Did I fry my first laser or is something wrong?

Hello -

First off Im a laser noob and this is my first project. I bought a Sony DVD-RW diode in a Aixis housing from StoneTek. Im driving it with a bench top DC power supply 2.9v @ 220Ma

The first several days it worked great, bright and focusable, perfect. Last night I go to fire it up, and its not the typical bright pinpoint of light I usually get, its very dim extremely small point of light, as if someting was in the way of the beam....

I took apart the housing and blew away any foreign objects (if they were there) put it back together and the result. Just a dim small point of light...

Im asking because I thought if i friend it I would get no light at all. This seems as though the laser has become misaligned or something... because I still get some light, just not usable.

Thanks for any input...

Re: Did I fry my first laser or is something wrong

I'm sorry to tell you this, but you most likely fried it. :-X

Re: Did I fry my first laser or is something wrong

Hmmm interesting. So did I drive it wrong? Do I need to build one of those driver circuits? I thought having a benchtop DC power supply could take the place of those circuits becuase its so controllable?

Re: Did I fry my first laser or is something wrong

judogti said:

Hmmm interesting.  So did I drive it wrong?  Do I need to build one of those driver circuits?  I thought having a benchtop DC power supply could take the place of those circuits becuase its so controllable?

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the death of your diode was mostlikely caused by a voltage spike
i have had any problems driving diodes directly from my benchtop powersupply
but not all of them are regulated good enouch to drive laser diodes

Re: Did I fry my first laser or is something wrong

I don't know, 220mA seems safe enough. Maybe it overheated? :-/ Or maybe it was one of the bad ones Senkat was having.There was a thread about a bad batch of diodes but I stopped watching it after a while.I'm not sure if everything is fixed now. :-/

Re: Did I fry my first laser or is something wrong

Switch said:

I don't know, 220mA seems safe enough. Maybe it overheated? :-/ Or maybe it was one of the bad ones Senkat was having.There was a thread about a bad batch of diodes but I stopped watching it after a while.I'm not sure if everything is fixed now. :-/

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yea 220 mA should be prety safe how whas it mounted

Re: Did I fry my first laser or is something wrong

could be static too for all you know, voltages so low you don't even feel them can kill the diode, i killed my bluray that way and i never remember getting any kind of zap, it was even in a complete housing

Re: Did I fry my first laser or is something wrong

Here is how it was mounted. I built a stencil cutter based on these specs ().

I dont think the mounting caused it to fry, its right in the open, held by a metal arm.

24.110.142.91/images/laser005. jpg
24.110.142.91/images/laser006. jpg
(Sorry for the links, I dont have the 20 posts yet to post them.)

I do think I got one of StoneTeks bad diodes. Which I would actually be pleased if it was, that would mean I didnt do anything wrong! lol. The 'bad' batch he got was max rated at 200 mA I think (many threads and they all say a little different details).

It sounds like I should add a driver circuit between the benchtop DC powersupply and the diode? (do you have any good links, I know there are a few on the forums, but is there a 'best' one to build?)

Re: Did I fry my first laser or is something wrong

When using a bench supply fit a capacitor across the LD as there is no way of knowing how smoothe the PSU start up is.
These days my LD's get a drive circuit straight away, which I supply from the PSU, it is much safer.

Regards rog8811