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.

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.
References in periodicals archive ?
The exceptionally high-resolution images proved the exoplanet verification power of the Gemini North 8-meter telescope when combined a method called reconstructive speckle imaging.
Speckle imaging with the Gemini telescope will provide Kepler's follow-up program with a doubling in its ability to resolve objects and validate Earth-like planets.
Ghez (University of California, Los Angeles) and their colleagues have used speckle imaging to search for binaries in the Hyades.
Even so, they had to push its resolution to the limit by exploiting speckle imaging, a technique that takes numerous short exposures in order to work around atmospheric turbulence.
BOSTON -- Researchers at Massachusetts General Hospital (MGH) have developed a new technique that uses laser light, called Laser Speckle Imaging, to identify atherosclerotic plaques that cause heart attacks, according to a report that will appear in the August issue of Circulation.
Using speckle imaging, which essentially shifts and superposes a succession of short exposures to sidestep the seeing, Andrea M.