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."

Comments

Re:Mindless

[DoraLives]

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.

...and?

[Sycraft-fu]

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:Ideas

[timmi]

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

[jd_esguerra]

Right. A smaller cell that could absorb the focused light would be more efficient and probably cleaner and more efficient to produce or operate. The issue I was addressing is that you can't really increase the output from the solar cell because you are still limited by the amount of light entering it. Consider this: A flashlight (with beam having a low divergence angle) is shining on a large perfectly efficent solar cell. All of the light is converted to energy. If the same (wide) beam is focused down to a perfecly efficient solar cell that is 1/100 the area of the larger cell, you will see the same energy. To obtain the full energy of the flashlight's beam, the lens would have to be at least as big as the beam cross section at their intersection in space. A cell of that same area as the lens would (theoretically) receive the same power from the flashlight.

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.)

Re:Mindless

[drinkypoo]

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.

concrete: "A hard, strong construction material consisting of sand, conglomerate gravel, pebbles, broken stone, or slag in a mortar or cement matrix."

I do not think that word means what you think it means. It seems as if you are confusing concrete with asphalt or tarmac(adam).

Guess what, setting shit on fire is fun! If you are relatively responsible about it and don't light shit on fire accidentally and/or let things get out of hand (note: many forest fires grow from the cooking campfires of the incompetent) then really, who are you harming? Well, anyone breathing the vapors. But besides them?