Polarisation

[buffo]

Maybe some kind of crystal exists with 4 faces that splits an incoming beam into 4 sperate beam with a polarisation 45° apart (* as input and |, -, / and \ polarisation as output).

If such a crystal existed, it would be *quite* amazing. It would also already be in use. (Just think how much better the beam from the Arctos red would be if they could use a crystal to combine all those beams instead of relying on fancy optics to get them positioned really close to one another.) Sorry, but the laws of physics are against you on this one.

Adam

[jeejeedr]

Are there polarizing filters/mirrors out there somewhere that transmit (or reflect) a certain polarisation and reflect (or transmit) ALL the other polarizations?
If so, it would be possible to combine multiple lasers using these 'things'. A quick search on google did not get me results (yet). So maybe someone knows I could stop my search or that I should continue.
What I've found are some researches where they do combine (lin pol) lasers in such a way that they form a pseudo-randomly polarized beam.

Probably I'm just dreaming off a bit too much (again)...........

[buffo]

What I've found are some researches where they do combine (lin pol) lasers in such a way that they form a pseudo-randomly polarized beam.

Assume that you have two lasers with 100:1 polarization ratio's. That means that for every 100 mw of output that is vertically polarized there is 1 mw of output that is horizontally polarized. Assume that they are both rated at 200 mw each. If you combine them, the resulting beam will have (roughly) 200 mw that is polarized in the vertical direction and another 200 mw that is polarized in the horizontal direction.

In other words, the combined beam is now UNPOLARIZED by definition. Not randomly polarized, but unpolarized. (Since the power levels are now equal in both planes.) The only way to make the combined beam polarized again is to filter out 50% of the power.

Note that this *isn't* the same as random polarization at all. Random polarization means that one or the other plane is still favored (that 100:1 ratio we were just talking about above), but the specific orientation of the polarization plane changes - often rapidly and unpredictably.

There are some fancy optics that can rotate the polarization of an already linearly polarized beam, and you might think that using many such optics might allow you to get beyond the 2 laser combination limit and end up with more power. But you just can't. (For a whole host of reasons that are at the very heart of electromagnetic wave propigation theory.)

So maybe someone knows I could stop my search or that I should continue.

Well, the search will probably lead you to sites that can help you understand the physics behind WHY you can't do what you want to do. So there is value in the search. But speaking purely from the point of whether the search will yield a result - yeah, you can stop looking.

I'm not a teacher by trade, which is probably why I've failed to explain it clearly enough. ops: I'm sure there are sites on the Internet that do a better job of explaining the physics though... (But it's 5 AM and I don't have the energy to google for them!)

Adam

[JimBo]

Maybe we could get the axicon that we were talking about in this thread.

Jim

[buffo]

I'd like to see that come to fruition. Lostgallifreyan was the one that was really pushing the idea, but I haven't heard anything from him in a long while. Steve Roberts (of alt.lasers fame) was also involved. Then the whole project just seemed to die. Wonder what happened?

Adam