17 Sep 11
Originally posted by twhiteheadWell that's how science works. If someone has done an experiment that shows the old news wrong, then a back and forth comes about in the journals with other scientists kicking in their two cents worth and when the dust settles, somebody is proven more or less right and someone else proven more or less wrong.
This is not about me doing new science (or claiming a new discovery). Rather it is about my understanding of the currently accepted explanation for Airy rings as described on Wikipedia.
Maybe my understanding is completely wrong.
It sounds like you have a hunch but you need to figure out how to go from a hunch to a theory to an experiment that backs that theory. Til then, it's conjecture.
So far the current theory works out in practice in that making a large mirror minimizes the size of the airy disk in line with current theory.
If there is a way to make the airy disk smaller with smaller mirrors, I would consider that a breakthrough in astronomy and most other optical devices.
I came up with a half baked idea that I mentioned earlier, I would like to follow through with it: a graduated absorption ring around the edge of a mirror where it starts out very thin and gets thicker, absorbing the light that would end up being in the fringes of the disk.
If it was shown to reduce the size of the airy disk, it would be experimental evidence of the validity of current optical theory.
At least I have a falsifiable test that could be done in the real world🙂
BTW did you read that last link I gave you?
17 Sep 11
Originally posted by sonhouseNo, you have misunderstood me. I am not challenging the currently accepted science on airy discs. I am seeking to understand what the science is.
It sounds like you have a hunch but you need to figure out how to go from a hunch to a theory to an experiment that backs that theory. Til then, it's conjecture.
BTW did you read that last link I gave you?
Yes. I am just not sure I understand it. I am however fairly sure that you don't understand it either and that your graduated absorption ring idea will not work.
17 Sep 11
Originally posted by twhiteheadwhy do you think that idea won't work? What don't you understand about the explanation given by that link?
No, you have misunderstood me. I am not challenging the currently accepted science on airy discs. I am seeking to understand what the science is.
[b]BTW did you read that last link I gave you?
Yes. I am just not sure I understand it. I am however fairly sure that you don't understand it either and that your graduated absorption ring idea will not work.[/b]
18 Sep 11
Originally posted by sonhouseBecause the effect applies to all apertures regardless of what tricks you play with the edges.
why do you think that idea won't work?
What don't you understand about the explanation given by that link?
I cant see how it translates to an aperture and a lens. I am also not convinced that for a large lens the intensity of light from the edge of the disk would be sufficient to cause problems. I believe the effect applies to the whole disk not just the edges.
19 Sep 11
Originally posted by twhiteheadDon't forget, the airy disk rings are also much lower in magnitude. If they were the result of problems with reflections, I would expect the rings around the main disk to be much larger. So it is entirely possible the edges contributes a lot to the rings.
Because the effect applies to all apertures regardless of what tricks you play with the edges.
[b]What don't you understand about the explanation given by that link?
I cant see how it translates to an aperture and a lens. I am also not convinced that for a large lens the intensity of light from the edge of the disk would be sufficient to cause problems. I believe the effect applies to the whole disk not just the edges.[/b]
19 Sep 11
Originally posted by sonhouseI don't think you understand the situation at all. For every star imaged by the telescope, the image of the star itself is not pinpoint, but slightly blurred, and there are airy rings around the stars image.
Don't forget, the airy disk rings are also much lower in magnitude. If they were the result of problems with reflections, I would expect the rings around the main disk to be much larger. So it is entirely possible the edges contributes a lot to the rings.
Every single photon that arrives at the image from the star is affected by the aperture - not just those that reflect at or ear the edge of the mirror.
Maybe it would help if we can get someone who actually understands more quantum mechanics than we do to give a more detailed explanation.
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19 Sep 11
Originally posted by twhiteheadYou don't need quantum mechanics for explaining this.
I don't think you understand the situation at all. For every star imaged by the telescope,
the image of the star itself is not pinpoint, but slightly blurred, and there are airy rings
around the stars image.
Every single photon that arrives at the image from the star is affected by the aperture -
not just those that reflect at or ear the edge of th ...[text shortened]... o actually understands more quantum mechanics
than we do to give a more detailed explanation.
Simply stick to Maxwell's equations on electromagnetic radiation.
It is simply the wave properties of light that mean that light passing through any
aperture will diffract.
Note for these purposes the mirror itself is acting like an aperture.
The larger the mirror (or if your doing interferometry the effective size of the mirror)
the less the diffraction so the finer the maximum resolution.
I would point out that there are already telescopes that can resolve some stars as disks
rather than points [Betelgeuse being a good example].
And also that can resolve planets around stars as separate points of light.
19 Sep 11
I am also curious about whether or not this limit is over come when there are two separate telescopes combined (I believe they do this somehow with radio telescopes).
My feeling is that the aperture size is what affects resolution and that combining two telescopes with similar apertures would not reduce the airy disc.
19 Sep 11
After a little research it seems that telescope arrays do conquer the airy disk, but to do so must collect and combine the light / radio waves from all telescopes and get them to interfere. This more or less proves that the 'edges' are not really relevant as there are more edges when there are multiple discs, yet better resolution is achieved.
So taking digital images from different telescopes and combining the results over the internet just wont work.
22 Sep 11
Originally posted by googlefudgeSo do you think my idea of a graduated ring at the edge of a telescope mirror could help make the airy disk smaller? What I am thinking about is coating the edge of the scope with something like nanotubes that absorb nearly 100% of the light but making it blend down to practically no thickness somewhere on the inside of the mirror, say 4 mm in or so, the idea there being to limit the amount of light at the edge of the aperture but to not create a distinct edge but a graduated level where you go from say 1% stoppage to 100 % stoppage of light. Seems to me that would reduce the size of the airy disk, maybe increase the resolution of a given telescope mirror.
Yes, every photon passing through the aperture is effected, to varying amounts.
The effect is greatest at the edges however.
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22 Sep 11
Originally posted by sonhouseWhy not have the sides of the scope completely open so the non incident light doesn't hit anything at all?
So do you think my idea of a graduated ring at the edge of a telescope mirror could help make the airy disk smaller? What I am thinking about is coating the edge of the scope with something like nanotubes that absorb nearly 100% of the light but making it blend down to practically no thickness somewhere on the inside of the mirror, say 4 mm in or so, the id ...[text shortened]... uld reduce the size of the airy disk, maybe increase the resolution of a given telescope mirror.
I am not totally sure what you are suggesting... however;
The airy disk is a function of diffraction and optical imperfections.
In an ideal perfect optical system it will still be limited by diffraction.
http://en.wikipedia.org/wiki/Airy_disk
(I know my links are all wiki, but wiki rocks)
24 Sep 11
1 edit
Originally posted by googlefudgeYes, but I am just talking about the rings around the airy disk. I think the actual center ring size is directly related to the mirror or lens size but the rings around it are related to the edge effects. Does that sound right? If so, maybe my idea of limiting the amount of light that diffracts would at least lessen the rings around the airy disks. Not sure what that would buy you in terms of resolution though.
Why not have the sides of the scope completely open so the non incident light doesn't hit anything at all?
I am not totally sure what you are suggesting... however;
The airy disk is a function of diffraction and optical imperfections.
In an ideal perfect optical system it will still be limited by diffraction.
http://en.wikipedia.org/wiki/Airy_disk
(I know my links are all wiki, but wiki rocks)
I wonder if anyone tried making a rounded edge of the mirror where there would be less light diffracted by the fact the edge of the mirror has some kind of shape, where the edge falls away in some useful fashion so there would not be a real edge.
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25 Sep 11
Originally posted by sonhouseah, no the entire thing rings and all, is the diffraction pattern.
Yes, but I am just talking about the rings around the airy disk. I think the actual center ring size is directly related to the mirror or lens size but the rings around it are related to the edge effects. Does that sound right? If so, maybe my idea of limiting the amount of light that diffracts would at least lessen the rings around the airy disks. Not sure ...[text shortened]... nd of shape, where the edge falls away in some useful fashion so there would not be a real edge.