TEC Controllers for DPSS Lasers - a question

[celas]

Hello

I have several medium and big dpss lasers that I am going to use in my RGB projectors. Unfortunately there is a problem - I have no temperature controllers for TEC cells and when I looked up their prices I was shocked - they are ABSURDLY expensive and I am never going to pay almost as much as a price of an entire high quality DPSS laser head for a flimsy pcb board with nothing extraordinary on it. So I found something on eBay and I wonder if it will work:
https://www.ebay.com/itm/TEC-Semico...h=item3f66c8ac97:g:sE4AAOSwAPlXh1n7:rk:1:pf:0
This cheap chinese thing can control one peltier cell for both cooling and heating. Unfortunately, I can see it works on relays so I wonder if it's suitable.
I think they relays would do 'click-clack' constantly (switching tec on and off to hold the desired temperature), it wouldn't bother me as long as it'd work fine.
To be honest my biggest laser don't even need elaborate cooling systems (for example my Jenlas D2 only requires that the baseplate temperature doesn't exceed typical ambient level, and the giant CNI-W head could probably manage cooling the diode conductively with that big ass radiator) but if I can do it for cheap, then why not. Or maybe there are nice DIY schematic solutions for making your own TEC controllers?

 

[jnrpop]

Hi celas,
Interesting that you posted this question, i have also been hunting for a TEC controller, or looking around for options anyway, and the cheapest controller i found was also the one you Linked above. I read some reviews somewhere that they work ok, but calibration is not to accurate for pre-existing temperature probes, and small Watt TECs.

Another option i found was by a company here in Germany, called Lasertack. They have a driver/TEC controller combo.

But besides that theres not to much around which has Read-outs for Temp, etc.

You could also modify a B&W 473nm module driver or old CNI module driver that have TEC controllers built in.

Hopefully another member can chime in with some advise.

Best of Luck
J

 

[brendon7358]

Not familiar with this at all just throwing this out there, could you use something like a fan controller for a pc? The one I have for mine even came with thermocouples. Granted it wasn't cheap but I know they make cheaper ones.

 

[diachi]

If the heads have internal TECs you likely don't need an external one. A heatsink or something else to soak up the heat is usually good, as long as it can maintain a temperature somewhere close to ambient.

Otherwise, any old PWM temperature controller will probably do the job as long as it can source enough current at the correct voltage. An Arduino would work.

 

[WizardG]

Using PWM to power a TEC tanks efficiency hard unless you can filter out all the ripple. TECs like analog controllers for their clean output but then you lose some regulator efficiency heating up the pass transistor.

 

[jnrpop]

I would love to implement a Arduino for control.
Then have inputs for the TEC, TEMP Sensor, LD, TTL, a FAN....etc. Using say a Blackbuck 8 for the LD supply, that would be a fun project.
I would need to start learning about the Arduino world now though, messed around with SB computers but not the Arduino´s....yet
J

 

[mojo_1234]

If you're interested in building your own one you should check the following page:

W's Laser-Projects page

It's really a great page and all of my DIY diode and tec drivers are based on his ideas. 100% suitable for holography!

 

[jnrpop]

Wow, some very detailed experiments mojo_1234 , Thanks for the Link, i look forward to some reading! i see he also setup a Temp controller using an Arduino, perfect

 

[celas]

Okay, since the TEC problem is somewhat solved, I have another question - I have a CC psu for jenlas but it doesn't support modulation. Is there a schematic for a 'modulation dongle' I could insert between psu and the laser head that would enable me to modulate the laser via ttl or analog? I need it cause it's gonna be used in a laser projector

 

[Cyparagon]

You should have thought of that before you bought the wrong driver. You can either reverse-engineer the driver to look for an injection point or buy the right one.

 

[hakzaw1]

your are very kind sharing this link with us. .

thanks again MoJo for the great sharing.
That lab looks fantastic.... hak

 

[Alaskan]

I have a JenOptik D2.3 and it needed two separate TEC controls, one for the diode temperature and one for the SHG crystal temperature.

Installation manual: https://photos.imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/misclaserdocs/misclaserequipmentinfo/D2.x Installation Instructions.pdf

Pinout attached.

 

[celas]

I have a JenOptik D2.3 and it needed two separate TEC controls, one for the diode temperature and one for the SHG crystal temperature.

Installation manual: https://photos.imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/misclaserdocs/misclaserequipmentinfo/D2.x Installation Instructions.pdf

Pinout attached.

Wow, thats a great piece of information.
I have a question, though - arent 3w and 5w versions the same thing? Even their pump diode currents are so close - they may be using the same diode. How much power were you able to get from your unit?

 

[Alaskan]

Don't know the answer to that, I had heard they use the same warning sticker on both the 3 and 5 watt units stating 5 watts max power. I got it running by manually controlling the diode current, diode TEC (cooling) current and SHG/second harmonic generation non-linear LBO/lithium triborate crystal TEC wired to heat the crystal instead of cool. I guess it is better to call a TEC a TEH when wired in reverse to heat, but wired either way they are often called a TEC anyway.

To get this to work manually, I had to adjust currents while closely monitoring the thermistor resistances (temperature) for both the LBO crystal and ~808 nm diode using three constant current variable lab power supplies and two DVM's. I did not have a LPM or power meter on its output, but it burned through wood just as fast, or faster than another DPSS laser I had with a measured output of four watts, so it may have been producing that much, or more. Although, having a much smaller beam diameter, it could have done as good a job due to having a higher power density too and actually have been lower output. There is no way to tell by eye if it produced 3 watts or even 5, but I could believe it may have been up to five watts by how bright it was, but still, you can't know by eye, guess yes, but know, not.

Was difficult to keep the JenOptik D2.3 DPSS tuned by hand watching both the thermistor resistance for the laser diode temperature as well as the LBO (knowing where they should be using a conversion table of resistance to temperature), but was able to do so for a few minutes to keep it running until I got tired of needing three arms. The longer the unit ran, the harder it was to keep everything adjusted properly for peak output power. I bought some cheap TEC controllers with a feedback loop from the thermistor resistors to make something which could adjust the temperatures automatically which used relays, but never wired it up. Don't know if they would have worked out or not. Alternatively, I could have purchased a solid state thermoelectric controller from optlasers.com in Poland, they are a reputable seller and design their own products: https://optlasers.com/tec-controllers/

LBO: https://en.wikipedia.org/wiki/Lithium_triborate

Edited: Corrected type of crystal and adding extra language for individuals who are new to DPSS to be able to more easily follow.

 

[paul1598419]

Yeah, running something manually gets old very fast. I have done it, too only as a test to see that everything was working properly. But, it shouldn't be too difficult to build something to do all that for you.

 

[Alaskan]

Yea, and the warmer the DPSS body gets, the harder it is to control by hand. I called the crystal a KTP in my last post, but according to the manual, it uses an LBO crystal. My bad.