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Instability

Atomicrox

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All my green lasers are far more unstable than my other wavelengths.They get stronger or weaker for no apparent reason and some of them even cease to function entirely just to come "back to life" a couple moments later.

I figure this must be because they're DPSS but I'd like to know if this happens to all DPSS lasers or just to low quality ones. Do the ones from O-like and Lazerer have these issues?

I'd also like to know why exactly this happens and if there's anything I can do to "fix" it.

Thanks!
 

Sigurthr

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Small thermal changes result in changes to the alignment and phase matching of the nonlinear cavity crystals which results in transverse mode changes and output power fluctuations.
 
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A quick fix if you would like to try, is take the worst one you have,
break it down and back off the current.

This is a good fix only for the ones that start bright and dim quickly.
Greens that just don't like being cold will not benefit from this.

:beer:
 

Atomicrox

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@Sigurthr: that seems to explain why they seem to have a "sweet spot" for temperature. Sometimes they start to improve after getting warmer but only up to a certain point.

@JLSE: their power changes mostly between firings, not during one firing :(
 

flogged

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All my green lasers are far more unstable than my other wavelengths.They get stronger or weaker for no apparent reason and some of them even cease to function entirely just to come "back to life" a couple moments later.

I figure this must be because they're DPSS but I'd like to know if this happens to all DPSS lasers or just to low quality ones. Do the ones from O-like and Lazerer have these issues?

I'd also like to know why exactly this happens and if there's anything I can do to "fix" it.

Thanks!
This is due to the complexity of a DPSS laser, compared to a laser pointer utilizing a laser diode. For a typical red laser pointer there's a small efficient laser diode. A DPSS laser has, in addition to an infrared laser diode, two crystals which the IR light passes through being converted to 532nm along the way. Each of the two crystals are very temperature sensitive, so with slight variations in temperature the amount of green light produced will vary considerably. If you want a stable green DPSS laser each of these components need to be temperature regulated (expensive)

In a pointer, until warmed up, there's going to be a lot of variation in output.
 




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