NUBM44 6W+ 450nm Laser Diode

TaterMay said:

As for the copper vs aluminum argument, some will say that copper will absorb the heat away from the diode better, but won't dissipate it into air as well as aluminum. However, the rate of heat exchange is dependent largely upon the difference in temperature. Since copper has better thermal conductivity, it stands to reason that the heat exchange with air should also be greater than that of aluminum.

Click to expand...

copper has higher thermal conductivity than aluminum, and a higher volumetric heat capacity. this means copper draws heat from the source faster and is able to hold more heat without rising in temperature as much as aluminum, therefore providing the optimum conditions for the thing your heatsinking to stay cool. if the heatsink warms up (as aluminum does faster) the component also warms up, until it is destroyed from thermal damage. with copper, this happens more slowly since it rises in temperature more slowly for the amount of heat put into it.

this makes copper the ideal heat-sink, to our knowledge there is not a better material for heat sinking.

however it is not a perfect heat exchanger. copper takes more heat to create a rise in temperature. This also means it needs to expend more heat to lower in temperature, giving rise to the thought that it doesn't cool down as fast as aluminum. this doesn't make aluminum a better exchanger either, since it has a much lower thermal conductivity than copper. the best heat exchanger is diamond, after that it's silver, then copper. silver doesn't beat copper by much though, so until there are great leaps forward in artificial diamond manufacturing and machining, we will be using copper modules.

barthchris said:

I have a bunch of Ricks hosts and heatsinks, They are the older Aluminium versions, does copper make that much of a difference?

Click to expand...

for this diode, i would say a copper heatsink is necessary. and it makes a HUGE difference.

micheal rosen said:

copper has higher thermal conductivity than aluminum, and a higher volumetric heat capacity. this means copper draws heat from the source faster and is able to hold more heat without rising in temperature as much as aluminum, therefore providing the optimum conditions for the thing your heatsinking to stay cool. if the heatsink warms up (as aluminum does faster) the component also warms up, until it is destroyed from thermal damage. with copper, this happens more slowly since it rises in temperature more slowly for the amount of heat put into it.

this makes copper the ideal heat-sink, to our knowledge there is not a better material for heat sinking.

however it is not a perfect heat exchanger. copper takes more heat to create a rise in temperature. This also means it needs to expend more heat to lower in temperature, giving rise to the thought that it doesn't cool down as fast as aluminum. this doesn't make aluminum a better exchanger either, since it has a much lower thermal conductivity than copper. the best heat exchanger is diamond, after that it's silver, then copper. silver doesn't beat copper by much though, so until there are great leaps forward in artificial diamond manufacturing and machining, we will be using copper modules.



for this diode, i would say a copper heatsink is necessary. and it makes a HUGE difference.

Click to expand...

Heat absorption and dissipation are the same process, simply in reverse. Why would aluminum dissipate heat better, yet not absorb it as well? The formulas for convection also do not take into account the surface material - only the temperature at the surface. If copper transfers heat better, it is going to take this heat out toward the surface more quickly than aluminum. Once it gets there, the dissipation is determined by the temp of the air and the surface material, along with the surface area touching the air, which will be the same for two heatsinks of the same size, yea?

Not trying to argue, just trying to understand it better, as always.

Actually. If you really care about heat SINKING, stationary water is better than copper. However, the thermal conductivity is so low that it doesn't really work in a heatsink. Also, corrosion. Everything else is right though

doubleone44 said:

Actually. If you really care about heat SINKING, stationary water is better than copper. However, the thermal conductivity is so low that it doesn't really work in a heatsink. Also, corrosion. Everything else is right though

Click to expand...

One thing I plan on trying to work with here soon is heat pipes. You know, the hollow copper tubes with water inside that you find on computer/gaming heatsinks? The heat transfer of those is MUCH better than copper alone. I think they would also look pretty awesome on a steampunk inspired build.

doubleone44 said:

Actually. If you really care about heat SINKING, stationary water is better than copper. However, the thermal conductivity is so low that it doesn't really work in a heatsink. Also, corrosion. Everything else is right though

Click to expand...

i wasn't even thinking about water, but yeah thats right. but who the hell is gonna bother with a liquid heatsink on a handheld laser XD

TaterMay said:

1. Heat absorption and dissipation are the same process, simply in reverse. Why would aluminum dissipate heat better, yet not absorb it as well?

2. The formulas for convection also do not take into account the surface material - only the temperature at the surface. If copper transfers heat better, it is going to take this heat out toward the surface more quickly than aluminum. Once it gets there, the dissipation is determined by the temp of the air and the surface material, along with the surface area touching the air, which will be the same for two heatsinks of the same size, yea?

Not trying to argue, just trying to understand it better, as always.

Click to expand...

i split up to the quote a little bit:

1. exactly. aluminum doesn't dissipate heat better/faster, the temperature just lowers faster.

2. not sure... i definitely think that the surface material would influence the rate of heat exchange between the air and the heatsink, since its more conductive it will conduct heat into the air faster. but that is an interesting thing to bring up. i wonder why it wouldn't be in the equations? perhaps because the thermal conductivity of air is constant, it doesn't matter what material you have providing the heat to it. although i can hardly believe that if the air is moving past/through the heatsink continuously.

TaterMay said:

One thing I plan on trying to work with here soon is heat pipes. You know, the hollow copper tubes with water inside that you find on computer/gaming heatsinks? The heat transfer of those is MUCH better than copper alone. I think they would also look pretty awesome on a steampunk inspired build.

Click to expand...

i thought of that too! that would look sick. i wonder if you would have to be careful when bending them though...

TaterMay said:

I actually cut solder first, which made me decide to try out the spring. I was very surprised myself. Feel free to throw out some more ideas to attempt to burn/cut through, as I have just finished another one that hit 7.24 watts peak.


As for the copper vs aluminum argument, some will say that copper will absorb the heat away from the diode better, but won't dissipate it into air as well as aluminum. However, the rate of heat exchange is dependent largely upon the difference in temperature. Since copper has better thermal conductivity, it stands to reason that the heat exchange with air should also be greater than that of aluminum.

Click to expand...

Yeah, I heard that argument years ago on this forum. Strange how it was said that AL will dissipate quicker than copper if all other things are considered equal, didn't compute in my feeble mind. I guess I'll just try the AL heatsinks and see how it works.:thanks:

Atomicrox said:

Steel wool, magnesium strip, charcoal and perhaps a thin copper wire. I never managed to ignite any of these with 3W.

Click to expand...

I've tried the magnesium strips with the 3W too, no dice. But I happened to have a pile of thermite I was trying to light at the time and to my surprise the 3W does it with ease when focused! Even an A140 will do it when focused tight. Thermite is notoriously hard to light with conventional means (lighter, matches, propane torch).

Of course this diode will light thermite when focused as small as possible, but what would be cool is if it could do it when focused to infinity. That would be impressive. Although not everyone just has a pile thermite sitting around. Well, never say never, If I were a betting man I'd say more than a fair share of the members here might have some tucked away for a rainy day.

I do have some Al powder and could mix up some thermite but TBH lighting that from point blank range sounds rather dangerous and I don't think the focus will allow me to get more than a meter away.

Nice find, anyways

Edit: perhaps with my 600mW 405nm. At least it's single mode.

Believe it or not, I've done it many times at probably half a meter away with no problems at all but its on maybe a few ounces.
I can definitely understand your apprehension, some seriously hot stuff there, don't want to be the winner of a Darwin award! :scared:
Probably also depends on the iron/aluminium ratio too, as you know different amounts either way can make a difference on how quickly the reaction takes place.

EDIT Just read the last line after I posted. Yeah, try with 405! You can get back to a comfortable distance. Cant remember if I did it with mine, its has died like they always do when driven high, unless your lucky. Hopefully the energy isn't too concentrated if you know what I mean. But it should work.:yh:

TaterMay said:

Since copper has better thermal conductivity, it stands to reason that the heat exchange with air should also be greater than that of aluminum.

Click to expand...

Not with the way 90% of pointers are built around here (one solid lump)

Cyparagon said:

Not with the way 90% of pointers are built around here (one solid lump)

Click to expand...

I would definitely like to see more finned sinks. I purchased a couple of finned aluminum heatsinks for my ray gun host, but they were a little smaller than I'd like. Still not sure what diode I'm putting in it though.

I think part of the confusion about heat loss/cooling our devices, is that heat LOSS for example can have 3 main avenues:

Conduction, radiation and convection.

The heat from a source needs to get TO a place it CAN be lost FROM.

So, a sink is used, typically via conduction, to get the heat to transfer to it instead...by direct contact.

As mentioned, water is a great sink material, as it takes a lot of energy to heat it.

Unfortunately, materials that can absorb a lot of heat don't tend to give it up well either...so, a sink is limited to short ENOUGH duration energy supplies, so they CAN absorb what's needed.

Once the heat is say, conducted to the sink...it has to be disposed of FROM the sink. (Or the sink ends up the same temp as the source in the device, etc...no longer cooling it...)

Now, that's where loss comes into play. If the device is in your hand, heat can be CONDUCTED from the sink to you...as one way of additional cooling.

If the heat is lost to the air, convection and radiation can be at play...with convection being the heated air carrying away that heat due to air movement, etc...

...and radiation being the heat radiated off as a function of the device's surface characteristics.


For example, a shiny silver finish is REALLY bad at radiating heat, but a flat black finish is awesome at it.

Fins, etc, increase the surface area available to lose heat through...and work best with airflow for convection cooling and as close to a flat black finish to enhance radiation losses.

Ironically, for the surfaces that you might be holding in your hand, the fins can reduce the conductive heat loss...by reducing the contact area for that loss. (Think of those desert lizards, etc, that alternate feet when on hot sand...the less contact, the less heat transfer, alternate contact allows alternate re-cooling, etc)

So, a sink is effective if it can draw off the heat from the part you need cooled, for a long enough period...and becomes progressively less effective as it's temperature rises.

So, cooling the SINK becomes the next step...and that's where people tend to get confused. Several posters mentioned aspects of this confusion, and gave explanations, but, I'm consolidating much of that here.

The factors become about the rates at which heat loss from the sink can be accomplished...and optimizing the solution to the application.

For example, if the device is held in a particular area, you would maximize conduction and worry less about convection or radiation.

If an area of the device will not get much airflow for convection, or contact for conduction, the losses might be tilted towards radiation of heat instead...and so forth.

:beer:

Teej said:

water is a great sink material, as it takes a lot of energy to heat it.

Unfortunately, materials that can absorb a lot of heat don't tend to give it up well either...so, a sink is limited to short ENOUGH duration energy supplies, so they CAN absorb what's needed.

Once the heat is say, conducted to the sink...it has to be disposed of FROM the sink. (Or the sink ends up the same temp as the source in the device, etc...no longer cooling it...)

Click to expand...

Hm. You are indirectly addressing an issue I am working on as well. I will try not to deviate far off the rails here.

You have a heat source. Nubm44. This heats up the copper module it is set in. That module then transfers heat to a copper "head" (heat sink host body.) through conduction.

Is it possible to say the diode at a set amperage will reach a constant max temperature and theoretically with a large enough heat sink surface area will reach a thermal equilibrium via atmosphere convection???
OR am I wrong and the diode will eventually die in a thermal runaway.

I don't have solid data here so I can't use an equation to plug the numbers in but I'm wondering if it's possible.
My specific situation is a distillation condenser that is getting way too warm on me but there are other variables here like flow rate etc. My thought process is if I have a large enough volume reservoir(disstilled water) it will eventually reach an equilibrium.
:thanks:

Down with Umbrella said:

Hm. You are indirectly addressing an issue I am working on as well. I will try not to deviate far off the rails here.

You have a heat source. Nubm44. This heats up the copper module it is set in. That module then transfers heat to a copper "head" (heat sink host body.) through conduction.

Is it possible to say the diode at a set amperage will reach a constant max temperature and theoretically with a large enough heat sink surface area will reach a thermal equilibrium via atmosphere convection???
OR am I wrong and the diode will eventually die in a in a thermal runaway

Click to expand...

I think this should be possible. I've seen many lower powered diode builds with an unlimited duty cycle of which the diode would definitely burn out if not heatsinked. This concept is pretty much the same except the diode will generate far more heat than a low powered single mode diode. The question is if the copper can dissipate the heat fast enough from the diode to keep it at a steady temperature without that temperature being any higher than the diode can handle.

Not an expert by far, but this is how I'd imagine it would work.

I have written a bit about this topic previously, and it never changed:

You can make a continous operating laser if the thermal resistances beyond your control are not the limiting factor. The thermal resistance here is basically that from laser die to case, and to some degree from case to heatsink as you cannot increase the size of the case.

Lets take a theoretical example:

Laser thermal output: 20 watts (resonable for a 6 watt output diode)
Die-to-case: 1 K/W
case-to-heatsink: 1K/W

In this example the laser would operate 40K above ambient if set in an infinitely large heatsink. With a maximum die temperature of 70 celcius and ambient temperature of 25 celcius this would be acceptable.

But heatsinks are never infitiely large. So how big does it need to be? We have only 5K of room here to ditch 20 watts, requiring a 5/20=0.25 K/W heatsink. This would equate to a fairly big cpu heatsink with the fan running.

The die-to-case and case-to-heatsink values would probably a bit lower in practice allowing for a smaller heatsink to do the job, but you must obtain the exact values from the diodes datasheet to know. This will give you an exact figure for die-to-case, but case-to-heatsink also depends on what you do in terms of contact pressure, thermal compounds etc, so this can be a bit unpredictable.

Re: V1 445nm Laser Diode

CDBEAM777 said:

Well...this Bad Boy is crying out for a little optical correction !!!

See the attached pic !!! I will be doing something like this !!

The flat section may need to be about 1/2" (15mm) longer ?? Dunno yet.

This unit pictured uses two C-lenses to correct the beam. Will the LD demand a 2mm collimation lens...( from Dave at LSP ) ??? Dunno ??? might...but I am betting not...my guess is that a G2....coupled with C-Lenses will do the trick !!!

Got one reserved with DTR.... Yes...I know this adaptor/C-Lens mount does not look sleek...But I assure you....It will greatly reduce the slow axis divergence and reign in a less than perfect aspect ratio...again....disclamer...not perfect...but a lot better....for those of you who care about divergence !! Pass the popcorn !! and hang on for the ride !!

Then...on to a dual...you bet !!!

Note: Thank you all for doing the break thru work on detailing the power nature of this LD !! Exciting times indeed !!! And Oh...Best to keep this " Rocket" outa yer Pocket !!! Hahahahaha

Click to expand...

Hello. Can you tell me where you bought the two "C" lenses pictured. I would like to buy a set. Thank you for your time, Ed.

Re: V1 445nm Laser Diode

Ed, Very soon these lens will be offered by one of our members. Likely available by early~mid-November. Thanx, Bob