Heatsinks

[electros]

Let me start off by saying I'm new to this forum, and haven't done a first build yet (Still researching and gathering the parts, I'm doing a 1 watt ir and phr build first most likely)

I work in the pc field as a technician and whats been baffling me the most with the home-brew lasers is the heatsinks that are being used. It seems everyone's using SOLID blocks of copper and that's considered a high-end solution (I've seen some tecs and water cooled ones but thats another story, obviously those wont work in a compact housing.)

I guess my question is why are these primitive metal heat sinks the best around for air cooling, it seems you could do so much more with heat-pipes, or even just fins. is it a lack of an easy way to obtain//make one? couldn't you "Overclock" a mediocre diode in to a great one with better cooling?

 

[Pontiacg5]

No, you can't really clock a diode like a PC, it has a limit where it will just die no matter how much you cool it. And while I agree with you in a way, more fins or heatpipes are needed, the way that most are doing it now is fine. The big hunks of copper and aluminum have a lot of thermal capacity, they can hold the heat and let it fade off pretty easily. Fins would help, but a laser really won't have too much airflow over it to move the hot air from the fins so it becomes a tossup between mass and surface area, and everyone seems to prefer mass.

Also, the current hosts don't really allow finned heatsinks. But hopefully I'll have some new hosts made soon, ones that have fins and TECs

 

[chipdouglas]

and basically in a hand held unit the solid heatsinks as you so eloquently put it transfer the heat to the host and your hand to some extent disapates it further.. also fins wont really look good in a hand held.

also about over clocking a diode... in side the diode where the laser lases there is a small wire. if too much current runs through it, it pops like a fuse..

michael

 

[rpaloalto]

A finned heatsink works great as a bench top or lab laser. The cooler you keep your diode the longer life she will give you.
However, most of our builds are designed to be hand held pointers. about 99% are modified flashlights. It would be very hard to incorporate a finned heatsink in most of these designs and still have it look good.
Plus as a hand held, your usually not using long duty cycles like you would on a labby.

 

[charliebruce]

It's also an order of magnitude more power. PC processors will put out somewhere between 45 and 200+w depending on how overclocked or power-hungry they are. Laser diodes will put out up to about 10w, until you start getting into the huge high-end systems, with which, to keep temperatures low (much more sensitive than processor dies) we use the "exotic" cooling (TEC, water).

 

[Morgan]

It's also true that almost all the diodes we use are massively overclocked already, (if overclocked means run way beyond factory specs). Some up to 5 times what they would normally experience in service. Considering the heatsinks they occupy in the original components these solid blocks are HUGE! Heat pipes, from my brief investigations and tutoring, are really only effective in a certain orientations, (usually vertical but depends on design), as they rely on latent heat transfer through evaporation and condensation and therefore would not suit handheld lasers.

If I may follow on from what rpaloalto says about flashlight hosts... The solid heatsinks not only hold a lot of heat, (although when saturated, volume doesn't mean as much as surface area), but they are there to transfer the heat to the exterior body and then the air. Fins would restrict that transfer.

M