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.

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.)