Hi, if I could just get things set up at home to wire my own unit up I'd be happy, my wife has me on too many honey-do projects right now. I have the power supplies needed, the power meter, even a couple of TEC controllers if I want to wire them in to keep the KTP crystal and laser diode at temperature but haven't set up to do it yet. I did try it without monitoring the KTP temperature and it put out green, but only 300 mw. I shouldn't have even done that, did that before I learned if the KTP crystal isn't kept at the right temperature, you can possibly damage something if adjusting the voltage high enough to allow a lot of power output from the 20W 808nm laser diode that can damage the crystal cavity it drives, maybe even the KTP itself if it isn't tuned to resonance by being at the right temperature? I still have much to learn about them.
I bought at 25 amp constant current adjustable power supply from the same seller fairly cheap, I think under 200 with shipping. You might look into getting one from him to drive the diode with.
Here's what needs to be controlled:
1. The temperature of the 808nm IR laser diode to keep it at 808nm, lower or higher temperature than specified on the unit and it won't be.
2. The voltage and current to the 808nm laser diode (limited current so you can't over drive it).
3. The temperature of the KTP crystal as written on the unit (via its little TEC which is wired backwards to heat it, instead of cool it) so it will be "tuned" to the right temperature for an efficient conversion, otherwise they are inefficient.
There are standard 10K monitor thermisters on the diode as well as the KTP crystal and you can just monitor their individual resistances with a volt meter to make sure your diode and KTP crystal are at the right temperature, using a chart to convert resistance to temperature. A TEC controller can do that for you and adjust the Thermo Electric Coolers (wired backwards if used to heat instead of cool) to keep things at the right temperatures but they aren't cheap if designed for lasers. I bought a expensive Wavelength Electronics MPT Series MPT5000 Temperature Controller (5 amp capable for $50 on ebay, hundreds if new) to control the KTP crystal temperature and a cheap 10A capable Chinese temperature controller for 10 dollars to control the laser diode temperature via its TEC wired to cool which might not keep the diode at the correct temperature well enough with this cheapo unit:
http://www.ebay.com/itm/321465614249 -
The specifications on the Chinese unit seem good but so much of their stuff doesn't meet their own specs I just don't know. For ten dollars I thought I'd try it, a "real" TEC controller capable of 10 amps for a laser, if such exists, could not be found on ebay when I last looked (I seldom buy my laser toys outside of ebay except for DTR's LPF online store). Keeping the KTP on temperature is more critical so I bought a fast loop controller for automatic control of its temp., the laser diode temp, I think might not be so difficult due to the large mass of the heat sink it has.
I'm betting the KTP can be kept at the right temperature manually by monitoring its thermister and adjusting the current as needed to its heater, but better to wire it up with a controller which gets its control feed back from a thermistor for automatic control.
