2776: Crystal Ball

Explain xkcd: It's 'cause you're dumb.
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Crystal Ball
They often use ball lenses to collect light at the ends of optical fibers, so when you look stuff up on the internet you're actually scrying through a crystal ball.
Title text: They often use ball lenses to collect light at the ends of optical fibers, so when you look stuff up on the internet you're actually scrying through a crystal ball.

Explanation

Ambox notice.png This explanation may be incomplete or incorrect: Created by SPHERICAL ABERRATION - Please change this comment when editing this page. Do NOT delete this tag too soon.
If you can address this issue, please edit the page! Thanks.

In optics, Spherical aberration is an image imperfection that occurs due to the increased refraction of light rays that occurs when rays strike a lens or a reflection of light rays that occurs when rays strike a mirror near its edge, in comparison with those that strike nearer the center. This causes the parts of an image reflected near the edges of a sphere (from the perspective of a viewer) to be distorted. As the viewer moves, the parts of the image which are distorted move as well.

This is the principle behind a Fisheye lens, which corrects for the distortion to provide an image that is circular in shape and tends to be convex (i.e, bulges outwards) towards the center of the image.

Transcript

Ambox notice.png This transcript is incomplete. Please help editing it! Thanks.
[A bearded wizard with a pointed hat is sitting at a table and investigating a crystal ball. Cueball is sitting at the opposite side.]
Wizard: Your future is hard to see.
Wizard: I can make out some hazy details in the center, but the off-axis components are particularly unclear.
[Caption below the panel:]
Wizards never did figure out how to fix spherical aberration.


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Discussion

I added an explanation of spherical aberration and the tendency of light to distort around spherical objects, as well as the idea of how fisheye lenses use this principle to do their thing. Darkwolf0218 (talk) 01:01, 16 May 2023 (UTC)

Thank you, the spherical aberration discussion is much better than before. Much better than the optics course I took where they consistently failed to notice that spherical aberration is because the lens is the wrong shape; it is an engineering problem not a physics problem.172.70.111.153 16:32, 21 May 2023 (UTC)

I can't seem to find the citation toolbar while editing on mobile. So dropping this here for a reference to ball lenses on fiber optic cables. Template:Cite web https://www.edmundoptics.com/knowledge-center/application-notes/optics/understanding-ball-lenses/ Iggynelix (talk) 12:37, 16 May 2023 (UTC)

We very rarely use Cites on this site. Just add a link (in alternate-word form to flow with the sentence, ideally).
I've never really used toolbar stuff (simple enough to tap in {s, }s, [s and ]s, as well as any <s and >s needed for HTML, etc), and it's simple to (eventually, perhaps checking via Preview that it's not totally messed up on the first go or two) work out what others did to add references and copy the style of the right kinds of them.
So if you want to mention a link to ball lenses, just do something like this. (PS., use the full ~~~~ when signing Talk contributions, I fixed yours without using the {{unsigned}} 'reminder'..) 172.70.86.31 14:28, 16 May 2023 (UTC)

Why am I now ear-wormed by "Beware of the Beautiful Stranger" by Clive James and Pete Atkin? "That ball needs a re-gun" I said, shelling out The future you see there has all come about" https://genius.com/Pete-atkin-beware-of-the-beautiful-stranger-lyrics https://www.youtube.com/watch?v=MeOYHZQqWao 172.71.242.202 17:56, 16 May 2023 (UTC)



I’m going to edit the part on the title text to be more broad, as Google isn’t the exclusive way to receive any kind of information on the internet 172.69.58.42 19:35, 16 May 2023 (UTC)

While we can all applaud the connection of spherical aberration to crystal balls, unfortunately the off-axis part of joke misses the mark as spherical aberration is an aberration that is generally uniform across the frame. 172.70.210.190 19:52, 16 May 2023 (UTC)

Yes, the comic seems to be confusing spherical aberration with coma, which makes it hard to produce a good explanation. I think the current reference to fisheye lenses, and distorted shapes, is a red herring. Spherical aberration rather appears as a lack of sharpness. 162.158.154.18 03:34, 18 May 2023 (UTC)


I'm new to the whole xkcd's websites and comic strips and I desire to meet some other xkcd fans as well!ArchaRaid (talk) 23:29, 16 May 2023 (UTC)

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