This document discusses adaptive optics in ground-based telescopes. It begins by explaining that adaptive optics helps remove atmospheric distortions to provide clearer images from telescopes on Earth. It then describes the three main types of telescopes - optical, reflecting, and radio telescopes. The document focuses on how adaptive optics works, using a deformable mirror and wavefront sensor to counteract distortions in real time. It discusses challenges like developing sensitive infrared detectors and fast adaptive components to enable observing faint exoplanets and other celestial objects.

1. ADAPTIVE OPTICS IN GROUND
BASED TELESCOPE
Guided by: Presented by:
V P Vinturaj Ajeesh . K. V
Lecturer in Electronics S5 EL, ROLL NO:03
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2. CONTENTS
 INTRODUCTION
 TELESCOPES
 DIFFERENTTYPES OFTELESCOPES
 OPTICALTELESCOPE
 REFLECTINGTELESCOPE
 RADIOTELESCOPE
 ADAPTIVE OPTICS
 BASIC PRINCIPLES
 SEEING INFRARED
 OTHER STARS AND OTHER EARTH
 CONCLUSION

3. INTRODUCTION
 Adaptive optics is new technology which in effect
removes the atmosphere tremor and helps the
astronomer see the image through earth based
telescopes more brightly.
 Without using this system the image obtained in
telescope on earth are seen to be blurred, which is
caused by the turbulent mixing of air at different
temperatures .
 It brings together the latest in computers, materials
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.
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4. TELESCOPES
 Telescopes are instruments used to study the
electromagnetic radiations from the universe.
 The word telescope is derived from the Greek
words “tele” (from afar)and “skopos” (viewer).
 The underlying principle of all telescopes is to
gather radiation from distant objects and focus it.
This increases the intensity of the radiations thereby
allowing the objects to be magnified.
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5. THREE DIFFERENT TYPES OF
TELESCOPES
 Optical telescope
 Reflecting telescope
 Radio telescope
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6. Optical Telescopes
 An optical telescope is a telescope that gathers
and focuses light, mainly from the visible part of the
electromagnetic spectrum, to create
a magnified image for direct view, or to make
a photograph, or to collect data through
electronic image sensors.
 Optical telescopes have been used in astronomical
research since the time of their invention in the early
17th century.
 Many types have been constructed over the years
depending on the optical technology, such as
refracting and reflecting etc.
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7. Diagram of Optical telescope
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8. Reflecting Telescopes
 A reflecting telescope (also called a reflector) is
a telescope that uses a single or a combination
of curved mirrors that reflect light and form an image.
 The reflecting telescope was invented in the 17th
century, by Isaac Newton, as an alternative to
the refracting telescope which, at that time, was a
design that suffered from severe chromatic aberration.
 Reflecting telescopes come in many design variations
and may employ extra optical elements to improve
image quality or place the image in a mechanically
advantageous position.
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9. Diagram of Reflecting telescopes
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10. Radio Telescopes
 A radio telescope is a specialized antenna and radio receiver used
to receive radio waves from astronomical radio sources in the sky
in radio astronomy.
 Radio telescopes are the main observing instrument used in radio
astronomy, which studies the radio frequency portion of
the electromagnetic spectrum emitted by astronomical objects, just
as optical telescopes are the main observing instrument used in
traditional optical astronomy which studies the light wave portion
of the spectrum coming from astronomical objects.
 Radio telescopes are typically large parabolic ("dish")
antennas similar to those employed in tracking and communicating
with satellites and space probes. They may be used singly or
linked together electronically in an array.
 Unlike optical telescopes, radio telescopes can be used in the
daytime as well as at night.
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11. Diagram of Radio telescope
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12. What isAdaptive optics ?
 Adaptive optics refers to optical system which
adapt to compensate for optical effects introduced
by the medium between the object and its image
 In order to avoid atmospheric aberration one can
turn to large telescope on the ground, which have
been equipped with ADAPTIVE OPTICS system.
 With this setup, the image quality that can be
recovered is closed to that the telescope would
deliver if it were in space
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13. BASIC PRINCIPLES
 An adaptive system refracts the wave fronts by
reflecting the light of a deformable mirror whose
shape is changed in real time to introduce an
equal but opposite distortion
 The information on how to distort the mirror
comes from a wave front sensor an instrument
that measures optical aberration imposed by the
atmosphere on light from a star.
 After the light reflects of the deformable mirror, a
beam splitter sends part of the light to a camera
that will capture the high resolution image
produced by the adaptive optics.
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14. DIAGRAM OF ADAPTIVE OPTICS
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15. BASIC FUNCTIONAL DIAGRAM
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16. SEEING INFRARED
 In the infrared, the hardware of adaptive optics
consists of an existing telescope, complete with
its primary and secondary mirrors, and adds a
separate box of optics, including the deformable
mirror, to perform the atmospheric compensation.
 One is that each additional optical surface beam
train absorbs some of the light from the target
object in the sky, making the object appear fainter.
 Also it emits light by virtue of its warmth ,
introducing thermal noise, further degrading the
astronomers, ability to detect faint objects
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17. OTHER STARS, OTHER EARTHS
 Per haps the most exciting scientific program to
benefit from the new approach to adaptive optics
will be to look at Jupiter like planets orbiting
other stars.
 Roughly 100 such stars have been found out
through observation of the effects on the motion
of there parent stars, but none has ever be seen by
direct imaging.
 It happens because they are extraordinary faint
and to compound the problem, they are right next
to something that is enormously brighter
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18. CONCLUSION
 There are many substantial technological challenges
in AO.
 Among them are the development of fast, very low-
noise detectors in order to be able to correct with
fainter reference stars; high-power reliable & easy to
operate sodium lasers, very fast processors exceeding
109 to 1010 operations per second; deformable
mirror with bandwidths of actuators and large
secondary adaptive mirror.
 The latter are especially interesting at thermal wave
lengths, where any additional mirror raises the
already huge thermal background seen by the
instruments
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19. THANK YOU