30w Red 1064nm laser not converting to green 532nm

[Richard Nield]

Hi, I really need some specialist help plse! I have a business doing 3D sub surface laser engraving (SSLE). Inside blocks of crystal. A 30w 1064nm red laser passes through a non linear ( QSwitched/ pulsed) crystal and changes to 532nm green laser. This green laser is focused and pulsed to burn images into the centre of crystal blocks. 1 month ano the red/ green conversion through the non linear crystal stopped.
The thing I noticed was a small cooling 24v DC fan had stopped.
Additionally there is a RF cable running to the non linear crystal from the QSwitch pulsing unit in the main 'red' diode laser housing. I am trying to find answers to the cause of the problem :
1). Above the dead fan are 2 ceramic heat sensors, with wires connecting to the same pins, could they pick up on the fan and cause the process to shut ( second harmonic generation)
2). The RF cable from the QSwitch would send a pulse to the non linear crystal as the red 1064nm laser passes through. What affect would the pulse have? How important is the pulse to the conversion to green.
I simply cannot find a cause for the non linear to stop changing the wavelength to green?
Does it require a pulse?
Can a heat sensor cause something to stop.

I would be extremely grateful for some serious feedback on the way forward. I have no response from China
Thank you

 

[WizardG]

Sounds a lot like your Q-switch....isn't switching. The conversion process needs high peak power. The Q-switch is what provides the very high peak power pulses the conversion crystal needs to be efficient.

 

[Richard Nield]

Sounds a lot like your Q-switch....isn't switching. The conversion process needs high peak power. The Q-switch is what provides the very high peak power pulses the conversion crystal needs to be efficient.

Thanks very much, I had thought of that. Why would the Q-switch suddenly fail?
Do you know how I could test it?

 

[WizardG]

If you have the means to measure the RF power being delivered, the pulse you refer to, that's where I'd start. But the gear involved, and the possible requirement for override access to your machine (in order to command the pulse be sent without the laser running) may be in your way. How well stocked is your workbench? You'll at least need a decent oscilloscope, and an assortment of termination loads and splitters.

 

[aaronnoraa]

To answer this question you may want to try asking PhotonLexicon member Mixedgas, he seems to be extremely knowledgeable and may be able to help.

 

[Richard Nield]

If you have the means to measure the RF power being delivered, the pulse you refer to, that's where I'd start. But the gear involved, and the possible requirement for override access to your machine (in order to command the pulse be sent without the laser running) may be in your way. How well stocked is your workbench? You'll at least need a decent oscilloscope, and an assortment of termination loads and splitters.

Many thanks. Unfortunately I do not have an oscilloscope, what was also suggested was to first replace the fan as sensors may have picked up that issue and shut the system down.....after which I will test for ulse with the laser on.

 

[Richard Nield]

To answer this question you may want to try asking PhotonLexicon member Mixedgas, he seems to be extremely knowledgeable and may be able to help.

Thank you, I will do so as soon as I have replaced the fan and seen if that works.
Everyone's help is much appreciated, at least I am more on track