inverse beam splitter?

I'm working on building an etching laser and want to have a visible red 5mw laser to serve as a guide, then switch to the IR laser for etching.

Ideally id like the opposite of a beam splitter. Basically shooting a red laser from one side, then switching to the IR laser aimed at the other side. The idea is that the red laser would travel the exact same path as the IR laser.

I figure there has to be a prism or something for this but maybe a beam splitter in reverse would work?

A polarized beam splitter cube will do just that. Even though it has splitter in the name, it can be used to combine two lasers. Just rotate
each laser so that it matches the polarization of the cubes surfaces so that it transmits the lasers in the fashion that you want it to.

Where do you get one of these? Preferably not online, but if it is only sold online, then what's a site to find it on? Thanks

I get a lot of optics from optical sleds after ripping out the prized diodes. The biggest one i have found were in the PS3 sled, while
other slightly smallers one have been found in DVD burner sleds. I think that you're application might suit a PBS cube from a DVD
rewriter because the cube will be set up for red/ir, i think the cube from the PS3 might have to much loss with a high powered
Ir since it is coated for 405nm aswell as red.

The only problem i can see with this is getting a cube that isn't too small.

Gryphon said:

A polarized beam splitter cube will do just that. Even though it has splitter in the name, it can be used to combine two lasers. Just rotate
each laser so that it matches the polarization of the cubes surfaces so that it transmits the lasers in the fashion that you want it to.

Click to expand...

Thanks, that's what I thought but I seemed to recall a type of prism that would always output a beam in a particular direction regardless of the angle of incident. With a beam splitter the angle of incident of both beams would have to be exactly 180 degrees, correct?

You can set up a PBS cube so that one beam passes straight through, then the second beam it shot into the cube at a perfect right angle to the
first beam. The cube will reflect the second beam at a 90 degree angle so the second beam is inside of the first one. Just make sure the PBS cube
is set up correctly, otherwise the second beam will be redirected in the wrong direction(back into the first laser)