Adaptive Optics is a technique to compensate quickly varying optical aberrations in an #optical system 🔭. A limitation is that the correction is only valid in a very small patch of sky 🌌. Multi-Conjugate Adaptive Optics, or #MCAO uses several guide stars ✨ to measure the light wave aberrations in several directions. The corrected field of view is enlarged by a factor of 10 to 20 to obtain the most uniform output image quality https://mavis-ao.org/mavis/

#MAVIS #AdaptiveOptics #ESO #VLT

While I'm dreaming about having MAVIS on the telescope, here's something rather more fanciful. MAVIS will consist of an adaptive optics system (to correct for the blurring effects of the atmosphere) plus two instruments, an imager and a spectrograph, but it's being designed with space for a 3rd instrument be added later. So... what if you put an eyepiece there?

Normally putting an eyepiece on a giant research telescope like the VLT would not work at all well because it's optically impossible to produce a magnification and exit pupil size that are suitable for viewing with a human eye. But if you've got an adaptive optics system on the telescope delivering diffraction limited images then that completely changes!

A quick search for really big eyepieces turned up this, and it actually would be almost perfect: https://www.explorescientific.com/products/100-30mm

At the 3rd instrument f/35 focus the 30 mm focal length would give a visual magnification of 9333x. The 52.2 mm diameter field stop would give a max on-sky field of view of 39 arcseconds diameter, which matches well with the 30 x 30 arcseconds field of view of MAVIS. With f/35 input the exit pupil of the eyepiece would be 0.86 mm diameter, so it would be easy to get all of the light from MAVIS into a dark adapted human eye with a ~7 mm diameter pupil. Maximum resolving power of the human eye is about half an arcmminute, and with the 9333x magnification that would correspond to about 3 milliarcsecond on sky, about 4 times better then the resolution of the images delivered by MAVIS. In practice that's a pretty good match, the image wouldn't look significantly over-magnified and blurry.

Because of the slow focal ratio/small exit pupil the visual surface brightness would be low so it would be rubbish for looking at nebulae or galaxies, but I bet planets would look amazing!

#Astronomy #Astrodon #VLT #AdaptiveOptics

While pointing MAVIS at Jupiter and Saturn would produce the most spectacular images, MAVIS observations of the ice giants Uranus & Neptune may be more significant.

This image is about as good as the Hubble Space Telescope's views of Neptune got: https://esahubble.org/images/opo2059a/. Higher resolution images have been obtained with ground based telescopes and adaptive optics, but they've been at longer wavelengths (infrared) which reduces resolution. With adaptive optics at visible wavelengths on an 8 metre telescope MAVIS should provide the sharpest views of Uranus and Neptune since Voyager 2 flew by them in 1986 and 1989.

Those Voyager 2 flybys happened during my formative years and were a big part of what got me interested in space, so observing Uranus and Neptune with MAVIS would be significant to me personally, too.

#Astronomy #Astrodon #VLT #AdaptiveOptics