Modulation efficiency

[DZ]

Interesting. I agree drlava, one of the most important tests is not even part of that review.

[tocket]

Hi dazebtwn. Welcome to the discussion. I think it's very nice to see results from more users, but your pictures are not working right now, which is really a shame since I'd really like to see them.

On another note I tried the DAQ and collected the modulation signal for the entire show at 100 kS/s, now I just need to figure out how to import this 800MB text file into MATLAB...

[DZ]

If you guys don't mind I would like to join in this discussion.

Hi dazebtwn, you are absolutely encouraged to join this thread. The more folks looking at this issue the better the chances are of an improvement being made.

Unfortunately, the images you added are not showing up for me.

[ElektroFreak]

^same here.. no images.

[DZ]

Very nice! I like the animation. That really shows a strong case for running them full power all the time through an AOM!

[MechEng3]

Greetings,

It is easy to see why a laser that is sluggish to respond to blanking would appear to "weak" when compared to CW operation. With the tec's setup for CW they appear to over cool in a pulsed system.

There is a laser that has to be better than most "bulk" lasers made. I have an RGB international laser that pre-heats the BiBo and presets a general field temp for the diode. So the temps should be very close to what it needs when it is blanked or left idle for a period of time while powered up....unmodulated. Fuzcub has working lasers from this manu....he may be able to perform a couple of tests....

[Zoof]

I don't have the fancy test eq. some of you have but I'm throwing my results back into the mix again. Also looking at scope graphs might lead people to strive for perfection while it is not needed for a decent output.

Here is the case where it was a problem for me: http://picasaweb.google.com/DrZoof/R...76997930531858

I've posted it before, sorry to repeat, but it illustrates well what the effect was of a low green duty cycle: yellow turns orange. I found it unacceptable and I got it fixed under warranty. Probably the curves don't look perfect but it is as good as not visible.

To help get this worked out with manufacturers we need to quantify what is an acceptable worst behavior, so what is acceptable for a show and what does that look like on a scope?

[FourDee]

Along with a constant power loop, I think some kind of feed-forward would be an improvement. I.e. more power demanded -> TEC's start cooling more

[ElektroFreak]

Agreed. That would be a great improvement.

The Chinese have been accustomed to making lasers that are very much cheaper than their American and European counterparts. Obviously this involves using simple cavities and only the most basic stability features, unless you're talking about some of their high-end scientific lasers, but those cost good $$$$$ even from China.

The reason so many people use Chinese lasers is because of the cost-effectiveness. If too many features are added, even the Chinese systems could become cost-prohibitive, so I also believe the current designs should be kept around for those who can't afford the high-end stuff (like me)..

[danielbriggs]

Again, just a thought:
I know AOM's have been mentioned.
However even taking into account the ~10-20% loss through it, would one PCAOM after all 3+ lasers run CW still average more "modulated power" than not having modulation and letting the power suffer from modulation?
But if you're spending that sort of £££ on a setup like that, must make sense to buy 445nm?

Another thought: Would TTL modulated lasers be affected more than analogue lasers? Me thinks so... just wanted to check.
*IF* one was running a TTL setup, wouldn't it be more prudent to run all the lasers fully on CW, and implement some sort of galvo, Z-blanking on each beam path?
Again... just ideas...
Still scratching my head for a good analog solution.