Posts

Melting, Burning, and Generally Obliterating Stuff with the Power of the Sun

I always find that I discover cool stuff when I am teaching about it – right now, for example, I’m lecturing to my introductory Stage Lighting classes about reflection, refraction, the Index of Refraction, reflectance, normal angles, and all of that kind of stuff.  I love it, I’m a nerd to the Nth degree.  I’m also lucky that my research karma is good!

Something I find quite sexy is capturing solar rays for the purpose of just destroying stuff in a non-military way.  Yes, I’m one of those campers who loves campfires for the sheer awesome power of them.  I came across a few videos of people harnessing the awesome power of our Sun into a small few centimeter-square area for the purposes of, well, burning stuff.  I have two examples – one is an expensive solar capture device that focuses a few square meters of sun into an area of an inch, and the other is a homemade solar reflector made from a satellite dish.  Even though the cheaper one is cheaply made (I mean comparatively, not offensively), it harnesses some amazing solar power!

Check out this first video – a lab environment, a huge mirror, and thousands of degrees of sunlight:

Here’s the second video, a homemade SOLAR DEATH RAY!

Awesome.

Thanks Hack-N-Mod!

Frosted Glass VS Scotch Tape

Okay, this is one of the neatest tricks – frosted glass + Scotch tape = clear glass.  You have to see this:

Is this magic?  Is this some kind of interstellar phenomenon?  It is certainly cool and mysterious, but it makes sense if you think about the way that light, reflection, and refraction work together.  This is a very simple analogy, but imagine a stretch of blacktop on a highway – when the sun is shining on it on a dry day, the blacktop is rough and not reflective at all.  The matte surface of the blacktop, if anything, has a diffuse surface that takes a beam of light and turns it into many beams of light, all separate and at less strength than the original – just like velour or a busted piece of porcelain.  I made a few images to express this phenomenon – the first shows a beam of light (incident light) hitting the surface of a matte object:

matte reflection

In the case of a frosted piece of glass, some light makes it through the glass (is refracted), but nothing in its original beam form – it is very diffused and spread, like so:

matte refraction

The Scotch tape trick is pretty cool, as it basically fills in the rough surface of the matte glass with the adhesive and whatever other goodies are in the glue on a piece of Scotch tape, allowing the light to pass through the frosted glass without a lot of extra refraction and diffusion.  The tape acts as a filler, in other words, giving less spread to the frosted glass, as below:

low refraction

Now obviously in the image above I have not accounted for real refraction, the normal angle of the glass, or any of the factors that would basically make the smarty pantses of the world say “a beam of light would never just pass through the two materials without SOME kind of refraction and diffusion!”  Well, you’re right.  My illustration was more to show that the diffusion would be less.  But does the overall point make sense?