Help with a DPSS Green Laser

Hmm. So I just joined the forum today, been eye-balling it for quite awhile now.. I have a couple of greenies, and one in particular thats giving me problems (sorta). It is a 50mW DPSS 532nm laser, has never been "modded" or altered in any way, other than being hooked up to a 4.5VDC supply. =). I notice that after approximately 2 minutes after running, it begins to seriously mode-hop and the beam characteristics change. (from one nice fat beam to two tiny green ones TEM11). Strange. Eventually the output sags to almost an unusable level (it is mounted in a projector). Would maybe active cooling prevent this? It does run warm, but nowhere near hot. Any advice would be most appreciated!!! Thank you.

Try backing off the current, or power it with a little less voltage..

Many of the driver boards will drop current when a lower voltage is
used. It sounds like a heat issue..

You could also try mounting the module to a larger heatsink, or use
thermal conductive padding between it and its existing mount.

Try to get the temp down a bit and see if that helps any..

Hello and welcome to the forum!:wave:

That is to be expected.
These cheap chinese DPSS pen modules (that's what I'm guessing you have...) aren't
meant to run continuously, they're "pointers" after all, not lab modules.

Yes, it is most likely a heat issue, It might be either the pump diode shifting
wavelength due to heat, or the crystals going outside of their comfort zone.

Welcome to the world of cheapo greenie modules!
You have to be lucky to reel in a good and stable one.

Thank you all for your quick response. I'll try to manage the heat that is emitted... would that also be a plausible explanation for the TEM change? Oh, and by the way its a flashlight-type host.. lol. Hmm.. i gotta think.. if its warm to the touch outside the module, its gotta be pretty toasty inside the optical cavity... maybe a bit too toasty.

It definitely is a thermal instability issue; I say this with a fair degree of certainty given the current circumstances in which the laser is running.

DPSS lasers are extremely temperature-sensitive- small changes in temperature can (and sometimes do) cause large variations in output. Consequently, as the laser warms up, some fluctuations in power output, and by extension, transverse mode, can be expected.

The problem here is we don't know the recommended operating temperature of the laser, hence we don't know whether it's meant to run warm (as you said), or whether it indeed is overheating.

The first thing you could try is to point a fan at it (if it has fins or similar), and see if that helps. The very least it'll do is keep the outside cool, sometimes the heatsinks themselves are extremely crappily made to, well, extremely crappy tolerances and hence do not conduct and transmit heat as well as they should.

Most green modules >50mW (and some high-end <50mW modules, such as those by CNI or Viasho) will have a TEC and temperature feedback in order to maintain the cavity temperature within the operating range. Your head probably doesn't have that, hence the instability.

OK so im back. I added the fan module from an Xbox 360 to the projector, mounted above the laser itself.. Along with the 532nm, I also added a 100mW 405nm GaN, for a two-color projector, looks really cool! The airflow is massive and now this laser has ran continously for about 15 minutes and shows no (noticable) sag in output nor TEM change. I will put up pics soon as I figure out how to do it (new phone). It was a perfect cure. Thank you all for your help! Will post a youtube video tonight hopefully. =)