Slashdot Mirror
19-Year-Old Makes Homemade Solar Death Ray
An anonymous reader writes "Concentrated solar power has the potential to generate immense amounts of energy — but it can also be amazingly destructive. American student Eric Jacqmain has assembled over 5,800 mirrors into his own parabolic 'solar Death Ray'."
This is what a science education lets you do. Stay in school kids!
Move sig!
Like ~2,000 years ago. Talk about an old story.
vos nescitis quicquam, nec cogitatis quia expedit nobis ut unus moriatur homo pro populo et non tota gens pereat.
5800 mirrors, the size of fingernails. Glued on an already parabolic disc.
He used an old satellite dish.
Couldn't he just have spray canned it with some reflective paint??
Or glued aluminum foil over it. Or chrome plated it. He chose the most cumbersome way. Everyone who works cutting glass gets some nicked fingers from time to time, imagine cutting 5800 tiny pieces.
I imagined at least 10x10cm mirrors. Now that would have been "solar power".
True, if there had been 5800 10x10cm mirrors. For the same surface size, the smallest the mirrors are the better focus he will get. Ideally, the surface should have an infinite number of infinitely small mirrors, i.e. it would be a smooth parabolic surface.
More specifically, there are two issues with your suggestion. Firstly, lasers are not power-limited by input light, but rather by the design of the lasing cavity and how efficiently it stimulates further emission. Many types do need a decent kick to get them going, but beyond that a bright source offers little or no benefit.
Secondly, even if more input light was useful, this mirror doesn't actually provide that much power. It's just the use of the parabolic reflector to concentrate the energy into a small energy that makes it look impressive. Looking at the dish, it's a few square metres in area, at most. That's only a few kW of light in total, of which only a tiny portion is at any one wavelength which would be useful for pumping a laser. An appropriate pump laser or even a decent flashlamp would be vastly better than this for stimulating laser emission.
Also, LASER. Light Amplification by Stimulated Emission of Radiation.
That is why the legend says soldiers with polished sheets of metal. From there on the quality of aiming at the focal point depends on how good is sarge with the baton and the "give me 80 pushups in full gear" aim correction method.
Realistically a trained squad can aim and keep aimed around 40-80. Probably a 100 tops. That is more than enough to blind _ANYONE_ on the attacking ship in the days before sunglasses. I doubt that this would have been enough to set it on fire though. In any case, with the captain, skipper and most of the crew blind while facing catapults throwing burning tar buckets and 1m diameter stone balls the ship was as good as burning anyway.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
The tiny mirror pieces are from a mirror ball. Yes, I actually do go out sometimes.
What, you mean the victim is a vegan and you've invited him to a BBQ?
Quidnam Latine loqui modo coepi?
It's already in use - arrays of mirrors all pointing at a tower. The heat melts salt (which requires 538C minimum) which is then used to power steam generators.
http://en.wikipedia.org/wiki/Solar_thermal_energy#Power_tower_designs
Please consider this account deleted, I just can't be bothered with the spam anymore.
The whole point of the death ray is to be able to adjust the focus point.
The Mythbusters tried to set a boat on fire... which was assumed to be an enemy boat passing along the coast.
You can't reasonably expect the enemy boats to sail exactly at the focus point of your death ray... or to either come closer or go further away in case they are not at the focus point of your death ray.
This 19-year-old hasn't made the focus point adjustable... so you can't set a moving target at a variable distance on fire with it.
Any dish shaped thing with mirrors has a focus point - especially satellite dishes - so this isn't exactly rocket science.
In the Himalayas, parabolic mirrors around this size are commonly used to boil kettles of water for tea/cooking.
It works at those altitudes, because the sunlight is more intense (less having been absorbed by the atmosphere), and because water boils at a lower temperature at the lower atmospheric pressure.
http://en.wikipedia.org/wiki/Solar_cooker#Solar_kettles
That depends a lot on how fast the vehicle is moving.
Is that an African or a European vehicle?
And the people shall be oppressed, every one by another, and every one by his neighbour Isaiah 3:5
You're retarded, small focused flat mirrors are more efficient and less prone to scatter than a non perfect parabolic shape. Not to mention the reflectivity of actual mirror is far superior to any sprays or sheeting you could cheaply purchase. There is a reason the cells of production solar plants use flat mirrors that they combine to form a parrabolic array.
I have the simple solution to that question: a girl said she thought it would be cool.
God invented whiskey so the Irish would not rule the world.
Yeah, I used to burn ants with a magnifying glass too when I was much younger than 19. Solar death rays are pretty common at that age.
Seven puppies were harmed during the making of this post.
That's how I ended up with a Zune... :(
They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
Stirling Energy System's SunCatcher uses this system to drive a stirling engine mounted on a parabolic mirror. It always seemed like a better, simpler solution than photovoltaic cells to me.
If all else fails, immortality can always be assured by spectacular error.
And, bearing that size in mind, a quick back of the envelope suggests that 1 MW is the input power of the light, not the delivered power of the laser. A quick search doesn't turn up any papers or detailed articles relating to this solar tower specifically, but other examples of such solar-pumped NdYAG lasers suggest a conversion efficiency of about 10 W laser power/m^2 of mirror, or about 1% of the incident radiation [1].
So, assuming that lasing efficiency for this system, this is not a 1 MW CW laser, but a 10 kW CW laser pumped with over a megawatt of input power, which necessitates significant cooling to keep the thing from melting. Compared to traditional laser designs, this is still not that impressive, especially given the effort involved in its manufacture.
[1] A solar-pumped Nd:YAG laser in the high collection efficiency regime
Often they "Bust" something that they consider to be highly implausible or statistically unlikely even if there have been one or two cases of it actually happening. The show is focused upon "can this happen under normal or slightly abnormal circumstances" more than "if the right set of circumstances happen at the right time and everything goes as wrong as possible..."
But concerning the solar "death" ray, the real issue was that while you can easily make one out of modern materials, they didn't have modern mirrors or modern optics 2000 years ago. They've taken this into account.
Besides, where are you going to get to see a canon made out of duct tape?
I had to follow up with an example that shows their stupidity.
Bimp burns.
Bimp with hydrogen burns fast.
Bimp with thermite burns slower than just hydrogen but still burns considerably faster than simple material.
Bimp burns super faster with hydrogen + thermite, which accurately reproduces historic tragedy. The conclusion of intelligent people is hardly surprising; accelerent do exactly that and thermite clearly works as an accelerent with hydrogen (likely the extra O being provided).Their conclusion - busted. WTF!?!?! But if you ignore their stupidity which is their "conclusion", the reality is, they absolutely "confirmed" the myth, which was thermite (their coating) played a significant role in the speed of destruction. Its literally impossible to view the material with any other conclusion and yet they believe they busted it. Seemingly, they came to a conclusion which isn't even remotely supported by the available material or their tests. WTF?!?