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Laser diode cooling, would sanding help? Answered

If I sanded the sides of my laser diode (essentially the same package as a stubby 5mm led), would it increase the surface area enough so that the cooling effects are noticeable if used in conjunction with thermal epoxy and a small active cooling system?
Datasheet: http://docs-europe.electrocomponents.com/webdocs/08d5/0900766b808d55b2.pdf

UPDATE: Ok, due to many unforeseen minor issues/problems that have arisen, I have decided to consider a flat diode package. Although the power and pulse width are somewhat smaller, It wont really hinder the end product (which will have loads of documentation on the build here).
New diode datasheet: http://catalog.osram-os.com/catalogue/catalogue.do;jsessionid=A8BC7E9CCE6FB1AA392B37F3F982A978?act=downloadFile&favOid=0200000200001347000300b6

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orksecurity (author)2009-09-02

Heat sink grease would probably help more...?

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user

Yes it would, but I want to add more surface area to the diode if it will help the active cooling system cool the laser faster and or more. I want to be as safe as possible since they're ~$40usd per piece

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frollard (author)The Ideanator2009-09-03

From all the pc cooling special stuff - people buff their heatsinks to a mirror shine - less inefficient grease getting in the way of good heat transfer.

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The Ideanator (author)frollard2009-09-03

The sink is going to be drilled/milled where the diode will be, so it'll be pretty smooth. Do you have any suggestions as to which grease/epoxy would transfer the most heat? might the diamond based stuff work well enough ( http://www.innovationcooling.com/overview.htm )?

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user

You aren't going to get a fraction of the dissipation through the plastic that you will get from the leads. Just look at the package !

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user

What about the new possible choice? It has barely any plastic at all.

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user

Besides, I was referring to the thermal grease there.

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user

You only have to look at the spec to see the thermal resistance of the new device at 200K/W is a lot worse than the old package at 160K/W. Do what I said, forget shaving the package - it won't make any difference, and just pump the heat from leads. You won't get better than that.

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steveastrouk (author)frollard2009-09-03

Its not so much the shine as the flatness you need. You can have a surprisingly rough "polished" surface.

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user

My best guess is that, on that scale, more surface area won't matter a heck of a lot. But that's just instinct; your milage may vary.

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The Ideanator (author)2009-09-03

Ok, I think I know what you're getting at now. you hadn't clarified the views you were using That darn plastic is going to get in the way so much, and since I'm a bit scared of killing the lens finish where it counts. I'd really like to leave the lens intact and shave off the lower 3/4 of the body. I'll ask their engineers how I should go about it, or if they have a flat version of this diode. On accident I found my ceramics kiln will melt Al, which should not have been a surprise since the label on the side basically alludes to it having the ability to melt some steels too (don't operate above 2250 F).

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seandogue (author)The Ideanator2009-09-03

lol...yeah, talk to their engineers, but don't be surprised if you're told something along the lines of "if man were meant to fly..." and they try to sell you another more expensive part.

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steveastrouk (author)2009-09-02

THE best thing is metal to metal contact. I haven't seen a plastic cased Laser diode before. What are you using ?

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user

Its a REALLY powerful laser (if attached to the right circuit)

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user

Being a very very jaded user of optronic datasheets, I'll lay good odds its not as you think it is :-(

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user

You are probably correct, since I know very little about them and I've never really used lasers before. I'm not really going to use it for the majority of the intended purposes it was designed for, nor is it going to be very scientific in nature. May I ask what qualms you have with their datasheets?

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Any data sheet rarely covers all the bases. They tend to look at a quite select selection of devices which means that optical devices tend to be brighter or more sensitive in the datasheet than reality.

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The Ideanator (author)2009-09-03

They might also let me mill some impeller pump parts too!

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The Ideanator (author)2009-09-03

I don't get what you're getting at in that pic, but I'm intending to do a lost wax cast for the baisic shape with the coolant tubes inside and fins on the outside and drill the middle as precisely as possible for the diode. It'll also have a nub on the front to thread so I can put it in the final "test casing"

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The Ideanator (author)2009-09-03

I'm not at all sure who has anything around here, I'm in a community college. I just started on the 27th, I shall have a better look around when I'm more comfortable and have lunch money (also they don't have a subway here). There are some CNC courses here, so there's probably a machine shop too.

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steveastrouk (author)2009-09-02

That device looks so small, I suspect cooling is dominated by the leads. Heatsink the leads with big PCB lands or something

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In fact, actively chill the leads with a peltier cooler.

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orksecurity (author)2009-09-02

Note that the rated duty cycle is 0.1% wjth a 100nSec pulse. (If I'm doing the match right, that means you can put out one of these extremely brief pulses every tenth of a second. Really powerful if all you need is a brief pulse for rangefinding and similar applications. Not hugely powerful if you're comparing it to lasers that can operate more continuously; over time, it's averaging 0.075W. That huge pulse does make it potentially more dangerous, of course; handle with appropriate care. Dunno whether that affects your project, but figured I should point it out in case you had missed it.

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user

I'm intending to run it quite a bit faster than that, but I'm not quit sure where you're going with the duty cycle bit, but further down it says: "Standard operating conditions refer to pulses of 100 ns pulse width at 1 kHz rate with 30 A operating current at TA = 25 °C." 1kHz is orders of magnitude faster then your estimate.

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Granted; I misplaced a decimal point.

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orksecurity (author)orksecurity2009-09-02

And those maximum ratings are for short-duration operation. In other words, this thing really does seem to be designed to put out a squirt of signal and then be allowed to rest. If that's what you want, great. If not, it may not be the component you're looking for.

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