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Technology: Optics

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      CommentAuthorAngus
    • CommentTimeAug 8th 2019
     
    Spherical aberration is simply the result of using lenses with spherical figure because they are simple to make. More expensive aspherics are well known. The formula may describe some sort of perfection in aspheric figure. If it can be made.
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      CommentAuthorgoatcheez
    • CommentTimeAug 21st 2020
     
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      CommentAuthorgoatcheez
    • CommentTimeSep 30th 2020
     
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    They walk among us?
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      CommentAuthorAngus
    • CommentTimeFeb 26th 2021
     
    That has actually been around since before I retired - so more than 20 years. One should always remember Shannon's formula when packing vastly more channels into the same amount of signal power.
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    TANSTAAFL indeed
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    A rotating triangular parabolic resonator
    https://www.youtube.com/watch?v=M0dDDO9o6u4
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      CommentAuthorAngus
    • CommentTimeNov 12th 2021
     
    From which we deduce that these are not intended to represent EM waves. Transverse waves on a liquid seems possible.
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    They appear to reflect and interfere like EM.
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      CommentAuthorAngus
    • CommentTimeNov 12th 2021 edited
     
    Posted By: Andrew PalfreymanThey appear to reflect and interfere like EM.
    All waves interfere, refect and diffract. But if they are intended to be EM waves the rotation is grotesquely fast. The corners would fly off.

    Doing the numbers = it appears to be of the order of 100 wavelengths across the thing. If the wavelength is 500 nm (in the green) then it would take an EM wave 1.7*10^-10 sec to cross it. It turns about 60 degrees in a crossing time, so the rotation period is a nanosecond and it is thus rotating at about 60 billion rpm.
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    Well spotted!
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      CommentAuthorAngus
    • CommentTimeNov 13th 2021
     
    Here's another. Particles this time.

    I'd like to see it done with fermions.
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    I presume because of The Exclusion Principle. Could be fun.

    From time to time that particle pattern reverts into an apparently much lower entropy state. Makes you think.
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      CommentAuthorAngus
    • CommentTimeNov 13th 2021 edited
     
    Right. It's the bounce or attraction or stickiness or friction I'm after. Much more fun. I suppose he could just emulate a snooker break.

    Hmm. If these are non-interacting particles making perfectly elastic collisions with the walls, isn't the entropy (whatever that means in this case) a constant? Still - it does keep breaking up into smaller particles. I am expecting these one day to come back together and make three red rings. Except for edge effect, I guess, or atmospheric friction or roundoff error or something.
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    Perhaps entropy is in the eye of the beholder...
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      CommentAuthorTrim
    • CommentTimeDec 27th 2021
     
    Integrated Photonics Meets Electron Microscopy in Unconventional Collaboration.

    https://scitechdaily.com/integrated-photonics-meets-electron-microscopy-in-unconventional-collaboration/
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      CommentAuthorAngus
    • CommentTimeDec 27th 2021
     
    Interesting. It's not very clear what you would use it for but we can anticipate great displays of ingenuity.
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