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Author Topic: Flat lens offers a perfect image  (Read 2353 times)

bvukich

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Flat lens offers a perfect image
« on: August 27, 2012, 09:50:41 AM »
https://www.seas.harvard.edu/news-events/press-releases/flat-lens-offers-perfect-image
Quote
The flat lens eliminates optical aberrations such as the “fish-eye” effect that results from conventional wide-angle lenses. Astigmatism and coma aberrations also do not occur with the flat lens, so the resulting image or signal is completely accurate and does not require any complex corrective techniques.


It looks basically like a diffractive optical element taken to it's logical, nanoscale, conclusion.  Very interesting.

Edit...  I should probably note this isn't currently suitable for visible light (THz through near IR), so your 70-200/2.8 pancake will have to wait.
« Last Edit: August 27, 2012, 10:09:25 AM by bvukich »

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Flat lens offers a perfect image
« on: August 27, 2012, 09:50:41 AM »

TrumpetPower!

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Re: Flat lens offers a perfect image
« Reply #1 on: August 27, 2012, 11:43:11 AM »
There's another important caveat: this just applies to the lens element -- the piece of glass. Your 70-200 would still need a (virtual) 200 mm between the front element and the sensor.

And there'd be another problem: this lens is far thinner than a sheet of plastic, and there's no way you'd be able to keep it rigid without doing something like...well...encasing it in glass.

Lastly, even at the infrared and longer wavelengths this works at, it's horribly dark -- it only lets through 10% of the light.

There's no need to completely despair, though; the technology is quite similar in principle to the diffractive optics Canon already is using in its green stripe lenses. I imagine, with time (maybe a lot of time), all the supertelephotos will have diffractive optics. Some day we'll probably see a 400 f/2 that's as light as a 70-200.

You'll still need a second mortgage to buy one, though....

Cheers,

b&

Brendon

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Re: Flat lens offers a perfect image
« Reply #2 on: August 27, 2012, 12:59:59 PM »
Not to get to nerdy here, but it looks like this is basically a plate of material with graduated index of refraction.  These have been built in the past for different applications.  The big problem with this is that there is no way to achromatize this type of lens.  For operating in the C-band (comms band) it doesn't hurt you too bad because most signals are very narrow (like for IR imagery) but if you tried to push broad spectrum light through this (visible light) the colors will separate badly.  Essentially all of the color bend at a slightly different angle through the lens creates the purple and yellow fringing that is often seen in high contrast situations.  If nothing is done to correct for the chromatic aberation, you get a smearing/bluring of the image that is much worse than the little fringes.

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Re: Flat lens offers a perfect image
« Reply #2 on: August 27, 2012, 12:59:59 PM »