Combining laser beams?

That's true if he wants to attempt such a build. Assuming you find a crystal that is high enough grade that can handle the intense power then you could in theory make a pretty powerful laser, in beyond short bursts. Personally, I don't see much draw for such a laser unless it was intended for scientific experiments since there is almost no showability. It sounds to me like he is just curious how they work since the main topic is about combining laser beams together.

ok i get it i have one moe qustion, what would happen if you pointed a laser beam already focased by a laser pointer lens into another laser pointer lense? would it continue in a beam or defuse? and if it continued what would hapen if multiple beams of the same power and wavelength threw the same laser pointer lens?

on a simaler note what happens to laser beams when passing through a convex or concave lens?

if any one can answer these qoustions it would be a big help to my project

Lenses effect laser beams just as they do any other source of light.

You wouldn't send a focused laser beam into another laser lens because you would just expand the beam. Its best to focus a beam and then combine them and be done. The fewer lenses and optics you pass through the less power you lose and the cleaner your beam will be.

Also, an output lens will affect the individual laser beams differently due to the different wavelengths and dispersion effects.

This is true but would it be enough to notice?

Mainly there is no reason to try to focus a focused beam. Focus the beams individually, combine them and then you have your complete finished beam. What else would you want?

It might depend on what you're trying to do. It could be as bad as "Dark Side of the Moon" prism-dispersion, or just something that causes a fringe.

Hmm, well anyway, the fewer optics the better. At least total output power wise and for size.