World Science Scholars
demonstration
Note

This demonstration walks you through the steps of the adaptive optics technology that is used to remove atmospheric distortions when observing outer space. To view the steps, click the "advance" button.
Step 1: When astronomers want to use a land-based telescope to observe a distant signal in space, they need to contend with noise introduced when the signal passes through the atmosphere.
Step 2: In order to see through the distortion, they shine a laser into the ionosphere, about 90 km above see level, to create an artificial 'reference star'. They use the reference star to measure the distortion that the atmosphere introduces.
Step 3: After observing the atmospheric noise via the 'reference star', a computer changes the shape of a deformable mirror to invert the noise, leaving just the true signal.

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Tohfatunnur Maya
I have one question: How deformable mirror can dictate the true signal and separate that from noise? If anyone can help me.
Jimbo Jitsu
Step 2: In order to see through the distortion, they shine a laser into the ionosphere, about 90 km above see level, to create an artificial 'reference star'. They use the reference star to measure the distortion that the atmosphere introduces.
Rupert Macey-Dare
Great demo- with thanks.
Luke Gurbin
So we see the 90 km may be also somehow solidifying in the circumpolar region as sodium or another type of layer and/or layers.
BAIRY SATYANARAYANA
This is how I understood the process: When astronomers use a land-based telescope to observe a distant signal in space, a signal is passed through the atmosphere. Then, an atmospheric noise distortion is introduced when the signal passes through the atmosphere. To overcome this problem, an artificial reference star is created by sending a laser into the ionosphere at a well known distance. The corresponding atmospheric noise distortion introduced is measured. Computer is used to change and modify the shape of the deformable mirror so as to invert atmospheric noise distortion from the received signal from the actual distant star. The idea is to remove undesired atmospheric noise part from the finally received signal making use of adaptive optics but not to remove the real noise distortion from the atmosphere.
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