NEW LOC Laser diode review.

[styropyro]

If your supplier no longer carries LPC-815 sleds, PM me because I have a supplier that has lots of them IIRC. I thought I remember reading that you no longer can get those, but I may be wrong.

 

[SenKat_Stonetek]

If your supplier no longer carries LPC-815 sleds, PM me because I have a supplier that has lots of them IIRC. I thought I remember reading that you no longer can get those, but I may be wrong.

Thanks for the offer, I'll keep you in mind if mine runs out These diodes were SUPPOSED to replace the LPC-815's - but after these reviews, I don't think they will !

 

[pullbangdead]

Re: These diodes

See my post in other thread: http://laserpointerforums.com/f44/diodes-killed-mw-ma-53416.html#post752744

 

[Meatball]

Thanks for that explanation PBD. I'm still curious however, why is it that these particular diodes are so much more sensitive to heat than the LPCs we use? I figured that since these were diodes were made from similar materials, and were both in a long open can package, that there wouldn't be such a difference. What is it about this diode that makes it so much more heat sensitive?

 

[pullbangdead]

Thanks for that explanation PBD. I'm still curious however, why is it that these particular diodes are so much more sensitive to heat than the LPCs we use? I figured that since these were diodes were made from similar materials, and were both in a long open can package, that there wouldn't be such a difference. What is it about this diode that makes it so much more heat sensitive?

Didn't someone say it's a shorter die? That's all it takes.

Rough approximation that's good enough in practical use:

Junction temperature change = dissipated power * thermal impedance

Thermal impedance for a rectangular stripe active region on a thick substrate goes as 1 over the length of the stripe. So if the length is cut in half, the thermal impedance is doubled, and therefore the temperature change of the active region is doubled.

The other factor is dissipated power, which is power going in as electricity that is not put out as light. I haven't done it, but compare this diode's performance just before the roll-over to the performance of the old red diode just before roll-over. It looks from a first glance as though the old diode is dissipating a bit less power than the new one, but I'm not sure. Compare those 2 factors to get a better look at the rollover. Then a whole host of other factors into play to determine WHY one of them is dissipating more power than the other, and a lot more variables come into play then that we have no way to look at without a lot more work. You can even break down the dissipated power into component parts when designing these things to look at where it's going and why.

Finally, the change in junction temperature could affect the diodes designs differently. Die length is clearly the first obvious one that jumps out at me though. It'd be interesting to see the L-I-V of both diodes overlaid on one another by someone.

 

[Doc]

A diode's wavlength is proportional to drive current, not just temperature. This characteristic could be employed to protect the facets at high current.

The new 500mW mitsu's do the same thing.

 

[andy_con]

laser-xh are stating this diode at 350-456mw

LPC822 Red brand new Diodes

 

[jayrob]

Their picture sure looks like a short open can...

Which are not nearly as good as a long open can. But I guess there's only one way to find out if it's something new or not...

 

[SenKat_Stonetek]

laser-xh are stating this diode at 350-456mw

LPC822 Red brand new Diodes

Yeah - they are stating that, because they have REFUSED to acknowledge the research provided here, in this thread. They have continually ignored my emails ! Well, if ignorance is bliss, then they are having a FABULOUS time !

 

[Hemlock_Mike]

Jay ---
Sorry, I didn't measure the die length. It "looked LOC" and I assumed - well - you know.
Still, this diode can be rocked back and forth over the curve like I've never seen.

HMike

 

[danilow]

this LD is in the LG-22X GH22NS50 dvd burner¿
I did kill 2 this weekend...

one in the harvest
another accidentally with a direct reflection of a focused beam directly into the laser cavity, its stop high outputing instantly, after that its seems like a 5mw pointer :/

i take off the 2nd ld from the aixiz module and connected to 1 Amp of current without any kind of heatsinking it bright for a whole minute smelling like a fire then its start to degradate slowly and sounds like potato chips

 

[Benm]

A reflection can probably kill it like any other red diode.

As far as power ratings go, i wouldn't say this diode is capable of sustaining anything beyond 250 mW CW output. Even using pulsed testing at various frequencies and duty cycles, i have been unable to push it beyond that.

Running it at 1 amp CW without damage remains impressive - these seem alsmost immortal, and would be the device of choice for kipkay projects. The output performance remains non-impressive to enthousiasts, but i do see a market for these diodes for beginners - you can torture them like LED's and beyond without damage, which is pertty unique.