Planning on Building an Actively-Cooled Micro Laser

[gazer101]

Hello LPF, I just wanted to hopefully get some insights before pursuing this project further: I want to take an NUMB44 diode and place it into the smallest possible enclosure while retaining a 15 seconds duty cycle (with plenty of cooldown time after).

Does anybody have experience heat-piping, thermoelectrically cooling, fan-cooling, etc. handheld lasers?
What are some common pitfalls?

Thanks a million!

 

[additude]

Yup, pretty much everyone heres does... I mean those credentials...
But you ain't gonna need no active heat piping massive cooling with a cooling fan, etc. for a NUBM44 your only gonna light up for 15 seconds then cool down and light up again.
I put mine in a laser pointer with SDX driver, polarity protection and two 16340 high Drain batteries.

 

[Shmackitup]

This company has some very small "Micro Fans" - https://www.pelonistechnologies.com/products/cooling/fans/axial-fans/micro-fans/

I haven't tried them yet but they seem feasible for use in a laser pointer. I've also seen some super small piezoelectric fans somewhere else, perhaps it was onlyfans or something like that.

 

[gazer101]

I've always wanted to build a high-power laser that doesn't feel like a blunt force weapon when I hold it

Perhaps I could make use of one of those <2cm diameter fans to make something with an JD-851-like form factor.

Alternatively, if I wanted to go even smaller perhaps I should look into a water-cooling type situation where the diode module and switch connects to an electronics hub on the waist that handles the cooling and electrical?

 

[RedCowboy]

You do realize that a micro-laser and an actively cooled laser are on opposite ends of the hand held spectrum .... right ?

Most people will just make a small laser with a small heat sink and limit the duty cycle, but if you want to keep it small and use fan forced air to cool it, then remember it's how much surface area that you pass the air over that counts, so this is where you can be creative with as many thin fins as you can fit on your heat sink, or maybe a spiral cut heat sink, but what I have seen the high end professionals who advertise an unlimited runtime do, is use a copper mesh, like a Brillo pad with wide ribbons stuffed inside the tube and a small fan blowing over it vented through the housing.

Also cutting fins into your head will help keep it cool even without a fan blowing on it and this maker uses the fins to hide the exhaust venting for the fan.

 

[gazer101]

You do realize that a micro-laser and an actively cooled laser are on opposite ends of the hand held spectrum .... right ?

Most people will just make a small laser with a small heat sink and limit the duty cycle, but if you want to keep it small and use fan forced air to cool it, then remember it's how much surface area that you pass the air over that counts, so this is where you can be creative with as many thin fins as you can fit on your heat sink, or maybe a spiral cut heat sink, but what I have seen the high end professionals who advertise an unlimited runtime do, is use a copper mesh, like a Brillo pad with wide ribbons stuffed inside the tube and a small fan blowing over it vented through the housing.

Also cutting fins into your head will help keep it cool even without a fan blowing on it and this maker uses the fins to hide the exhaust venting for the fan.

View attachment 75881

I can 3D print a custom heatsink-module out of aluminum for now, its actually remarkably affordable for small prototypes.

The main issue is that I can't cheat the laws of physics, small laser modules and big fans don't really mix. If only there was a way to have a fan with no moving a parts or some way to radiate heat without relying on inefficient and space-consuming radiator-air transfer...

Electrohydrodynamic (or electro-aerodynamic) fans look promising but they haven't really hit the market yet sadly

 

[RedCowboy]

I don't know what this is but you can read about it, still the tiny fans are your best bet.

VacMotion product: V-VUH-10-66 - Mini in-line vacuum generator with built-in exhaust. 0.99 scfm vacuum flow

VacMotion product: V-VUH-10-66 - Mini in-line vacuum generator with built-in exhaust. 0.99 scfm vacuum flow

www.vacmotion.com

You can search for ionic flow stuff, but you can just as well use a tiny fan like these.

DELTA BSBX103HK-00C7E 1504 DC3.3V 0.06A 15mm mini micro blower fan cooling A20 | eBay

Power 2-3.5 volts.

www.ebay.com

MF15B-05 5V 1.5cm 15mm 1505 15x15x5mm mini micro fan server cooling small B13 | eBay

Size : 15X15X5MM. 1 Piece - small dc fan 15mm x 5mm. Noise : 17dBA. Pressure : 1.6mmH20. Wind : 0.42CFM. Speed: 13,000 turn.

www.ebay.com

 

[RA_pierce]

Those "air-jet" coolers from Frore seem cool but only time will tell if they can deliver a viable product.
For the duty cycle you describe, optimized passive cooling seems sufficient. If you want to build a proof of concept for miniature active cooling, I'm 100% supportive but for now we are limited to tiny fans. Once you factor in the power source and a regulator for the fan in addition to the laser hardware, it will be difficult to keep the size down. It might be more worthwhile to just make a waterproof laser and submerge it in water between cycles. Then you can call it "liquid cooled."

 

[gazer101]

Yeah membrane-based and piezoelectric fans are also cool, but I think fully solid state fans relying on ion flow stuff to generate wind are the end game