445nm split and recombine beam?

[Phredy1]

Just a thought of how I could improve the beam on the 445nm.... Why couldn't you split the beam with a mirror on 1/2 of the beam, reflect that beam to a halfwave plate and then combine the beams back with a PBS? It seems like that would be a way to get close to 1/2 width maybe? There probably is a reason it won't work, but in my mind's eye it seems like it should work. -Gene

[Phredy1]

Wierd.....CR don't seem to be working. All in 1 line.

[wondertwnz]

Seems like a good idea, I will be interested to see if someone can make it work.

[p1t8ull]

It does work and is a good way to reduce the beam diameter.

In the hope that the divergence would be acceptable, I tried using the longest FL single aspheric collimating lens I could find (which was 8mm and large diameter so high NA and very low losses as there was no clipping) and then split the ~8x2mm beam to either knife the pair of 4x2mm beams together or use a PBS as you described, but the divergence with this lens was still over 1.5mR so not really good enough.
Using a longer FL collimator would mean the beam diameter increasing >4mm, again not really all that great.
To reduce the 4x4mm beams divergence would require secondary collimation, so again a beam diameter increase.
At the end of the day there are less complicated ways to get better beams from these diodes.

So once again, that nasty fast axis and the laws of physics get together to eat up another pile of time and money.. heyho

[badger1666]

It does work and is a good way to reduce the beam diameter.

In the hope that the divergence would be acceptable, I tried using the longest FL single aspheric collimating lens I could find (which was 8mm and large diameter so high NA and very low losses as there was no clipping) and then split the ~8x2mm beam to either knife the pair of 4x2mm beams together or use a PBS as you described, but the divergence with this lens was still over 1.5mR so not really good enough.
Using a longer FL collimator would mean the beam diameter increasing >4mm, again not really all that great.
To reduce the 4x4mm beams divergence would require secondary collimation, so again a beam diameter increase.
At the end of the day there are less complicated ways to get better beams from these diodes.

So once again, that nasty fast axis and the laws of physics get together to eat up another pile of time and money.. heyho

hi simon
and how do we split these beams in half ??
i tried and got nowhere ,when i put a splitting mirror anywhere near the beam it
just muffed up the whole beam

thanks

[andy_con]

chris its all about using the right edge if the mirror, you want a nice sharp edge.

[badger1666]

chris its all about using the right edge if the mirror, you want a nice sharp edge.

hi andy i know this but you try and split a 445nm diode beam , you be suprised at what happens when you do try , try it and see what happens to the far field beam
but after a few meters you can split it no problem. it somthing to do with the diodes being astigmatic simon did explain it all to me, and i gave up trying

[Phredy1]

chris its all about using the right edge if the mirror, you want a nice sharp edge.

Andy:
That was exactly how I had it in my mind to split the beam.

Simon:
Could you put a anamorphic prism pair before the split and another anamorphic prism pair after the PBS? Or is that getting too expensive and too much losses to make it worthwhile?

Who has gotten a 4mm x 2mm beam (or better) with decent divergence from a 445nm diode? And how did they do it? I have seen a ton of posts on what lens to use and can't really figure who has a solution for the 445nm that works good.

Thanks,
Gene

[allthatwhichis]

Or is that getting too expensive and too much losses to make it worthwhile?

I'd be interested to know; I'd be happy with 1W with a tight beam and low divergence out of 4 diodes and a fat beer mugs worth of glass... Only the glass will be expensive.

[Phredy1]

I'd be interested to know; I'd be happy with 1W with a tight beam and low divergence out of 4 diodes and a fat beer mugs worth of glass... Only the glass will be expensive.

There MUST be a way to get a decent beam out of these diodes..... I have 24 of these diodes just waiting to be put in something that works good. If it takes 4 diodes to make 1W of great beam 445nm I would be happy.