Ice is Nice....

[kiyoukan]

Heard someone say they were paying 55$ a tec driver.
This is not mine and came from LPF i think HIMNL9

http://laserpointerforums.com/f67/si...tml#post741817
in parts its just under a few bucks, it uses the temp and thermistor to adjust the 555 to pwm drive the TEC.

[Stiffler]

A couple questions...

1.) Has anyone established a practical lower limit for TEC cooling? I know they can be stacked for a greater temperature differential, but how low can they go?

2.) How does TEC cooling (or any cooling) effect alignment? Surely the contraction that comes with cooling will make alignment a bit of a challenge, how is it dealt with?

[kiyoukan]

tbh not very much.
i made a post once with all the different types of metal and there thermal propertys including creep and expansion and contractions.
the tempureatre manly affects parts being bent under stress. but making a 24mm solid block of 6061or brass colder will not cause it to shrink by any measureable ammount that we could feasably measure.
granted not going to extremes with this aka right below metling temp to - 50c.

[CDBEAM]

Well....first. PB..my TE amp is 4 @ 12VDC and your 3.3 W@ 18c....WOW...I like this !! !!YES...Ice is nice !! PL... I really like the concept of no bells and whistles for the TE. The concept of going " Controller less " for the TE is extremely desireable !!! Just let the thing go...let it free range !!! We have more than enough other things to go wrong !!!

As far as condensation....I want to hit around 0c....and see what condensation problems arise ???

Now....as far as having the AL plate between the LD holder and the cold side of the TE.....well....this is a VERY nice arrangment....especially when on the next level down in the projector case....the electronics reside....and that level is fan cooled....and the uppermost level is optics...and sealed !! Possibly a interface of iridium foil between the LD mount/ base plate....and a layer between the base plate and the cold side of the TE ???? Mmmmm ??? The use of IF will then require a bolt down for the sandwhich.....but the maximum Thermal Transfer Gods will be better served !!!haha

Some module makers put the TE/Radiator/Fan atop the Laser Head....but....then....one is dumping the thermal load back into the optics level....and ultimately back into the LD ??? Seems not the best arrangment ??? Hey...It's ALL good !!!

AND....Kiyou...welcome back...." Prodical " keep your nose clean... hahaha....we all FU !!! The true measure is how we handle it !!!

BEAM Out_______

[planters]

The coldest I have been able to MAINTAIN in a real world operational projector with G71 diodes and TEC to air cooling (basically as described here) is -6 C. This is with 6 diodes and 200W of cooling.

At 0C you will have only seconds before gross condensation fogs the lens. Forget about it. Trust me on this I have been working with these systems for more than a year.

Do you remember this video?

http://www.photonlexicon.com/forums/...ight=projector

[CDBEAM]

Well...yes...I do remember that video....and when watching it again....I turn the same " 532nm " color with envy !! hahaha

OK...I see that when you go down to -6c.....I assume one MUST contain the arrangment of G71 LD units inside an hemetrically sealed chamber.....and I also assume that you MUST use a hot wire heating coil to heat your two AR output windows....thereby eliminating condensation of these windows.

I do not want to go to this extent...but perhaps that is the only way to acheive such a low C ???...I may have to settle with....say 10C....OK....Maybe that is acceptable ?? I suppose it all depends on how low...do ya want ta go !!!...and what will you do to acheive that temp !! Do I understand your set up correctly????

And yes....in a dual arrangment I set up....I also equalized the distance from each LD output to the first Plano concave of the cylindericals to acheive a parity to the corrective optics. See pic.

Do you feel that iridium foil would be the best choice to couple the interfaces ??...or....just stick with Artic Silver ??

And....What can we learn from the " Overclockers"....Heat pipes ?? Water cooling ??? Yikes...In the end....I want to acheive a balance between cost~complexity~performance.....Many roads lead to Rome...as they say !!!

Thanx for ALL you contribute to PL.....and do consider adopting me..you have....mmmm....A great work area !!!!....I could live comfortably in your workshop !!!hahaha

Beam Out_______

[planters]

Sometimes, I feel I do live in my work shop...hahaha!

If you want the most benefit for the cost and complexity and yes the overclockers are the group to study because they represent a large base of moderate budget experimentalists then I can personally vouch for water cooling. There are slick, relatively low cost rigs out there and following a few simple rules they simply WILL NOT LEAK. The heat removal is enormous, there is no dust, they are compact and they can be nearly silent. I am now using it for the big blue module in the big projector you just saw and for the big green that will soon replace the puny Vashio shown in the video.

In any case, The A.S. two part thermal EPOXY rather than a grease sandwich is best, simplest and if you want to disassemble for what ever reason just remove the diode and reverse the current to the TEC and warm the mount to approx 100C. The glue will soften enough to twist the brass off.

At these low delta Ts the window does not need heating and the box does not need insulating; just sealing.

[CDBEAM]

Well....I can imagine alot of less desireable places to live and work !!!!!!!!!!!!!!

I will shift over to the 192W TE....and see how low I can go...and I assume I MUST enclose the LD mount+optics is a sealed case to mitigate the condensation. MMMM....gonna hafta expand the perimeter of my AL optical base plate to accomidate an enclosure. More fun !!!

As to the aspect of water cooling ???? I must study up on this. I know that water cooing is MUCH more efficient than TE. And, the very good thing is that the Overclockers have paved the way and thereby have created a market .....so there is a huge offering of products out there....off the shelf....and at very reasonable costs.

Which water cooled units do you use ??? What delta T do you acheive ??

Thanx for the tip on AS epoxy !!! and....have you employed iridium foil for heat transfer....IIRC....you have....is it the way to go ??? BUT....doesn't IF have an issue with degradation over time ???

In closing....the ONLY thing I see missing from your Dream Shop are.......The Robot Girls... formerly owned by " Harcort Fenton Mudd ".....from the original Star Trek Series !!!
See the pic of Eric's real Laser Lab Assistants !!!

Thanx for all the help so far !!!
BEAM OUT_________

[dave]

That is a very very crude circuit! You are not going to get very accurate control of the TEC at all

Heard someone say they were paying 55$ a tec driver.
This is not mine and came from LPF i think HIMNL9

http://laserpointerforums.com/f67/si...tml#post741817
in parts its just under a few bucks, it uses the temp and thermistor to adjust the 555 to pwm drive the TEC.

[steve-o]

Mudds women ..lol CDB .. good one .. they need to put trek orig back on tv one more time ,, even tho I've seen them all 15 times over .. still can't stop watching ..