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Adaptive optics for visual observing


kingsbishop
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I doubt it, for adaptive optics you will need a composite miror made of several parts and this puts you in the realm of big expensive professional research telescopes, and they have no time for visual. 

Live luckly imaging is more likey to be in development, I think this is perfectly possible nowadays and will be a big selling point for planetary observers.

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On 24/11/2022 at 04:28, kingsbishop said:

Hello I’m wondering if adaptive optics work on visual observing or if there is something like that in development?

I imagine any adaptive optics system that works for imaging will work for visual observing too. However the cost of such systems is still very high, far out of the reach of us mortals. I think I have seen telescopes with adaptive secondaries before, but they were "ask for quote" price!

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It would be useless for amateur observing needs.

Problem is that seeing is both time and direction dependent. Each point in the sky has its own wavefront aberration and is in principle different to any other point in the sky.

To be precise - there is very small "window" around a point that has same / similar aberration - something like few arc seconds in radius - and this is zone that adaptive optics works in.

Such system can't even correct field large enough for planetary observation (in visible light) - it is mostly used for stellar sized objects.

 

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Here is a bit more on this:

Quote

isoplanatic angle
 

Another parameter of importance in adaptive optics is the isoplanatic angle, http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/theta.gif0. Suppose that there are two stars close together on the sky. What angle would these two stars have to be separated by in order for them to pass through approximately the same turbulent region of the atmosphere? Figure 62 shows that this can be estimated from the angle over which the turbulence pattern is shifted by a distance of only r0, in which case the beams from the two stars would share a substantial fraction of the turbulent region (shaded in yellow). Assuming that the turbulent layer is at an altitude h above the telescope, the isoplanatic angle is hence given by

http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/theta.gif0 = r0 / h.

At a good observing site on a typical night, h = 10 km and r0 = 10 cm at http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/lambda.gif0 = 500 nm. Hence http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/theta.gif0 = 10-5 radians, which is ~2". Detailed arguments lead to a more accurate version of this equation: http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/theta.gif0 ~ 0.314 r0 / h. The isoplanatic angle determines the area on the sky over which adaptive optics correction is effective. The dependence of http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/theta.gif0 on r0 implies that much wider fields (and hence more extended objects) can be corrected with adaptive optics in the infrared than in the optical, making the technique much more attractive in the infrared. The increased isoplanatic angle in the infrared also means that many more natural guide stars are available, as discussed below.

taken from :

http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/telescopes/phy217_tel_adaptive.html

 

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