Homemade incinerator beam! - Page 4

Kamog · #31 July 27th, 2004, 02:12 AM

Do you think you can put an additional mirror at the focal point of the 16 you already set up, so that now you can use the 17th mirror to direct the beam in different directions? You just turn the extra mirror around to move the beam to different targets.

I'm not sure if this would work because the light beams may diverge again after being reflected.... There must be a way to keep the beams parallel, like using a convex mirror or using a lens or something.

Suicide Junkie · #32 July 27th, 2004, 02:30 AM

Bigger is better, of course, but I don't think you'll find converging mirrors much larger. And certainly not for a buck each

Rather than a small mirror at the focal point, you'd want a fairly large plane mirror closer in.
You can use it to move the focal point around where you like.
Alternatively, you could put the small mirrors in the shade and set them to a fixed focus, then use the large plane mirror to reflect sunlight onto them at whatever angle you need. You can move the one big mirror to follow the sun instead of all the little ones...

David E. Gervais · #33 July 27th, 2004, 03:45 AM

Quote:

Originally posted by mottlee:
.... alas is a pipe dream I do not have the free time to do this in the daylight hours

hmmm, do the same setup to reflect moonbeams,.. hmmm use a focal mirror to redirect the beam and aim it at passers by... The moonbeams should be 'enhanced' enough to fool people into thinking it's a full moon out. Sounds like a very good way to ferret out wherewolves.

speaking of focal points,.. I have a nice laser pointer that has a wavelength of 650-680nm with a power rating of 5mw. I did a test to see how far I could 'point it and still see the red dot,.. my max distance so far has been about 1000 yards (approximately 3 length of a football field. It was still clearly visible and could obviously shine further. But I had no targets further away and didn't feel like taking a walk just to test it with greater ranges. Maybe tomorrow night I'll try it.

anyway, babble mode off.

Cheers!

Kamog · #34 July 27th, 2004, 05:47 AM

1000 yards is pretty far.

I have only tried it in the daytime, and the range isn't very far at all. One time, I was at work in the board room for a meeting, and still waiting for some people to arrive. So we played with the laser pointer and pointed it outside at cars driving by, but we couldn't even see the red dot.

Laser pointers are so cheap now! You can buy one for $1 at the dollar store. I remember when they first came out and I got the impression that only the very important top executives used them for presentations.

Ruatha · #35 July 27th, 2004, 06:00 AM

Me and two friends where having a LAN weekend and I'd borrowed a projector from work, so at around midnigth we pointed it at the neighbouring apartment block about perhaps a 100 meters away and played some UT2003 with a approx 30x20 meters image, not for very long as we thought some people might disapprove of having blood projected into their apartments, but what a image, it was great, good enough for a movie!!
But it was a dark night.

Kamog · #36 July 27th, 2004, 06:31 AM

I remember reading an article some time ago that said that in ancient Greece, over 2000 years ago, Archimedes used the same technique of using multiple mirrors to focus sunlight on enemy ships and burning them.

[ July 27, 2004, 05:33: Message edited by: Kamog ]

narf poit chez BOOM · #37 July 27th, 2004, 06:42 AM

I read that in elementary school. Not sure where.

EvilGenius4ABetterTomorro · #38 July 27th, 2004, 05:07 PM

In the late 1800's some scientist came up with a plan for the Heliograph. Using a vibrating mirror you could use sunbeams to transmit a voice message like a phonograph. Didn't explain how it was received though. Would you need a vibrating mirror to receive it? Maybe a dark colored diaphram? If Google is up I think I'll search it and Archimedes too. I'm getting too many evil thoughts. Must...have...outlet...for...thoughts!

Jack Simth · #39 July 27th, 2004, 06:05 PM

The reciever just has to have high-fidelity detection; it doesn't necessarily need a recieving mirror at all - a solar panel shaded against direct sunlight feeding a mic input would do the job. From the description below, one simple idea would be that the vibrations on the mirror caused by sound waves would slightly change the angle of reflection, resulting in a measureable difference in reciept at the target; a small target either has the signal or has the signal interrupted - the length of those interruptions then determines the wavelength of the sound wave that produced it. A basic amplitude modulation system, really. A sufficiently large target can actually recieve the beam all the time, but at different locations - in which case, the sound wave gets graphed in it's entierety and you get better fidelity.

Quite frankly though, a laser link is more reliable (not weather-dependant, don't need to constantly adjust for the position of the sun, can use a specfic set of wavelengths to help filter interference from other sources {can even pick frequencies the sun hardly uses so that you can broadcast even with the sun directly behind you}, et cetera).

geoschmo · #40 July 27th, 2004, 07:20 PM

Figure a steak the size of one of your mirrors is getting enough energy to raise it's teperature to 90+ degrees on a hot day. You only need it up to 200-300 or so to cook it. You could do it with 3 or 4 of your mirrors there. You wouldn't need or want to focus them as precisecly as you are doing there of course. You want the focal area of the reflected light about the same size as what you are cooking instead of down to a point like you are doing when burning sticks.