Displays That Harvest Light Instead Of Creating It

mach10 writes: "An article here shows that a scientist has been able to create fibers that collect ambient light, strong enough to power a dotted matrix for display. It can reach 30 times ambient light, and they are soon hoping to expand the area to replace signs on roads. Hrm ... But my sundial watch still doesn't work in the dark =\" Add this to some ultra-efficient light source (like white LEDs?), a low-power processor, human power and some solar cells, and most of my requirements for portable computing happiness would be met.

Comments

Only need a few cm, works under any light level

[The Fun Guy]

My physics-major college roommate used fluorescing glass fibers in a project at Fermilab, and he brought some back home to play with. They were maybe 25cm (~10 inches) long, and very narrow, similar to fishing line. When exposed to light perpendicular to its length, a surprisingly bright purple light came out of both ends; the brighter the incident light, the brighter the flashlight-type dot of light that came out of the end. If you covered up part of the fiber, light still came out the end, just dimmer. The longer the fiber exposed to the light, the brighter the dot. We tried this with incandecent and fluorescent bulbs, bright sunlight, dim sunlight, candlelight, flashlights of various brightness, any light source we could lay our hands on. The only thing that changed was the intensity of the glowing dot.

A similar technique is used in light-gathering spotting sights. These are popular with bowhunters, and are essentially a rod of fluorescing plastic (~5cm long, ~0.5cm in diam) that you mount on your bow to help you sight on the target. The end is tapered and set at a right angle such that the incident light that hits the side of the rod makes the tapered little point (~0.2cm in diam) glow really brightly. Based on my rough estimates of the dimensions, I'd say that the area of the side of the rod (capturing incident light) is ~100X the size of the glowing tip. As with the narrow fibers, it works under any light level except complete blackness, and remember, under very dim conditions, even a faintly glowing dot looks bright.

I can't help it,

[FreeJack1]

but after reading the article and especially observing the image alongside it, I have to say that I'm impressed that the scientists have finally discovered a Lite-Brite toy! What is it that they're hoping to accomplish with it, besides drawing pretty and colorful pictures?
Never mind...
--

Vote Homer Simpson for President!

Re:3000% energy efficiency

[malahoo]

No, it works like this:

1. Lots of free, ambient light hits the fiber
2. Some of the energy in this light causes the fiber to flouresce
3. The light produced by this flourescence is channeled to and focused on the ends of the fiber.

You're not violating Thermo, because the input energy is not amplified by 30x, it is being transduced, with considerable inefficency, and sharply focused.


If you're not wasted, the day is.

Not a power source

[KarmaBlackballed]

...Add this to some ultra-efficient light source...
Some folks are misunderstanding the principle here. These fibers are collecting ambient light, not amplifying it. Like all things in the physical world, there is a power loss through the fiber, so you are not getting something for nothing.

Think of this invention as analogous to a rain gutter where light is the water and the gutter is the optical fiber. When it rains, water is "collected" along the length of plumbing that edges the roof. No extra water is created, but the volume of water at the end of the pipe is an amplification of what would have been there without the gutters.

The innovation here is that no one has created a fiber that easily collected ambient light along its length before. The only other way I know of to focus ambient light is to use mirrors or lenses. Clearly the fiber sounds cheaper, less bulky, and less fragile.