Solar projector?

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Has anyone done any work toward using a solar light source in place of an electric one?

I mean using some kind of focused beam of sunlight channled into a projector? It sounds nuts I know but just think about it for a few seconds.

Maybe a fiber optic strand that has a large collector lens (larger than an OHP lens perhaps) that focuses sunlight into one end of it, and emmits it where the light source would be in a DIY PJ, or even in a commercial one for that matter. Could a fiber-optic strand do something like that?

Thoughts? Links to info about such a project?

Sorry, I couldnt sleep cause this popped into my head, and rather than lay there and listen to the crickets, well here I am. :eek:


C.
 
addendum to the record: Polishing the bottom of a "coke" can will yield a reflector that will ignite flammable materiel at its focal point, somewhere 1-2 inches from the center. Polish with chocolate and a rag, as the article I read instructs.

Of course, if you have both chocolates and cokes, and don't have any way to start a fire, you are likely in America and can walk to the nearest civilisation or road and be in good shape pretty quick! :D
 
Ok, well I got a few more thoughts on this crazy concept. but first to answer the "Why solar?" question. Why solar anything? Because sunlight is free and very powerfull.

But what is considered desirable in a PJ light source?

Full spectrum white light?
Pinpoint source?
High intensity?
Low power draw?
Not too hot?

Ok well full spectrum is covered with the sun. No problem there.
Hard to find anything as bright, so intensity is covered too.
Not much is cheaper than solar.

Now as for the light being too hot. I dont know anything about fibre optic cable but doctors put cutting laser light through it so I assume it will handle some focused sunlight, even if you have to filter out most of the UV and IR before the collector condenses it to the fiber opening. In effect, stepping down the heat before it gets to the collection end of the cable.

As for putting too much light on the LCD I imagin the collector lens could be focused depending on how much light needed to be used.

I saw a Camera Obscura that made me think of this. Solar projection isnt unheard of.

Will fiber optic cable put out a usable dot of light though, one that can substitute for an electric arc etc.?

ps. thanks for replying to my delerium

C.
 
In the early days of photography, solar enlargers were not uncommon. In many cases, the setup consisted simply of the camera fitted against a hole in the wall.
For 'entertainment' projection, the intensity would have to be higher of course, requiring some sort of condenser system. As long as it's properly designed to spread the light cone over the LCD surface, I don't think fire is much of a risk, but some sort of IR filtering would be sensible, and a UV filter would be essential.
 

ace3000_1

diyAudio Member
2003-03-10 5:16 pm
spain
I dont know anything about fibre optic cable but doctors put cutting laser light through it so I assume it will handle some focused sunlight,

Totally different. Laser isnt actually light, is a different form of energy, thats why its not in the light spectrum chart :bigeyes: and would behave very differently then light in a fiber optic cable.


But what is considered desirable in a PJ light source?

Full spectrum white light?
Pinpoint source?
High intensity?
Low power draw?
Not too hot?

I'll give you another, a light sorce that dont move!!! ;)

After you build a motorised Equateral mount to track the sun, i dont think you light source is going to be so cheap anymore.

As for the heat, it would be more effective if you wer to filter the incoming light before you intensified it rather then the otherway round, same goes with the UV, otherwise you will be lucky to find a filter to hold upto these conditions, and a filter of a large size wont be cheap also.

Trev:)
 
Laser isnt actually light, is a different form of energy, thats why its not in the light spectrum chart

Who told you that? Laser is indeed light, thats what the "L" stands for. Laser is simply light in which all the photons move in the same direction.

A tracker is pretty simple to build, hell a converted telescope mount could do the job. People build stuff like this as well for DIY astromomy. That is just simple mechanics, I didnt even think that was worth mentioning, of course the earths rotation is a design consideration, but its not rocket science.

As for cheap, how much does it cost to buy a typical DIY PJ source, along with its required electric system (transformers etc)? keep in mind that cost of operation is not an issue, nor replacement cost for burned out bulbs.

Not trying to be negative here, but you would have a hard time cooling down focused sunlight, then you would have the UV aswell.

I can see that you arent trying to be negeative Ace, hehehe it seems to be effortless for you so far ;) JK.

The way I see it in my head, the sunlight would be filtered before the fresnel lens condenses it to a point where it enters the fiber optic cable. It would go like this... IR/UVFilter-Lens-F.O.Cable-LCD-Projection lens-Screen

Anyway, this is just a thought excercise. I dont imagin its the best, easiest, cheapest, etc. I was just wondering what you experts might have to say about this old ensomniac's goofy idea.

Thanks for humoring me guys.

C.
 

ace3000_1

diyAudio Member
2003-03-10 5:16 pm
spain
Laser = l(ight) a(mplification by) s(timulated) e(mission of) r(adiation)

Lasers are totally diff then normal light, i can asure you. Sure they projuce visible light, but their bandwith is somewhat diff to the standard light table, (the reason why they arent on it) and thats why im saying its different to normal light. They are a coherent electromagnetic field, which when designed to projuce visible light they can only projuce a single freq of light (typical of 3mhz), not a wide spectrum like a normal bulb.

I can see that you arent trying to be negeative Ace, hehehe it seems to be effortless for you so far JK.

LOL, im just pointing out the issues you will encounter along the way, besides, someone has to do it!!!:D

A tracker is pretty simple to build, hell a converted telescope mount could do the job. People build stuff like this as well for DIY astromomy. That is just simple mechanics, I didnt even think that was worth mentioning, of course the earths rotation is a design consideration, but its not rocket science.

Yeah thats true, but im focusing on costs here, its still not free :)

As for cheap, how much does it cost to buy a typical DIY
PJ source, along with its required electric system (transformers etc)? keep in mind that cost of operation is not an issue, nor replacement cost for burned out bulbs.

For me cheap (150w), but i agree, with others using the 400watters the power and maintenence aint cheap.

The way I see it in my head, the sunlight would be filtered before the fresnel lens condenses it to a point where it enters the fiber optic cable. It would go like this... IR/UVFilter-Lens-F.O.Cable-LCD-Projection lens-Screen

Thats the way id do it, atleast thats the saine way :D

Trev:)
 

Gizmotech

Member
2005-03-27 12:26 pm
Well if you hold a projection lens to and near a white wall opposite your window (with the window open), you can project the outside image upside down and inverted on the wall.

So I think it could be possible and without any evidence or experiment, I don't think it is fair to critisise this idea.
 
Hi, this is my first post here, but I've been lurking about the forums for a while now. I just thought that no one commented on using Capain Black's idea for commercial projectors, but instead of using sunlight, using regular bulbs that are used in diy projectors. It would fix the problem that they have of not being able to fit the bulb directly in the projector and also keep the heat source away from it by being able to build a seperate box with fans, lighting and lenses and then channeling it to the commercial projector. I don't know if no one said this because it's a bad idea, or if fiber optic cable is too expensive to make it practical, but it was just my 2 cents.

Anyway, back to lurking....
 
It's just not a practical idea.

1. Tracking the sun is more complicated and expensive than you think. Not only is there the motorization and accurate timing of a very large collector, but there is a certain amount of complicated optics tricks in order to maintain a constant focal point and angle of the light output during different portions of the rotation. It would have to remain exactly the same and converge the light to exactly the same point at all times.

2. Even at full brightness, the sun isn't really up to the task. If you have a 400W MH bulb shining onto a white surface from a few inches away, you can't look at the surface. If the sun is shining onto a white surface, you can look at it as much as you care to. Sunlight shining on a wall might look bright enough, but remember that the LCD will block most of the light. In order to achieve the same brightness, you'd have to use a collector several times larger than your projected image. In order to get the same brightness as a metal-halide bulb, you'd need a collector something like the same or half the size of the projected image.

3. I don't know about you, but I and most other people get home and start our free time when the sun is close to the horizon. Very few people have a completely unobstructed view of the horizon. There's always a tree, or another house, or something. Plus I'm not in the mood to get home and immediately watch a movie. Maybe I'd like to relax, have dinner, then start up a movie and watch it in the late evening. I'd have virtually zero use for a projector during the day.

4. Clouds.
 
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