# Can We Store Light?

Discussion in 'Other Engineering Trades' started by Issue, Apr 22, 2012.

### IssueStar

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When we generate electricity from sun light, some of the light escapes. Even so, can we have something to store light?

Please take into account, I am talking about storing light and not generating light.

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Light is just a form of energy. It's everywhere around us, stored perpetually in other forms. We just want to convert it into light energy whenever we need it.
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### IssueStar

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What you are talking about is solar panels. Where we

2. Convert it into Electricity
3. Use it as power for electrical gadgets.

I am talking about a box. Let us call it a magic box. Think rationally and tell me whether it is possible.
1. A magic box which I open.
2. Point it towards sun.
3. It stores light.
4. I close it.
5. I get light by opening it again.
6. I get only that much light which is stored in that box.

This thought occured to me while I was watching this advert.

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I'm not talking about solar panels. Your original post talked about 'storing light' and I said, since light is just form of energy, it's already stored in the Universe in different forms. What you're planning to do is already possible with solar cells that can power a small LED. Will do the same thing that you plan to do.
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### IssueStar

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OK let me change my question a bit.
How do we store "Light" in the form of "Light" itself? I do not want to store it in the form of heat (or any other form of energy) for instance. Is there any way?

### aNaNCertified CEan

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we know that light is a wave. A wave cannot be stored as it is. It has to be converted into some form.
For instance, take the case of sound. can you store sound as it is ? no. you have to convert it into some other form. same is the case with light

### Jyothi JoCertified CEan

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Light is emission of energy from electrons(from sun). If light has to be stored in box it means energy have to be stored,since light is nothing but photons (energy packets). Energy is stored only when it is absorbed by the electrons in atoms i.e,the electrons are excited to higher orbit levels with this energy absorption and this electrons would not remain stable in its higher orbit and thus tries to come back to its original state of actual orbit (since every electron has its own potential energy).This electron doesn't fall suddenly .For example if you take an electron which absorbed energy and excited to third level orbit so within in a fraction of seconds it falls to second level by emitting little energy and again it falls from second to first level by emitting little energy where this energy is absorbed by the other electrons.So if you want to watch the light that you have stored then you need to emit the energy from the electrons that has been stored when you exposed to light, but electrons don't posses the energy you have given because it has already emitted to attain its original orbit level. Thus you can't see the light when you open the magic box . I think its clear.
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### A.V.RamaniMentor

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We may have to rephrase what Issue is taking issue with. Heat is also an electromagnetic wave. Yet we have no problem storing it as heat and getting it back as heat. Likewise can we think of a way of storing light as such and get it back?
Theoretically may be possible. Let us consider a chamber with totally reflecting walls with zero absorption. Let the light be injected into this and the injection port sealed. This can be done using a Kerr Optic Shutter.
The trapped light will keep bouncing around. If the Kerr shutter is opened the beam will jump out and escape.
How does that sound, Issue?
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### IssueStar

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@bioramani sir. This is exactly what I was talking about. The magic box is indeed the apparatus you just explained. However it would be rather difficult (impossible) to get material with zero reflection.

### Mr.DonApprentice

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hmm, A Prism which cannot allow any light to escape through it!

### IssueStar

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If the light escapes through prism, it will be of no use. We want to trap it.

@bioramani sir. Do you know about the concept of perfectly black body? It uses lamp black as the inner coating. If it is replaced by glass mirror and the aperture is made to have OPEN/ CLOSE arrangement, it can be used to store light. How about it?

### Mr.DonApprentice

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What about A Shutter with ms delay time.

### A.V.RamaniMentor

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### A.V.RamaniMentor

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The Kerr Optic shutter has a femtosecond action.

### A.V.RamaniMentor

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These are called light spheres and used for measuring the total light output of lamps and such. Low level light signals are also trapped for measurement in spectrophotometers. I have used these for some measurements very long back.
http://www.rp-photonics.com/integrating_spheres.html
This is an interesting paper on storing and recovering light after a delay of 1.5 Secs, which is very long for light.
http://prl.aps.org/abstract/PRL/v103/i23/e233602
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### IssueStar

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@Mr.Don Never thought of TIR and prism. Good thinking.

@bioramani sir interesting application it is, the integrating sphere!

### KenJacksonApprentice

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I have read that astronomers and cosmologists expect to see a bright circle around a black hole, if they ever get an unobstructed clear view of one. Why? Because some photons pass so close that their paths are not only bent by the black hole's gravity, but actually go into orbit. The bright circle will be caused by photons that weren't quite close enough to get sucked in, but were close enough to do a partial orbit or a few orbits or even quadrillions of orbits before finally breaking free.

So there may be a huge number of photons in orbit around every black hole in the universe. We could think of them as being in storage. (As an aside, time passes very slowly near the event horizon, so would the photons appear to be traveling in slow speed from our vantage point?)

That's not very practical, if you're looking for a practical way to store light. But I find it fascinating.

### Vivien.hugoCertified CEan

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Store light? This reminds me of the fairytales I've read when I was young?

### the scientistCertified CEan

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last year i have read about an experiment in which the light rays(photons) passing through a crystal halted just for a very small duration of time.............
we can call it ""storage of light""" though for small time but it is!!!!!!!!!!!!

### Anku2993Apprentice

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