back to article Fireflies donate gut feelings to LED research

Structures that help fireflies produce bright light from their abdominal lanterns have been mimicked in the lab to increase the efficiency of LEDs. In their Optical Express article, the researchers explain that the jagged structures they found on the Photuris Lampyridae firefly enhanced the glow of their lanterns. By creating an …

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Devil

Ever see a Fresnel Lens?

The "jagged structure" looks like a form of a fresnel lens which was used in lighthouses to make kerosene lanterns much brighter.

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Boffin

Re: Ever see a Fresnel Lens?

But a Fresnel Lens is just a normal lens with as much of the 'useless' middle bit removed as possible. [useless because the bending of light you want a lens to do happens at the air/glass interface] The distortions that the 'steps' create mean it's only useful for focusing homogeneous light rather than, say, images.

This is aiming to reduce reflaction, which I would think was almost the opposite effect (except that I can't tell from the Reg article if that's how it works)

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Pint

reflaction

I seem to have invented a new word. I meant refraction (assuming that the "reflection" in the article is caused by total internal refraction.... (if it isn't then I meant relection, of course... :-) )

Beer icon because I clearly need one.

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Pint

"relection" ?

Have another beer from me, as one was clearly not enough ;-)

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Devil

Re: Ever see a Fresnel Lens?

Two downvotes? Really? Look at the structure in the picture in picture b & c and then look at the lens cross section in the Wiki article http://en.wikipedia.org/wiki/Fresnel_lens

and tell me I'm wrong. What came first the Fresnel lens or nature "bioengineering" a method to amplify/concentrate light (more light means fireflies have more mating opprotunities) and still allow the insect to fly because the Fresnel design cuts 50% of the weight (and reduces internal reflections)?

Whoever downvoted me has the observational skills of a doorknob and the intelligence of a gnat.

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Thumb Up

Re: Ever see a Fresnel Lens?

Have an up-vote from me. However, I think the main thing about a Fresnel lens is that it works by reflection, rather than refraction. That's how you can have those plastic stick-on lenses in the rear window of a people carrier or other such vehicles.

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Re: Ever see a Fresnel Lens?

"it works by reflection, rather than refraction."

No, it is certainly a refractive device. Essentially it's just a regular lens with the thickness cut out. If you take a normal round plano-convex lens and slice it into thin round sheets then bore a hole in each slice such that the next smaller slice fits inside it you will have made a Fresnel lens. This gets rid of a lot of weight and I imagine if one is going to walk a lens to the top of a lighthouse it makes sense to use a lightweight lens (ouch).

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I dunno about the lenses

I rather like the idea of tame fireflies as indicators!

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Coat

Re: I dunno about the lenses

Don't get too excited, it'll no doubt get cancelled after just one series...

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Coat

I think...

..the first generation of firefly inspired LEDs may be a little buggy...

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Sems to be an optical impedance matching layer ffor optical devices

The claim is not that it's novel.

It's that it can be retrofitted to existing devices and 55% improvement is IMHO very impressive.

Which is good.

What would be interesting is to know how this differs from the random pyramids etched into single crystal solar cells to improve absorption of light rather than emission as the goal (improved coupling between the hardware and its surrounding environment) is pretty much the same.

Thumbs up for building it, not simulating it.

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Re: Sems to be an optical impedance matching layer ffor optical devices

Hopefully it can be used for solar cells (they could really use a boost), but just being able to improve lighting efficiency alone is brilliant (bad pun). I have 5W LEDs in the kitchen that replaced 50W halogens. If they could be 3.5W instead, there's a saving. It's not big, but it looks like the cost implication will be minimal, and saving energy is saving energy.

And what about other devices? Can this be used to lower the power consumption of LCD monitors by increasing the efficiency of the backlight? Can it be used to make plasma screens more efficient? Perhaps there's some peculiarity that restricts it to LEDs, but it's worth considering.

Very interesting - I like this.

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Re: Sems to be an optical impedance matching layer ffor optical devices

Reading the paper the gallium nitride has a high refractive index, similar to that of diamond, and therefore has a low critical angle of 23 degrees. That means any light coming to the surface at an angle greater than 23 degrees from the normal is reflected internally. In general it doesn't work the other way around but I could see where if a solar cell has a similar refractive index the pyramids may allow the light into the solar cells and any light reflected back up toward the surface has a better chance of being reflected back inside the cell rather than just leaving as it came in. Sort of like an internal retroreflector or a light trap if you will. Very cool stuff indeed.

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Re: Sems to be an optical impedance matching layer ffor optical devices

" In general it doesn't work the other way around but I could see where if a solar cell has a similar refractive index the pyramids may allow the light into the solar cells and any light reflected back up toward the surface has a better chance of being reflected back inside the cell rather than just leaving as it came in. Sort of like an internal retroreflector or a light trap if you will. Very cool stuff indeed."

This was pretty much why the technique was developed. One of the benefits was it was designed to not need a photographic process (it's a random etching process).

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Coat

Finally...

A possible way to implement RFC1217 encryption?

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