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Things You Can Do With A Giant Fresnel Lens

michael posted more than 10 years ago | from the toasty dept.

Toys 469

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."

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Forget that... (-1, Troll)

Anonymous Coward | more than 10 years ago | (#9222065)

Just think what I could do with a Giant Felching Lenny!

Basu Gasu Bakuhatsu (0, Funny)

Anonymous Coward | more than 10 years ago | (#9222066)

Basu Gasu Bakuhatsu :chiyo:

EEK! (5, Funny)

intekra (754612) | more than 10 years ago | (#9222067)

Lets hope this doesn't get into the wrong hands! This can be worse than WMD's!

Re:EEK! (5, Funny)

Dizzle (781717) | more than 10 years ago | (#9222079)

It already is because this actually exists.

Burnination (5, Funny)

OneFootIn (696599) | more than 10 years ago | (#9222071)

And to think, when I was a kid I had to settle for burning ants with a magnifying glass.

Re:Burnination (2, Funny)

edoc (772148) | more than 10 years ago | (#9222166)

This is what happens when you don't grow out of those times! On a positive note at least you have some change of getting laid.

The list should be (0)

Anonymous Coward | more than 10 years ago | (#9222074)

Things You Can't Do With a Giant Fresnel Lens! It's much shorter!

Nice picture of a giant fresnel lens in action (4, Interesting)

PissingInTheWind (573929) | more than 10 years ago | (#9222076)

Right here: Cooking with Light [armory.com] .

Link doesn't work anymore... (1)

antdude (79039) | more than 10 years ago | (#9222183)

File exists, but access forbidden by user

Re:Link doesn't work anymore... (1, Informative)

Anonymous Coward | more than 10 years ago | (#9222200)

You can still access it by copy/pasting the link.

Re:Link doesn't work anymore... (1)

antdude (79039) | more than 10 years ago | (#9222224)

Mucho bien! That worked. :)

Ants (3, Funny)

eightball01 (646950) | more than 10 years ago | (#9222077)

Now the ants really don't stand a chance!!!

Re:Ants (5, Funny)

wankledot (712148) | more than 10 years ago | (#9222121)

Even ants the size of horses.

Re:Ants (1)

edoc (772148) | more than 10 years ago | (#9222205)

Even horses the size of ants!

Re:Ants (4, Funny)

antdude (79039) | more than 10 years ago | (#9222171)

DOH! :(

Re:Ants (1)

iminplaya (723125) | more than 10 years ago | (#9222203)

Not even the giant ones [64.233.161.104] ? Bet you were thinking of the other ones...huh?

But can we stop "Them!"? (1)

turnstyle (588788) | more than 10 years ago | (#9222204)

Regular ants, maybe, but how about Them! [horror-wood.com] ?

Re:But can we stop "Them!"? (1)

iminplaya (723125) | more than 10 years ago | (#9222228)

Damn, you're the second one I caught reading my mind today! Post timed almost to the second.

Re:Ants (0)

whovian (107062) | more than 10 years ago | (#9222234)

Protect the Queen!
Which one's the Queen?
I'm the Queen.
No you're not.
Freedom!
Horrible, horrible freedom!

Re:Ants (1, Funny)

servognome (738846) | more than 10 years ago | (#9222239)

I for one pity our ant overlords.

That's something I always wanted to try (2, Interesting)

Sycraft-fu (314770) | more than 10 years ago | (#9222242)

I used to quite enjoy absing ants with a little 5x7 fresnel lens (as well as fireworks, water, a shovel, and, well anything else pretty much). I saw these giant ones in ES and figured they would be the ultimate ant-abuse. You could probably create a fairly wide circle in which the temperature would be sufficient to roast an ant. So rather than zapping them one by one, blanket a colony and watch the burnination.

Avoid antabuse at all costs (4, Funny)

plover (150551) | more than 10 years ago | (#9222294)

A buddy who was in the army was busted for showing up drunk, and they made him take antabuse [wisc.edu] . According to him, when you're taking it drinking even the smallest amount of alcohol makes you puke puke puke.

Ideas (3, Interesting)

panxerox (575545) | more than 10 years ago | (#9222080)

Mount it in front of your monitor for a really big image Write your name in the side of someone's car Wipe your harddrive permanently There has to be a way to increase solar cell output with these (not at direct focus of course mabey larger area at 25% focus)

Re:Ideas (2, Interesting)

DoraLives (622001) | more than 10 years ago | (#9222161)

Wipe your harddrive permanently

I daresay this may be the long sought for absolutely sure method for permanently removing data from a hard drive in such a way that nobody, not even the NSA will be able to recover it.

Job well done, guys!

Re:Ideas (1)

timmi (769795) | more than 10 years ago | (#9222180)

I seem to remember something to that effect, but the diagram showed solar panel "Strips" that were covered by a lens that was like a half circle above and wider than the panel.

Re:Ideas (1)

BiggerIsBetter (682164) | more than 10 years ago | (#9222214)

How about using it as a heat source for a steam turbine?

Re:Ideas (1)

servognome (738846) | more than 10 years ago | (#9222265)

I doubt it would work, all the lens does is concentrate the same amount of energy to a small spot. You could boil the water in the cm^2 spot, but it wouldn't be an efficient way to get power. Also, the steam would reduce the efficiency since it would absorb some of the light.

Re:Ideas (2, Interesting)

jd_esguerra (582336) | more than 10 years ago | (#9222220)

I'm no expert in solar cells, but would it really be possible to increase output of a solar cell just by focusing light to s smaller spot ? If you are focusing light (energy) from a lens that is a square meter in area down to a cell with a 1-cm square area , how is that different than having a cell of 1 square meter in area ? Unless there are marked efficiency differences between a 1-m^2 sensor, and the 1-cm^2 sensor, the energy "captured" would be approximately the same, right ?


Your energy output is going to be equal (in ideal sense, but always less-than that in reality) to the solar energy that hits your light collecting optics, be it a big-ass lens or a photovotaic cell. Its a thermodynamics issue.



Re:Ideas (3, Insightful)

timmi (769795) | more than 10 years ago | (#9222260)

It's more efficient because it's cheaper. the chost prohibitive compinent of the system os the solar cell, whereas the lens and the litle bit of mechanics to keep it aligned is relatively cheap, (or at least that was the case when the idea was widely talked about)

Re:Ideas (1)

Punboy (737239) | more than 10 years ago | (#9222267)

Hmmm, but the more solar energy the cells recieve, the higher the output. You may get the same output from 1-m cell as you would from a 1-cm cell under a fresnel lens, but then again it is the same. Meaning you get the same energy in a 1/100 the area.

Re:Ideas (1)

QuantumSpritz (703080) | more than 10 years ago | (#9222283)

Solar Panels typically have a lot of surface area not devoted to photovoltaic cells - some type of lensing could be used to focus the light that would normally hit the unused portions onto the reactive areas. Or, if a cell is more efficient with more light coming in, then that's another possible use right there.

O_o (-1, Troll)

hot_Karls_bad_cavern (759797) | more than 10 years ago | (#9222081)

jesus tap dancing christ. terror is right. the fabric of the universe is being ripped with the speed of government entities swarming to your house!

A good use (3, Interesting)

KoriaDesevis (781774) | more than 10 years ago | (#9222082)

Maybe not very practical, but it might make a good paint remover. I have seen work crews remove paint from wood surfaces with a heat gun that looked like a big hairdryer, so I would think this type of lens would be helpful for stripping paint off metal surfaces such as water towers and so forth.

Re:A good use (1)

YomikoReadman (678084) | more than 10 years ago | (#9222138)

Saying that using this might not be practical for stripping paint is like saying a screen door on a submarine isn't a practical exterior hatch. They destroyed a penny with it, among many other things, and in theory they could melt quartz.

Re:A good use (1)

taniwha (70410) | more than 10 years ago | (#9222159)

well stripping paint from titanium might work (got and old Blackbird that needs painting?) ... but a wood surface? maybe you need more insurance .....

Re:A good use (1)

nuclear305 (674185) | more than 10 years ago | (#9222244)

I think those crews were merely trying to remove the paint from the surface, not completely obliterate both the paint and the wood surface.

That would be like burnings ants with a giant fresnel...oh....damn....

Terrorism... (5, Funny)

Mz6 (741941) | more than 10 years ago | (#9222084)

I wonder what his Terrorist Quotient is? [slashdot.org] .

A use for AOL CD's (4, Funny)

ErichTheWebGuy (745925) | more than 10 years ago | (#9222086)

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!

Re:A use for AOL CD's (2, Funny)

clone22 (252516) | more than 10 years ago | (#9222280)

I entered that idea in a contest a couple of years ago, but the lamp won.

Since each CD is an individual reflector you can mount each one independently on a flat surface with a wedge or two to direct light to the focal point.

All we need now are... (5, Funny)

Fiz Ocelot (642698) | more than 10 years ago | (#9222087)

Sharks with...giant Frensel Lenses attached to their heads!

Choice quote... (0)

Anonymous Coward | more than 10 years ago | (#9222091)

"It seems when you are wearing #12 arc welding lenses, you can't see much short of the sun and whatever is in the lens' focus. (Like your hand on fire.)"

This one doesn't seem to have any pictures. It may actually survive the slashdotting for a short while.

wtf (-1, Troll)

Anonymous Coward | more than 10 years ago | (#9222097)

why isn't it spelt "frenel"?

gay fucking fags :/

Re:wtf (4, Informative)

timmi (769795) | more than 10 years ago | (#9222276)

It's pronounced fer-NEL and it's spelled Fresnel because it's named after the french guy who invented it.

Giant Fresnel Lens ... (4, Funny)

john82 (68332) | more than 10 years ago | (#9222098)

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.

Re:Giant Fresnel Lens ... (1)

lukewarmfusion (726141) | more than 10 years ago | (#9222145)

I read an article the other day about a guy in Bloomington, IN that caught some cicadas, sauteed them in butter and garlic, and got hives.

So don't eat 'em. But burn away!

w00t (0)

Anonymous Coward | more than 10 years ago | (#9222102)

jibba jabba

If only I had this as a kid (3, Funny)

Anonymous Coward | more than 10 years ago | (#9222105)

This is just like the magnifying glass and ant game only this scales up to poodle sizes. Oh well. If I ever have a son...

Re:If only I had this as a kid (0)

Anonymous Coward | more than 10 years ago | (#9222185)

This is just like the magnifying glass and ant game only this scales up to poodle sizes. Oh well. If I ever have a son...

or DAUGHTER!!!! Speaking as a female optelectronics grad student. I want one of those lenses.

--Martine

Mindless (3, Interesting)

Roland Piquepaille (780675) | more than 10 years ago | (#9222109)

Chalk actually burns under this thing.

Chalk burns eh? Creative chemistry, more like it. Here's another fun thing you can do: drop your "burnt" chalk in a glass half-full of water, let it bubble, and put your finger in it. Let me know how it feels.

So do aluminum cans. They smell really bad.

Aluminium doesn't smell bad when it burns. I suspect whatever soda pop chemicals remaining in the can do.

It seems that normal concrete will start emitting plumes of smoke just before it pops

As would burning tar, or any other heavy petroleum derivate.

* Mike's car.

Well, not yet. But it's plastic, so it would go up in no time at all. Or maybe we could just shrink-wrap the body around the frame.


Try focusing the lens on the round plastic thing that smells funny, on the rear side of the car...

Seriously, this article is all about playing with a new destructive toy and not much about using the toy in question to do interesting science-related experiments.

Re:Mindless (2, Interesting)

Siva (6132) | more than 10 years ago | (#9222165)

Here's another fun thing you can do: drop your "burnt" chalk in a glass half-full of water, let it bubble, and put your finger in it. Let me know how it feels.

aw, at least explain for those of us who lack the chemistry knowledge and the stock of burnt chalk what will happen...

Re:Mindless (5, Informative)

dgatwood (11270) | more than 10 years ago | (#9222266)

Chalk is limestone. If you burn it, you get lime (calcium oxide). Add water, and you get calcium hydroxide. It's a very strong antacid.

Re:Mindless (5, Informative)

Lehk228 (705449) | more than 10 years ago | (#9222277)

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

Re:Mindless (2, Informative)

mlh1996 (446618) | more than 10 years ago | (#9222282)

Ok, working from memory here, and being lazy, so I'm not going to bother balancing equations:

Chalk (Calcium carbonate) + Oxygen -> Calcium oxide + Carbon dioxide
Calcium oxide + Water -> Calcium hydroxide

Calcium hydroxide is a strong base, so putting your finger in it will probably result in severe alkali burns.

Re:Mindless (1)

DAldredge (2353) | more than 10 years ago | (#9222167)

It's called fun. Not every damn thing has to be 100% correct down to it's smallest detail.

Relax, have a drink, get laid, something!

Re:Mindless (5, Insightful)

DoraLives (622001) | more than 10 years ago | (#9222197)

this article is all about playing with a new destructive toy and not much about using the toy in question to do interesting science-related experiments.

Yeah, and I guess it shouldda been Smiley Captioned for the Humor Impared, too.

Re:Mindless (1)

geekoid (135745) | more than 10 years ago | (#9222202)

True, but there will be people who will post links to other interesting things.
That will make it worth while.

Now if you will excuse me, I have some carpenter ants to take care of...

...and? (4, Insightful)

Sycraft-fu (314770) | more than 10 years ago | (#9222208)

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.

Re:...and? (1)

maxbang (598632) | more than 10 years ago | (#9222297)

...which they did with a high degree of success

Yep. I'd say within a third or even fourth degree. Whichever one is the degree that means the flesh has burnt from your bones, that's the one.

Re:Mindless (0)

Anonymous Coward | more than 10 years ago | (#9222237)

Lighten up Roland. I was going to describe the huge dump I just took, but now that you mention it, there's little or no scientific value in that discussion. You're the reason people beat up geeks.

Re:Mindless (2, Insightful)

Cecil (37810) | more than 10 years ago | (#9222240)

Seriously, this article is all about playing with a new destructive toy and not much about using the toy in question to do interesting science-related experiments. ... you say that like it's a bad thing?

Re:Mindless (5, Informative)

modecx (130548) | more than 10 years ago | (#9222245)

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).

ooh! ooh! (1)

jpellino (202698) | more than 10 years ago | (#9222110)

just remembered we have one of these - 6' diameter - someone thought it would help with solar collectors back in the 80's - gotta dig this out!

I have one of these. (4, Interesting)

Qender (318699) | more than 10 years ago | (#9222111)

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.

Re:I have one of these. (1)

DoraLives (622001) | more than 10 years ago | (#9222218)

Is there anything else anyone thinks I should burn with it? it's in my garage.

Burn the garage!

Laser Communications (5, Interesting)

Rob Carr (780861) | more than 10 years ago | (#9222114)

Besides destorying things, these fresnel lenses cand be used for all sorts of constructive fun.

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 [qsl.net] 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!

I, for one... (1)

3) profit!!! (773340) | more than 10 years ago | (#9222127)

I, for one, welcome our new Fresnel lens overlords!

Hanging wall art (3, Interesting)

G4from128k (686170) | more than 10 years ago | (#9222134)

Hanging a Fresnel Lens in front of a white wall projects a nicely focused image of the room onto the wall. Depending on the arrangement of the room and windowage, its poosible to watch the world pass by on projected image. The optimum distance from wall to lens is approximately the focal length (or a little farther if the subject is close to the lens.

Just make sure the sun never gets to the lens or it will burn an arc across the wall.

Oh great (2, Funny)

iminplaya (723125) | more than 10 years ago | (#9222137)

Now the Dept. of Homeland Security is going to order various municipalities to block the sun [64.233.161.104] .

If you like burning up stuff with a lens... (4, Funny)

PissingInTheWind (573929) | more than 10 years ago | (#9222139)

you'll love this flash game: Ant City [channel4.com]

a giant fresnel fp (0)

Anonymous Coward | more than 10 years ago | (#9222142)

and it's aaaaalll mine!

Scaled Up (1)

StuWho (748218) | more than 10 years ago | (#9222146)

IANAPH but it the lens was say 300 feet by 300ft, would it still be possible to focus the light to a 1cm point? And if so, does the size of the lens increse the temperature?

Re:Scaled Up (2, Informative)

jd_esguerra (582336) | more than 10 years ago | (#9222288)

IANAPH but it the lens was say 300 feet by 300ft, would it still be possible to focus the light to a 1cm point? And if so, does the size of the lens increse the temperature?

Probably not, and yes. A lens of that size would be extremely difficult to build and operate. Instead, you'd use an array of smaller lenses, or even better, mirrors. If you look at large telescopes, most use mirrors in part because of weight issues and manufacturing issues with lenses over say 1-meter.

The size of the lens does increase temperature, or at least the energy density at the focal point. A bigger lens (or mirror) can capture and direct more solar energy.

Higher standards (1)

KalvinB (205500) | more than 10 years ago | (#9222154)

Burning things has been done again and again and really isn't Slashdot (any news really) worthy.

Unless you find a way to pull a MacGyver with it and foil some terrorist plot or something I can't say I'm too impressed.

Ben

$99 for the cheap fresnel... (4, Interesting)

NoMoreNicksLeft (516230) | more than 10 years ago | (#9222158)

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?

Re:$99 for the cheap fresnel... (5, Interesting)

nelsonal (549144) | more than 10 years ago | (#9222243)

If you follow the sun perfectly you could figure on about 1 kW of light (cheesy rule of thumb) hitting your turbine. Assume 30% efficiency and you have 300W of electric power generated for an average of 12 hrs per sunny day. Three light bulbs (or 6-8 florescents) or one fully loaded computer (300 W power supply, no electric heat, iron, or oven. Oh and you'll need a capacitor bank to handle your inductive load when motors start. Go grab your power bill and see how many kW/hrs you use in a month and then figure out how many fresnel lens/turbine array's you would need to achive that power. Storage would be a mofo, although you might be able to sell it into the grid in your area.

Re:$99 for the cheap fresnel... (5, Informative)

Roland Piquepaille (780675) | more than 10 years ago | (#9222253)

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%)

- In bright summer daylight, at noon the sun provides 1200W/m2

- This fresnel lens is 80x100, so captures 1200 * 0.8 = 960W at best

- A good steam engine, with a condenser and exhaust reheater provides has an efficiency of about 30%, so it would give 960 * 0.3 = 288W in mechanical power

- A good alternator, going at its preferred RPM (not necessarily that of the steam engine's prefered RPM, but let's assume) has an efficiency of about 90%, so it would give 288 * 0.9 = 260W

So you'd get 260W in the best possible conditions, in the brightest of days, in summer, at midday. Throw some clouds and, assuming the entire thing doesn't stall and stays at its nominal efficiency (not likely, but let's assume), you get about 6 times less power, so about 43W

In short, you're better off with solar panels: perhaps a little less efficiency for the same price, but more surface and a lot less aggravation.

Re:$99 for the cheap fresnel... (1)

mikeophile (647318) | more than 10 years ago | (#9222292)

A steam engine can get a theoretical 22% efficiency so from a one square meter frenel focusing around 80% of the light striking it, you could get around 200 watts of power on a good day.

YMMV

This is plain sick... (1)

k.ellsworth (692902) | more than 10 years ago | (#9222162)

... I need one... My inner kid thinks, with a little magnifier i fried some ants, whit this i can fry/burn many BIGGER things... like: -fish -rats -big spyders -5.25" floppies -SCO stock... (worthless actually) wow i need one... added on my wish list.

Vinyl Siding and Frensel Lens Don't Mix (1)

auburnate (755235) | more than 10 years ago | (#9222168)

Its funny to see the lenses leaning against the vinyl siding of that house. Although the focal point is off, it would be funny/ironic in the cosmic karma sense if that lead to the burning down of that house!

alternate heat source for furnace (1)

ed8150 (554077) | more than 10 years ago | (#9222173)

a while ago i started work on a propane heated furnace. i used kaowool and a small trashcan to fashion what i thought was a reasonable efficent furnace. this frensel lense give me the idea of perhaps powering said furnace via the sun. does anyone know if this is possible? i wish to melt down aluminum and copper(my crucible is steel so no go there)

wow, the lense isn't that big (+ob. cluster joke) (1)

real_smiff (611054) | more than 10 years ago | (#9222178)

i had no idea the sun was so powerful. what would happen with.. a beowulf (sp.?) cluster of these? :p shame the good ones cost 224 USD :/. probably a good thing. i'd only damage my eyes, wallet and god knows what else.

PLUS... i live in Britain. just how often could i use this (and how much less power would i have?). i've often been to Australia & NZ and have seen how much more powerful the sun is out there...

very geeky btw.

hahahahaha (1)

geekoid (135745) | more than 10 years ago | (#9222182)

In the colony, ants burn YOU!

hahaha.

fp (0)

Anonymous Coward | more than 10 years ago | (#9222201)

fp

Would this be possible? (4, Funny)

Fiz Ocelot (642698) | more than 10 years ago | (#9222207)

Would it be possible to build a giant one, say 100 square feet, and focus it into a fiber optic type of cable, essentially using it for a cutting laser?

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.

Re:Would this be possible? (2, Insightful)

pedantic bore (740196) | more than 10 years ago | (#9222256)

It wouldn't work as a laser per se, because the light would not be coherent. Only the light beams that are more or less parallel to the end of the fiber would find their way through the cable (although this could be increased with a few more lenses along the way).

As far as the fresnel-lens-in-space idea is concerned, it scares the crap out of me. If the thing gets knocked out alignment (maybe dinged by some of the tons of space junk already in orbit you suddenly have a death ray tracing random patterns across the planet, with no off switch (short of destroying the lens).

The more popular name.... (0)

Anonymous Coward | more than 10 years ago | (#9222209)

The Scourge of All Ants!

OK OK! Enough ant comments! (1)

antdude (79039) | more than 10 years ago | (#9222211)

Maybe it was a very bad idea for me to submit this story. [grin]

Possible source of free lenses (4, Informative)

cybermace5 (446439) | more than 10 years ago | (#9222213)

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....

Bravo - we have sunk to a new low! (0, Offtopic)

Shivantrill (654978) | more than 10 years ago | (#9222216)

This reminds me of a Beavis and Butthead episode. Heheheh
Seriously, which category does this fall under, News for Nerds or Stuff that matters? Perhaps neither since this was not very newsworthy or interesting.

Why doesn't someone go plagerize another Wired article or dig through the archives to re-post something. That would be more interesting than a couple of boneheads randomly frying stuff
Hehuhhuh.

I'll have you know... (1)

y2imm (700704) | more than 10 years ago | (#9222223)

It's at least $0.01 per 10.....Americans...*shakes head*.....

Re:I'll have you know... (1)

The_Chicken_205 (723443) | more than 10 years ago | (#9222255)

$0.01 per 10 Americans? :D

CTY hijinks with a giant fresnel lens... (1)

silentbozo (542534) | more than 10 years ago | (#9222227)

When I was at a summer camp back in Junior High, I temporarily "liberated" a large magnifying lens meant for magnifying television sets. The damn thing required two of us to maneuver it into position, and in the intense summer sunlight we toasted salsa until it turned black, carved letters out of concrete on the sidewalk, and liquidated several nickels (they may look solid, but don't touch them - the inside can be quite runny and extremely hot.)

I now have two fresnel lenses, not quite that large, which I eventually will be using to set up a solar-powered forge. Also, I now have welding glasses and gloves, two things that would have come in handy when we were roasting coinage.

reality.sgi.com (1)

d_p (63654) | more than 10 years ago | (#9222238)

Some guys at SGI did some stuff like this in the 90's and had a page on reality. They melted pennies and other cool stuff. I have been looking for a mirror of that site but it seems to be gone for good.

I love Edmund Sci !!! (0)

Anonymous Coward | more than 10 years ago | (#9222249)

As a kid I lived a half hour from the Barrington, NJ headquarters. They had a massive warehouse open to the public that was stocked with everything including motors, telescope parts, electronic components and even a bin of Jabba the Hut heads.

I picked up my first (and last) fresnel from the Ed Sci outlet, but quickly had it confiscated by my mother when I set the lawn on fire.

Hmm, The Ant Equivalent (5, Funny)

Danny Dale the Not-S (778706) | more than 10 years ago | (#9222279)

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...

And remember (3, Funny)

Flower (31351) | more than 10 years ago | (#9222281)

Do not taunt giant Fresnel lens.

Froogle (1)

supz (77173) | more than 10 years ago | (#9222284)

Oooooh. The first thing I did after reading that, is check out froogle:

http://froogle.google.com/froogle?ie=utf-8&oe=ut f- 8&q=fresnel+lens&btnG=Search+Froogle&scoring=p

Is 7x11 inches good enough to burn anything cool?

The Warper (2, Interesting)

mcguyver (589810) | more than 10 years ago | (#9222289)

http://www.noah.org/acidwarp/warper.html [noah.org]
A frenzel lense + acidwarp = good times in a college dorm room. A 10 foot wide light show on your wall is pretty cool. People seemed to like it but covering your computer with a lense and a cardboard box was a little nerdy.

Or...you cal sell these on eBay!
175" DIRECT BIGSCREEN BIG SCREEN HOME THEATER TV KIT
Sell kits to create 175" large TVs on eBay! The 175" 6.5x Lens Home Theater Kit is amazing! Simply put, it is a Projection unit that when attached to your ordinary TV will project the image up to sizes of 175".
/sarcasm

Slightly more usable Fresnel lenses. (1)

cant_get_a_good_nick (172131) | more than 10 years ago | (#9222302)

Canon just came out with a new lens that uses Fresnel tech, or at least pseudo Fresnel. See the new 70-300 DO on canon EF lens site [canon.com]

It's no a perfectly flat fresnel, but it does do ladder step stuff to put a 300MM zoom in a failry small package.
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