how to make a laser?

[pixie]

I've used the plugin for maxon cinema in the link I gave regarding mathematical functions

[Kram1032]

x²/4f is quite a simple formula, isn't it?
If you don't mind faceting too much, it's easily doable by hand... And else, a script which does it should be done easily, too...

[CTZn]

Well I like alex22 solution better, even if you can't get parallel rays with IES. Are you guys going to as for his IES or definitely forget about it ?

[alex22]

I just built a parabol by hand and its much easer to get it in focus now! Was actually quite easy thanks to the spin tool.
edit:I put in the IES, its very simple, just look at it in texteditor

[Borgleader]

Hmm, this makes way for some very intriguing scenes

[CTZn]

Thanks alex22

Now that we have an 1° spread light ray, the maths must be easy to find the right parabole for it !?

[v_mulligan]

Nice, how do you do the parable?

There are some in the New Testament, though I'm not a particularly big fan myself . A parabola is the curve defined by a quadratic equation, the simplest being y=x^2 and the general form being y=a*x^2 + b*x + c. A paraboloid is the surface formed by rotating a parabola about an axis. This is the shape of satellite dishes and telescope mirrors, since it will cause parallel rays to converge to a focus -- or make rays diverging from a focus parallel.

I tried it with an special IES and an squashed halfsphere as mirror, but I can't get it parallel, its always diverging a bit.

Cool! You just discovered spherical aberration .

[v_mulligan]

Incidentally, I'm impressed that this works. It's a tribute to Indigo's ability to model the physically accurate behaviour of light.

[alex22]

My second test is made with a paraboloid.

Here a picture showing it:

[CTZn]

Excellent, how about using a lens now

[v_mulligan]

Umm... I'm not sure you're doing it right. Unless that paraboloid is a very, VERY dense mesh, you're probably just reflecting your light in a flat mirror.

What you really want to do is have rays coming from your source in a broad arc -- say, 45 to 90 degrees. These should then strike your paraboloid and reflect back so that they're parallel. The diameter of the laser beam will be approximately the diameter of the paraboloid, so you want to use a very tiny emitter, a small paraboloid, and a large scene.

[alex22]

actually your right, but I didn't notice earlier just how large my mirror is. Will going to adjust it.

[v_mulligan]

Here's what I meant. On the left, I've got a tiny hemispherical emitter at the focus of a parabolic mirror, with a small beamstop in front of the emitter to prevent it from flooding the scene. On the right is an ordinary cube. You can see the green beam reflected from the mirror is the same size as the mirror and it doesn't spread out at all. Pretty good laser, eh? All this needs is a little fog in the scene so that the beam is visible.

Incidentally, the laser is green, here. The red rods are not part of the laser setup -- they're just to add a little more illumination so that you can see what's going on, here.

The diagram at the bottom shows why you DON'T want to use an emitter with only a 1 degree spread. You want a nice wide spread to use the full curved surface of the mirror, and to minimize the amount of light blocked by the emitter itself.

[v_mulligan]

Here's a version with a little bit of fog so that the beam is visible. Of course, the size of the emitter setup, intensity of the beam, and fog thickness would all have to be adjusted to get the desired effect -- but the proof of principle is here.

Again, the red rods have nothing to do with the laser. They're just for extra illumination.

[OnoSendai]

Very cool experimental setup v_mulligan.