Solar Death Ray

solar death ray

you know summer is coming when hackers start crawling out from winter hibernation, desiring nothing more than to burn things.  not satisfied with a magnifying glass, this project’s author created a 6′ x 4′ parabolic reflector that uses 112 mirrors to direct the sun’s rays at a single point

36 thoughts on “Solar Death Ray

  1. it dosn’t work to well they tried this on mythbusters to attempt to set a wooden boat on fire but it didn’t work if you managed to concentrate the beam more it would work a little better

  2. Um, didn’t they just prove on Discovery Channel’s “Mythbusters” show recently that this was a big load of b.s.? I don’t think they got it above 200 degrees F.

  3. This isn’t new..nor is it a myth (which was on mythbusters and somehow it didn’t work). There have been pages written about this.
    Basically, you take a large piece of plywood and a lot of 1″x1″ or 2″x2″ mirrors, and screw two corners of each into the board. A dab of silicon sealant (figure this out on your own you hackers!) in a third corner acts as a hinge.
    Next, you get an incandescant lightbulb in a dark room (don’t do this outside yet) and focus each mirror individually, by adjusting the screws. You can watch the reflection on a wall – you’ll want to get each mirror pointing towards one spot.
    The creator of the site added a little aiming rod so you can support things…I’ve read about +200 mirror versions that melt copper pipe in a few seconds. Crazy stuff.

  4. It was a myth on Mythbusters because they were trying to validate the possibility of sinking a boat using this technology. When the hot spot is only at a particular focal point and the target is moving…myth busted.

  5. #3:
    good luck finding a lens that’ll take that kind of heat. fresnel lenses were originally developed because of uneven heating in high temp applications, but even those won’t be able to take this kind of heat. the focal point could be variable though if you put some kind of synchronized angle system on the backs of the mirrors, or if you used a flexible reflective dish with a pull string on the back so you could alter it’s focal length. barring those ideas, a complicated series of smaller lenses in the reflected light’s path may be able to narrow the focus as well as make it variable. but hell, keep it simple, keep it fun: get a cheap smooth curve wok, bondo it, chrome spray it, done.

  6. (ref. to #6) #3 said that one could melt copper pipe in a few seconds, i think that it could get wood hot enough to burn even if it was moving slightly (old skool boats used sails, something with an outboard might be safe enough)

    and you could still give any enemy sailor melanoma if they try to attack you :)

  7. The mythbusters show, I believe, was about sinking boats many meters away in ancient Greece–that is, with metal mirrors from their shields or something. They weren’t saying that a solar collector isn’t possible, just that the ancient Greeks very likely were not able to utilize this as a doomsday weapon. ( is something about that which someone linked on Slashdot.)

    In fact, solar collectors similar to this death ray in principle have been used as solar cookers before. I think you can make one with cardboard coverend in aluminum foil. Of course, it won’t be nearly as cool as this one. They’ve also been used to boil water for small power plants. ( is something I found on the subject at Google.)

    Also: I agree with myukev–this would be soo much more awesome if it bent the rays back to make a beam (versus a point), even IF a lens wouldn’t work. Maybe another set of mirrors . Now I just have to hope some guy does this.

  8. One of the only way i can think of to get a dynamic focus point is to use a rubberised/flexible reflector membrane encased in a cylindrical hermetic box. depresurising the container flexes the reflective membrane inwards thus making the focus point move along an axe prependicular to the dish. all this is of course pure speculation, beacause where the hell does one get a reflective flexible membrane. still makes for a good hack idea tho.

  9. This doesn’t really work. The Mythbusters tried it with a much much larger version and it couldn’t even come close. It produces a very blinding light though.

    Eric Wilson

  10. This isn’t really parabolic per se. I built such a thing when I was in Argentina and impressed by how bright the sun was there. Mine was a real parabolic dish made of scrap wood I found in the trash. It was covered with aluminum foil. I couldn’t melt steel, but I did bake a cake and I think it was used for a while to heat water for yerba mate. The real trick for me was that I didn’t have a computer handy and I did all the design with graph paper. It’s doable. Here’s some pix.

  11. Eric: You didn’t pay attention to either the myth buster show or the link, did you? Myth busters tried it on a moving target. The link does it on a still target placed exactly where it needs to be, and painted black if needed. I have built one, using 20 mirrors, to heat a sub inside aluminum foil. It does work, needs time and sun, depending on how many mirrors you use.

  12. Actually the target on mythbusters was stationary. But as with many of the myths they bust they did this one kind of haphazardly and I really didn’t buy the results. I didn’t think they did a very good job focusing the mirrors.

  13. There is an issue of Popular Mechanic or Popular Science (forgot) that featured (to the best of my memory) a company that melted lead (630deg F)by using parabolic mirrors made of mylar backed by aluminum coating. This issue came out…a bit over a year ago.

  14. To everyone who doubts that this can work… Have you ever seen what happens when you focus the suns rays with a magnifying glass?

    When using a large parabolic, for instance, you can succeed or fail depending on the quality of the parabola. If it concetrates the energy into a small enough area things are going to happen!!

    If the parabolic is not real ‘clean’, or it diffuses too much, all it will do is gently warm things up.

    This flat-panel mirror array can come close enough to a good parabolic to be QUITE effective. Check out the pictures on the site… they’re not faked ;)

  15. First of all, this is no mith… Solar “Death Rays” have been around for quite some time… This seattle version is nothing more then your standerd 9th grade science project… Second, the channel “MythBusters” has proven them selfs “fake” as time and time again they take real events and poorly reconstruct them to “prove” they are fake.. What would happen to the world if everyone was told that a dime droped off the empire state building could kill a person? An episode of MB said that thaT myth was a bull of crap… Obviously it is not… check the local news papers… even look at the sidewalks around the Empire State building, there is more then 1 repair mark… The show Mythbusters is little more then a show to prevent “forest fires”… The Solar DeathRay is real… next we will say that Teslas Death ray is fake… LOL, which was announced shortly after september 11TH that the DC is circled in “Death Rays” There was even an episode on Modern Marvels talking about how the USA has alread begun installing the SAME EXAXT rays in DC in Passanger Airliners for protection against terrorists… Case closed ;)

  16. I made one in college with an ’emergency space blanket’ stretched over a 54″ kids’ wading pool (hard to find one with a round upper rim with no decorations). Even stretching was with 64 bags o3 30 pennies each (all the old 3.1 gram copper ones), the seal was rubber cement, and the sides were taped as the penny bags were removed. Air was evacuated by sucking on a Bic pen tube stabbed into the side of the pool. The whole thing cost under $10 (this was back in the 1970s).
    The smallest focal “point” was 1.5″ x 2.5″ at 13.5 feet; a lightly crumpled brown paper towel dropped through the focus would burst into flames, and it melted lead tire-balancing weights in a few seconds.
    I have built several since, and with one I have felt the warmth of moonlight, and have seen jupiter-shine in the palm of my hand.
    Regarding myth-busters, they did an impressive amount of work polishing the bronze mirrors, but their MIT-inspired set-up was really bad, focusing one square foot at a time with no parallelism. The NASA guy was closer to the right track, but he would have needed a few dozen such units.
    There are at least two easy ways to build such units using materials and tools readily avaialbable to Archimedes. If I get the time, I’ll tell myth-busters how to do it right and see if they try again – they should be able to set a boat on fire in a few seconds if they do it right, although they’ll need to polish a lot of bronze!
    As for the “ray” that some people are talking about, forget it. The sun have a diameter of about 1/2 a degree, so your beam will always diverge by at least this amount (unless you use it to optically pump a laser, but I think that that would be beyond even Archimedes). So at 100 yards, the best spot you can get is 1 yard in diameter, which is why even with an excellent parabola it takes a lot of mirror area (at least a thousand square feet to light paper, and more like 10,000 square feet to light a wooden ship in a few seconds). But at 50 yards, divide the are by 4, etc.

  17. Hi Achim we’ll be fixing the problem with the characters soon. The reason the photo doesn’t come through is because the site isn’t formatting the image for us to grab. We’re using microformats now and are reading pages in a pretty specific way.

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