Fixing my CNI laser

[badger1666]

but did you get back any of the missing 100mw you said you were down on

[Carl B]

I don't think I have gaind any more power and as Rob Stanwax said to me once that the optics are just not as well tuned as my other CNI. Anyway I've got a bad ass 300mW (doing a steady 370mW) laserwave unit now and may buy a second one in the near future. Just glad this laser is still alive and the solder joint looks to be holding well.

Carl

[stanwax]

The gas fill in not so important on the greens as other dpss types. With blue the main reason is to keep the SHG from absorbing moisture from the air. As far as Im aware all SHGs appart from KTP are hygroscopic meaning they will absorb water. This will degrade the performance slowly over time and unlike silca gel that is packed with many products to help against moisture - the process is not reversible.
As can be clearly seen from the photos there is a heavy rubber seal around the top (and indeed the bottom) which forms a hermetic seal keeping the factory gas fill in and the moisture out.
I think any inert gas should do and think that they may be nitrogen filled when built. Argon (from a welding suppliers) is probably easier to obtain, though the best mig welding gas (and therefore most popular) is only 95% argon and has a splash of CO2 and O2 in there for good measure - it welds a treat does that mix

Rob

[FrankenPC]

I've been messing with my blue CNI trying to get it to work. It's mind blowing how cheaply made these things are. They are asking WAY too much money for them.

[FrankenPC]

For the record...there is NO way these devices could retain a noble gas. They are full of leaks. I believe the main reason behind the sealing of the cavity is a simple one: The TEC's cause condensation. Condensation DESTROY's lenses under high temperature.

[Carl B]

Thought I would give this thread an update

As mentioned above I did manage to reattach the black wire to the pump diode but for one reason or another the output power was down quite a lot (around the 30mW mark). Anyway while paying Rob Stanwax a visit yesterday I left my CNI head with him to have a look at when I had gone.

Well I had only been back home half an hour when I got a PM from Rob that he had it back up to 104mW after just 10mins of playing and then a second PM soon after that to say it was back up to 154mW. Nice one Rob and it seems I have my laser back up to what it was doing before I opened it for the first time.

Carl

[stanwax]

And here is a pic of the insides with my version of the diode wire. I needed to lift the case for access so attached a curly flex wire to the diode so it didnt break off

Rob

[MechEng3]

Is the KTP angled a bit to keep the backwards traveling green beam out of the diode? Seems JDS thought it was a good idea to do this...not shure of any other lasers. Nice work ....glad to see one back in action.