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Custom power supply for DPSS head - Looking for advice

Spoomples

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I just barely got a 58-GHS-305-048 Melles Griot head off of eBay. I might have been a bit too hasty about getting one without its fancy control box, but I'll turn this into an opportunity for a project. I think I can manage it, but a little extra advice is always useful. I might turn this thread into a build log once I start, to give back a bit and provide a reference for others.

Powering the 808nm pump diode: Whats the best way to go about this? I was thinking of making a driver with a bunch of parallel LM338s, making a driver with an opamp and a beefy MOSFET, or buying a cheap constant current buck converter from eBay and filtering the output with a big capacitor and inductor. The main issue with building a driver is getting an appropriate input voltage, and the main issue with a cheap buck driver is the output spikes.

Controlling the internal temperatures: What are the TEC power requirements, and are there specific things to watch out for? I'm planning on using an Arduino to read the thermistors and control the TECs. The temperature tables for this specific head are published, so I don't think that will be too bad. I might place the Arduino sketch up on GitHub for others to use for their purposes.

Connectors: Is it possible to buy or make connectors for these heads? I'd prefer it if I don't have to open it up and cut the internal wiring. I own a 3d printer, so I could make a connector if I could at least buy some properly sized pins. I'd also be willing to buy a cable or trashed PSU with one from a member, should anyone here happen to have one laying around.

Tuning: Best way to go about it? I don't have a proper LPM, so would a basic TEC or photodiode be enough to tune the internal temps? I wouldn't get a true power rating, but I could tell how it performs relative to itself.

Misc advice: If there is anything you think is worth mentioning, to either me or anyone reading this in the future, feel free to post it.
 



Alaskan

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What output power is that head rated to produce? Also curious about the wavelength.

I haven't built a DPSS yet, but have used outboard power supplies to run a Jenoptik head once at 532 nm for 5 watts output, controlling the temperatures of the diode and SHG crystal TEC's with hand adjustable DC power supplies, I was having to jump back and forth between the controls for the diode current, diode TEC and crystal TEC so much I felt like a one armed paper hanger. It worked, but was too much work and a flurry of adjustments to keep everything at their sweet spots. I was monitoring the resistance of thermistors to keep everything in range.

If I had a constant current driver for the diode current it would have been easier, and TEC temperature controllers for the diode and SHG crystal TEC's I wouldn't have needed to adjust stuff by hand. You can buy cheap Chinese TEC controllers which use relays, or get a more sophisticated and accurate TEC controller PCB from optlasers.com in Poland which aren't too expensive.
 
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Spoomples

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What output power is that head rated to produce? Also curious about the wavelength.
...
Its a 2.5W 532nm head. I ran across your post about the Jenoptik when I was researching this subject, which helped reassure me that I won't immediately blow out the pump diode.

As for the TEC controllers, those seem to be made for specific thermistors. Maybe that could be worked around if its close enough to the one in the head, or if I manually swapped them out? There are also these little things floating around on eBay and aliexpress.
 

paul1598419

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Once you settle on a driver you'll need a PS that can output 5 volts at 100 amps. Mine, which is 1300 mW takes a 5 volt at 75 amps. With the pump diode and crystal temperatures needing good TEC control, you might wish you had gotten the driver meant for it.
 

Cyparagon

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Mine, which is 1300 mW takes a 5 volt at 75 amps.

375 watts in; 1.3W out? For DPSS green? Are you sure? I thought Melles Griot made good lasers.

I mean, decent optical conversion is ~20%, and the pump is ~50%, so the pump shouldn't need a lot more than 13 watts. Even if the driver is dumping the extra 3V in linear mode, that's maybe 33 watts. In what world is fan/TEC going to make up the remaining 300+ watts here? What am I missing?

OP, if you're still watching the thread, what's your budget?
 

paul1598419

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Yeah, that is overkill. Mine, like many, came as a package with the SMPS as part and parcel of the whole system. It was likely the least expensive way to power this. These are still being sold at Techhood, as far as I know. Of course the PS can be as robust as you wish as the driver package will only pull as much current as it needs. These SMPSs are very inexpensive and the one I have is well under $20.00 new.
 




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