Does light travel through a tube filled with water?

[Pancake]

I would like to 'pipe-in' some natural sunlight into my bedroom.
Here is what I mean:

How To Make Free Light From Water Method - YouTube

How To Make Free Light From Water Method - YouTube
Video: click to display

The thing is, I live in a condo, so I can't drill into the roof...
I am wondering if light will refract within a tube filled with water? Maybe if I wrap the tube in reflective material? Or would I have to?
Thanks for the help.

[Malice]

Pfft, really shows their level of intelligence that they weren't able to figure it out on their own.

[Spatula Tzar]

I've seen those things. It would make far more sense to use a skylight. The more area sunlight shines onto, the more light you have. Obviously. It's impossible to tell how much light they provide without knowing the exposure settings on the camera, too.

Anyway, a tube with water carries light through total internal refraction, just like a fibre optic cable. The things you have to watch out for are losses from light leaking out, and losses from the opacity of water. The first can be addressed by covering the tube in a reflective material as you said, but there isn't much you can do about the second. Air is much more transparent than water, so if you're using a reflective tube, there's no need for water.

A far bigger problem is how to channel the light in the first place. Simply placing the end of the tube in the sun will give you as much light as a same size hole cut in the roof, like the stupid bottles. You need something like a parabolic reflector to focus lots of light onto the end of the tube.

This is more difficult than it sounds. Even if you do get a good reflector, and don't mind losses from not tracking the sun, you'll have the problem of melting the light pipe. Try focusing a big lens on a mirror, and watch it burn through. This is why commercial products tend to have very large diameter light pipes. Still, you can channel a fair bit of energy through it without melting.

You'll then need some sort of diffuser inside the room, less you prefer blindingly bright spots and dark shadows. You can find a high quality one inside an old LCD.

[RDProgrammer]

Originally Posted by Spatula Tzar

You'll then need some sort of diffuser inside the room, less you prefer blindingly bright spots and dark shadows. You can find a high quality one inside an old LCD.

This (diffuser) is really all the water does in the first place.

RDP