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Things You Can Do With A Giant Fresnel Lens
Ant writes "Here is a link where this guy always wanted Edmund Scientific's Giant Fresnel Lens. 'Melts asphalt in seconds!' the ad said. When he went to graduate school he met several other people with the same enthusiasm for aimless destruction through bizarre means, and just enough combined cash to make it happen. Thus the reign of terror began."
Lets hope this doesn't get into the wrong hands! This can be worse than WMD's!
[intekra] - [www.plex.nu]
And to think, when I was a kid I had to settle for burning ants with a magnifying glass.
Right here: Cooking with Light.
A message from the system administrator: 'I've upped my priority. Now up yours.'
I wonder what his Terrorist Quotient is?.
Hmmm.
A friend and I were discussing what to do with all of our AOL CD's. We both came up with the idea that you could make a similar device out of them.
Welcome! You've got fire!
bash: rtfm: command not found
Sharks with...giant Frensel Lenses attached to their heads!
Meet Brood X of the 17-year Periodical Cicada.
Snap! crackle! pop!
Why waste such a monster on mere ants. I realize there are some of you out who would think of a certain movie and popcorn (lots of popcorn), but you've got to agree this is more unique.
I found one of these at my school last year. The first thing I did was take it to the parking lot to set paper on fire. The asphalt under the paper burned. I also melted pennies with it, and it can make holes in soda cans. Is there anything else anyone thinks I should burn with it? it's in my garage.
A perfect example is a laser communication system. A laser beam can be modulated and used to transmit audio. The receiver needs to collect as many photons as possible from the laser transmitter - hence the use of the fresnel lense. Signals can be bounced off clouds - I've heard of transmissions going over 60 miles!
The Amatuer Radio Laser Communications Page has a good primer that has a link to a lot of the basics. And no, you don't need a ham license - although it helps!
This sig seemed like a good idea at the time....
Even ants the size of horses.
My sig is blank, I typed this by hand.
you'll love this flash game: Ant City
A message from the system administrator: 'I've upped my priority. Now up yours.'
Could you do something serious with this? Put the damn thing in a rig that follows the sun, and a small steam turbine under it, just how much juice could it provide?
I wish I knew the math to this, but damn, if it could provide even a small fraction of the power I use during the daytime... (by this, I mean 5-10%)
Anyone want to impress me with their math/physics skills?
DOH! :(
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
Yeah, and I guess it shouldda been Smiley Captioned for the Humor Impared, too.
Is it fascism yet?
Or what if you had a few massive ones in space, could you focus enough energy for use in a fusion reactor? You'd amplify all of that free energy and I don't really know what I'm talking about. Perhaps you could attach it to a shark's head.
Playing with a toy is the POINT of a toy. I have a new Radeon 9800 Pro that, I am made to understand, has a pretty bitching vector unit that can be used for scientific calulations, rendering and the like. It is not used for any of these educational pursuits, however, and is instead used to render lightsabers which I then use to cut up bad guys it also renders. In other words, I bought it as a toy.
It doesn't sound to me like they ever intended to do much science, it sounds like they intended to fuck around and burn shit, which they did with a high degree of success.
Not as big, maybe 14 inches across, but overhead transparency projectors have a big square fresnel lens in the base. Since a lot of businesses, schools etc have moved to LCD projectors, you might be able to find an old overhead that no one cares about. Still concentrates a lot of light; you can't look at the spot and it'll burn lots of things. Probably not metal, though.
Cooking idea: Take a length of thin all-thread and turn it with a slow motor, with a matching nut fastened to a board so that the all-thread and motor are slowly pulled along. Spear a few hot dogs on the all-thread and set the lens to a medium concentration. Spin up the motor, and the sun will cook the hot dogs in a spiral....
...
1) Aluminum cans have a thin coating of plastic on the inside to provent the soda's acid from etching the aluminum. 2) they have all sorts of paint on the outside. That's what smells bad. Not left over soda.
But, onto the other point: many geeks like high amounts of kinetic energy. It's true. Often, this love tuns into the irrational lust for wanton destruction of random objects. Sometimes, something is learned by the results, sometimes not. But it's the journey that's important (fun).
Constitutional rights may be respected, repealed, or modified; but they must never be ignored.
Check out my sci-fi/humor trilogy at PatriotsBooks.
It's pronounced fer-NEL and it's spelled Fresnel because it's named after the french guy who invented it.
antacid= Base, which is worse for skin than acid, Acid you will feel and pull your hand away because the human body can feel the burn from acid, a base will eat through your skin and you will just feel "slippery" s it turns your flesh into soap
Snowden and Manning are heroes.
of a Nuclear Bomb.
Imagine kicking over an ant hill, then frying thousands of the little fuckers with each sweep of the beam when they come pouring out. Considering you can melt nickels and cut soda cans in half with this thing, it's possible you can actually [i]glass[/i] that anthill!
Just make sure it's fire ants. Those bastards deserve it...
Almighty Railgun
You Speak a Lethal Gospel!
Bloody Gibs Follow.
A buddy who was in the army was busted for showing up drunk, and they made him take antabuse. According to him, when you're taking it drinking even the smallest amount of alcohol makes you puke puke puke.
John
Which leads to my observation that, when presented with a large electromagnet, a REAL geek immediately constructs a railgun
I mean, really. Is there anything more beautifully destructive than a railgun?
Lack of creativity is no excuse for not having a
Ants? I'm more worried about the humans.
So I agree with timmi. But remember that the ore optics you have in your system, the less light will reach the photovoltaic cell. Optics are not perfect. (By the way, mirrors are lighter than lenses, and are easier to build and control.)
Here are a few references to increasing solar cell output with Fresnel lenses. Enjoy!
Projection tv's use them! :)
since I repair them for a living, ive actually done this.
its quite fun, but do be careful!
I like using the fresnel from a 60" projection tv the most
I have burned up phone books in no time with it, and I have tried cans, I got one to melt.
next time you see a projection tv in the trash, get the lens.
the lens will be the innermost of the 2 (or 3, if there is a protective screen)
have fun!
"But a professor," I try to explain...
"You can't have one."
that's actually how some solar power stations work. They have a bunch of mirrors that aim the sunlight to a glass globe filled with water, the water boils out and powers a turbine, condenses out and returns to the globe via a valve and pump.
Overall it works better than solar cells because it's so simple and you harness the heat energy rather than the light itself, but therer's only economy to it on a large scale, you need enough space to get a huge amount of water to constantly boil. Also, it's significantly harder to get this thing working on less-than-ideal days; solar cells still collect juice on slightly cloudy or overcast days, but this method doesn't work nearly as well.
Still, a good way to apply solar energy when in conditions that permit. I'd like to set up a small unit with a fresnel lens and 'boiling globe' to generate hot water (which I'll pump through a radiator) for my house in the winter. The problem I see is with safety, that beam has to be EXACTLY where I want it or I'll burn the house down.
"Sometimes, I think Trent just needs a cup of hot chocolate and a blankie." -Tori Amos on Nine Inch Nails
One thing that cannot be overstated is the use of eye protection. And, whatever is selected for that application must handle IR as well as visible light. (Nearly all of the UV is absorbed by the plastic the lens is made out of, so it is not much of a factor.)
Using such a lens, to focus solar radiation, can produce power densities equivalent of a Class-IV laser; where the warnings typically read "avoid exposure to direct or scattered radiation". Even if focused to a spot size of 4cm^2--at an estimated 1kW--the power density would still fit 2.5W/mm^2. This is the same level as a 10W laser, with 2mm beam focus.
Granted that the focus is only at one point, it is easy to overlook when scattered radiation--from a "point" source--can be dangerous.
As the article states, use very heavy welding goggles, and maybe have some sunglasses on under those! It is also recommended to ensure that the goggles cover the infrared parts of the spectrum effectively.
Also note: laser safety goggles would be ineffective for this application, due to the fact that they typically use dichros, which typically are not very "wide-band". They reflect very specific wavelengths--very efficiently. But, since solar radiation is very wide-band, a lot of it will still get through.
...the original uber-cool use of the Fresnel lens, namely, in the first actually useful lighthouses.
From one of the articles: "Cylindrical Fresnel lenses provide a 7:1 concentration, allowing a single multijunction GaInP2/GaAs/Ge cell to collect solar energy equivalent to that gathered by seven cells."
In other words, a fresnel lens does not help in terms of energy gathering. On a cost or mass per area, it does.
"I'm not impatient. I just hate waiting." - My Dad
I don't know what you were doing in chemistry (probably wearing the proper equipment) but lye burns like all hell once it gets through the first couple layers of skin.
"It has always been this way and it won't change, god bless the fucked up USA" The Briefs