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C-mount 3000mW 808nm Not working. HELP!

tye3333

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Hi Guys,
Im kind of new to lasers but have a strong electronic background. I have a large RGB show laser and the green laser stopped working. :-(
I got a replacement C-mount 808mW 1064nm. This is mounted on a heat sink behind 2 crystals and lenses to get green. easy! I replaced the diode (!Forgot the heat sink compound!) put the whole thing back together and away she went!
After running for about 15min the green started to flash, dim, flash and bright again.
At this point I remembered the heat sink compound, pulled down the laser again, added the heat sink compound and tried again. This time it was a little dimmer but working. So I pulled the unit down for a 3rd time to look for alignment faults, put it back together and it was dimmer again. After much work and trying this and that the laser now is not working at all.
I can see the diode is emitting a red glow but no green after going through the crystals. my question is:
Did i kill the diode the first time i ran it with no heat sink compound?
Was it the heat sink compound that killed the diode?
Can i use heat sink compound or not, maybe i should use something else?
Is there something else i did wrong?
Maybe my diode is ok just cant get it aligned?
Any information on these diodes would be so good!
Thank you everyone for your help with is!
if it is my own silly fault thats ok, ill just try again :)
-Tye
 
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diachi

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Re: C-mount 3000mW 1064nm Not working. HELP!

Hi Guys,
Im kind of new to lasers but have a strong electronic background. I have a large RGB show laser and the green laser stopped working. :-(
I got a replacement C-mount 3000mW 1064nm. This is mounted on a heat sink behind 2 crystals and lenses to get green. easy! I replaced the diode (!Forgot the heat sink compound!) put the whole thing back together and away she went!
After running for about 15min the green started to flash, dim, flash and bright again.
At this point I remembered the heat sink compound, pulled down the laser again, added the heat sink compound and tried again. This time it was a little dimmer but working. So I pulled the unit down for a 3rd time to look for alignment faults, put it back together and it was dimmer again. After much work and trying this and that the laser now is not working at all.
I can see the diode is emitting a red glow but no green after going through the crystals. my question is:
Did i kill the diode the first time i ran it with no heat sink compound?
Was it the heat sink compound that killed the diode?
Can i use heat sink compound or not, maybe i should use something else?
Is there something else i did wrong?
Maybe my diode is ok just cant get it aligned?
Any information on these diodes would be so good!
Thank you everyone for your help with is!
if it is my own silly fault thats ok, ill just try again :)
-Tye
Do you mean 3W 808nm C-mount? You wouldn't pump a crystal set with 1064nm.

Do you have proper eye protection for 808nm? That red glow is just a secondary emission, that diode could still be emitting a lot of IR which is potentially very dangerous to your eyes.

Could be the diode is dead, could be the alignment is out, could be the crystals have been cooked due to being pumped too hard.

Was the diode you replaced also 3W?

Did you get heatsink compound on the die? That'd certainly kill it. You'd probably have been fine without heatsink compound as long as the diode was secured properly.

Some pictures may help us identify the problem. Close up pictures of the crystals and diode would be nice, as long as you can get sharp pictures.
 

tye3333

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Re: C-mount 3000mW 1064nm Not working. HELP!

Hi Diachi
Thank for the quick reply! Yes it is a 808nm, sorry for the confusion.

The green laser is rated at 1W and from all the information I could find the 3W 808nm is the correct replacement. Dose this sound right?

When I first replacement the diode it worked with very little ajustments. Then it started to dim without the heat sink compound.
Once I added the heat sink compound it was close to the diode, Very close! But I don't think it was touching. After this it was harder and harder to get green until nothing.

I don't think it was over powered. 3.3v yes?

Sorry the laser has gone out for a run of shows so I can't take photos at the moment, this is the best example I can show you for now, I'll post real photos as soon as possible: URL BELOW

As for eye protection, any recommendations?

Thanks again
Tye

Online Shop Research 1W 1000mW 532nm Green DPSS Laser Diode Module TTL Analog for option|Aliexpress Mobile
 

diachi

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Re: C-mount 3000mW 1064nm Not working. HELP!

Hi Diachi
Thank for the quick reply! Yes it is a 808nm, sorry for the confusion.

The green laser is rated at 1W and from all the information I could find the 3W 808nm is the correct replacement. Dose this sound right?

When I first replacement the diode it worked with very little ajustments. Then it started to dim without the heat sink compound.
Once I added the heat sink compound it was close to the diode, Very close! But I don't think it was touching. After this it was harder and harder to get green until nothing.

I don't think it was over powered. 3.3v yes?

Sorry the laser has gone out for a run of shows so I can't take photos at the moment, this is the best example I can show you for now, I'll post real photos as soon as possible: URL BELOW

As for eye protection, any recommendations?

Thanks again
Tye

Online Shop Research 1W 1000mW 532nm Green DPSS Laser Diode Module TTL Analog for option|Aliexpress Mobile

Sounds like you *may* have killed it by driving it too hard (The diode that is, although too much pump power will burn/crack crystals too) - typical operating voltage for such a diode is <2.5V @ <3.0A - 3.3V would be more typical of a 650nm diode. The spec sheet for whatever diode you bought should tell you what the operating voltage/current should be.

I'd expect to see a pump of anywhere from 3-5W in a 1W head so you have that right! 30% efficiency from 808nm to 532nm at best in this sort of design.

As for safety glasses - I found a pair of used safety glasses from a lab on eBay, so I got a good deal for a certified pair. That kind of quality would run >$100 new. You can take a look at Thorlabs or perhaps Edmond Optics for a similar quality set.

Sets from Eagle Pair seem popular on here but I haven't used those so I can't comment. Laser safety glasses,IPL safety glasses,eaglepair-EP-8 190-470&800-1700nm OD5+
 

tye3333

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Ok this is some fantastic information! My 3.3v was what I though it should be driving at, I can not remember what the voltage was when testing it sorry.

Are the power supply's that drive the diodes current limited or are the diode them self current limited and you can just supply the voltage?

If my power supply feed is ok, what else do you think I could/should be looking at.

Thanks again
 

diachi

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Ok this is some fantastic information! My 3.3v was what I though it should be driving at, I can not remember what the voltage was when testing it sorry.

Are the power supply's that drive the diodes current limited or are the diode them self current limited and you can just supply the voltage?

If my power supply feed is ok, what else do you think I could/should be looking at.

Thanks again

The power supply should be current limited, but that doesn't mean it is! Diodes aren't current limited.

It's also possible that it is current limited but was originally driving a 4W or even 5W diode and thus was actually supplying 4-5A which could also kill your diode that's only designed to handle 3A.

Other things to look for, cracked crystals, burn marks on crystal faces, alignment, is the power supply still functional (Is it getting whatever modulation signal it needs, if any?). May have a better idea once you can provide some pictures, especially if you can *safely* get some pictures of the insides while it's running.
 

RedCowboy

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Yes it sounds like maybe he powered a 3w diode with a 4-5w diode's power supply, if it was a 1w 532 then it could use easily have used a 4-5 w 808 pump diode, actually I would be surprised if it was a 3w pump if it was a real 1w 532 output, that would mean a very efficient crystal pair.
 
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diachi

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Yes it sounds like maybe he powered a 3w diode with a 4-5w diode's power supply, if it was a 1w 532 then it could use easily have used a 4-5 w 808 pump diode, actually I would be surprised if it was a 3w pump if it was a real 1w 532 output, that would mean a very efficient crystal pair.
Sounds like the most logical answer, glad you came to the same conclusion! 3W is about the minimum pump power you can use to get 1W out with these linear designs, something higher quality or in a lab may do better.
 

tye3333

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Hi guys
Thanks for the info, I have a photo of the code on the original diode, dose someone know what it mean?
If I put a 5w diode in place of a 3w laser would it hurt it, or just be under powered

Photo:
https://www.dropbox.com/s/dr2sc1kx2g5hx84/File%2026-11-2015%2C%2010%2008%2021%20AM.jpeg?dl=0
 




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