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FrozenGate by Avery

B&W Tek BWB-10-OEM - 473nm 10mW

It is still using the feedback, yes. And no, with the v5 driver mine had, the pot that is listed actually doesn't have a whole lot of effect by itself. To get a stable regulated 30mW I had to pretty much fine tune all of them, though only two had really 'big' effects on performance.
 





I have done some work with the pots on the v5.0 board. You will notice the pots are marked W1, W2... W5. These are Bourns 12 turn SMD pots as seen here Trimmers | Digi-Key

W3 sets the on delay. Min delay is CCW, Max delay is CW

I turn the other pots full CCW 12 turns to ensure they are fully to the CCW side. Then, I turn them 6 turns. This sets them to the middle of the range of the pot.

These are my settings and with this I get an 11mw average, 15mw peak.

W2 - 1 turn CW from centre
W1 - centre
W4 - 1 turn CCW from centre
W5 - 1 turn CCW from centre

oddly, I was getting 20-30mw out of this laser and i had a 56mw peak on start up. I am not sure why I am not getting those kind of readings now. I simply have no clue.

Update: Originally I had W2 at 2 turns CCW from centre. however after running the laser for a number of minutes, the driver heatsink got very hot and the output of the laser dropped a lot. I adjusted it back to centre and its running cooler and more stable now.
 
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Plexus, you have some nice information there. I'm curious, what numbers did you have before you adjusted the pots?

I ordered my laser over the weekend and it shipped today. I would prefer not to make adjustments if I don't have to, but so far these things look quite hardy.
 
Do you mean the original positions? I don't know. its not possible to tell where you are on a multi-turn pot like that because they turn infinitely.

I can get the beam to drop in power by adjusting W2 CCW (i believer). but i can't get much over average 10mw.

I dont understand because a few days ago i was getting 20-30mw out of it. Then a few days later I turned it on and it was only average 10mw.

One thing that happened was there is a flat copper wire/harness going from the input cable to the head of the diode assembly. this broke of on mine. i tried soldering it on and it was for a bit but then came loose. so i soldered it back on making sure to get enough heat into the heat sink to solder. i have an accurate digital iron and am well versed in soldering techniques to limit heat damage. Its running within a narrow tolerance right now around 10-11mw.
 
If you've had a power falloff without changing the settings, then your pump diode is most likely degrading from having been overdriven. It's one of the reasons I stopped when I hit 30mW.
 
I had it running on average 24mw. so that doesn't seem too out of spec with other people's experiences. like i said i turned it off over night and the next day fired it up and was getting the usual 10-11mw average. it could be the pump diode degrading but i am not sure. maybe there was a bad connection or something that was causing this. the circuit is complex so its not easy or even possible to reverse engineer it.
 
The problem here is we're dealing with DPSS. There are a lot of variables and no two will probably be exactly the same when it comes to efficiencies. It's the 56mW peak your getting on startup that worries me. Mine doesn't do that, but i'm still using the optical feedback as well. Assuming a 5% efficiency, which, as old as these are, is probably on the high side. That translates to 50mW per 1W of pump power. Since these were originally spec'd at 10mW, I find it hard to believe they would use pump diodes rated for more than 500 or 600mW.. Since at 10mW output, that would still mean a pump drive of less than 50% of it's maximum rating.. Which would give a long life.

It's possible the pump diodes in these could be 1W or higher, but I doubt it. There's no reason for them to be and it would just add to the manufacturing expense.
 
all true qumefox. it might have been some strange anomaly. because now, the head is running fairly stable at 11mW which is spec. if there were a degradation of the LD i would expect less stability, less power. i can only assume that my readings of 24mw average and that peak output were some strange anomaly perhaps with the LPM, measuring set up, etc.

at the moment, with as much controlled twiddling, i can't get more than 11mw average out of it. i have found that turning up (CW) W2 will get the head to lase but any more than the position where it lases (pretty much 6 turns, or 50%) there is no added output, but the driver gets hotter.
 
I have to say, I really like the colour of 473nm. its such a pretty powder blue. it is also more visible than 445nm. its really interesting to look at 445 and 473 together - 445 is that much more violet. but 445 alone doesn't seem as violet as when you have both colours together. i almost like 473 more than multi-line argon. i am very happy we have to opportunity to get 473 so cheap from that ebay seller, otherwise i would not have bothered because of the high cost of $/mw for this wavelength.
 
Your apc is properly lined up, and not blocking most of the beam at aperture?

Have you opened the head unit?

The only cause for instability would be because

1. Its unstable thermally

2. Driver is not getting proper feedback signal

3. Laser is on fire

So the stabilization LED does not turn off then I presume?
 
No, the LED doesn't turn off. I cant speak for thermal stability because the TECs could be broken and i don't want to re-align the diode/crystals. However, the beam is not being blocked, feedback is hooked up and the laser is mostly not on fire.
 
No, the LED doesn't turn off. I cant speak for thermal stability because the TECs could be broken and i don't want to re-align the diode/crystals. However, the beam is not being blocked, feedback is hooked up and the laser is mostly not on fire.

Good. Mostly is the least of what these units produce.

Have you expanded the beam to see any extra modes?

Is your dot very clean? Or is there a good splash on one side of the dot?

I'm thinking, if not thermal issues, and the laser is getting good feedback, there may already be a slight alignment problem.

It can't be a "BIG" alignment problem of course, because you're obviously still lasing!

I believe that in this thread, you will find a photo showing a pot you can adjust to control pump current. If you tap into the diode's anode lead and get a good current reading over time, you should be able to determine is your pot needs and adjustment or not.
http://www.photonlexicon.com/forums/showthread.php/11161-BWB-10-OEM-473nm-laser-module-info-thread

Funny thing is, I have not yet heard of any of these units "needing" a pot adjustment. They were supposedly simply ripped out of the previous equipment they were being used in.

Also, as an experiment, try removing the APC sensor for a few moments. Observe dot brightness, and diode current if you can. That will give us clues as to what is holding back some power.
 
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its actually incredibly likely to be alignment that is giving me problems. this is the same laser in the OP but it took some HARD hits in shipping.
 


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