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Open can?

NeedAnotherEye

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Hello!

I'm probably gonna get a lot of differing opinions on this one, but I'm wondering what the advantage is, if any, of opening the can on a laser diode? The only thing I can think of is getting rid of some optical speckling that won't clean from the laser window, but at the risk of dirtying up the laser itself... Would you clear this one up for me, before I prematurely tear into a laser diode?

Thanks in advance for the info!
 



pullbangdead

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Depends.  

Red diodes sometimes come with open cans, so there is probably no science reason why opening the can will reduce the laser's performance, and removing the lens will reduce reflections (guaranteed to give you more power, but the power gained won't be much, maybe a percent or 2.).  But there's the big risk of killing the diode in the process of removing the can, because it's tiny, fragile, and the little wires are VERY easy to break.


Violet diodes, there is some debate.  The PHRs have fragile windows, so if your window breaks out, there's not reason not to do it.  The window being broken can kill the diode just as easily was breaking it while cutting the can off.  But, if the can is still intact, there's some debate about whether or not exposing the diode to atmosphere will hurt it.  It won't hurt the GaN itself really, GaN is very inert, but if the facets are coated with dielectric materials for mirrors/DBRs (distributed Bragg reflector), then those mirrors can oxidize, leading to damage, and eventually COD.  This is not proven, but it is a thought.


Really, to me, if the engineer that built the diode felt it necessary to put the can on it, I leave it unless there's a reason to take it off, such as with the damaged window in chido's link or the window of a PHR being knocked loose.  And the resk of the diode being damaged goes up dramatically without the can there, as shown by the link above (without the can, it would have been dead).
 

NeedAnotherEye

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Cool, thanks for the replies. I have a laser diode that had its window broken when I was prying it out of a lens housing (very cheap red laser pointer, no loss), so I tossed it in a bag since I was playing with my DVD-RW diode anyway. Yesterday I used a pair of scissors to score the can of the broken laser diode (it cut through surprisingly easily), then I carefully pulled it away to expose the diode itself. Now I have two working laser diodes, the one from the DVD-RW and the one from the cheapie laser pointer! I'll leave the can on my DVD-RW diode, since its window is perfectly clear.

Thanks again!
 




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