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Issue with a new DL viper 55mW

yoonie

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Aug 11, 2019
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Hi guys,

I'd like to have your thought about what could be wrong on this laser :
When I received it, I put 2 1.5V AAA that were almost new and working in a flashlight that I have.
The laser turned on for barely 2 sec then flickered and turned off.
I could turn it on again but I had to press several time the power button before having a start.
Tried with some 1.2V nimh, same behavior, by insisting on holding the power button, I could see that the device sometimes started after 3 to 5 second holding it.
So I felt like a warm up might be necessary, but the fact that i could not stay on for more than 20 sec without flickering and dimming proved me wrong.
(note that I never held the power for more than 30 seconds, even if no light were emitted... just in case)
So I went to charge up 4 brand new AAA 1000mAh nimh, and the laser did start on first try, but never stable. And again went dim after only maybe 3 starts.
(when dimming and flickering an artifact could be seen as if there were some TEM issue)
Put my second pair of nimh fully charged, and it did not start at first but eventually started after several attempts... And for once, it appeared stable for maybe 5 sec with a correct gaussian and round dot, and visible beam as I'd expect it from a 55mw ; exposed my skin to check for tingle as I have no LPM and yes power was there.
But it did not last : on the next starts it flickered and eventually did not start again, even after recharging my Nimh.

Now Adam from DL suggested that I get new 1.5V batteries, which I did, but the laser still refused to start, I feared that it somehow fried.
And to be honest, I had a 55mw CNI laser for 10 years, and it coupled with many kind of batteries, 1.2V nimh or 1.5V regular, even if I know it'd prefer the 1.5V, it was totally fine with 1.2V... never experienced this kind of stability issue.

Now, the interesting part is here, as I had nothing to lose since it was not turning it on, and it seemed to react when I had my battery at max power, I decided to put one of my 10440 3.4V 320mAH paired with an nimh inside the laser.
Well, guess what, it started straight away, just one click that I did not hold for more than a second, so I knew it was not fried.

Right after that, I have put back my 1.2V nimh and the laser is working fine since then, no stability issue at all ; still waiting to see how it behave after I go through some battery cycle, so I'll be toying with it.

Do you guys have any idea what could have been the cause and how could overpowering it for a very short time seem to have fixed the issue?
Should I expect failure to appear soon? (I'm not asking for science here as I can't provide any measure, but your intuition will do ;) )

Thanks !
 



paul1598419

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I have always used new 1.5 alkaline batteries when powering these laser pointers. I have had issues using the 1.2 volt rechargeable batteries, so I never use them now. Mixing different types of batteries in the same laser is dangerous and you are lucky you didn't have any bad outcomes from doing that. I wouldn't ever try it again. Smoke has been known to occur or even explosions. Without having the laser in front of me it is difficult to help you with this. It may be a misaligned crystal set or some other reason causing it to intermittently mode hop. I would need photos at the very least.
 

ultimatekaiser

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the Viper is the 55mW green I assume? (It's been a while) I've a yellow version and it works fine with both AAA primary and rechargable cells. Though on the NiMH batteries it tends to die faster due to the high current draw. Primaries will often work better due to their higher initial voltage too. if it worked after the lithium, I'd say you might've had a poor connection before that righted itself, or the laser was too cold before. The doubler has to be at a fairly precise temperature to work properly, both in regards to doubling, as well as the cavity construction/layout. DPSS lasers can be very touchy when it comes to temperature, and fractions of a degree matter, and no two are exactly the same. The only other thing I can think of, is that possibly you had the batteries in backwards? (oof very bad) But i'd lean more in favor of the first two. Once in a while I've seen one that makes relatively shoddy contact with the tailcap.
 

yoonie

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Hi Paul,
thanks for your opinion, I want to make things clear :
I would not mix batteries of course, I mean not even 1,2V and 1,5V. Furthermore I would have never tried to put a 10440 into a device that is not designed for it in normal circumstances.

Some context : I ordered on August 30th a DL 55mw, I received a defective one with a divergence that was above 12mRad, so I had to RMA and it was not cheap, nor fast.
Receiving this new one, and after what I have detailled, I had nothing to loose to follow my guts on a laser that was totally dead.
I knew that there was a risk to fry it, but as I said, it was intentional and never planned to let this battery for more than a few seconds, on only had one click with for less than a second.

Anyway, what's done's done and I'm glad I followed my instinct (which I expected to confirm if it was a dead diode or a power management issue.)
My point in this is : how a device that was not working properly before could get fixed by such action. Any expert have a clue about what changed?
Remember that my first attempt to start the laser was with regular 1,5V, and that before putting the 10440 I did put new one as well.
And more over, until now the laser is totally fine with the same 1.2V that I have tried before.

Seems like the driver had some benefits from my action but I'm totally clueless.

And although I have a tendency to write much, don't make a big deal out of it, I'm just asking in case someone could enlighten me, but more over ; for others who might encounter similar issue to know if a controlled "overpowerage" could help fix an issue.
if not, I more than fine with.

Sorry for the long post, I hate reading myself as it looks always dramatic, but trust me it's not I'm just really bad at synthesizing.

cheers :)
 

yoonie

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the Viper is the 55mW green I assume? (It's been a while) I've a yellow version and it works fine with both AAA primary and rechargable cells. Though on the NiMH batteries it tends to die faster due to the high current draw. Primaries will often work better due to their higher initial voltage too. if it worked after the lithium, I'd say you might've had a poor connection before that righted itself, or the laser was too cold before. The doubler has to be at a fairly precise temperature to work properly, both in regards to doubling, as well as the cavity construction/layout. DPSS lasers can be very touchy when it comes to temperature, and fractions of a degree matter, and no two are exactly the same. The only other thing I can think of, is that possibly you had the batteries in backwards? (oof very bad) But i'd lean more in favor of the first two. Once in a while I've seen one that makes relatively shoddy contact with the tailcap.
Hey Kaiser, thanks !

Yes, going your way.
I'm sure DL had this one checked before sending it to me, and I felt like at first start, it was like the laser was too cold.
After all the attempt, it felt like some contact really could not get back to their initial state ; and that only the overpower (- as quick as it was)
managed to fix some contact ; could it be by dilating them back to their initial state.

And of course, they weren't used backward ;) I had another CNI 55mW for 10 years and used to its behavior, depending on what batteries I had in, it goes same as your experience.
I also toyed with the tail cap when I had the initial issue to make sure it was not a contact issue.

But your point about the doubler is really interesting as I have no idea about what is a doubler

Cheers :)
 

ultimatekaiser

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Yes. a green laser isn't really green at first it's actually 3 lasers in one! which is why they are more expensive than diode pointers. ;)

They're an 808nm IR diode pumping a crystal to get 1064nm IR light, which is then frequency doubled to 532nm light which we see as a bright green. The crystal that does this doubling is very picky about temperature and alignment, and if anything is off by even a tiny margin, then the laser may not work at all. I'm betting it was a minor connection or temperature issue. The lithium would have similar but slightly voltage if it's only one cell, and it has a higher current capacity, so if the connection is minorly shoddy it would have an easier time bridging the gap briefly. I think one or two of those I had to fix for people from the factory because they had poor tailcap contact, maybe becaus the spring was constricted too much at the - terminal. so I had to add a little scratch and solder blob on the inside.
 
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yoonie

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Ah, thanks yeah I know about the DPSS mechanism :)
Just didn't know it was called a doubler, make sense now and should have guessed.
 

WizardG

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If the laser exhibits the kind of instability you were seeing again you might try a pair of NiZn cells. 1.9V fully charged for a little overdrive if that's what your new toy prefers.
 




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