
Graphene optical lens 200 nm thick breaks the diffraction limit - srikar
http://www.swinburne.edu.au/news/latest-news/2016/01/focus-on-results.php
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ChuckMcM
Link to the paper:
[http://www.nature.com/ncomms/2015/150922/ncomms9433/pdf/ncom...](http://www.nature.com/ncomms/2015/150922/ncomms9433/pdf/ncomms9433.pdf)

This is an excellent result. It could also provide an interest boost to solar
in terms of $/watt by focusing more light into a small area. Fun times.

~~~
dogma1138
> It could also provide an interest boost to solar in terms of $/watt by
> focusing more light into a small area. Fun times.

I can't find a single use of this for solar based on the specifications of the
lens in the paper. Also photovoltaic really doesn't need focusing it doesn't
give you anything because eventually the amount of power you get per surface
area is the same so it doesn't matter if you cover a 50 sq/m area with a lens
and focus it on a 5 sq/m cell or have a 50 sq/m cell to begin with, also
considering that photovoltaic cell efficiency drops with temperature you
really don't want to focus any light on them as it will tank your power
production.

Thermal solar does need focusing but mirrors will actually work better than
this for that application as well because you need to reflect the light to a
central location anyhow an a collection mirror does both at the same time.

~~~
TTPrograms
See
[https://en.wikipedia.org/wiki/Concentrator_photovoltaics](https://en.wikipedia.org/wiki/Concentrator_photovoltaics)

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JumpCrisscross
It seems like every month brings a new "miracle" application for graphene. Are
these breakthroughs as surprising for the experts as they are for the
layperson? If not, what fundamental properties would allow one to extrapolate
its applications?

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biomcgary
A molecular scale Fresnel lens! Now we can create retro style nano-projectors,
even if the transparency will be thicker than the lens.

~~~
tgb
Is it really a Fresnel lens? I was thinking it was more of a diffraction
grating. The paper describes it as

> The 3D focusing is a result of the interferences of wavelets originated in
> the lens plane from different zones19, as illustrated in Fig. 1d.

Which suggests it's more about interference than about Snell's law.

~~~
frozenport
Things with rings are generally called Fresnel lenses, even if its not about
interference, see:

[https://en.wikipedia.org/wiki/Zone_plate](https://en.wikipedia.org/wiki/Zone_plate)

~~~
dTal
Fresnel zone plate, yes. Fresnel lens, no; they are not lenses.

This does look like a microscopic zone plate. This is not a new idea though,
it's how we focus X-rays as most materials don't refract X-rays very well; I
guess they just managed to make a really small one. I wonder in what sense it
"breaks the diffraction limit".

~~~
crispyambulance
It does not "break" the diffraction limit. The title is inaccurate. The actual
paper doesn't say they've broken the diffraction limit. They only achieve a
subwavelength focal point.

I'll make an attempt to mansplain this...

The actual diffraction limit depends on wavelength (lamda) and the numerical
aperture (NA) of the lens. Diffraction limit is ~ lamda/(2*NA).

In traditional objective lenses used in confocal scanning microscopes, the
diffraction limit has been ~0.5 microns. If you increase NA, it also means
decreasing working distance-- to the point where the focal point meets the
surface of the lens.

They've managed to increase NA with their zone plate, but since their "lens"
thickness is "200 nm", they still have a useable working distance.

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Eridrus
Would this also allow visible light microscopes to zoom in further than they
currently can?

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sandworm101
What is the operating temperature of such lenses? Is this one of those magic
devices that only exists near absolute zero?

I assume these can be built into sheets to focus light onto masks. No doubt
intel might be interested.

~~~
bcraven
"Just over two years ago, PhD student at Swinburne’s Centre for Micro-
Photonics, Xiaorui Zheng, tried fashioning a lens using graphene oxide — a
variation of the super-strong, atom-thick carbon material, graphene. The team,
led by Associate Professor Baohua Jia, developed a three-dimensional printer
that could quickly and cheaply produce the lens using a sprayable graphene
oxide solution. Lasers were used to precisely pattern the surface, creating
three concentric rings of reduced graphene oxide, which enabled its
extraordinary focus"

No I think it's purely geometrical.

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zwu
imaging if the lens being used for the light field display, could be another
solution for a mixed reality display device that the Magic Leap is developing.

~~~
soylentcola
Even more "traditional" VR/AR devices would benefit from techniques to make
thinner lenses. Advances in optical engineering will have as big a part to
play in that sort of thing as processing power and faster chips.

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huxley
I find the "billionth of a metre thick" phrasing painful, but I guess it's
better than if they'd written that it was "a trillionth of a kilometre thick"

~~~
Florin_Andrei
BTW, it's not even 1 billionth of a metre thick. It's 200 nm. That's 0.2
microns. That's 2 * 10^-7. It's 0.2 of a millionth.

They should have just said 0.2 microns instead. It carries just as much actual
meaning for the layperson, and it's a lot easier to parse if you are
scientifically literate.

~~~
nitid_name
I thought convention in SI units was to drop down a level when at less than 1
of a unit..?

~~~
lytfyre
A pretty common approach (at least in Canada) is to use prefixes at intervals
of 1000 - mm, m, km and then larger unit to one decimal for large values -
700m as 0.7km, 0.9l instead on 900ml, and so-on.

you'll rarely see cl, dg, or hm used here.

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theandrewbailey
> It’s early days, but the new technology has the potential to reduce the size
> and weight of mobile phones in which cameras are currently dependent on
> thick and heavy lenses.

Maybe by comparison to this, but hardly anyone cares about the size or weight
of their phone camera lens.

~~~
hanief
Counter example: the protruding camera bump on iPhone 6/6S.

~~~
Cthulhu_
I like to think that's more due to the total thickness of the camera unit, not
so much the lens. That, or the required distance between the lens and sensor.
Either way, it's a bad design decision, one they're embarrassed of themselves
(it's edited out on sideways images of the device on apple's website)

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gavman
My apartment mate (currently a PhD student in Chemistry) noted that the
research is cool, but article this is based on in Nature Communications is pay
to publish, so err on the side of skepticism.

A quick Google search found this:

[http://www.the-
scientist.com/?articles.view/articleNo/41072/...](http://www.the-
scientist.com/?articles.view/articleNo/41072/title/Nature-Communications-Goes-
OA/)

"At present, researchers can choose an open-access option when submitting a
manuscript to the journal, selecting one of three publishing licenses:
Creative Commons Attribution 3.0 Unported (CC BY), the more restrictive
Creative Commons Attribution-NonCommercial-No Derivs 3.0 Unported (CC BY-NC-
ND), or Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA).
Authors pay a fee of $5,200 to publish a study under a CC BY license, and
$4,800 for each of the other two... Update (September 23): After this article
was published, Nature Publishing Group's Amy Bourke responded to The
Scientist, noting the flat article processing charge (APC) to publish in
Nature Communications: $5,200"

Edit: other users seem to note that the journal is very reputable. I do not
know myself, was reporting my apartment mate's reaction since he is much more
knowledgeable in the area. It is clear from conversation I mis-understood his
response. Apologies.

~~~
hiddencost
Uhm, Nature Communications is a subjournal of Nature Publishing Group. There
is literally no more reputable publishing group. None. Nature, their flagship
journal, is the highest impact factor journal in the world.

~~~
scott_s
I upvoted you, but I want to add text in agreement since such upvotes can't be
seen as an endorsement. gavman's warning about the reputation of the venue is
unwarranted.

~~~
gavman
I talked to my apartment mate about it. He said that when he showed the
article to his advisor, she had the reaction of "they're pay to publish". I
can't speak to the reputability of the journal, just providing his response.

~~~
hiddencost
EDIT: sounds like a misunderstanding more than anything.

Here's [0] a link to the rankings of nature journals. Nature Communications is
3rd in general science, and Nature is 1st.

Tim Gowers and the freedom of knowledge group are pushing hard on journal
fees.

[0][http://www.nature.com/npg_/company_info/impact_factors.html](http://www.nature.com/npg_/company_info/impact_factors.html)

Old post :

I can speak to the reputability of your friend's program. The statement is jaw
dropping. It is so wrong as to make it hard for me to believe he goes to an
accredited university.

~~~
gavman
As I said in a comment below, he's at a top tier program (CMU), so it's likely
I didn't understand his adverse reaction. You mention below his/his advisor's
adverse reaction may be about "a movement to move to no cost journals", not
about reputation. When I see him tonight I'll ask.

