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Beam splitter/combiner cubes for 14w of 450nm

RedCowboy

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I have been looking and maybe I should put this under wanted to buy?

Is anyone aware of a 10mm x 10mm x 10mm or larger splitter/combiner cube capable of holding up combining 2 NUBM44's both beam corrected via cylindrical optics?

I may not even use a wave plate, the beam shape plus wont be all that misshapen, I just need one that's 10mm cube that will take 14 watts in the smallest area no less than 5/16 x 3/16 inches.

I'm hoping someone has already done this and knows of a good cube with low loss that won't fail.

If this is in the wrong thread I will move it, thanks.




PBS Blue - Opt Lasers




This should handle it no problem. Right?
Am I reading this right, will this take a 1000 watts per square cm?

So 15 watts is no problem Right??

Anyone?
 
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Pi R Squared

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PBS Blue - Opt Lasers


Am I reading this right, will this take a 1000 watts per square cm?

So 15 watts is no problem Right??

Anyone?
That has to be a mistake. The expensive ones that Thorlabs sells are I think mostly 50W and 70W, and that's even the smallest 5mm ones if I remember right, they have several sizes up to 2 inch. I would think though that any cheap one could handle 15W, that one you linked to they probably meant to claim 100W.

Alan
 

RedCowboy

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Thank You Pi R Squared
I wanted to rep you for your help but I will have to owe you.





You know I think a pair of 7875's beam corrected and cubed although having half the total energy of 2 x 44's would have a better energy density and less total waste heat.

I suppose I should do both and conduct a test, I have yet to correct a 7875.

Thanks again
 
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Cyparagon

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that one you linked to they probably meant to claim 100W.

Alan
You're misunderstanding something fundamental here. There's a BIG difference between power and power density. A 2x4mm beam is 0.08cm². A 15W beam with these dimensions would therefore be 15W/0.08cm², or 188W/cm². If what you said was true, this cube would not be able to handle a typical 8W beam.
 

RedCowboy

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So according to the sellers spec, I'm good to go for 15 watts?
 

Pi R Squared

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You're misunderstanding something fundamental here. There's a BIG difference between power and power density. A 2x4mm beam is 0.08cm². A 15W beam with these dimensions would therefore be 15W/0.08cm², or 188W/cm². If what you said was true, this cube would not be able to handle a typical 8W beam.
Yes I understood that the power was for cm² but I wasn't thinking about the size of the beam, you are correct, thanks for pointing that out.

Alan
 

Alaskan

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Just don't take the beam out of infinity focus, if you focused the beam to a tiny spot on the cube, then you could have a problem. I recently asked this same question of opt lasers and that's the answer I received. Since cyparagon just explained it, I guess I don't really need to chime in but wanted to talk about it a little differently, in regards to infinity focus being safe for the levels you are wanting to push through it.
 

RedCowboy

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Oh yes, thanks I thought about that, but that's good info, I specified 5/16 by 3/16 as my merging points for all the energy. :)
 

Light superglue

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Hi Red Cowboy,

I am new here on LPF. Although I have been reading the forum since 2007, have only registered just now, so my 1st reply will be to your thread.

Exactly last week I have checked some PBS from different suppliers in combining two NUBM44 purchased from DTR.
The combining itself was unexpectedly easy because at such big divergence the 2 beams look one (+ shaped spot, both beams focused to infinity) even if not perfectly superposed!
The difficult part would be after waveplate and cylindricals or anamorphic prisms will be added.

I have checked several PBS from different suppliers, and those from Lasertack, Stanwax, even cheap ones from Ebay (techhood) and Aliexpress (Tiangreen Lighting Technology) work the same (I obtain 10.88W, my LPF is thermal, bought in 2007 from a LPF member), however one PBS from Aliexpress (U-laser Optic Technologies) was crap, reflects all light and I only get 5W with it. Most probably they have sent me a NON-polarizing beamsplitter!

So, back to the topic. The combined output is not even close to 14W, and one of my NUBM44 drivers is preset 5A to give 7-7.36W laser output alone. 2nd at 4.5A and output mesures 6.5W alone. It seems to me that light from these diodes is only 80% polarized.

To make the optical stand for PBS checking I had to buy some stuff: smallest breadboard from Thorlabs, 3-axis holder from banggood (techhood sent crap like in aliexpress, not what was on the picture). I used 2 knobs of a RGB dimmer to make beams adjustment with lowest voltage feed possible to DTR's SXD drivers, then checked output at full voltage of 3 cells LiPo battery.

I tried to add the picture (of this equipment when not in use), but it did not pass into 800x600 limits. I do not have software to resize at hand. Sorry. I could PM you if you are interested.

Anyway, I will still try to correct the beam shape and then maybe DIY a portable version of it in the future...
 

RedCowboy

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Thanks Light superglue, that's good information.

You can upload pics to photobucket or one of the many sites like it for free and then right click the uploaded pic at photobucket, click properties, copy the addy then when you post here click the pic icon backspace out the extra http and paste, then you will have full size images in your post.

That's a shame so much power is lost, I don't know if the cylindrical lens may waste a little but the increase in ability is fantastic and the beams wild axis is reigned in nicely.

Probably the best result would be to cyl correct 4 diodes then KE with a hi lo block to make a 2 x 2 stack then use a reduction telescope.

The cube sounds very wasteful.

You say your cubes were polarizing I wonder if using a non polarizing cube and a 1/2 wave plate and matching the rectangles would make a difference in efficiency.
 
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Alaskan

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Please forgive such a basic question, but I must ask, you are indeed turning each diode to find the peak of the power out in each polarity through the cube, correct?
 

Light superglue

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Hi, Red Cowboy,

Thank you for explanation, but I simply rescaled the picture, it still seems to be in decent quality.

Now to the topic.
No, PBS is not wasteful. I repeated the test this morning and now I think that 10.88W is the limit of my old LPM thermal element. That's why I got this reading with any of 4 good PBS I have here. And, logically, from diffrent suppliers they could be at least a little different... So, once started combining these powerful LDs I (we) have to look for one new up to 100W maybe to be sure if one day we try to combine 4 or more.

So, I have mesured the maximal output of each of 2 LDs before and after PBS (cheap one from techhood on Ebay, positioned in the big clamp) after rotating the lasers into positions of maximal output through PBS.
The one in shaft-holder gave 7.2W with driver set at 5A before PBS and 7.03W after PBS (focused to infinity, spot at 5M - horizontal line).
The 2nd in 3-axis holder gave 6.38W with driver set at 4.5A and 6.36W after beam was 90 degrees reflected from PBS (also focused to infinity, spot at 5M - vertical line).
Very little energy seems to be lost and switching on two at once I should have obtained 13.39W, but my LPM always showed 10.88.

A non polarizing beamsplitter is simply half-mirror - it should reflect half of each of beams to combine - that could be the reason why I obtain 5W with the one received from Aliexpress.
 

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Light superglue

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Hi Alaskan,

Your question is completely right. Of course I have checked the position of polarisation at very start. But at that time I only had an old PBS bought in 2008 from Novalasers (this company does not exist any more) and I do not even remember what AR coating it has. Sure not for 445 nm, because in those years I only had 808, 680 and week 532nm DPSS to play.

I could hardly reach 9.6W of blue output with it at my "optical stand", but to find maximum output position it was fine.

Reason for my low output reading must be LPM limit. Where can I get one new up to 50-100W?

I am thinking to build something like in your picture of Optlasers stand in post 17, thread about Difference bw P and non-PBS. But with NUBM44 instead of 638nm.
 

Alaskan

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OK, well it seems you are an advanced experimenter, I just didn't know for sure. I buy my laser power meters off of ebay, so far every one of them turn out fine. Maybe you could use a 50% mirror and shoot through that to be able to measure more power? That way, the meter would still be in scale and you would just double what ever reading you would get. I guess even a simple piece of optical glass would reflect a percentage you could calculate.... Or, if you know the loss through a certain piece of glass by measuring it at low power, if several pieces of glass were stack up and they had enough loss, knowing that loss, you should be able to calculate the power into it.

Cyparagon, where are you?
 
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