
Flat lens offers a perfect image - co_pl_te
https://www.seas.harvard.edu/news-events/press-releases/flat-lens-offers-perfect-image
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sbierwagen

      Operating at telecom wavelengths (i.e., the range commonly used in fiber-optic 
      communications), the new device is completely scalable, from near-infrared to 
      terahertz wavelengths, and simple to manufacture.
    

Ho ho, very clever use of words there. Terahertz is far-far infrared, (1mm to
.1mm (1,000,000-100,000nm) wavelength) while NIR is around 1,000nm. Visible
light is 740-380nm.

To the best of my knowledge, (this isn't my field) nobody has ever made a
visible-light metamaterial. The antennas are too small. There's no real
physical reason we can't make red-light metamaterials, the problem is just
fabrication. (A parallel can be drawn here between metamaterials, desktop
nanofactories, and fusion reactors)

Additionally, it would be tricky to make a panchromatic metamaterial lens:
metamaterials are tuned very precisely to one frequency, (color) constrained
by the physical size of the antennas, and they can't transmit any others.

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soup10
I don't get why every science article gets negative comments like this. Just
because something doesn't have immediate practical applications doesn't mean
its not interesting research.

Of course it's annoying when they are overly optimistic(either because of
journalists trying to make the finding interesting, or researchers trying to
get more funding), but that's to be expected.

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DenisM
Where headline is not accurate, it bears pointing out. I had no idea that this
is not in fact a visible light lense.

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jasonwatkinspdx
The headline is accurate (unless hacker-news had one that has one that has now
been edited away).

If you had read the article you would know precisely what wavelengths the
device is applicable to (3rd paragraph even), and why it's an exciting
research development.

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001sky
That chart is misleading. The use of the "visible spectrum" to illustrate
gradations of "delta" in the IR band is redundant. A luminosity scale, in grey
or monotone (say red?) would be more appropriate from a visual design
perspective. No?

~~~
jasonwatkinspdx
False color images are common, but yeah I agree that's somewhat confusing.

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cs702
As an amateur photographer with a small collection of DSLR and MILC camera
lenses at home, I'm quite excited by this: "In the future we can potentially
replace all the bulk components in the majority of optical systems with just
flat surfaces." In other words, this will allow large-sensor cameras to get a
lot smaller and thinner.

Edit: WRONG! As sbierwagen points out[1], even though the press release states
that the technology is "completely scalable" [to different wavelenghts of
light], it actually works only with wavelengths _greater than_ that of visible
light. Too bad :-(

sbierwagen: Thanks for the clarification.

[1] <http://news.ycombinator.com/item?id=4433970>

~~~
djmdjm
Sorry, read sbierwagen's comment for the bad news: metamaterials like those
used to construct this lens are tuned for very specific wavelengths so unless
your photographic aesthetic is centered on a very particular colour of IR then
you will be out of luck for quite a while.

~~~
sbierwagen
Metamaterial lenses, if you can make them in visible-light frequencies, might
be useful in the microlens array for light-field cameras, where they could act
as both the bayer color filter pattern and as focusing element, and where
their excellent optical qualities would be really helpful. (The Lytro light-
field camera's lousy optical performance is mostly due to the microlens array:
they have to be made of conventional materials, and the only lenses that would
fit are singlets, which have chromatic abbertation and barrel distortion out
the ass.)

But as the primary light gathering element, no.

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co_pl_te
Hi, sbierwagen.

This is certainly beyond my field of expertise, but I don't see how the
inability of this new lens to focus in the range of visible light detracts
from the main point of it being a distortion-free lens whose "focusing power
approaches the ultimate physical limit set by the laws of diffraction."

Although I agree that the press release makes it appear as if this will have
direct implications on imaging in the lay sense (this isn't going to make a
future iPhone the perfect camera), there are certainly applications of such
technology that aren't consumer-focused and don't require visible light that
stand to benefit from this research.

As blacksmythe notes, the lens created is not your stereotypical refractive
lens, but is more along the lines of a Fresnel lens or zone plate. I'd be
interested in hearing more about the differences between the two, especially
with regard to the limitations of each. Would anyone who read the write up in
Nano Letters or has a better understanding care to comment more on the
implications?

I agree the press release is a tad sensationalistic and possibly
(intentionally) misleading — but what do you expect from a press release?
Although the findings presented may not be as earth-shattering as a mass-
produceable visible-light metamaterial, I still think it's a noteworthy
development that shouldn't be dismissed so easily.

~~~
ehsanu1
OT/Meta: Please use the reply link to post replies, so that coherent threads
can be maintained.

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blacksmythe
From the summary article, it looks like they have made a Fresnel lens, which
can also be quite flat but works over a limited wavelength range of light.

In order to achieve broadband operation, the phase change vs wavelength of the
metamaterial needs to approximate a large delay. If a large delay is not
feasible to implement, this summary is overstating the importance of this
result compared to prior technology.

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JoshTko
Couldn't you just put one of these lenses in front of every single CCD
subpixel to create a flat lens?

~~~
jws
You would end up with very little light gathering capacity. The number of
photons exposing each pixel would be only the ones emitted from the source
that managed to strike the pixel directly. The same as a pinhole camera.

The thing about a lens it is lets you grab a relatively huge area of light and
sort it all out so the right bits go to the right pixels.

I already did arithmetic once today (erroneously as it has transpired), so
I'll pass on this, but although a metric dumptruck load of photons fly off ov
things, when you are 10 meters away, and have an image element the size of a
CMOS pixel, there aren't a lot of photons per second to let you sort out 256
levels of intensity without random noise.

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th0ma5
Anyone play with a pinhole on a CCD or CMOS sensor, or otherwise "no" lens?
For a non-lens-distorted picture?

~~~
vladoh
As far as I know the problem is that the amount of light that goes trough the
hole is very low and you cannot see much or you need a very strong light
source.

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Sharlin
Or you have to expose for a long time.

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Luc
Or use more than one pinhole... E.g. <http://pinhole.stanford.edu/zp.html>

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mrich
As a myopic geek I am looking forward to ultra flat glasses :)

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danvk
Will this be useful for Astronomy?

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wamatt
One word: Cellphones

