A couple of years ago there was some discussion of fresnel lenses. This kid came up with something that puts my fresnel to shame, in true Archimedes fashion:



More here:

Eric Jacqmain invented a 'Death ray' dish that had the intensity of 5,000 suns | Mail Online

Dude that was an amazing video. The music was awesome too.

-Sal

I've seen this before. Why 5800 mirrors? It'd be much easier to spread aluminum foil over the dish - you'd probably have similar reflectivity, too, considering it covers all the area and it's first surface by nature.

And aluminized mylar would work better than aluminum foil, but the problem would be keep it smooth while attaching it to a parabolic surface. This kid's next project is to build a super solar death ray consisting of 32,000 mirrors!

And if you put Stirling engine on that you'll get free energy. Other thermal engines works too.

I like when he heats up the rock! Makes me whant to build a big one to melt big rocks into thin tile.

Edit: also mabe thats how the ancient egyptians were such good stonemasons?

LOL ..... ancient egyptians was using dry wood and water, mainly

damn cant add the video..
http://www.youtube.com/watch?v=z0_nuvPKIi8

as seen on

somebody asked for a "death sun ray"...

Could one not just take an old TV satellite dish and spray it with some chrome acrylic?

Genius for its simplicity though. This will have to become a summer project of mine.

^ yes, if the paint is mirror chrome and the dish is clean, it may work ..... also, with "offset" dishes, you already have a focus point holder arm (if you don't melt it )

if the dish is textured which mine happens to be. the spray idea wont work.

^Sandpaper and/or paint stripper

You'll still get more accurate results if you aim each individual facet.

I'm sure if you are interested in this sort of thing you will have seen this video of a less-DIY version:
YouTube - Jem Melts Rock Using Sunshine - Bang Goes The Theory - Series 3, Episode 5 Preview - BBC One

Interesting but I noticed that he's protecting his eyes but has his hand in the peripheral area of the focal point. That much UV is not good for human flesh in the long term. He needs to use a grabstick to avoid that problem.

Like he said, 3 people sunbathing collect that much sunlight.
1 person sunbathing for 3 times as long.....
We already have a highly specialized process in place to deal with the damage caused by ultraviolet light.
The only real danger here is the intensity of the energy causing damage from the heat.
It would be like shining a high Watt ultraviolet light in your eyes and then worrying about cancer. The immediate damage to your eyes is caused by the intensity of the energy, not the potential mutations in the cells involved.

Awesome video.

needs one of these

^ no, you need one of these ones



Ben-Gurion NSEC, Sde Boker, Israel, 400 square meters of parabolic mirror, concentration factor 10000/1 ..... with one of these mirrors and a sunny day, you don't melt stones, you will VAPORIZE them

This is more like it. This should look familiar to those of you that watched the movie "Goldeneye."

Arecibo Observatory - Wikipedia, the free encyclopedia

^^Cool stuff right there.

So.. it looks like mirrors do a pretty good job, and paint is an untested method, but I don't want to lay down 2,000 mirrors. That's something called "work". Is it worth it? Lol

hey, and what about this?


now he has a high power concentrated source of light... I'm thinking about some colimation optics

NO!

Reminds me of mythbusters. They have tried twice now and have not gotten this to work. Granted they are trying to get some distance...

I like where this thread is going
Question for anyone that knows: Because the sun is so far away the light that reaches us is basically "collimated" right?
So shouldn't it be easy to use some relatively inexpensive optics and throw it down a fiber optic cable to a centralized power plant?
I don't know anything about it so I'm sorry if this is a stupid question