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Question on using polarized beamsplitter/combiner

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I understand that when using a polarized beamsplitter/combiner cube to combine two same-color beams, that one of the beams must be oriented one way, the other beam 90 degrees to that. The resultant beam, I would guess, then has both H and V polarized components, yes? If so, how does one cascade beam combiners? I have an image posted below of such an array - I need to know where this image came from (this was posted SOMEWHERE on LPF, but I cannot find the original post) and how it is done - because this is exactly what I am doing, only on a smaller scale. THANKS for the info!

Dave
 

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Re: Question on using polarized beamsplitter/combi

You're thinking of an Arctos unit. Those are not cascaded PBSs actually. Arctos makes reds where, with mirrors, they shove a bunch of red diode beams in close proximity. IE, you end up with a grid of 200mW red beams side by side. In the end, they do combine two of these grids through a PBS, but that's the only time. The rest is just a bunch of beams side-by-side.
 
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Re: Question on using polarized beamsplitter/combi

Cool! Yes - in looking at it I can see the beams side by side. Makes sense. So I am correct that you can only combine 2 beams and then you're at your limit because the beams then contain both V & H polarization, and more cubes would just drop out 1/2 of the incoming component?

Thanks for the info & reference, now I have something I can follow up on.

Dave
 

andy_con

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Re: Question on using polarized beamsplitter/combi

yes you can only combine two beams using a cube.

for more than two beams you need to start using mirrors
 

roSSco

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Re: Question on using polarized beamsplitter/combi

That's a cool picture, I can see why you saved it. :)
 

zxn474l

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Will these "cubes" combine the power of the two lasers together? a 200mw red and a 200mw red into a cube...will the output beam be 400mw? If yes will the cube cause any divergance of the final beam? PLEASE answer and tell me where I can get a good beam combining cube! THANKS!
 

.3lite

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Will these "cubes" combine the power of the two lasers together? a 200mw red and a 200mw red into a cube...will the output beam be 400mw? If yes will the cube cause any divergance of the final beam? PLEASE answer and tell me where I can get a good beam combining cube! THANKS!

No, it all depends what cubes you want to use for it, I think they are like 75% effective? maybe more, maybe less, but you will never ever get 400mW from two 200mW lasers splitted.
 
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You may get 10% optical loss if you are sloppy with your setup. It is a lot easier to get better then 75% efficient.
 
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Man this is old, haha. I am also looking to build a similar set up. Combining multiple "weaker" (cheaper) lasers into one stronger output. I hope to reach 400w-1kw for welding purposes. Did you ever find out the info you needed? did you build yours? if so could you share?
 

diachi

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Man this is old, haha. I am also looking to build a similar set up. Combining multiple "weaker" (cheaper) lasers into one stronger output. I hope to reach 400w-1kw for welding purposes. Did you ever find out the info you needed? did you build yours? if so could you share?

What power are the weaker lasers? How many? Is that 400W-1,000W average? Peak?
 
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I am considering 40w CO2, so 10-25 of them. It would have to be average, as the welding machine could be running for hours at a time. the reason for the range of power is for different materials being welded.
 

diachi

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I am considering 40w CO2, so 10-25 of them. It would have to be average, as the welding machine could be running for hours at a time. the reason for the range of power is for different materials being welded.
Going to be problematic for a variety of reasons...

10-25 40W CO2 lasers will require 4kW-10kW input power. You also need to come up with a cooling system that can remove 4kW-10kW of waste heat.

This will take up a lot of space.

Combining 10-25 40W CO2 lasers is on an completely different level from combining a bunch of 0.2W laser diodes. For one, standard glass optics DO NOT work with the 10.6µm light emitted by CO2 lasers. You need ZnSe or similar for the lenses and beam splitters. Mirrors are usually the gold plated variety for CO2.

The beams need to be polarized in order to combine them with a PBS. Most cheap Chinese CO2 lasers almost certainly aren't polarized.

Aligning 10-25 completely invisible beams is going to be hard.

By average I was referring to the mode of laser operation, i.e. pulsed or CW, not the run time or duty cycle. Pulsed operation results in very short, very high power pulses with a lower average power. CW is just that - continuous wave, same power all the time.

Any experience with a similar setup on a smaller scale? Any experience with lasers? High Voltage?
 
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i was an auto mechanic for several years, i am now an engineering student, and working for a 3d printing company. i want to build a metal printing 3d printer. there is one that i watched a video on that uses a 400-1kw laser to weld together metal powders layer by layer to create a finished part. i have built single diode lasers at home, and a small engraving machine with one of the 5w diodes. i have some space to work with at the shop. I'm just trying to wrap my mind around all of what will be involved in building the laser portion of such a machine.
 
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diachi

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i was an auto mechanic for several years, i am now an engineering student, and working for a 3d printing company. i want to build a metal printing 3d printer. there is one that i watched a video on that uses a 400-1kw laser to weld together metal powders layer by layer to create a finished part. i have built single diode lasers at home, and a small engraving machine with one of the 5w diodes. i have some space to work with at the shop. I'm just trying to wrap my mind around all of what will be involved in building the laser portion of such a machine.
Different type of laser altogether. SLS machines typically use Yb-fiber lasers at ~1050nm, not 10,600nm. Can't remember off the top of my head by the Yb-fiber lasers may be pulsed too, so peak power is much higher than stated in that case.

Have you considered building an SLS machine for low melting point polymers first? It's a whole different ball game when moving to metal - there's a reason the machines for DMLS cost so much.



also i have access to night vision to assist with aligning the IR lasers
I'm 99% sure night vision doesn't work at 10.6µm.
 
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well sls uses liquid polymers that solidify when exposed to the laser. in this machine it just uses the laser to weld/fuse the powdered metals. so i figured a laser that is strong enough to weld, could be fitted using mirrors to an existing CNC, and then threw the magic of code we could "print"
 




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