Old 04-29-2012, 01:48 AM #1
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Default Instability

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!


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850nm: module (8.8mW avg|7mW rtd)
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Old 04-29-2012, 01:50 AM #2
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Default Re: Instability

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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Old 04-29-2012, 02:10 AM #3
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Default Re: Instability

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.

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Old 04-29-2012, 02:28 AM #4
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Default Re: Instability

@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
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low 445nm: C6 from Survival Lasers (1351mW pk|1289mW avg|1100mW rtd)
high 450nm: NewWish (12.6mW pk|5mW rtd) | Dominator by Blord (3010mW pk|2779mW avg during 5min)
462nm: 501B by Atomic (1507mW avg)
473nm: BWB-10-OEM labby by CNI (10mW rtd)
~462-476nm "Tunablue" by Atomic (1.5W pk)
480nm: hostless by Atomic (101mW pk)
505nm: hostless by Atomic (103mW pk)
low 520nm: MXDL pen by DTR (31.6mW pk|28.8mW avg)
high 520nm: Laserlands (8mW avg)
532nm: NewWish (28.6mW pk|26.8mW avg|10mW rtd) | Dapper (30.3mW pk) | Classic (120.0mW pk|103.1mW avg|100mW rtd) | "The Green Box" by Atomic (176.7mW pk|140.0mW avg)
589nm: Spartan from Dragon Lasers (58.4mW pk|37mW avg|50mW rtd)
632.8nm: HeNe pointer by Atomic (0.68mW rtd)
635nm: NewWish (4.6mW avg|5mW rtd)
638nm: Classic from Lazerer (409.3mW pk|389.4mW avg|415mW rtd)
650nm: NewWish (10.6mW pk|5mW rtd) | Dilda (216.3mW avg|200mW rtd)
685nm: laser-in-a-box by Atomic (30.4mW pk|29.3mW avg) | 501B by Atomic (32.4mW avg)
780nm: module (2.7mW avg|5mW rtd)
808nm: Classic modded from a 532nm (162mW avg)
850nm: module (8.8mW avg|7mW rtd)
980nm: NewWish (81mW pk|5mW rtd) | 2nd line around 490nm

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Old 05-07-2012, 02:27 PM #5
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Default Re: Instability

Quote:
Originally Posted by Atomicrox View Post
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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