Driving ADLAS DPY 315 II

[atomd]

Hi,
I purchased a few of those laser heads recently and I'm looking how to drive them correctly. The cavity has an output photodiode, a connection to pump diode and 3 TECs: for the nonlinear crystal, for the whole cavity and for the pump diode. I drove the LD with roughly half the maximum power and when scanning the temperature of nonlinear crystal I got green output. The problem is that it's extremely unstable, temperature changes by just a single mK change output power by like 50%. Does anyone know how the controller works, ever used them or has a controller that could be reverse engineered? I also attached a plot of output power vs temperature of cavity and nonlinear crystal. There's also a strange prism and a bunch of optics at the output, maybe someone knows what they are for?

The things I already reverse engineered:

• the nonlinear crystal isn't NCPM LBO and it's most likely a KTP 1x1x5mm
• the active medium is Nd:YAG, 7mm long, around 0.7%
• there's a brewster window in the cavity to force polarization

[mixedgas]

The 1064 I tore down at my former employer had two pump diode modules that needed to be very tightly cooled or heated to bring them into the pump band, combined by a polarizing prism. Massive array electronics on the board. There were numbers hand painted on the pump modules where the factory screened the diodes for the correct temperature / wavelength / current. Evidently the earlier diodes were far more sensitive to temperature then the current generation. Diodes had an internal TEC and the module package was on a TEC.

I scrapped it because 5-10 mW of raman stable 1064 laser with a very dead, very complex controller just was not that useful. That was one of the first DPSS cw greens on the market, back in a time when making inherently stable ones was still 10 years out. It probably suffers from the "Green Problem" as it used to be known, inherently huge amounts of noise in the doubling process.

No manual, and I don't work there anymore, board went into the trash as a waste of time when other drivers existed. I briefly powered up the diodes and came to the conclusion that I could build or buy a 1064 DPSS far more cheaply than fixing the beautiful Adlas.

1064 had the cavity and optics mounted in a say 25 mm aluminum tube, with the pump array separate from the tube and cavity. Extreme care was taken to include massive stable heat sinks and copper emc gaskets, one Photodiode internal to the cavity.

Coherent bought Adlas for some strange reason it was funded as a startup by Amoco Petroleum. ... The plant is still in Germany some place, or was until very recently. (edit Coherent Lubeck)

This looks very similar to what I tore down:

DL180 1991 Vintage DPSS Laser Teardown ADLAS 321 - YouTube

*** Warning, video may be traumatic to watch for those who know how much these originally cost.

Hopefully yours is less complex than the 1064 was. Good luck.

Steve

[TheHermit]

What a coincidence. Just watched Zenodilodon's recent video on this very subject.

His excellent YT channel is dedicated to repairing laser systems, including DPSS, using his own TEC controllers, etc.
Looks like something he might like to help you with.
Zenodilodon@gmail.com
(Tell him TheHermit sent you 😎 )
BR
Roj