Power fluctuation on start-up

Quick question regarding my Jet Laser Equality 532nm-500mw laser. I am running it with a (fully charged) "high discharge" Panasonic NCR18650PF. I have noticed that when I first turn the laser on (no warm up)....the beam brightness fluctuates (for about a second) before stabilizing. It is very subtle, but noticeable. I can only see this fluctuation in the reflections/corona around the beam. The beam itself is stable and maintains its shape. Is this a characteristic of DPSS 532nm laser?

Mike

Very likely. DPSS is know for instability, and usually will need some warm up until full output is reached.
Nice choice with Jet Lasers!

ChaosLord said:

Very likely. DPSS is know for instability, and usually will need some warm up until full output is reached.
Nice choice with Jet Lasers!

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I think you are correct. Gray from Jet Lasers said the same thing! Awesome laser. I have never had better customer service than Jel Lasers. Awesome company!

Yup, gray is definitely one of the most easy and pleasant people to work with. Jet Lasers is also known for their quality and overspec lasers. I got my first laser from them... then started building my own, Muhaaa.

It depends a bit on what causes this: If it happens when you cold start the laser, but doesn't when you briefly turn it off and on again, its probably some thermal issue with the dpss laser you needn't worry about. Getting long-term stable output is much more important, and if it stays at constant output for several minutes after the initial blip you actually have a nice laser there.

If it does produce this flicker when you briefly turn it off and on again it might be a driver issue. This doesn't have to be a bad thing either though, some current drivers are designed with a 'soft start' that ramps the current up (usually in a split second) instead of putting it on full blast straight away. This arguably improves diode life.

Thanks for all the help! Really loving the 532nm (500mw) beam. Goes forever and is much brighter than my 3 watt 445nm! Wish I could purchase (portable) 1+watt 532. The closest being the JL PL-E Pro at 800mw.

My Skylaser HL532 does exactly the same thing. The fluctuation I see is because of a mode change, I'd say yours is too given what you said about the beam characteristic.

Got some more instability last night....after warm up. This was different, however....

Was focusing the beam to get the tightest spot, when I noticed the beam brightness drop and the beam itself became a little fuzzy. Occurred for about 1 second and then went back to normal. It did this a few times over 15minutes or so of intermitant use. I think the laser had been on for about 5 minutes total.....never running continuously for more than 30 seconds. Laser was slightly warm. Temperature outside was 75 degrees. Fully charged IMR Efest battery.

Is this something normal to DPSS style lasers? I don't want to send it back to China if this is normal

Well, I don't trust efest batteries. I have one, and my mitts 500mW actually output 200mW less with the efest battery. So it could be the battery. I'd try a Panasonic or AW IMR batt first.

It is fairly normal: the efficiency of the whole process (pump coupling, solid state laser and doubling) all depend on temperature.

One thing often overlooked is the first part: The 808 nm pump light that powers the solid state laser has to be within a rather narrow range of wavelength. The actual wavelength produced does however depend on the pump diodes temperature. So does the range that is acceptable as pump light for the solid state laser, albeit to a lesser degree.

If this is off for any reason, the pump energy will not fully be absorbed by the solid state laser and output power will drop. It may start working better again once temperature has evened out across the whole laser.

The complexity of all these steps and the narrow tolerances can sometimes lead to strange situations. Often 532 lasers as a complete unit have some optimal working temperature, but in some cases there might be more than one. You could, for example, have one that works well at 25 degrees and also at 40 degrees, but not that well at 35 degrees (centigrade). If this is bothersome in your application you could consider getting a replacement unit, but all of them have a temperature optimum unless the unit is thermally stabilized.