Big red

[buffo]

Yeah, getting them really close is often good enough, but if you use a polarizing beam splitter, you can super-impose one beam on the other so they are *perfectly* aligned. (concentric, if you will) There are some nice pics in the gallery section of various projectors that have a pair of Maxyz modules installed for red. Browse around and you'll see what they look like.

Adam

[carmangary]

Probably a stupid question to you all but I am new to lasers. If you shine a fat beam through a pinhole, will it make a skinny beam?

[buffo]

Probably a stupid question to you all but I am new to lasers. If you shine a fat beam through a pinhole, will it make a skinny beam?

Questions are what the forums are for dude! And it's actually a pretty good question...

If you shine a fat beam at a pinhole, two things will happen. First, you will effectively "mask" out the part of the beam that won't fit through the hole, which means that you will loose some of the total power of the original beam. But the power density is normally greater at the center of a beam, so you won't loose as much power as you might think. And, since the fat part is now masked, you'd think that you would have a nice thin beam exiting the other side of the pinhole. And you will, in a sense. But there is another effect at play here, and that is diffraction.

Light is a wave, and so it will tend to diffract around the edges of the pinhole. (Just as waves in a harbor will diffract around a breakwater.) The effect of this diffraction is that the nice, narrow beam coming out of the pinhole will now begin to spread out! Not like a floodlight, mind you - it's still a laser beam - but the divergence of the beam will increase dramatically. The smaller the pinhole, the more the divergence goes up.

So, if you start with a 10 mm beam, and you pass it through a 1 mm pinhole, you will end up with a low power, highly divergent beam that is not very usefull. But if you've got a 6 mm beam, and you pass it through a 4 mm pinhole, you might only loose 15-25 % of your power, and the divergence will not increase by much, so you can still use the emerging beam in your laser show.

Still, it would be better to buy a laser that has better beam characteristings to start with. Failing that, the other option is to place the mask in the center of a set of collimating optics. (Set two lenses of equal focal length apart from each other at 2X the focal length, then place your pinhole mask in the middle at the focal point of the first lens.) This will limit the effects of the diffraction around the hole.

Adam

[aijii]

Cruch,

One option is to use adjustable collimating lenses in front of the green and blue to play with beam size vs divergence...

We have just finished building the "guts" of an RGB (pics soon) where the green and blue lasers have adjustable focus.... this lets us compensate for the shitful beam our Arctos red laser puts out.

[liteglow]

wow.... if you use a actros red I guess the total mW output of that laser is alot
I hope to se pic soon