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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.
So, when (and where) can I pick up my almost free night vision goggles?
They're already here (kinda). Binoculars (with large lenses) collect more light than the unaided human eye and can serve to amplify the light- you just need to find binoculars that have large lenses and low magnification. This works especially well in low light (dusk, not dark) situations.
A cluster of these fibres could be formed together to form a panel. This could be fed a light source from a few white LEDs that could form large panels of white light fitted flush to ceilings or walls. With clever "fibre plumbing" entire walls could give off cool white light, and could be switched to pull daylight deep into a room from outside. Also, imagine the possibilities of large light strips covering the front of cars, powered cheaply by LEDs...
Now wash your hands.
So... I'm thinking the biggest breakthrough here will be for indoor marijuana growers, who will no longer have to consume suspiciously large amounts of electricity in order to nourish their kind bud?
"The best we can hope for concerning the people at large is that they be properly armed." - Alexander Hamilton
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.
The man who does not read good books has no advantage over the man who cannot read them. - Mark Twain
They've had shotgun sights that use this principle on the market for several years now. You have an inch-long stick of fiber mounted along the end of the barrel that collects light and channels it towards the shooter's eye. They work pretty well, but they can be fragile.
At any rate, this is nothing new.
Jon
All opinions expressed herein are my own, and not those of my employers, who are appalled.
A well conditioned human can pedal at about 45 watts for 2-3 hours, 30 for a long time, and 60 for 30 minute bursts.
So, the human powered option is out for many applications.
The fibers *MAY* have applications in solar systems. What kills the cells is heat buildup more than anything else, and the concentrator *MIGHT* not allow infra-red to pass, but allow the other parts of the bandwidth to pass.
A company called (methinks) marathon solor used to have a light conentration system for its cells to boost output. Such a method is economical *IF* the cells are expensive and the fiber is cheap. (oh, and they are now bankrupt)
Given that you can now buy solar cells as shingles to go on your roof, I have to question if the economics are right to use fiber concentration on silicon cells.
Home power is a nice place for figuring out how to get off the grid, and this gent thinks the future for cheap solar is heliostats. Combine a heliostat with a helium-as-working-fluid sterling cycle prime mover, and you may just have a winner!
If it was said on slashdot, it MUST be true!
Hang on, if it needs ambient light to operate but creates 30xambient - you've got an infinite power source. Each light will create enough light to power 29 of its fellows which could then power your computer system (okay, might need a few more than 30 but..). Continually environmentally friendly power source for the cost of a few bulbs...
Richy C.
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I've yet to see anything that says how long it has to be to pick up enough light. If it's short, then great. If it's 1m or so, it's hardly practical as a screen or goggles!
I've a feeling that this may also be fundamentally limited by the amount of light around. 30 x 0 is still 0, so for night work, you may need some more severe amplification.
Grab.
This is very interesting: because the fibers collect ambient light, the screens will get brighter if there is more ambient light. This is very useful if you are sitting in an environment where the light-intensity changes a lot (for example: sitting in a train in bright sunlight, and then the train goes into a tunnel)
This would solve a lot of my problems with my TFT-screen.
you don't need current to have the voltage; for a system like an LCD that is like a capacitor, you only need a current to change the voltage.
... that's why current LCD displays get such good battery life when used in devices.
switching the voltage on liquid crystals requires a lot less power than backlighting
-------------------- the list is long. dirac angestung gesept
Interestingly, the blue Nichias has quite a lot of UV output, which can be used for blacklight applications with a filter.
Unfiltered CCD cameras hate the blue Nichia light, probably because of the UV stuff. They think the (rather pretty) deep blue light is tinted magenta or cyan.
"So, if these fibres take in light and output it 30x brighter, why not make a feedback loop?"
It's a great idea, but the problem is that you're getting more energy out of the system than you put in. Energy efficiency doesn't go over 100%, so either these phosphors have energy hidden in them (and they'll run out over time, like batteries), or this system collects a lot of ambient light and concentrates it into a small space.
Does my bum look big in this?
Never mind...
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Vote Homer Simpson for President!
But it doesn't say how long each fibre needs to be to produce its two dots of light. I assume that (up to a point) as you increase the lenght of the fibre, the ends get brighter. So for 30x ambient do you need a 1 meter fibre? 5 meters? 100 meters?
Let's see if we can find some real linkage...
If you're not wasted, the day is.
If you're not wasted, the day is.
uh, no. a voltage is just a potential difference between two points, this can even be just electrical charge. No flow of current has to be taking place, of course voltage is not just something which flows, it is the means which can cause a current, or transfer of charge. In short, yes you can have a voltage (potential difference of charge) with no current flowing. How the fuck do u think lightning works? Or capacitors for that matter?(especially parallel plate ones) do E-fields suddenly not exist?
Malike Bamiyi wanted my assistance.
As I recall, there is a small transient current during switching (basically, it's like charging a capacitor), but practically no continuous current draw. That's why LCDs are low in power.
--Joe--
Wanna program the Intellivision? Get an Intellicart!
Program Intellivision!
Yeah, the article is about using ambient light; but if you add an efficient light source, all you're talking about is adding a known and reliable *source* for the ambient light. For instance (to be arbitrary) if you were exploring a deep cave and wanted to read all the email you had recently downloaded as a tarball from your server ala RMS, what would you do? Or if you were in a dark bedroom, truly truly dark?
... you get a warm glow and read away.
...)
If there's no ambient light to be had (and you don't want to waste your high-power flashlight, which creates a strong beam using lots of battery juice), you switch on the small bank of LEDs (or are there even more efficient light sources? I don't want to drop in cyalume sticks all the time;) )which fit in your portable computer analogous to the backlight in a normal notebook
What I wonder is how long a fiber has to be, and in what configuration, to capture enough light to be useful (For instance, will it collect efficiently if a good portion is coiled? That would seem important in a space-saving screen
Also, what is the tightest resolution that could be achieved with these little dots? Lite-bright? 15" SXGA?
The article doesn't really address those issues, unfortunately.
simon
"Hey Carlito, r'membah me? Benny Blanco from the Bronx!"
And I thought blue ones were expensive...
...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.
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Give me LIBERTY, or give me a check.