Pangolin ? laser not perform at maximum

[rfourt]

@ rfourt

This is pretty easy to believe that if you project a single circle it looks like one thing, but if you project four circles it has higher power. Steve already gave the answer to this and so did I, but, unless you really understand lasers and what goes on inside them, you would not catch, or understand, the answer.

The reason is "thermal modulation" which results from "light modulation".

And it should be understood by everyone in the world (or that is my wish) that this has nothing to do with the FB3 or Pangolin software.

Bill

Im sorry that i dont know whats going on inside a laser and all the electronics behind it etc etc. I dont think i will ever learn..And im not sure i want to learn everything inside or behind it either. I create Wonderfull shows and exciting BeamShows, and im a Pro at what i do, thats my proffession, not electronic enginering or photonic-physics professor wich i believe i dont have to be.

What i do know is that i DONT want to make 3-4circles to be able to reach "almoust" full power of my laser. I just want to make one circle and set it to full power and i then wish it would be full power. If its becouse of my laser then ok.. If ts becouse of FB3 or the software, then ok also.. just let me know what i could do to fix it. Buy a new Laser?

Im sorry i missed the explanation as i said in my post, the language barrier is an issue here for me sometimes, especially with the complicated electronics talk, so i still dont understand why this is not working and that is why i started this thread from the beginning.

Yes my first thought was that it is becouse of FB3 or the software, becouse that is the things i have some knowhow of. So my conclusion was simply that, and i dont think i was totally way off as there has been issues with the Targeted beams power before that has been fixed now though.

So i still have the question, What do i need to do to make FB3/software to work with my system and giving the laser the power it needs to shine its bright wonderfull light at full power..

Yes i understand there are thousands of different systems out there. with different modulation reqs etc etc.

But if the reason is that there are only a few laser manufactures that can handle the full potential of Pangolin. I think you should have a "Minimum Requirment List" Or a list with Lasermodules that do meet the requirments needed to run them in fullpower.


EDIT:
ok i saw Steves Post now.. sry i totally missed it.

Although i think one solution to this would be. Put in an option in QS or LP that you can switch on full power. If i make one 255 green circle i want it to be at full power. if i make more then one circle i want them to be full power also.. Yes i understand that they will not be seen as full power. But i just want to work around the same problem we had with the Targeted beams before. Wich you fixed.

I understand that complexed /cues and animations with multicolors still will have this problem depending on the quality of the laser/PSU as you said, some PSU/lasers especially DPSS isnt either fast enough or thermal or etc etc. But im now talking about One Color or perhaps 2. not mixed..

[Doc]

This gives me some hope for a tuning standard for the two mirror cavities. How bad is the decay or gain if blanked for a few seconds and then returned to the pattern?

Steve

Once fully normalised (about five minutes for this module) there are no obvious or outlandish anomolies; there certainly were before this last tune up.

During my six and a half hour show on Saturday it performed very well. She even seemed to light up at full power after 15/20 minutes idling (ambient temp in the club was around 85°).

I must mention that I realigned the cavity when I was in there (under modulation) which really cleaned up the beam profile.

[DMills]

Um Dan, you should know, the pump diode can shift as much as .2 nm per % C or more and emits a wavelength profile that when plotted looks like a train of irregular spikes. The ND adsorption profile is also a train of spikes. The spikes can line up and overlap in variable amounts while shifting.

Yea, aware of the thermal tuning of the pump diode and of the absorption spectrum of Nd, but there is not a great deal that can be done about the diode junction to diode mount thermal resistances, which unfortunately are going to be the major ones for fast modulation.

It is even worse then that actually as once you get to more then a few watts of pump you start looking at fibre coupled multi diode arrays, which are anything but monochromatic (Actually this might HELP on aggregate).

The Nd: emission profile is 1.1 nm wide in most lasers, with a secondary offset "hump" driving the ktp batty with phase matching effects and the "green noise problem".

That is what an intra cavity etalon is for no?

So you have KTP temp, diode wavelength shift due to temp, and localized optical heating effects in the lasing crystal, plus adsorption shifting in the KTP. its a mess.

Obviously, but everything you can take out of the equation is going to help. How much of an issue is thermal lensing in typical small DPSS?

Nobody at PL has really tried light feedback except me, DZ and Heroic, and none of us have published anything.. Hint! I'd go after light but I don't have a dpss I can spare for hacking.

Going with light feedback requires a pump diode considerably more powerful then would otherwise be required and I suspect that many here would rather run the pump at full power and forgo the feedback stabilisation (500mW of stable linear modulation or 1.5W of ragged non linear mess, decisions, decisions).

Oh stuff it, just stick an AOM in there....

Regards, Dan.

[rfourt2]

I have done some testing now. And the results are very interesting. i Will continue doing more testing NeXT week (monday) and document it on video. So you see its not BS.

[rfourt]

Ok.. i have done some real testing now with an OSC. and yep it gives me 5Volt, so as i said it isnt the FB3 nor the SOftware but infact the Driver to my VIASHO.
Becouse when i test with the OSC connected and the VIASHO driver connected it only gives me 4.5Volt. or as i said before i think it is only 4.3Volt.

The funny part is that i have gott a Crappy 650nm LION laser, with the smallest and probably cheapest driver ever, and that takes the 5Volt perfectly.

her are some pics. both are with a circle animation and the first pic is with 300points and
THe second pic is only 20points.



I would really like to Thank "Buffy" for contacting me by PM and explaining how to solve this problem, and giving me some ins and outs on how to do propper testing.


ALso i really think that there should be a list of compatible LaserDrivers. I understand that there are thousands of drivers out there so the list could be long and probably take a long way to finish/test.

But here is the first driver that dosnt work with Pangolin FB3 out of the box.

"VIASHO VIII-A"

[norty303]

I think this could be related to the impedance of the FB3 outputs (already touched upon in an earlier thread about 'poor' FB3 performance)

I would guess the simplest way of fixing this is to use a buffer circuit on the colour lines. Rob Stanwax and Dan Briggs already have the MatILDA boards and I believe Edison or one of the gang involved in the projector case group buy have their own version of a buffer board. Easily fixed and not too expensive really.

[danielbriggs]

But here is the first driver that dosnt work with Pangolin FB3 out of the box.

"VIASHO VIII-A"

That's worrying...!
I've got a 1W Viasho here still on the shelf. I did connect it up once to my FB3 a while back and it was noticeably dimmer. I just put this down to the cavity running under modulation losses rather than CW and thought no more of it.
*But* I was looking to replace the driver anyway with a nice PicoDrive DPSS, for size reasons; but now there might be a technical reason to change it too!

Best Regards,
Dan

[Lasermad]

"contacting me by PM and explaining how to solve this problem"

If making a list might also be pertinant to provide a workaround / solution


Drivers that doesnt work with Pangolin FB3 out of the box.
IE- provide full 5v

"VIASHO VIII-A" - Solution ???????????????????
"Laserwave" - Fixed for 2010 models

[gottaluvlasers]

the buffer circuit will fix this. it is an extremely easy circuit to build. i will try to dig out the schematic when i get back. or these boards by dan and rob will probably be your *much* better solution.

LaserWave had this problem about 6-8 months ago also. The input impedance on the modulation inputs were too low. Therefore was never allowing the laser to reach a full 5V input. Bridge immediately fixed it. Send Viasho an email and tell them of this problem. Better yet, measure the input impedance of the driver. it should be a bare minimum of 10K ohms.

-Marc

[buffo]

Guys, just to clarify: The problem is *NOT* with the FB3. It's with laser manufacturers that don't follow the ILDA spec for high impedance inputs on the modulation inputs for their laser driver modules.

You will experience this same problem on *numerous* controllers if you happen to have one of these drivers that has a low input impedance.

I sent a PM to Rfort because it appeared that this thread was devolving into a urinary olympics, and the real message (that you need to measure the voltage with an Oscilloscope) was getting lost in the clutter. As I suspected, he did not catch this information when it was posted earlier.

The bottom line is that people are *way* to quick to blame the controller, be it Pangolin or another brand. As I said above, this low impedance problem affects NUMEROUS drivers, including Laserwave. Well, that's not really fair, since LaserWave has since changed their design to solve the problem. But last year, it was a problem even for them.

More to the point, Pangolin performed an extensive research project on laser diode drivers back in the summer of 2008 (this is the project that Francesco Loon was working on for them while he was here in the States), and they found several other problems with the drivers they tested. Hayden's post above enumerates most of the common problems rather well, but not many people seemed to be listening to him.

As for a list of drivers, the problem is that they're inconsistent, even among drivers from the same manufacturer. So a list isn't very useful. If you have this problem, a quick solution is to use an op-amp as a unity-gain buffer on the color input. I've posted a schematic in the gallery that shows you how to hook this up. It's incredibly simple, and shouldn't take you longer than a minute or two to hook up. Here's the link: (The circuit uses a TL-082 op-amp.)

Adam