From Sun to Fiberobtics

[schabiazabi]

Can someone explain me in simple terms how to collect sun using a mirror and send the light into fiberobtic cable?

I understand the sun collection idea, but I have no idea how to "send" the light from the mirror into the cable.

Thanks in advance.

[john_g]

Looks like this company do it, look at the solarpoint devices - not sure if they give an explanation of how it works, but may give you some ideas.

Brighten Your Home - Hybrid Solar Lighting

[dR-Green]

I would imagine that you use a parabolic lens to focus the light to a point, and then put the "input" end of the fibre optic cable at that point to collect it. I'm not sure if there are any special requirements for this, because that point will get pretty hot and could melt things that you don't want melted. But I think that's the basic principle of it.

[schabiazabi]

I would imagine that you use a parabolic lens to focus the light to a point, and then put the "input" end of the fibre optic cable at that point to collect it.

I agree with this and this is what I thought, but this is a limitation for me as I want the wire to be very wide (10 inch and up to 24inch). That would me the bottom of the bigger dish has a 24 inch whole.

That's why I'm asking if there is device that will allow me to have a narrow whole in the dish, but carry "tons" of light into the wider cable.

[dR-Green]

I agree with this and this is what I thought, but this is a limitation for me as I want the wire to be very wide (10 inch and up to 24inch). That would me the bottom of the bigger dish has a 24 inch whole.

That's why I'm asking if there is device that will allow me to have a narrow whole in the dish, but carry "tons" of light into the wider cable.

That would just be a matter of focus. Instead of using a lens that focuses it to 1mm spot at 6 inches distance for example, you can use a lens that focuses it to 10 inches spot. I would think that if you go to a parabolic reflector manufacturer they should have all these options available or at least know what you're talking about because it's all basic lens design principles.

Parabolic reflector - Wikipedia, the free encyclopedia

Lens (optics) - Wikipedia, the free encyclopedia

[edit] I don't know if any of these programs would be useful here, I suppose it depends whether or not they let you put a reflective coating on the lens

Engineering Calculations

OSN: WinLens3D Basic - free lens design software - optical design, zoom, raytrace, lens, prism, mirror, aspherics, tilt & decenter, solid model, autofocus, glass map, gaussian beam

dbOptic FREE Optics Software Download

[schabiazabi]

^ I'm sorry, I was not clear enough. The lens size is not the problem. Let's say my "last" small lens (right before the light goes into the fiber optic cable) is going to be 6inch wide. This lens focuses the light into my 6inch wide cable. So far so good. The problem starts when I increase the width of my cable.

When the width of my cable grows to 12" wide, the lens would have to grow and the big dish would have to grow in order to have the same amount of light (by proportion) at the wider cable.

So my question is: is there a device that can take the x amount of light from the 6 inch lens, pass it through a small "whole" (another device), and shine the light on my 12 inch wide cable without losing the original amount of light (x).

To put it another way: Big amount of light --> through a small whole ---> into a wide fiber optic cable. Wide --> narrow --> wide (with no, or minimal loss of light).

I'm very new to this, but it is something that interests me a lot.

Here is a picture of someone doing something like this, but it's hard to tell what happens after the last lens.
http://www.brightenyourhome.net/0_0_...g?u=1995394991

The device (pipe) that captures the light is small. Is that enough to capture a lot of light? Hard to tell. There is very little information out there.
From the picture it does not look like there is fiber optic cable sticking out there through the pipe.

In the link above this is what is says: "The technology concentrates natural sunlight into a small bundle of optical fibers that "pipe" sunlight directly into a building or enclosure.

Special lighting fixtures called hybrid luminaires diffuse light throughout the space, delivering up to 25,000 peak lumens. "

There is no way to light up a building from such a small (narrow) fiber optic. There must be something in between.

[dR-Green]

The device (pipe) that captures the light is small. Is that enough to capture a lot of light?

A lens doesn't produce more light out than what's coming in, it just focuses what light there is coming in to it to a particular point, known as the focal point. The focal point is where the light will be the most intense, because all the light that's entering the lens is being focused to that point. If you move the lens and increase the size of the point of light you're looking at, then there is still the same amount of light falling on any given area, it's just not as intense as it was because now it's being scattered over a wider area. But there is still the same amount of light there, because it's still whatever is coming into the lens in the first place. If you want to focus more light into that same sized area then you need a bigger lens to collect more light.

So my question is: is there a device that can take the x amount of light from the 6 inch lens, pass it through a small "whole" (another device), and shine the light on my 12 inch wide cable without losing the original amount of light (x).

Sounds like you need a plano-convex reflector to widen the beam over a 12 inch area. Dunno how you'd get this to work efficiently with a dish arrangement though, unless you put loads of smaller fibre optic cables around the outside edge of the big dish and then use the plano-convex reflector to reflect it to the outside of the dish Doesn't seem the ideal solution, probably better and easier to just get bigger lenses.

http://upload.wikimedia.org/wikipedia/commons/a/a7/Lenses_en.svg

[QuarterPole]

Wolfram Alpha says that 25k lumens is "1.3 × luminous flux of a typical cinema movie projector"
Consider the size of one cell in a movie reel. Consider the size of the movie screen, and how much light the projector puts into the theatre. Consider, from Wikipedia, this: "Bright sunlight provides illuminance of approximately 100,000 lux or lumens per square meter at the Earth's surface."
Can one collect and reflect and refract the light of 1/4 of a square meter into the size of a postage stamp? I think so, but it's gonna be hot!.
In answer to your question, though. Yes, if the focus distance is 'n', then at 2n from the lens, your 'spot' is back to lens sized (and upside down), and at 3n, you are twice lens-sized, however, your light 'x' is now spread over 4 times the area.
A 12 inch bundle is a _huge_ amount of fiber.
I think you are right in saying "no way". Fibre is mood lighting at best, I think. Ever see one of those shrubby looking lamps?

[Kokomoj0]

you can use an optical collimator as your input alignment device. If you put it into the 12" then want to go to a 6" (which is 4 times smaller area), then you use a lens after the output or another collimator to bring it back down to 6 inches.

Wider to smaller or 12" to 6" after exit would be best for heat considerations

[dR-Green]

In answer to your question, though. Yes, if the focus distance is 'n', then at 2n from the lens, your 'spot' is back to lens sized (and upside down), and at 3n, you are twice lens-sized, however, your light 'x' is now spread over 4 times the area.

Yes but how would you get that to work with this kind of arrangement

http://www.brightenyourhome.net/0_0_0_0_224_153_csupload_28742700_large.png?u=1995394991

Because as you increase the distance of the small lens to the cable then you're going away from what's coming in from the big lens, so you'd also have to increase the size of the small lens to make up for that. And in the end with such a big cable and small (or "big") lenses you'd end up blocking all light in the first place. So I think it all should be built to proportion to begin with. Assuming that's the design schabiazabi is going for/working with.

[QuarterPole]

This is... a difficult arrangement. That dish has to be aimed, for one thing.
"It all should be built to proportion to begin with."
Yes.
The focus point is somewhere inside the white tube. The bundle of fiber, or a lens to bring the rays back to parallel, is as close as possible to the focus point, with the temperature limit, or I suppose the, uh, maximum light load (???) of the fiber/lens being the limiting factor, and the cost of fiber being the reason for staying near the limit.
If I happened to have a double reflector rig and a bundle of fiber laying around, I think I would find it easier to move the fiber than either of the reflectors. As you say, one cannot just move them, or they go out of focus.
So if you wanted to put lots of fibers so you could spread the light around in the building, you would move the fiber ends away from the focus point, to whatever distance made them fit. For the given example, 6 inch lens to 12 inch bundle, that point would be twice as far from the focus as the lens is. The hole, the narrow bit, could be quite small if it was at the focus.
In the photo example, this point would be way down below the dish, outside of the frame.
So, dR-Green, to answer your question... I wouldn't. I would have to do the math on how much sunshine a given fiber can handle, and then divide my total collector area up to see how many fibers I need, and just place them accordingly. I would mirror coat the inside of my white tube, too, so it wouldn't have to be perfect. Really, though, "I" would be forced to start with a cobble job, like gluing broken mirror bits to a satellite dish, "Solar Death Ray" style, and then running the fibers out to where the horn should be.
This is starting to sound like fun.