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Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

Light superglue

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Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

As promised earlier in other threads I am trying to make a 20+W blue single beam laser by combining 4 high powered LDs in a way I suppose this disco module does it:

https://www.kvantlasers.sk/product/16w-445-460-nm-kvant-laser-module

In the same time I aim to fit all parts on a 120x70mm baseplate made by a CNC shop jors has recommended to me. Maybe it could even pass into Fenix TK75 head Alaskan recommended but at least I think to manage installing it on a toy RC tank chassis later…

As you can see on picture, using of binned 06 and 08 LDs with well collimated ball lenses saved some space so I can install square waveplates lateral to PBS cubes like it should be. But if I wanted to use standard length Cu modules with G-2 collimators, it seems to be more ergonomic to position waveplates (round ones) in front of PBS cubes.
Unfortunately all PBS cubes I have tried (and I have them from 5 different suppliers) are designed for the planned beam path when wavelpates are on the way of beam which comes from the side (at vertical fast axis orientation of modules because I plan to install LSP cylindricals vertically after beam combining).

Can anyone say if any PBS cubes exist which could combine such beams if polarisation rotated one came from front (through round WP) and the not rotated one from the side?
 

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Benm

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

What exactly is the problem you need to solve here?

It looks like you could easily rotate any of the lasers by 90 degrees to fit the required polarizaton or fast/slow axiz issues if required.
 

Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

I want more optical flexibility without major mechanical changes.

If C-lenses are installed vertically on these 10dollars Optlasers mounts, the adjustment will be just shifting them left-right.
But if all modules are rotated 90°, the lenses have to lay on side, so I need to shim the hight of mounts and not sure if mounts with such feature can be found which would fit this compact set up.
Do you know any regulable hight micro tables which would be not super expensive?
 

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Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

I thought of it in the earlier versions of design but the size of these mounts would not allow to fit them all in a such small area - even mounts with smaller footprint like in Lasertack micro KE set would need minimum 150x90mm baseplate in order to be placed loose enough for all adjustment screws to be accessible by hex-keys.

So at the end all PBS cubes are the same and there is no way to find one which would allow WP in front when modules and cyls are not tilted, right?
 
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Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

OK, no more answers here can mean that all PBS cubes are same.

At the end I have chosen to simplify the setup thanks to the fact that the BP width still allows to put waveplates at the sides of both PBS cubes.

But surprise, surprise! Having adjusted the beams from two NUBM06 and two NUBM08 I surprisingly noticed that the combined 08s beam was more reflected from the 2nd inner surface of the Dichro than from the 1st outer surface. Look at the diffrence between pic. 2 (only 08s are on) and pic. 3 (06s turned on as well)!

This effect disappeared when I turned the Dichro around - must be due to very close WL gap or a non-equality of coatings on both Dichro sides???
 

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Alaskan

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

Interesting and nice looking project. What are those power boards? Ebay China CC?
 

paul1598419

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

I've been following this thread in hopes of learning something. It is all very interesting. I'm hoping you will get all the kinks ironed out and look forward to the end result and how it was accomplished.
 

Alaskan

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

I'm not sure what he means by reverse yet.
 

Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

By "reverse" I was referring to a PBS which would work in a different (opposite) way than on the sketch made by jors in post 4. This would allow to use WPs in front of PBS cubes (setup on pic. in my original post 1) without need to tilt diodes and cylindrical mirrors...

But anyway it seems that it was not possible.

The drivers are Buck-3606 from Ali. I have been using them one year long and did not burn any of Nichia diodes yet. Without any protection (lasorb) up to 4.5A current. Also was driving 4 NUBM44 connected in series but still at 2A only...
 
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diachi

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

By "reverse" I was referring to a PBS which would work in a different (opposite) way than on the sketch made by jors in post 4. This would allow to use WPs in front of PBS cubes (setup on pic. in my original post 1) without need to tilt diodes and cylindrical mirrors...

Not sure I'm getting you...? You'd rotate both diodes to the same position (meaning polarization is in the same position, as well as beam geometry), and then use a waveplate in front of one to rotate the polarization 90°, allowing you to combine them both with a PBS while having the beams overlap...
 

Alaskan

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

If that is all he is after, take a look at optlaser 4 watt RGB, he does that with two red diodes. Using my iphone, not easy to see well with my old eyes.
 

Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

Hi Diachi,

And now imagine please that I DO NOT WANT to rotate/tilt diodes and cylindricals but want to have the choice of putting WPs either in front or by side of optical axis of the combined beam leaving all other components untouched - the only thing needed would be an alternatively structured PBS cube with polarisation mirror oriented in a perpendicular way to what all existing PBS cubes have.

This is mainly theoretical question, not very essential in practice anyway.

Edit: Alaskan, you are exactly right, this is what Optlasers do in 4W but I think that in order to match divergence of red LDs to G+B LDs they expand fast axis, not the slow axis as I want with my blue LDs.
 
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diachi

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

And now imagine please that I DO NOT WANT to rotate/tilt diodes and cylindricals but want to have the choice of putting WPs either in front or by side of optical axis of the combined beam leaving all other components untouched - the only thing needed would be an alternatively structured PBS cube with polarisation mirror oriented in a perpendicular way to what all existing PBS cubes have.
Still not understanding what you want to do ... Could you provide a drawing or a more detailed description? Maybe I need more covfefe?
 

Light superglue

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

Well, let me explain it again with drawing.

In post 4 jors has made a draft how all (let´s call them "normal") PBS cubes work.

I want a different PBS (let´s call it "reverse") in order to be more flexible with design of linear setups...

Maybe they do not exist but I doubt that making one would be a problem for an optics manufacturer...
 

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Julian95

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

how are you polarizing the light before the waveplate without losing power?
 

diachi

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Re: Need "Reverse" PBS for 20W "laser tank gun" prototype - do they exist?

Well, let me explain it again with drawing.

In post 4 jors has made a draft how all (let´s call them "normal") PBS cubes work.

I want a different PBS (let´s call it "reverse") in order to be more flexible with design of linear setups...

Maybe they do not exist but I doubt that making one would be a problem for an optics manufacturer...
Oh I think I see what you're saying now, you want a PBS that has the pass/reflect polarization rotated 90° to what you have just now?

how are you polarizing the light before the waveplate without losing power?
The light from a laser diode is already linearly polarized.
 




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