My Math Forum Any shape of glass that bends rainbow light into laser can also hologram in sky

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 January 14th, 2015, 01:29 AM #1 Senior Member   Joined: Jan 2013 Posts: 209 Thanks: 3 Any shape of glass that bends rainbow light into laser can also hologram in sky "AP Physics 2: Optics 5: Dispersion Prism and Rainbow" light bends in prisms at an angle that depends on the angle of the border it hits and difference in speed of light (in air or in the prism, or prism and air on its way out). A prism that reflects a rainbow into a laser would have a cone on the rainbow side. Video projectors are many small lasers. They would work directly into such a prism. The prism would have to be adjusted for different amounts of water in the air since that determines the drop sizes which act as prisms in the air. It would also have to be adjusted for where in the air you want the hologram. It would also make a better solar collector in some air conditions, since it could collect a known frequency by the angle outward from the sun or other light source, and this would be collected from a big circular area in the sky instead of just 1 smaller area. Also, the difference in how this device works forward and backward can be used to measure gravity, since we are accelerating 9.8 meters/second faster each second (how fast things fall if ground not accelerating them up). Last edited by BenFRayfield; January 14th, 2015 at 01:36 AM.
January 14th, 2015, 07:34 AM   #3
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Quote:
 Originally Posted by BenFRayfield "AP Physics 2: Optics 5: Dispersion Prism and Rainbow" light bends in prisms at an angle that depends on the angle of the border it hits and difference in speed of light (in air or in the prism, or prism and air on its way out). A prism that reflects a rainbow into a laser would have a cone on the rainbow side.
I believe you mean 'light ray' instead of laser.

I've never seen someone try and reflect many rays of different colours back into white light, but I don't see why it shouldn't work. I guess it would just be difficult to get all the rays to line up at the same point with the right incident angles. The final result should be a white light ray, not a cone.

It's the frequency dependence of refraction that causes the rainbow and colours of the sky to be the way they are. It's cool

Quote:
 Video projectors are many small lasers. They would work directly into such a prism. The prism would have to be adjusted for different amounts of water in the air since that determines the drop sizes which act as prisms in the air. It would also have to be adjusted for where in the air you want the hologram.
Projectors use lenses to magnify an image onto a screen. There is no specific need for prisms, but I understand that this depends on the design of the projector. You certainly don't want it splitting up all the colours as it would ruin the image!

You could correct for water vapour, but the effect is so small that you don't really care. If you wanted to correct for it, you would use adaptive optics rather than a prism, which is something that is done in astronomy to correct for atmospheric attenuation of the incoming light (basically scattering by water vapour).

Quote:
 It would also make a better solar collector in some air conditions, since it could collect a known frequency by the angle outward from the sun or other light source, and this would be collected from a big circular area in the sky instead of just 1 smaller area.
When you have a solar collector, all you care about is how much incident radiation there is and the absorptivity and emissivity of the collector surface. You want as much radiation as possible, so you don't care about the particular frequencies of the incoming light.

Quote:
 Also, the difference in how this device works forward and backward can be used to measure gravity, since we are accelerating 9.8 meters/second faster each second (how fast things fall if ground not accelerating them up).
You can use an interferometer to measure g. Look it up!

Since you are interested in prisms and the way they split up colours, look up spectrometers. They are devices that detect the intensity of incoming radiation as a function of frequency. They are one of the most important tools you can use in astronomy along with the telescope and the CCD camera. With a spectrometer, you can get much more information about the nature of the incoming radiation from the celestial object you are observing, so you can find out more about it. Spectrometers even allow you to find out the chemical composition of matter in space

January 14th, 2015, 07:46 AM   #4
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 Originally Posted by BenFRayfield Light is momentum. When something moves and is not superpositioned, it is quickly emitting and absorbing the same light. I think they call this "momentum quanta", except its not quanta. Its about the optics, speed of light in various materials, and angles of prisms. All light is momentum.
I mentioned in a previous post that light carries momentum and can exchange that momentum when colliding with particles, but that doesn't mean that it is momentum. Light is characterised by fluctuating electromagnetic waves. Please be careful not to misunderstand what I write!

The momentum carried by photons is quantised in units of $\displaystyle m\hbar$ where m is an integer.

Quote:
 Since all mass is light (depending where its viewed from, see lorentz)
Nope. Mass is a property of matter. Light is not matter; it is characterised by fluctuating electromagnetic waves.

Lorentz worked on the motion of charged bodies (electrons specifically) which formed the basis for special relativity. However, I'm pretty sure he never claimed that "all light is mass". Even if he did, he would have been wrong.

Prisms have been known for a very long time (since Newton's 'Optiks') and they aren't particularly special. You can buy them from shops for next to nothing

Many medical devices already exist that can scan the human body. Perhaps you should look them up before trying to invent your own?

Last edited by Benit13; January 14th, 2015 at 07:52 AM.

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