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FrozenGate by Avery

Combining two NUBM36 with a PBS cube or by knife-edging prism method

You clearly haven't been working with TECs before. Yes they can get hella cold, but ones you add heat to the cold side it's game over, especially when stacking them. You can throw as many TECs you want on it, and may at some point start seeing some cooling, but you are way past practicality then.
 





I didn't say it they cant do it, but you'll be wasting stupid amounts of power. Freeing water is not equivalent to cooling a 100W diode.

Also, driving them them with a potentiometer? Now I think you are full of shit. Show me this setup working and I'll take back my criticism.
 
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We are not companies, we are are hobbyists. A company may not care how much money and energy is needed for an exotic solution, but asking that for a single member is not reasonable.
 
You're out before showing your solution you say is working? I let you have the satifaction of making me wrong. I just dont like you telling people to spend money on something without evidence.
 
I'm not doing your homework of researching the solution that you claim to know. That's not how this works. YOU show US.
Your talk of driving a 400W TEC with a potentiometer already screams how much you don't know your stuff.
If you already have problems cooling a diode as it is, and with a 400W TEC per your example, you now have to figure out how to cool that extra heat as well. You show me how this is effective, if you can.
 
Most potentiometers can only dissipate 0.25mW. Expensive ones maybe 1W. It will melt, if not go up in flames if you try to control 400W with that. Maybe you remember what I told about PWM, this is one application where such is useful.
 
@Light superglue
What is the beam width at ~5 cm from the lens array?
I wonder if knife edging could be done with a "mirror array" that is slotted to pass the beams from the other diode array. Perhaps complicated to manufacture in one piece. See my crude sketch.
 

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FireMyLaser said:
Most potentiometers can only dissipate 0.25mW. Expensive ones maybe 1W. It will melt, if not go up in flames if you try to control 400W with that. Maybe you remember what I told about PWM, this is one application where such is useful.
Click to expand...
Exactly since TECs are a resistive load.
 
Don´t do PWM with TECs, they will loose a lot of there already bad efficiency.
Think about it, if the PWM is at high level, the tec will be running at 100% reducing the efficiency (look at COP curves from known manufacturers)
If the PWM is then at low level, the tec will let the heat flow back through it.

There is a paper from TI? if i remember correctly, that came to the conclusion that PWM drive reduces the efficiency by another 40% compared to constant current / voltage drive.

For high power tec drivers i would contact the member Phillip. He does have 240W ones that can be daisy chained to 1200W if i remember correctly.
 
Yes I've read this too, but it is a common technique still. I used the PWM example as he had questions about it before and why it is commonly used to vary power. A pot would never adjust a TEC without a meltdown, but a PWM controller would.

It is nonsense anyway in the countext of this thread, a controller would not be needed to begin with, as if it would work too well.
 
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Hi RA pierce,

At 5cm all beams are about 1mm wide. Seeing the beam centers separation in NUBM36 is 3.5mm, you will only have 2-2.5mm to place the mirrors.

The thinnest long mirrors I have found are ones taken from KE-block of A130. Their size is 25x5x1.1mm

I saw you in the thread about shaping lenses. If you could slice those mirrors along into 2, better 3 slices, then you could maybe do what is on your sketch.
 

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Well, now I have finally burned my PBS after trying to give 3A current (full power) through all the emitters.

So I put the thermal sensor on the top of the cube to see how much the PBS would heat and first at 1A current the warming was not very great: it just warmed up from 25 to 30ºC in 30 seconds.

At 2A it warmed up much faster: from 30 to 45ºC in the same 30 sec period.
At 3A even faster: from 29 to 55ºC. And the black mount plate PBS was atached to became very hot as well.

Then looking at the cube I saw those marks, which were sharper where the emitters were closer and less pronounced where emitters were further away. So I suppose that the epoxy or reflecting layer has burned due to high energy concentration and this might not have happened if the beams would not enter the PBS after 1-2 cm path but after 20+ cm path where the beams would already have diverged from 1mm to 2 mm width and the energy density fallen by half or more...
 

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That sucks.
Since the prism is already ruined, it may be worth trying beams with lower power density for a longer duration to find the damage threshold.
Do the projectors use bonded optics? If so, they've figured out a way to avoid this kind of damage and so it may be worth studying.
I think the projectors use dichroic mirrors, right? Some of the focusing optics might be bonded achromats.
I also imagine that the laser is not operating in CW.
 
Dunno if this diagram helps any a bit..
It's beam combining for welding applicatons..

www.spiedigitallibrary.org

500 watt blue laser system for welding applications

This paper presents a 500 W continuous wave blue laser system for industrial applications, based on high power, high brightness laser diodes at 450 nm. The system builds upon the company’s 150W modules introduced recently. The modular system architecture allows efficient power scaling; a...
www.spiedigitallibrary.org www.spiedigitallibrary.org

00004_PSISDG10900_1090004_page_2_1.jpg
 
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Yes, in this sketch the beams enter the cube after a pretty long path, so I think they are well diverged at that point and have lost the initial power density. Due to this they do not burn the cube.
This is what I meant by saying to maybe combine beams 20+ cm away of emitters.
But if we want to focus the result into the smallest possible point, will these already diverged beams be fine for that? I doubt...
 
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