Feeble output from FB3

[norty303]

I dropped the scan rate to 17kpps for the show. The beams were barely visible :-(

Worse than before, or the same?

If the same it does point to an impedance issue which could be fixed by the use of a buffer board like MatILDA or something.

If it got worse with slower modulation rate, I'm not sure what the problem could be...

[smokeAndMirrors]

Worse than before, or the same?

If the same it does point to an impedance issue which could be fixed by the use of a buffer board like MatILDA or something.

If it got worse with slower modulation rate, I'm not sure what the problem could be...

The same - subjectively.

[MisterWilling]

If the same it does point to an impedance issue which could be fixed by the use of a buffer board like MatILDA or something.

I am having this same issue, my LW green outputs around 550mW when in CW mode, and the most I can get out of it is under the FB3 is 350mW. I have tried serveral patterns with no modulation and static beams, in both analog and TTL mode. Results are always the same.

The buffer board didn't help any with output increase. I know this is a complex issue since there has been huge amounts of talk about it but I am working on an easy quick fix. I will have to do some more testing when I get a chance. Its very likely that this laser just outputs alot more when in its CW mode.

[norty303]

and the most I can get out of it is under the FB3 is 350mW. I have tried serveral patterns with no modulation and static beams, in both analog and TTL mode. Results are always the same

And therein lies the rub... if you are using an FB3 then you are always modulating.

And if your laser responds poorly to modulation (e.g. it has a poor response with a slow rise time up to full power) then you will never get CW levels of power out of it. Equally, even if you have good modulation response, and your laser actually achieves full output, your meter will only show an average of the on/off cycles (i.e. lower than expected)

However, just because your meter shows less energy, it doesn't necessarily mean that the eye perceives it any less bright - if your laser actually achieves its full brightness on each cycle, there's a good chance thats what you perceive. Only you can tell if a static beam via FB3 is as bright as a CW beam.

Also, have you tried an alternative DAC? It could be you will see exactly the same effect on that too.

Given that a few prominent members of the board have dropped Pangolin in favour of alternatives, it would be interesting to know if they got the desired benefit? And if it did change things it would be interesting to know how their new DAC/software is different from Pangolin?

[MisterWilling]

However, just because your meter shows less energy, it doesn't necessarily mean that the eye perceives it any less bright - if your laser actually achieves its full brightness on each cycle, there's a good chance thats what you perceive. Only you can tell if a static beam via FB3 is as bright as a CW beam.

I understand this, I'm not going strictly by my power meter because I'm more concerned with perceived output rather than numbers. Visually if I switch between CW mode and output from FB3 it looks nearly 30% or more dimmer. So would that mean that the laser is possibly achieving full output only in pulses and it looks dimmer because I'm viewing the average output? If so why would it still have a completely similar output of a static beam as projecting a pattern?

Also, have you tried an alternative DAC? It could be you will see exactly the same effect on that too.

I tried a RIYA DAC and it produced a similar result as the FB3, even when it was told to just produce an un-modulated beam.

I'm not trying to blame anything on the FB3 or Pangolin like others are. I'm just trying to see if I can get a workaround to it. I tried a buffer board and it made a 0% difference. I was thinking maybe applying a small amount of voltage on the mod line(like .5v) so it would get more voltage when under full modulation but I'm not sure how that would work or if it would be dangerous. I know the laser doesnt start to modulate until at nearly 60% voltage so it wouldn't effect it turning the beam all the way off.

[norty303]

Have you tried putting 5v on the mod line from a regulated supply? How does this compare to CW?

BTW, I'm not sure there is a fix for you, short of just switching the thing to CW and scanning like that. All the time you are blanking you'll be introducing modulation.

even when it was told to just produce an un-modulated beam

I seem to recall 'someone' saying on a previous thread that most software and DAC solutions needed to have some downtime each cycle, in order to do essential processing, so it could be that any of the more advanced products on the market will suffer exactly the same issue.

[Pangolin]

somehow I feel that Bill's attitude - "it's not us that is at fault, it's the way other people make their projectors" is not exactly reasonable. Or even sane.

Hehe. Bill’s attitude is -- you never know WHERE the problem is without adequate testing, and we certainly get a lot of non-qualified statements on this forum being made by people who have never tested their projectors with real equipment.

At Pangolin we have real test equipment and real test methodologies. We can find the problem very quickly, and we can also see what ISN'T the problem. So far in all of our testing we do for everyone from hobbyists to manufacturers, we generally find that the problem lies with "projector connections". After a while, we became motivated to write an article about it:
http://www.pangolin.com/resguide12.htm

The article has been influential at helping to solve the problem. When I went to China at this time last year, projectors were a real mess. This year, thanks to us translating the article into Chinese and distributing it to all manufacturers we can find, they're pretty much right on (with the exception of the occasional inverted axis). So I am happy to say that progress is being made...

In your case, what I would like to see is for you to get this projector into the hands of someone who has real test equipment. Then we can turn these non-qualified statements into real numbers. After that, we'd really have something to talk about. That's what I like about LaserFreak and the various PL meetings. We can get together and put the projectors to real test equipment and real scrutiny, and see where the problem lies. Another thing you can do is find a buddy with another projector and plug yoru FB3 onto their projector. If the problem stays with your projector, well, I'm afraid there's only so much that Pangolin can do to improve your projector (one being the projector connections article).

In the mean time, you should know that every single FB3 that is shipped is tested three times before it goes out the door, and the FB3 is likely the single most reliable piece of hardware we've ever put out. They hardly ever come back for repair. So -- although literally anything is possible, it isn't likely that you have a FB3 hardware problem.

And since I literally now have permanent holes burned in my wall, where (during the tutorial video) I was telling people what not to do during beam alignment or they would burn holes in their walls (hehe), it tells me that the software can put out a lot of power if used correctly, and with a projector with the right projector connections.

In closing, I will say that I am sorry that you are having problems, but more sorry that you would place the blame on Pangolin and on "Bill's attitude" without qualifying this in any way. Once you've done real measurements with scopes and power meters, then we'll all have something to talk about. In the mean time, you should take it as a good sign that literally thousands of FB3 users are not having any problems what so ever!

Best regards,

William Benner

[norty303]

that literally thousands of FB3 users are not having any problems what so ever!

Or at least they aren't aware they or, or aren't talking about them. [conspiratorial smiley]

It should be noted that since the last round of discussions on this subject, at least one laser manufacturer has taken steps to improve the 'modulated' performance of their lasers, rather than going for outright CW power, as this is the 'real world' characteristic for a laser show projector. I would guess that the cheaper you get, the more likely that the laser modules will be unlikely to have good performance when modulated, however I'm not sure if that phenomena affects diodes lasers as much as it does DPSS. Someone with more knowledge than me could answer that one easily enough...

[smokeAndMirrors]

Can I first say thanks to Pangolin to responding - it is appreciated. And I absolutely agree that cold, hard measurement is an important requirement for "blame" (though I would not use such an unpleasant word).

I think the problem is that I am what you might call a laser lightweight. I don't build 'em, I buy them and use them in shows. In much the same way as I don't know every circuit and solenoid in my car and shouldn't need to in order to drive to work, I do sort of feel that if someone charges me quite a chunk of money for a product, I don't expect there to be a whole stack of deeply technical issues which I might not even be able to understand, let alone fix. As I said, this isn't Pangolin's fault, indeed one could argue that Pango have gone further than anyone to try to if not resolve then at least spread awareness of this problem. That doesn't change the fact that my 1W projector and FB3 don't do what I expect. That might be a function of my expectation, but Pango are so darn proud of their gear that they promote its near infallibility, which can do nothing other than stoke expectation. If there are disclaimers ("may not acheive optimal performance under conditions X, Y and Z") they're not on Page 1 of the manual :-) And it's certainly the case that laser manufacturers say "Pangolin compliant" rather glibly.

I guess this industry needs standards across the board. Obviously ILDA is only a start.

[norty303]

One thing I would like to see (probably something for a LEM) is a direct comparison between a projector using 'good' laser modules (i.e. those that are considered to perform well under modulation) against one that is bad (i.e. one that performs badly under modulation and may also have impedance issues)

I'd like to see with my own eyes just how much of this is down to the laser modules themselves, and how much is down to the nature of the beast (DACs modulating the output - which is by no means solely a 'Pango' thing)

Of course this comes back to the fact that if you want to be doing this right, you shouldn't be modulating them at all, but using an AOM instead...


Come on you folks that 'jumped ship', let us know what you've found, is the grass any greener over there?