Modulation efficiency

[DZ]

Optical feedback is a straightforward and fairly simple solution, making it the ideal choice.

I wish I could say this was true! Then it would be somewhat easy to fix with an optical feedback loop. Take a look at the attached photo, between the two black lines is where the problem is. An optical feedback look just isn't going to be able to compensate for that, no matter how hard the feedback circuit is trying to correct, it just isn't going to be able to fix it. Unless you set the top end of the feedback loop to the lowest part of the valley (between the two lines in the pic), you'll still have image problems. So in this case, lets says it's a 100mW blue laser, the bottom of the valley is probably around 15% of total output. So with a feedback loop, I can make a 100mW blue laser absolutely stable with a max output of 15mW. All lasers will be different, this one just happens to be this low, however it falls pretty close in line with some of the other scope traces I've seen for blue lasers.

Which really brings us back to AOM's, that might be the best solution, at the moment, to compensate. Or a combination of feedback loop (to make CW laser stable) and AOM.

[ElektroFreak]

You're right. As I said before, I firmly believe that 100% stability from any DPSS while under direct modulation is impossible regardless of what you might do to achieve it. Optical feedback would only offer some improvement.

Unless you set the top end of the feedback loop to the lowest part of the valley (between the two lines in the pic), you'll still have image problems.

That's precisely what I suggested in post #48, and that is the only way it would work.

[DZ]

Other than the first small oscillation, it looks like your 532 is achieving full output even on the short pulse...what is the timescale/div?

I don't recall, I'll take a look at the scope when I return and see what it was set for.

So anyone have a stash of AOM's laying around?! I gave my last one away years ago. Didn't think I'd need them with solid state stuff.

[ElektroFreak]

I meant to add that I like the idea of using optical feedback along with an AOM. That would yield the very highest stability. Those lucky individuals that own projectors that utilize Coherent Verdis (and most other extremely high-end systems) are already there. The Verdi has optical feedback (among many other stability features) and cannot be directly modulated. That means either AOM or galvo blanking.

[clandestiny]

Excellent post mr tocket

[clandestiny]

Since Steve mentioned this- I like the Adat through the Layla arrAngement

What would be the playback platform once digitized? Mutitrack audio program or laserboy?

[mixedgas]

Since Steve mentioned this- I like the Adat through the Layla arrAngement

What would be the playback platform once digitized? Mutitrack audio program or laserboy?

for viewing the waveforms,

Laserboy has a neat waveform scope mode once you have made the wav files with another program, ie laserboy doesnt talk to direct to ECHO's stuff. Laserboy probably gets you a better sample by sample viewing, but how fast you can index in it I dont know. If James will take my phone call, I'll ask.

Multitrack audio editor is probably easier.

Echo's stuff just "plugs in" to most audio programs as 4 crosslinked stereo soundcards, at least when I've seen it used.

I'm gonna be using Echo Gina in a few days, I'll let you know what I learn.

If I understand correctly, with Ms Gina you can use the ADATs dacs for playback as well. Lightpipe is cool.

Steve

[clandestiny]

Thanks Steve, I have a layla right here, I'm going to check it out-

[heroic]

I wish I could say this was true! Then it would be somewhat easy to fix with an optical feedback loop. Take a look at the attached photo, between the two black lines is where the problem is.

Hmmm.

Could you scope the diode drive current? I am wondering if there might be some issue with the drivers on these Chinese DPSSes. That initial spike seems awfully high...

[Zoof]

Red diodes seem to work fine, green DPSS aren't that bad, and Blue DPSS can be replaced with 445nm diodes. The latter hasn't been brought up here yet so I'm throwing it in. There is a thread where the 445nm diodes are proven to be a cost effective replacement for higher power levels. The need for an extra AOM, cost and space wise should make the 445nm diodes even more attractive.