Adaptive
optics is a new technology which is being used now a days in ground
based telescopes to remove atmospheric tremor and thus provide a
clearer and brighter view of stars seen through ground based telescopes.
Without using this system, the images obtained through telescopes
on earth are seen to be blurred, which is caused by the turbulent
mixing of air at different temperatures.
Adaptive optics
in effect removes this atmospheric tremor. It brings together the
latest in computers, material science, electronic detectors, and
digital control in a system that warps and bends a mirror in a telescope
to counteract, in real time the atmospheric distortion.
The advance
promises to let ground based telescopes reach their fundamental
limits of resolution and sensitivity, out performing space based
telescopes and ushering in a new era in optical astronomy. Finally,
with this technology, it will be possible to see gas-giant type
planets in nearby solar systems in our Milky Way galaxy. Although
about 100 such planets have been discovered in recent years, all
were detected through indirect means, such as the gravitational
effects on their parent stars, and none has actually been detected
directly.
WHAT IS ADAPTIVE
OPTICS ?
Adaptive optics
refers to optical systems which adapt to compensate for optical
effects introduced by the medium between the object and its image.
In theory a telescope's resolving power is directly proportional
to the diameter of its primary light gathering lens or mirror. But
in practice , images from large telescopes are blurred to a resolution
no better than would be seen through a 20 cm aperture with no atmospheric
blurring. At scientifically important infrared wavelengths, atmospheric
turbulence degrades resolution by at least a factor of 10.
Space telescopes
avoid problems with the atmosphere, but they are enormously expensive
and the limit on aperture size of telescopes is quite restrictive.
The Hubble Space telescope, the world's largest telescope in orbit
, has an aperture of only 2.4 metres, while terrestrial telescopes
can have a diameter four times that size.
In order to
avoid atmospheric aberration, one can turn to larger telescopes
on the ground, which have been equipped with ADAPTIVE OPTICS system.
With this setup, the image quality that can be recovered is close
to that the telescope would deliver if it were in space. Images
obtained from the adaptive optics system on the 6.5 m diameter telescope,
called the MMT telescope illustrate the impact.