [37], the derivative of out-of-plane deformation [38], and the shape measurement [39].
Traditionally, astronomers have eliminated some of this blurring in visible-light images by using speckle interferometry, which creates an image composed of many short exposures.
Pappalettere, "Experimental and numerical characterization of sinterized materials with speckle interferometry and optimization methods," in Proceedings of the 10th Youth Symposium on Experimental Solid Mechanics (YSESM '11), pp.
Speckle interferometry, discovered by Antoine Labeyrie in the early 1970s, is the simplest means for coping with atmospheric blurring and reaching the full diffraction limit of a telescope.
Imaging tecniques such as speckle interferometry -- which essentially "freezes" the motion in the atmosphere from moment to moment by taking a succession of quick snapshots--are already pushing telescope technology to greater precision.
The more adventurous can examine the chapter on speckle interferometry for the amateur.
The equipment was used in a technique called speckle interferometry, developed to help earth-bound astronomers compensate for the shimmering distortion of our atmosphere and employed primarily to distinguish between close-together "point sources' of light such as binary stars or Pluto and its moon Charon.
Rutten has been using another telescope on La Palma, the 45-centimeter Dutch Open Telescope (DOT), to achieve 0.2-arcsecond resolution of the Sun using speckle interferometry. But that technique is limited.
Known as speckle interferometry, the technique uses computer analysis of thousands of images taken through a mask with seven pinholes.
A second, comparatively inefficient technique is known as speckle interferometry. With speckle, astronomers combine thousands of ultrashort exposures to characterize and remove atmospheric disturbances.
But the Harvard-Smithsonian group's method, known as speckle interferometry, takes a lot of images, sometimes through special masks, as the point of light jumps around.