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FrozenGate by Avery

473 crystal question

wolfhunter9154

wolfhunter9154

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I bought one of these Non-Functioning 473 nm Blue Laser, DPSS, BWB-10-OEM - eBay (item 320715493145 end time Aug-01-11 10:34:54 PDT) to play around with and learn about the insides of it. I turned it on and for the first 1-2 seconds, it is bight, but then it began to dim to very low levels (less than 1 mw). So I opened it up and began my troubleshooting. I noticed that the "crystal chamber" (the white thing before the exit in the picture) was getting rather warm. Now, I have no experience with these, but from reading various sources, I believe that the TEC may be bad and the crystals are no longer at the optimal temperature. So basically, my long, drawn-out question is what temperature should this chamber be/is the warmness normal? Also, one thing I just remembered, is that when I had a fan blowing on it, it seemed to lase brighter, for a longer period of time.
 

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wow yours is much different than mine.
Mine did not have those 2 black things it just had a diode one lens and the crystal in a smaller assembly
 
Yeah, I have your version of the laser head. When you bought it, what did it say on yours that was wrong with it? Mine said "MODE", so I knew that it is entirely functional except the mode was off. What about yours?
 
Mine said low power, but the reason I think it is something with the crystals is because form what I can tell, the 808 output remains steady
 
Well, what they are going to do is they are going to tell you what the end result was that led to decide that it was no good.

So they decided that low power was the problem, but they don't know why. If you determined that the 808 output is steady and good, then there is something between the input and the output that is not up to par, i.e. damaged. So there are two options. One is that the alignment is off in one of the crystals or that the temperature is off in one of the crystals (or both). If alignment is an issue, then you're essentially screwed - these are like superglued down, so the chances of fixing that is minimal. If it's the temperature... you are still probably screwed, because it means you have to remove the crystals in order to get to the TEC so you can fix it (probably a bad TEC, could just replace it), and then realigning them would be a problem. Even if you did manage to realign the crystals, then you would be stuck with trying different currents through the TEC in order to keep it at the desired temperature.
 
In that case, maybe Ill just mount some fans to it to keep it cool. Thinking back, im not so sure about the pump output, but if anything, it seems to get stronger as time goes on.
 
The problems with mounting fans is that these crystals don't necessarily just need to be kept at room temperature. The TECs are designed to set them to the exact temperature necessary - with just fans, it would be too difficult to control the temperature.

And regarding pump output - my guess is that it gets stronger as time goes on because the optical feedback from the front of the head does not read 10mW, so it pumps out more 808nm in an attempt to correct it, but because something is off about the crystals, it will never be able to reach that power level.
 
lazerman121 said:
wow yours is much different than mine.
Mine did not have those 2 black things it just had a diode one lens and the crystal in a smaller assembly
Click to expand...

I would like to see pics of this 473nm head. I have five of them and they've all been identical to the OP's picture. With the cmount pumps these use, I don't really see how your setup would be able to focus the pump well enough to even lase.

Wolf, If your crystal assembly is getting warm, then either the TEC is dead, the driver for it isn't working, or there's a bad connection somewhere.

Also, no, the crystals aren't 'glued down' at least not in a fashion they aren't adjustable. the OC has adjustments, and the doubling crystal mount will move side to side and front to back if you loosen the screws and break the epoxy. These are FAR more adjustable than any cheap 532nm pointer you'll run across. I've had one of mine completely dismantled, and the doubling crystal completely out of it and I managed to make it work as well as it was originally when I was done. I don't advise playing with the OC alignment though. If you screw that up and lose your intracavity 1064nm, your pretty much screwed.
 
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Ok then tomorrow I will try to take the TEC out to test it. Would anybody happen to know the optima temp for the crystals?
 
You won't be able to separate the cavity from the TEC without breaking the TEC. But you will be able to check it for cracks, etc. If it's not cracked, check all the wiring. And the 'optimum temperature' is going to vary from crystal to crystal, and how they're mounted, etc. There isn't really a single answer to that question. The answer is 'whatever temperature gives the highest and most stable output'. But I do know all mine get cool, not warm, when they're running.

I just had a thought. The TEC could be fine and working correctly, but it could have a bad thermocouple as well.
 
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It's basically a temperature sensor. The two small gray wires going to the front of laser head and under the crystal set. That's what those wires go to, the thermocouple that tells the driver what temperature the crystals currently are, so it knows how much current to feed the TEC to reach it's target temperature. It's an active system. The driver doesn't just feed the TEC a constant current. It varies depending on what temperature it's already at.
 
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