I've been thinking of a different kind of cooler for high powered lasers, using a CO2 cartridge, get a valve of some kind to allow the gas to slowly release through a heat sink attached to your diode and you will have more cooling than a huge chiller without wires or tubes attached to it. You can buy them from small to large, I'm certain this will work fine, just that you will need to replace them, of course. I'm thinking this would make any laser uber cool in more ways than temperature alone. Releasing the gas can cause a heatsink it flows through to get extremely cold, even ice up if you release enough gas fast enough. I am sure there is a speed of release that will produce the right cooling without using them up too fast, even for 100 watts of dissipation, especially since your battery won't last long anyway.
Example:
http://www.ebay.com/itm/Genuine-Inn..._Merchandise&var=&hash=item339049e2b9&vxp=mtr
Oh, by the way, I've been gathering parts and the needed test gear for the same kind project now for two years. 808nm with a bar laser diode isn't going to be a very tight beam, but that isn't what I want anyway, I am going to use a 40+ X large beam expander for mine to reduce divergence (series of expanders with a lot of loss, unfortunately, thus why I am starting out with so much power from the laser source). I don't want to use this for anything other than a long range beacon which won't have a concentrated enough beam to harm anyone, less you point it at someone too close. I have a lot more ideas for it than I am posting about, but I am facing the same issues you are. As far as current limiting goes, for something like this, it might be easier to just keep the thing so damn cold it can't run into destructive over current thermal runaway than try to use a solid state current regulator but I'm also working on that too. One way of handling it might be to use both a thermal and current fuse or switch which will turn off the power, just in case the thing runs away and starts pulling too much current or gets too hot but they need to be fast acting. That said, from what I've come to find, if the diode is kept cold enough that won't happen very easily, some say it can't happen.
I believe I've solved the power source problem for a portable high power laser like this and that is to use a single (or paralleled) 2 volt lead acid battery. From what I've found, the 2 volt cyclon battery is the best thing to use. You can buy single cell 2 volt 25 ampere hour ones fairly cheap on ebay.
Example:
http://www.ebay.com/itm/BATTERY-ENE...US_Rechargeable_Batteries&hash=item27e3ef84ef
Here's a discharge graph for these types of batteries:
http://www.atbatt.com/media/sku_pdf/Cyclon_Selection_Guide.pdf - Look for the "state of charge..." graph. This graph shows that the battery voltage dips less than a couple of tenths of a volt from a fully charged state before being completely discharged (high of 2.14 volts to a low of 1.96 volts), close to ideal, I think, as it allows your laser device to keep on lasing at closer to full power until the battery is completely drained.
For my own unit, I think I will use three or more 8 ampere hour ones, they are fairly slim and I can wire three in parallel in a long tube. Of course, you won't be using a current regulator with a 2 volt battery for a 2 volt diode, the losses (even if it could be engineered) would be too high to reach the voltage you need to fire off the diode. For this battery use thermal and current cut-offs/fuses and cool the hell out of the laser diode with CO2 and I think it will work fine without problems, as long as it doesn't get so cold you cause other problems with thermal shock to the laser diode or the lens having condensation on it. One of the things I am thinking of doing is to build in a wire wound rheostat or variable high current wire wound resistor (if it doesn't cause damaging voltage spikes due to inductance or switching, still working on this idea) in series with the battery to slowly turn up the voltage to the diode to just below the amount needed to lase to allow it to warm up first, this will keep you from thermally shocking it with full current when fully energized, especially important if you chill it with gas. Alternatively, you might just use a non-inductive high current voltage dropping resistor in series with the battery to bring the diode up to operating temperature first without actually lasing enough to produce much if any IR output and then just bridge across it with a shorting switch to take it out of the circuit allowing full lasing voltage. In this setup you would have two on buttons or switches, one to warm it up and another to "fire" the laser. This might be a simpler way of preventing thermal shock and would be much physically smaller to deal with than a high current wire wound variable resistor with the problems it might possibly induce. Still, unless you can find some way of "soft starting" the voltage to the diode (a mechanical switch is a hard start and if you have wires to your battery, you will have some amount of inductive spiking), I'd have a fast acting spike suppressor across the diodes terminals, it is a good practice to have one anyway. You can probably find one which is designed for these diode bars for just ten bucks but I cannot seem to find where right now, I bought mine a year ago, forgot who makes them.
Edit: Found it, they are called Lasorb ESD absorbers and here's a link to one on ebay:
http://www.ebay.com/itm/LASORB-ESD-...646?pt=LH_DefaultDomain_0&hash=item58b16de256
Remarking on a members post earlier in the thread; sure, it's a steep learning curve if you don't have background in lasers, and as he recommended do some projects with small ones first and in time it won't be so daunting. One thing I've found is some folk can get quite angry with a newbie undertaking something this challenging at that kind of power in IR due to the fear you will harm someone, if not yourself, with your toy. I completely understand that concern as it would reflect poorly on all laser hobbyist, but don't let them get you down, keep pressing but be safe.
Disclaimer: I am not a laser expert, not even close... but I do know a few things about electronics in general. Because of this, confirm and do your own research from other sources before using my suggestions.
See my big laser and RGB light beacon:
http://imageevent.com/qdf_files/tec...dlightwavecommunications/irledandlaserproject
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