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.

[flecom]

sooo... more importantly, why does it matter so much? where are you going to get a red that will have comparable beam specs (aka isnt a flashlight)

unless your using 660, in which case 1W of 445 is going to be way too much... so just use a pinhole?

[allthatwhichis]

If the process works well enough on these it might work well on the 638nm diodes to get close enough to a watt that could then be added to a quad of 660...

[flecom]

If the process works well enough on these it might work well on the 638nm diodes to get close enough to a watt that could then be added to a quad of 660...

a watt of 660 isn't very useful for beam shows, its barely visible unless the room is seriously smoked up... and by the time you stack up/combine/knife edge enough of them your beam is going to be pretty big

and the 638's are looking like they are going to be worse than the giant 650/635 reds so we are back to square one

the only diodes that give you decent brightness and dont suck are the 150mW 642's... but even then, you would have to combine a bunch to get a decent power, which means stacking beams, which gives you a gigantic beam again... so again, your screwed no matter what

unless you go all crazy with telescopes, wave plates etc... but all of that is extra losses, and a lot of $$$ and space in your projector

[andy_con]

a watt of 660 isn't very useful for beam shows, its barely visible unless the room is seriously smoked up... and by the time you stack up/combine/knife edge enough of them your beam is going to be pretty big

and the 638's are looking like they are going to be worse than the giant 650/635 reds so we are back to square one

the only diodes that give you decent brightness and dont suck are the 150mW 642's... but even then, you would have to combine a bunch to get a decent power, which means stacking beams, which gives you a gigantic beam again... so again, your screwed no matter what

unless you go all crazy with telescopes, wave plates etc... but all of that is extra losses, and a lot of $$$ and space in your projector

i disagree with most things you say there.

using the correct lens you can get a good beam with red.

you can get 5watts of red in a 5mm beam, arctos can get 7 watts of 640 in a 5mm beam.

5mm isnt big

[Zoof]

... then split the ~8x2mm beam to either knife the pair of 4x2mm beams together or use ...

just a thought, wouldn't it be the fast axis that you want to split, thus splitting the 8x2 mm beam into two 8*1mm beams? Otherwise you just end up controlling the slow axis....

So my GUESS is that it would be best to first run the beam through two pairs of prisms to first greatly expand the beam (up to 5x) and reduce its divergence before splitting it. So the too fat fast axis is then split into two slimmer beams which are then joined into a single slim beam. Also using a lens with not a too large FL would be better to prevent the slow axis from becoming to big at aperture.

[p1t8ull]

when i put a splitting mirror anywhere near the beam it
just muffed up the whole beam

No idea Chris, mine looked ok so I would need to take a look at your setup to see what could be causing the muffing (whatever the fek that is )
I don't know about you but I'm done trying this method now anyway, so won't be spending any more time on it TBH.

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?

The prisms before the PBS would work, but after going through them the beam would be pretty square and low divergence, so the splitting/folding idea will neither work or be neccessary.

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.

You'll need more than just a lens, either cylinder lenses or an anamorphic prism pair will need an invite to the slow axis correction party.
With a 4mm focal length collimator on a single diode and a pair of prisms I am seeing a beam of just over 3mm round with .9mR divergence. The distant spot is a bit of a line but this can easily be squared up with a tiny focus tweak.

[wondertwnz]

sooo... more importantly, why does it matter so much? where are you going to get a red that will have comparable beam specs (aka isnt a flashlight)

unless your using 660, in which case 1W of 445 is going to be way too much... so just use a pinhole?

The pinhole is my thought as well, I am going yo build a quad and (Knife edge and PBS) then just hit a pinhole to get the beam size down. I will probably loose a lot but hoping to keep about 50% of the power or more and have a 4mm beam. If you are not worried about losses like me why spend a lot of time and money on Glass?

Larry

[flecom]

i disagree with most things you say there.

using the correct lens you can get a good beam with red.

you can get 5watts of red in a 5mm beam, arctos can get 7 watts of 640 in a 5mm beam.

5mm isnt big

5mm is fine, but is the 445 even that big uncorrected? I think people here are trying to get 473nm sized beams out of these diodes and I don't see the point...

My 650's are 5mm which I would consider huge but when doing beams who's going to notice?

Even with graphics it's not THAT noticeable since the 445 is big and the 532 is also pretty big (1.5w fairly large beam)

[catalanjo]

just a thought, wouldn't it be the fast axis that you want to split, thus splitting the 8x2 mm beam into two 8*1mm beams? Otherwise you just end up controlling the slow axis....

So my GUESS is that it would be best to first run the beam through two pairs of prisms to first greatly expand the beam (up to 5x) and reduce its divergence before splitting it. So the too fat fast axis is then split into two slimmer beams which are then joined into a single slim beam. Also using a lens with not a too large FL would be better to prevent the slow axis from becoming to big at aperture.

For what its worth I agree with Zoof !

That's what I call konstruktive kriticisme.

Cheers

[flecom]

wow overcomplicated much? lol

make a tiny hole in a piece of black aluminum, done!

[gottaluvlasers]

ok-

i love all you guys and please, for the love of god, sit back and *REALLY* think about what im about ot say...

What you guys are talking about are "problems" that exist to *NOBODY* on the face of this big blue planet except you laserists who try to perfect things that cant (and dont need to be) perfected. LOL.

Come on guys. are we *really* expending this much time, money, effort, headaches and "research" into 4mm vs. 5mm vs round beam vs. square beam vs. "blueish halo" or "reddish halo" vs. 1.2mrad vs. 1.8mrad vs. who knows what else.

1) 445 vs. 473- NOBODY knows the difference.....except a few of us (us meaning laserists in the know) between the 2.

2) round beam vs. square beam- Almost damn near impossible to notice or see or have *ANY* idea of unless you project a stationary blue beam for an extended period of time and draw EVERYONES attention to it and point it out. In which case, that makes a pretty boring lase show in itself.

3) 3mm vs. 4mm. vs. 5mm or whatever- Again, who notices? who cares? (other than all of us ding dongs here trying to re-invent the wheel)

4) We are *laserists* who are paid (for the most part) to perform shows and provide an entertainment media to an audience. has *ANYONE* in the history of the galaxy and universe and time and space *EVER* have a client or audience member or guest or nightclub or ANYONE say, "Hmmmm....pretty good laser show, but did you see the size of that blue laser beam? it was square and not round!" Or, "Can you believe that crappy laser show we just saw, the white beam had a blue-ish halo around it."

5) the majority of the "issues" of these 445 diodes exist when projecting a stationary non moving beam at large distances. when does this EVER come into play during a laser show?

Sorry, maybe im a "realist" and not a perfectionist. i make shows and equipment to please the people that are going to be watching and paying for my shows. It seems like the only reason why some of this 445 argument comes into play is to try and see who can come up with a magical solution and post it here. It really poses no "real world" achivement to come up with some of the solutions being sought after.

Sure, if it was a simple lens solution to magically make things all better, GREAT. but it obviously isnt going to happen.

get a 445 diode throw a lens in front of it. Clean it up a little bit and do some shows. TRUST ME, the only people who know anything otherwise is people on this forum. And even then, its a few and far between.

Sorry, lol...not degrading anyone or saying your dumb or anything obviously. I just cant for the life of me figure out why this is turning into such a HUGE project. Guys...we have multi-watt blue lasers for the same cost as a night out on the town with a hot chick! LOL. where as before 200mw of blue costs as much as most of our first cars.

then we had problems with the blue dpss "noise" and instabilitys.

Sorry, just my 2 cents. I just did a show for over 2000 people and had the owner literally trying to kiss me afterwards becasue he had so much positive feedback for the display. that was with 2W of 445. and it looked FOOKING beautiful!!!!!!!!

im pleased with the people i am trying to impress. Square 445 beams at 5mm.....Keep em coming baaaaby!!!

Love y'all.....

-Marc

[flecom]

like I was saying before, I could stack several un-corrected 445nm beams and still not reach the size of my 650nm beams, and nobody said "man look at those giant beams" when 5W of RRGBB was flying around the room at SELEM

that being said, if you want to concentrate 100% on graphics shows AND have tight red/green lasers (dual LOC's and some low power nice beam DPSS) then you could easily run one of these 445's @ 1.2~W and put it on a pinhole, then bam, done, nice tight beams all around and probably like ~1+W total white output, which is NOT bad for a graphics projector for most purposes

[gottaluvlasers]

AMEN!!!


Hallelujah!!!!


Woooo freakin Hoooo!!!!

[polishedball]

nobody said "man look at those giant beams" when 5W of RRGBB was flying around the room at SELEM

Hmm I think I remember you bitching about it (just cause i saw em at the store already)

[flecom]

Hmm I think I remember you bitching about it (just cause i saw em at the store already)

what kind of laserist would I be if I didn't bitch about diode beams? lol

some day I can look forward to winning the lotto and making a stupid nice OPSL projector