Parabolic solar ray gun a.k.a solar death ray

I'm sure this project has been done many times in many forms, but I just wanted to add my project to the list. As I was throwing out my clutter, I found one panel of an old, fiberglass tv satellite that I hadn't thrown out yet and I was also throwing out a bunch of junk CD's. This is when the idea came to me to make solar ray gun. I didn't want to spend/waste alot of time, so I didn't cut the cd's into smaller circles -- I just hot glued the cd's directly to the surface of the satellite panel. Since the panel is curved (parabolic?) and the cd's are flat, but flexible, the cd's will somewhat conform to the curve of the curved panel and focus the solar beam into a smaller pattern. For this particular panel, I was able to get a piece of wood to start smoking, about 3 feet in front of the panel and the beam focused down to about a 3 inch diameter pattern.

Comments

[kdavis17]

If you combined the parabolic instructable with the instructable: simple solar cooker http://www.instructables.com/id/Simple-Solar-Cooker/ with this parabolic heating method, would that make the heat more direct under the cooking pot? I looked at these two pages while searching for something else and thought, hmmm what is these two ideas were combined?

[erob1]

Just tried this, but prior to gluing the factory CDs to the parabolic surface, I had taped the entire parabola with aluminum foil tape (available at walmart for $4.00) to compensate for the area left blank by the CDs. Unfortunately, once tested in direct sunlight, I had multiple beams aiming in different directions. Upon further investigation, I realized that EACH CD had a reflection of the image in front of it, not like a true mirrior, where there exists only one reflection of each object (aka not multiple distinct reflections on each CD). After of course failing, I removed every CD and was left with a paraboloid shape covered in aluminum foil tape, and the reflected light was significantly more brighter (was seeing green for 2 minutes afterwards) light, but I could not conclude much because the center portion of my paraboloid shape was blank. I had basically a parabola alum surface with a donugh hole in the mirror (talk about giving new use to your dirty clothes hamper lid..).

[erob1]

Nice... I would love to try this... anyway, I signed up to this website (username) just to download the plans (thought the picture is worth 1000 words..) and now that I'm logged in, I can not find the download link! :)

[dhymers]

neat idea, but quite possibly the best way to make these is with a 3 ft or larger direct-TV or other satellite dish, cover it with adhesive backed chrome vinyl (available online or at your local sign / decal shop) Cut it into strips and over-lap them applying to the surface of the dish. I highly recommend sanding it before installing the vinyl, its well worth it. You can set bits of wood on fire in under 15 seconds, or you could focus the beam onto a flat plate of thick steel, and heat it for cooking.

[aristide202]

vinyl is semireflective , it works like mirror sunglasses , a part of light is reflected a part passes through and so heat does

[dhymers]

The Chrome vinyl I used is 100% opaque, it is basically a mirror finish.

[nemitor]

ahh, so its like a reflector. Just focuses the light into a beam - like a magnifying glass. cool

[kishida]

Yes, similar to a magnifying glass / lens. In fact, there are telescopes that use a more perfect (parabolic?) version of this reflector instead of glass lens.

[aristide202]

it is parabolic. One side mirror is much easier than a two side lens to make.
Anyway that's a 1/10000s inch surface job

[shawntherobot]

could you use tinfoil that isnt wrinkled

[aristide202]

we'are not looking for optical grade perfection , just for heat

[aristide202]

What if you don't have so many junk CDs ? Just try aluminum foil or even aluminum foiled tetrapack juice boxes if not yet banned, Both quite reflective too and easily collimable.
I used tetrapack also for custom made inside car sunshields for a few summers in extremely windy Corsica island . Absolutely an amazing top class look and anyway the most functional ever.

[Opcom]

I like this - a great use for all those pesky AOL free trial CDROMs. I mean, how many does one really need? Yet they are in abundance. Nice find on the substrate too! This reminds me of an old project from years back. Consider a much larger version: the AASBOR {tm}- "Active Array Steered Beam Obliteration Ray". It uses one image recognition system, one processor, and one robotic positioner per element, yet costs as litte as $100 for a 1000-element array of about 780SQ. FT. This is because the optics, robots, mounting system, and processors are free. I'm not going to do an instructable, because it does take time to get all the components together for photos and the like, and I already have projects that demand my constant attention, but I thought this would be a good place to mention it as a compliment to the system shown herein. 1. find 1000 discarded record albums. Free.. either really bad tunes or so scratched they are to be pitched. The older albums are more rigid, they will do better. 2. Buy or find 1000 sq. ft of 12" wide aluminum foil. 3. cut the foil into sheets to just cover one side of each album. Glue it or tape it, matters not. Just make sure it is flat and shiny side up. These are the reflectors. 4. get 1000 of your best friends and go to the local sports stadium. Give each one a reflector, accompnied by any appropriate safety warnings (may be conveniently affixed to the backside) Place the volunteers in a roughly square pattern on the bleachers. This comprises your optically steered robotic aiming system and is the final step in the project construction. Note: an optical filter may be necessary on each robot to avoid the glare damaging the optical sensors. Some old sunglasses should do. 5. Place target (approx 2FT square) and instrumentation (optional) in center of field. Wait for 9AM or 10AM. A carbon disk or sphere is useful because it won't easily melt or vaporize. 6. program the system to actively steer the reflected beams of sunlight at the target and activate. Be sure to shoot video from several angles. safety notes: It is unwise to remain on the field during the test, as experience has shown that due to buggy software, this type of system, in nearly every instance, eventually mistakes a screaming person running in circles engulfed in flames for the stationary target. The bug has not been corrected, use at your own peril.

[extrordinary1]

Have you tried using mylar to cover the old albums? Great idea with the foil, as you inspired me to do something else with mylar vs. foil. I know where to find a lot of old albums very cheap.

On the other hand, I built a cooker that used a radiant heater aimed at the dish so I didn't need a tracking system for one, just powered it up with storage batteries and an inverter, all connected to a wind generator. Which later inspired me to build a furnace that sat in the basement, added a cold air return vent from upstairs to the base of a set of square pipes welded aluminum, I was heating up painted with high temp paint. Cook the paint outside due to the nasty fumes it creates curing out. You can get a much hotter surface this way, 24/7. I later built another unit to sit in a shed outside the house and used household ammonia like meat lockers use or RV refrigerators use for an ammonia absorbtion cooling system. In the winter I then had dual heat sources, as I could use the heat side of the ammonia system to help heat the house, rather than dump it outside.

One man showed me a compound solar heater he built to heat his home with on sunny days. That is what inspired me to design the other system so I wasn't restricted to sunny days only, or nothing at night time. This gave me heat 24/7 much cheaper than the power company, definitely cheaper than natural gas!

[acaz93]

instructable?

[kishida]

Well, I was thinking that just the picture was "worth a thousand words", plus the brief description. This was also meant to give ideas for other projects. You could glue all the cd's to a flat board, then warp/pull the board against a large ring (such as a old bicycle rim without the spokes) using a bolt in the center of the board to variably focus the solar beam...

[Derin]

If it is so,you can make it a slideshow.

[testicle]

sorry about the spelling mistakes.. maybe my distillation experiment??????

[testicle]

tnx for the reply. The diameter was about two and a half feet, the drum was an old alininum pot plant holder, from the 70's I think...I must say it was not my idea, rom an old popular science mag. I will post the article soon. I hope it can help over insrtructibles... I am EXP with som great stuff.. between working...I am willing to give to you guy's for free. power to the poeple....

[testicle]

Another good way to make a reflective parabola, is to use some reflective mylar sheet streached over round drum. Suck out air and bingo!!.Have used this to burst into flames a ball of newspaper @ 30 ft...Great site! Power to the people....

[kishida]

I like your idea and that you were able to burn at 30 feet. What was the approximate diameter of your drum? What did you use for the drum? Thanks.

[meritsetgo]

great use of what's at hand, the reason for the low output is that cd's have a thick, clear, plastic layer that acts as a heat insulator and robs much of the reflected light's energy. If this layer were removed (and do not think it is possible anyway without destroying the cd) then you would increase "power" but then i am afraid the shiny metal layer would start to corrode...however your idea is very clever, so much that i am making a parabolic death ray prop for my kids to go out and kill godzilla once and for all.

[Lftndbt]

Nice use of otherwise disposed of stuff! One question though.. What happened on the right hand side of the dish? You were going so well and even, then you screwed the top corner... Ran out of cd's? LoL!! :)

[kishida]

Actually, I had plenty of cd's (lol, why do I save them anyway...), but only 2 would fit in that corner, so I just spread out the 2 cd's in that last space. Now that you mention it, it would have looked nicer, if I had stayed with the pattern.

[frettiyeti]

break old mirrors and reglue them togather......lots of fun picking the glass spilters out of your fingers but ive heard it works very well..old TRVO sat dishes are also found in junkyards..........

[kishida]

I like that idea, except for the splinters. Maybe if I coat the back with contact cement, then coat the parabolic surface with contact cement, place the mirror on top of the parabola, then break the mirror... I was thinking of using/cutting mirrored plexiglass, but I didn't want to spend the money. I also was thinking of using an uncut piece of mirrored plexiglass, and have a center bolt to pull/curve it against a rim...

[falconphysics]

I saw a much larger one at a high school science fair once. Unfortunately he never got as much heat as he figured he ought to get from his 6 foot diameter dish. CD's just aren't reflective enough.

[kishida]

Yes, the CD's were less reflective/ideal than mirrors and I also used factory created CD's (AOL, Earthlink, etc.) over used writeable CDR's because the CDR's are even less reflective. I was thinking of cutting mirrrorized plexiglass pieces, but I was being cheap and lazy, so I used the old CD's.

[falconphysics]

You might also try one of those mylar emergency blankets. It should be more reflective and be pretty easy to put on and pretty cheap.

[kishida]

I did try attaching a mylar sheet from a automobile window shade with spray glue, but it had a somewhat wrinkled texture, so I'm afraid that it might have diffused the sun too much to get a good focus. I wish I had one of the mirrored finished mylars sheets lying around to try...

[servant74]

Wouldn't using some spray glue and aluminum foil work as well?

[kishida]

It might, but I'm not sure. I'm wondering if the foil might not be smooth/uniform enough and might disperse/diffuse the sunlight too much. As each of the CD's are glued, they will curve to match the curvature of the underlying parabola. Besides, I didn't want to waste any aluminum foil and had plenty of waste CD's to play with.

[RaisedByRobots]

ingenious use of old CDs. I always wanted to make a parabolic kiln for firing clay for free. This could be one way to do it!

[kishida]

Let me know if you make it. I don't know if it's possible or feasible. I'm wondering if you can build up enough heat to fire up a small object or not. You would also need to track the motion of the sun, either manually or some kind of timer. A while ago, I was giving thought (never built) to building a solar oven to cook beef stew all day and I was thinking piecing together a solar tracking device made from a lazy susan, a fixed weight, pulleys and a slow leaking container of water to shift the weight to move the lazy susan through pulleys... Another tracking idea was to use some kind of wind-up / unwind device or toy to attach to the lazy susan... I'm not necessarily a renewable energy / green person, but for the sake of free cooking, I was avoiding the use of house current to drive a timer/motor.

[RaisedByRobots]

Seems like if the parabola was pointed up to the sky and had a wide enough distance from the vertex to the focus it could catch the majority of the sun's angles. I think it probably would get hot enough to fire clay. Since Indians fired their clay using only hot coals and desert sun, I think it would. Maybe it would get too hot though, that's what I'm thinking.

[kishida]

It would be interesting to try. Maybe you can do a small scale test to see if it can work. I would be interested in the results because, ever since playing with clay at a crafts class, I always thought it would be fun to make/fire a piece or 2, now and then.

[PKM]

Nice use of CDs! Oh, the fun we had building one of these with an entire circular satellite dish and rolls of foil.. but you have to burnish the foil and stick it down with huge amounts of tape to get a decent reflector. Shame.

[erfonz]

You should put this in the forums.

[kishida]

Hi, Thanks. I didn't think this project would initiate discussion.

[Coffee bean]

tesla live on!!