Open Can alright, but long or short?

[anselm]

Can someone please tell me what kind of diode this is, so I can estimate
the maximum current it'll take?
It's out of a DVD burner, maybe 18x or 22x...

I can see it is open can, but is it SOC or LOC?

The other diode is the IR one from the same sled.

Thanks

 

[Blord]

Looking at the picture I would say that it is the LOC diode.

This is the SOC.
http://laserpointerforums.com/f48/close-up-soc-diode-58739.html

The spec:
Red laser - Laser Wiki

 

[GoRdOn_B]

here is a picture of a LOC from a LPC sled

hope it helps

 

[anselm]

Looking at the picture I would say that it is the LOC diode.

This is the SOC.
http://laserpointerforums.com/f48/close-up-soc-diode-58739.html

Hmmm, thanks but that one looks suspisciously like the one I have. :thinking:
What am I missing?

 

[Blord]

The bar in the middle is longer. That is why it called LONG Open Can.

 

[anselm]

Ah OK, small but important detail.
I thought the actual can would be longer/shorter.

Thanks.

 

[anselm]

Hmm, so I hooked this diode up to my prototyping lm317 (with a 200 ohm pot).
At first I had a ~5 Ohm resistor in series with the pot, so the current would
max out at around 250ma, with the pot turned all the way "up".
It did produce a nice dot and burned the proverbial black trash bag.
Then I thought, "Hmm, these are supposed to handle 420ma, so let me change
the 5 Ohm resistor to a 3 Ohm one."

Dumb idea.
The diode went dim immediately, like it was with the 5 Ohm resistor and the pot
turned way down. It still varies in output when I turn the pot, but now it's about as
strong as a 2$ 5mw red pen running on exhausted batteries.

Is this what you people call a "LEDed" diode?

I then proceded to measure the current produced by my driver using a selfmade dummy load
I used two methods, measuring voltage over a 1 ohm resistor and also using the DMM directly in series @ 10A setting.
Both methods gave the same result = ~420ma.

So what gives? Was this a SOC after all?
Did the diode/resonator bar get pre-damaged by my fingers as I manhandled the poor thing
when I soldered on the leads?

Oh well, it's all training to avoid killing the nichia diode.

 

[Blord]

My condolences with your lost. You have fried your optical resonator in de LD.

"Hmm, these are supposed to handle 420ma, so let me change
the 5 Ohm resistor to a 3 Ohm one."

I have always difficulty with this phrase. Nothing is sure when you overdrive your laserdiode. They run fine on spec but when you pushing up your mileage may vary.

It is the same game as overclocking CPU's. On default all cpu's run without problems but when you overclock it, some will hit 4.5Ghz and other will stuck at 3.5Ghz. But they have all kind of protection inside preventing damage to them. I am also a specialist in oc cpu's you know

 

[anselm]

Hmm now that I think about it:
Could it be the diode commited suicide by reflection?
Because it was mounted in an O-like diode housing with the 3-piece lens AR coated for 445nm.
Maybe the wrong coating threw too much light back onto the resonator?

 

[Blord]

I don't think so. The lightbeam from the LD start in a point. When the beam hits the first lens it is already few mm thick in diameter. And when this reflected beam hits back to the LD it is already larger, it doesn't convert back to a point.
So the reflected energy is just a very small portion of total energy.

But when the beam leaves the lens module and reflected back by a external mirror, all the energy will convert back to one point thru the same lens module and that can destroy the die.