AltasNova 635nm Destruction

[GoldMagnet]

A good friend of mine who supplies a lot of my bits, has just read my keychain pointer mod, and sent me this, he is a very technical person so I thought I would post it for reference for AtlasNova 635 pointer reference (that was the pointer he was adjusting).

"In a bored (and slightly wreckless) moment, I stripped one of my red pointers last night. It was set to 28mA/3.5mW, and was delivering 25mW at 70mA. The 25mW beam was pretty impressive (for a red one), I have to say.
It popped at 83mA/~32mW. It was interesting that no mod was required to get this adjustment range, I just turned up the pot.

I wonder how long it will be before some of those doughnut shaped military DPSS modules get onto the surplus market. They probably deserve the sort of control normally reserved for radioactive materials!
I'm sure we will get one though, it's just a question of knowing the right people!".

Regards


Gold

[The_Doctor]

wreckless?
I'd say that was plenty of wreck. :twisted:

That reminds me of the Philips OF4944 9mm 655 nm diodes. They were rated at 3 mW and 45 mA. They could take 76 mA reliably and put out about 10 mW doing it. and last for thousands of hours too, at widely varying temperatures. (And if cooled to -20°C, could rival the brightness of a 658 nm 35 mW output with no change in current input).

I also found that a Samsung 635 nm diode could take 76 mA, and oddly, though it didn't die suddenly if pushed further, it did get dimmer again, and brightness rose as I returned back to 76 mA.

So maybe 76 mA is common in being a good point to assume as a maximum to push a laser pointer diode to.

Some Opnext diodes like being pushed too, especially the 35 mW and 50 mW diodes, though these want a lot more than 76 mA. The bright ones, 80 mW or more, HATE being pushed. I can't help thinking that Opnext were already pushing too hard to reach that output from a single mode diode.

(Off topic, talking of diodes, I'd like to buy one or two Sony 350 mW 658 nm diodes to play with. If they're not horrible expensive, I want to see if they stand retroreflection better than the high power single mode Opnext diodes, which ALWAYS die instantly if you reflect their light back into them even with a dirty mirror. I haven't found a source of those Sony diodes, let alone one I can likely afford to buy from).

[Spec]

I also found that a Samsung 635 nm diode could take 76 mA, and oddly, though it didn't die suddenly if pushed further, it did get dimmer again, and brightness rose as I returned back to 76 mA.

Sounds like a mode hop, did the profile change as you were ramping it up?

(Off topic, talking of diodes, I'd like to buy one or two Sony 350 mW 658 nm diodes to play with. If they're not horrible expensive, I want to see if they stand retroreflection better than the high power single mode Opnext diodes, which ALWAYS die instantly if you reflect their light back into them even with a dirty mirror. I haven't found a source of those Sony diodes, let alone one I can likely afford to buy from).

Those diodes are like the holy grail. Its rumored to exist but I havent found one anywhere dispite my best efforts in looking.

If you come across any, tell us here, Id love to play around.

Welcome to the forums, by the way.

[The_Doctor]

Thankyou.

I don't think it was a mode hop, it was a very gradual effect from a single mode diode. It might have been related to temperature, therefore wavelength, as it was a visual thing, not metered. (I don''t have a meter, yet..) Even so, it looked odd, it happened fast and recovered fast with current change, rather than tracking temperature. It didn't lag as it would with heat. It was smooth, directly related to the big capacitance I put across the diodes for soft start control, but I know the capacitor isn't causing the oddity. One possibility I considered was a proportional fall in wavelength due to overdrive like that found in some sine wave audio oscillators if you turn their feedback too high or put too much energy into them. That could possibly be confirmed if the linewidth broadened, but I don't have anything to measure that either... That happens in the audio oscillators, but I suspect the two systems are too different to parallel in this way, but it's the best model I can come up with.

About those diodes, if I do, I will. I think the best way we can get them cheap is to share info, and use the group buy thing to get them, and spread the word to get the prices down by sheer demand. Right now I'd settle for the 250 mW. I have NO idea what they cost though, raw, and that's the way I want them. I really like those MaxYX modules though, but ideally I want to carry on building my own. I stopped doing that when I found that I couldn't get good prices for 80 mW any more, and I can't get more powerful diodes economically. I did several envelope pushing things, but there's not much to be gained from that on lower powered diodes unless I can get stronger ones to apply what I learned on them, and afford to lose a few trying, too...