trying to repair two Quantum Entertainer

[matratzki]

Hi guys,

I got two used Quantum Entertainer Lasers and now I am trying to repair them, because the output is less then 50mW

I already checked the pumping Diode, it should be okay and puts out more than 3W.
I also tried to readjust the cavity and the Temperatures for Diode and Yag, now I get 50mW 532nm.
The crystalsand lenses look very well.
What else could I do?
The Yag Temperature was set to 70°C, I reduced it a bit and the power increased, but the lowest Temperature I can set is 65°C.
The Diode Tec Temperature was set to 27°C... I increased it to 37°C

Best regards
Mathias

[mixedgas]

If you cant verify the pump wavelengths, that is also a issue. Also 3 watts is not much pump. What was the rated ouput power in green?

Steve

[matratzki]

I already looked for a maximum when I adjusted the Diode tec.. But I do not known how high i can turn the diode temp? I think it was rated for 600mW

[mixedgas]

When these things fail, it is almost always, alignment, KTP, or pump diode.

Pump diodes do shift in wavelength with age. Especially ones from a few years ago with impurity migration issues. That is why you need to check the wavelength.

Can we have pics of the cavity?

Good stuff is 10% conversion. Really great stuff is 25% conversion.

Steve

[dsli_jon]

Hi Mat -

When these things fail, it is almost always, alignment, KTP, or pump diode.

...aaand when the cavity get's exposed to room-air, since these puppies were always hermetically-sealed in a class-super-duper-xyz clean-room by the Mfg..

Mat - couple questions - a) which 'model' of the entertainer did you get - the 'older' Black one - ie:

..or the 'newer' gold-ano'd ones? ie: ...I ask, because the older black-ones, did have a 'seal-integrity issue', around the collimating-lens 'nosecone', and were (apparently) prone to exterior-air 'seepage', and thus = xtal-surface contamination = low-power.. (...and it don't take much to kill the efficiency, when your 'top-end' is only 6-700mW of Green..

b) were these 'opened' by-you, or, did they arrive doing low-power? If-so, you might see if the seller is willing to 'fess-up' / give some sort of 'concession', as an opened-cavity contamination-scenario seems more likely than both of these having 'diode or temp-reg' issues.. then again, I suppose if they both have umpteen-thousand hours on them..

lemme know..

PS -

Can we have pics of the cavity?

..I think I know 'what you were thinking'... Nice.. but, just fyi, these were significantly different / simpler, internally, than the 2W Excels, so.. not sure the beam-waists / optical-spacing / sizes will be of much use, at-least in 'emulating' the 2W Excel-layout scheme.. For that, like I said, if someone could 'afford' to buy that '532 Gem' FS on eBay, for 'sacrificial R&D purposes', that would be a gold-mine of real-world optics data, etc, relative to the 2W quest, over yonder.. .02¢

cheers...
j

[matratzki]

Hi,
thank you for your help.
So I would need a spectrometer to measure the wavelegnth..But would it be possible to find the correct wavelength by turning the temp higher.. or lower by shifting wavelenght. What would be the maximum recommended Temperature for the Diode?
first i opened it in a clean room (medical clean room), but the power was already down. So the second time I opened it at home. No changes in output power.
The laser has many working hours on the internal counter... I got them nearly for free, but propably I got more power out of them... the beam is so great )

I got the second type.. but my ones are not goldern.

[mixedgas]

You really need to check the spectrum, power, and mode of the diode to rule out the KTP.

For ND:YAG, its 808 +/- 1 nm. For Vandate, the spectrum can be wider. My guess is you have YAG.

Thanks for the pics.

Steve

[matratzki]

Hi Steve,

so I need someone with a spectrometer to find out the wavelength and if it is single or multimode.
Could be difficult to find somebody with a spectrometer at home
I already measured the power.. 3120mW
It is a pitty.. I got NO informations from Quantum.. the only thing they told me, was"well buy a new one"

You are welcome

[matratzki]

Another queston:

What would be the ideal temperature for a YAG crystal? Is 70°C not much to high?

[dsli_jon]

hi Mat -

..first i opened it in a clean room (medical clean room), but the power was already down. ...The laser has many working hours on the internal counter...

Mk, if the power was already-down, yes, that *may* suggest diode-issues, but are you sure the previous-owner did *not* open it?.. Again, contamination was a 'Mfg.-admitted-killer' for these pups.. and, once 'compromised', not-surprized you would not see much 'worsening', by opening it at your house... just 'food for thought'... However...

..What is your definition of "many working hours", on the diodes, like 5000+ ? 10K? Short of that, I'd suspect something else.. 3W certainly sounds-like low-output, although I admit I don't recall what the 'proper-spec' was for these pups.. Wondering if the previous-owners may-have touched diode-pins in the DB-connector, when connecting / disconnecting, etc, or, some other diode-damaging actions.. pretty-sure these units did *not* have any sort of 'lasorb'-type devices, at the time.. I'm guessing by the 'newer alloy-substrate' your models are 'Gen 3', ~2008 > beyond...

For Vandate, the spectrum can be wider. My guess is you have YAG.

Quite-certain they used YVO4 vs YAG and LBO vs KTP.. a certain 'gringo' I know has a manual in his NY-archives.. ..though, admittedly, that was for units mfg.-before 2005, so.. I suppose they may have 'changed-games', but.. not sure why they would opt to go YAG / KTP for these lil' units..

.02
cheers..
j