The Big Green Thread (I'm gonna regret posting this in the morning)

[planters]

How are you controlling the TEC right now? Did you try that digital controller that I linked you to yet?

No. Actually I forgot about the link and I will go back and look for it. I think one of the issues was that I am looking for a turn key, thermistor, driver and read out with a adjustment pot The "control" at this point is a seat of the pants, trial and error continuous low, cooling drive voltage to the TEC as in 0.3W and the stability provided by the water cooled TEC (room temperature on the heat exchanger). Despite this I have seen 800mW @ 20% pump power, but as the measured temperature slowly varies @ the KTP holder, modes will walk across the projected spot and the power varies significantly. This does not occur with the fundamental when the KTP is removed and the1064nm spot is focused through an output coupler. It is not the vanadate.

I am using a paralleled 4 channel Badpip driver. I only have one running. Can't wait till there are some more options.

[shrad]

check maxim-ic website, they have turnkey evaluation boards for TECs with 0.01°C stability for as low as $30 for what I recall

I got two 3W controllers for 50€ two years ago, they have a manual pot, an I2C pot and a 8-bit binary input for set point, and a thermistor input for sensing... they also have a DB25 for all to be connected more neatly

[logsquared]

I have a wavelength electronics MPT-2500 sitting here that may work. Its a bi-polar analog 2.5 amp precision controller. No readout. However it does have a monitor out for your VOM.

http://www.teamwavelength.com/produc...ct.php?part=29

[planters]

logsquared,

PM incoming.

[planters]

I now have the 532nm output at 1,200mW @ 25% pump power. At this power level The divergence is still quite good. I am including a link to some images that I uploaded today that show the beam against a grid with 2.5mm squares. Near field the beam is 2mm in diameter and @ 9M the beam by my estimate is 5x6mm. The slight asymmetry in the far field is caused by the slow drift of the KTP temperature. After adjusting the KTP alignment you can watch these low power modes slowly walk across the beam and if the temperature drift is reversed then these same modes walk back across the beam. This will be corrected by the temperature controller from logsquared ( thanks Woody) and a mode limiting aperture stop within the cavity (boots and suspenders). I am waiting for the second driver to arrive to permit the second pump to be installed. While I am waiting, I am working on the components for the orange, TRUE cryogenic laser. I hope to have this up and running soon.

Pic 1
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Pic 6

[Meatball]

That's astonishing work! How many hours now into the alignment and optimization? Over 20?

[chad]

That's Really great! Well done.

+5

chad

[dsli_jon]

I now have the 532nm output at 1,200mW @ 25% pump power.

http://postimg.org/image/a3c9vvbpt/ *awesome*-werk, Cap'n.. Ps - I see you've discovered those 'Israeli' vertical-drive mounts, eh? Nice, aren't they? Especially fer the bux, vs Thors, et al..

cheers to the Progress.. ..keenly-tuned in to watch for moar colours..
j

[shrad]

the world suddenly gets easier when you use an IR camera... once I did this I was able to align 1064nm almost perfectly, and I just had to place the KTP and tilt it for one or two times till I had green

it must be something you cant live without with a z-fold, except perhaps with an autocollimator

you did very nice, results are very encouraging

[planters]

Ps - I see you've discovered those 'Israeli' vertical-drive mounts, eh?

Yes I did, but I think these were originally manufactured by Coherent and sold to an Israeli Co. as an OEM component in a production laser. I suspect a medical laser.

That's astonishing work! How many hours now into the alignment and optimization? Over 20?

Probably, but the optimization includes things like determining the need for the KTP temperature controller and designing the aperture stop etc. It's fun. Walk by, switch it on, take a few measurements, adjust a mirror and then fabricate a small part. Each time it gets a little better and the physics makes a little more sense.