can you take an image of an Airy Disk??

[Merlin66]

I know you can easily see the Airy disk under steady seeing conditions with good optics, but can you actually take an image of the Airy disk??

( The maximum diameter of the central peak of the Airy disk is = 1.342 x Focal ratio (micron) - for green light)

[Darth Takahashi]

Over sampling is the key to revealing the airy disk with a ccd.

[Merlin66]

I think I agree...

If we have a CCD camera with a 7.5 micron pixel, and say go for an oversampling of 4 pixel (?) then the focal ratio would have to be

(4 x 7.5)/1.342 = f22....

Not an uncommon f ratio for planetary imagers....

[Darth Takahashi]

Exactly, I'd go even higher when possible , even F36/48 would give you a nicely defined airy disk out to the third ring etc...

I've always wanted to try eyepiece projection for planetary imaging to try to push for these higher F numbers. Until now I have never gotten around to it?

[FraserClarke]

I'm sure I have some images of a airy disc taken through an aperture mask. I'll see if I can find them tomorrow.

As well as high f/ratio, you also need a short exposure time (i.e. webcam). The eye is very good at seeing/ignoring the short term instabilities in the image which blur out a longer exposure.

In the meantime, the most impressive on-sky airy disc image I've ever seen is from the Large Binocular Telescope in Arizona (though only using one of the telescopes). Their adaptive secondary produced a fantastic image with 10 airy rings visible (just). The excess of light outside the 10th airy ring is an artefact of the adaptive optics system. I'm pretty sure this image is log-scaled.

Image is from this webpage, which also has more info; Untitled Document

[Merlin66]

Whooooo

Now THAT's what you call an image!!

Fantastic!