Torturing a 20mW 635nm diode

I'll probably get jumped on for this but I don't care, It's my diode and i'll abuse it how I want. :na:

To start off with.. My 'super high tech laser experimentation area' here at home.. At least until I finish painting the extra room and put down new carpet. Most of my laser stuff lives at work right now.



Awesome, isn't it? :shhh:

But anyway. I'll get right to the meat of this since I wasn't in a position to record a whole lot of data (literally.. hanging over the edge of the couch, while trying to simultaneously keep the cats away)

Said diode from DJNY's GB in a module, in a heatsink hooked to the spectrometer. It's being over-driven here at 150mA (datasheet max is 90mA) which is as far as I dared push it.. I may have 10 of these, but that doesn't mean I really want to kill one.



My fiber to heatsink adapter is another miracle of side-of-couch engineering.. It's the front out of one of the MDXL pens stripped of its guts. I discovered this was a tight fit in the 12mm hole in the heatsink, so I taped the fiber in one end, stuffed the other end full of papertowels to act as a diffuser so the spectrometer wouldn't get overloaded, and I was good to go.

But regardless. One may ask.. but how much did it output driven at 150mA? Well, here's the answer to that, using one of my red AR acrylics, which are the lowest loss lenses I have for reds.



As you can see, 32mW. Not too shabby from a 20mW raw output rated diode. I ran it for a little while at that power. and it was solid at 32mW so if it was degrading, it wasn't doing it quickly.

I know some people will probably be whooping and hollering about it not being worth it over-driving them due to the wavelength shift.. Well. I didn't forget about the spectrometer results.. Here you go.



I personally can live with 638.83nm. And for the purists who will still yell 'But it's not 635nm!'.. Well. This particular diode was never capable of that anyway under 'normal' conditions. Sure you could stick it on a TEC and cool it.. But is it really worth going to that trouble for a 20mW diode? Even at threshold, this diode started out at 636.74nm.

32mW of 639nm equals 27mW of 635nm, so it's still a net gain as far as i'm concerned, and side by side with 660's, 639 is going to look just as different as 635 will.

This concludes this evenings diode torturing. I'm going to bed.

Good night.

Great results :beer:

I've know somebody that used liquid nitrogen to cool a red diode to get something like orange out of it. Not really practical, but it can be done.

Pics wont load for me

Yeah I think the power might be off at the office, which is where the DNS server for my domain is. We're in the middle of some storms here and I know all my UPS's here at the house have been going crazy all morning. Let me try changing the links using the IP address.

Ok, hopefully the images will work again now until I can get to the office and see what's up.

Have you measured a HeNe or green with that yet?

I've measured 532nm.. which resulted in 532.32... which is close enough for me. I'll carry home a HeNe if you want but I get the feeling the results would be about the same.

Now ready for the next attempted shoot down. :na:

I plan to run one of the ebay 35mW 685nm diodes through the ringer tonight.

I'm just pointing out it doesn't make sense to report results to 0.01nm when it isn't capable of measuring that precisely.

It's like mister bluefan touting his 10nanowatt-precision power meter in a lit room or saying your laser is 1.2592837429385239487239462835 mRad according to a divergence calculator

Hey now. I just state what the spectrometer reads. heh. Can't accuse me of altering data then.. And if people want it rounded, they can do it in their heads.

The 685nm test will have to wait. with a slip of the finger, it turned LED.. They don't like 300mA by the way.



Spectrometer said it was running at a hair over 689nm at 40mA though.

I'll press another in a aixiz module tomorrow. I'm not going back to work tonight.

And that's one more vote for the type of PS that FP has that allows you to lock voltage and current. I was considering a cheaper one till I just read that.

Qume,

I got I think - memory here only - about 50mW for a 'while' out of one of the 685s at ... I want to say 100mA? I may be off on that current, i'll check in a bit. But I do know that they don't run with much headroom. They can't be pushed very far; i've already leded one by not going too far over the limit.

Good thing is, they were cheap and I got a lot.

I totally know what you mean by "while trying to simultaneously keep the cats away".

I have four of them and they all looove lasers. It makes metering, picture taking, etc. a worrisome process, because I don't want a blind cat.

Last night, I was taking pics of a customers 1.2W laser I built for them, and, out of nowhere, my 18lb cat pounced on it. :tsk:
I then am chasing him trying to see if he's blind....

Anyway, :gj: Qume! Thanks for taking one for the team

Nice results. I may have to keep this in mind when I build my next one.:beer:

jcranmer said:

And that's one more vote for the type of PS that FP has that allows you to lock voltage and current. I was considering a cheaper one till I just read that.

Click to expand...

Well. Irrelevant in this case, since I needed to turn the current up anyway. I just got carried away. I actually had every intention of killing this particular diode, These were cheap and I have lots of them. I just wasn't planning on killing it until the END of the tests, lol, not at the beginning. Though I have been considering changing the linear taper current control pot in this PSU to an audio taper pot.. Which would mean the 0-500mA or so range would be roughly the first 3/4 turn of the knob, and the last quarter turn would be 500mA-2.5A range.. It'd mean a lot more control at low currents at the expense of the ability to fine tune exactly at high currents. I'm still up in the air on doing it though. A better solution would probably just be for me to buy another lower current powersupply to test low power diodes on.. That, or buy a REALLY good programmable PSU to do it that I could program limits and ranges in.

aryntha said:

Qume,

I got I think - memory here only - about 50mW for a 'while' out of one of the 685s at ... I want to say 100mA? I may be off on that current, i'll check in a bit. But I do know that they don't run with much headroom. They can't be pushed very far; i've already leded one by not going too far over the limit.

Good thing is, they were cheap and I got a lot.

Click to expand...

Good to know, I'll try to do power tests first next time to see what current 50mW is and stay under that when I do the spectrometer tests.. And yes, I bought a small mountain of these as well. heh.

DTR said:

Nice results. I may have to keep this in mind when I build my next one.:beer:

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I thought you had more of the 40mW ones, DTR. heh.

qumefox said:

I thought you had more of the 40mW ones, DTR. heh.

Click to expand...

Built my last 40mW one in that MXDL Pen but I still have a 20mW from DJNY's group buy.