"Super"cooling a laser?

[brtaman]

Hehe thanks scog, had great fun with that venice...may it rest in piece(s) :-/

Yeah rc heli's are also awesome I am currently building up a t-rex 450 clone the copter-x (same shit just gives me choise of esc and motor-)...lol would be flying already, if I didn't spend most of my dough on this hobby ;D

Nice job with the e6750...intel really hit the jackpot with the c2d...it seemed almost hopeless in the days that 939 and 754 ruled the pc world...and all intel had was the preshots

I saw the honeybee cp when I ws helping my bro get a chopper, seems good, but my bro wanted the belt cp (wants the same size as me), whats the diff between it and the king?


brtaman

 

[Scog]

I can't remember exactly, i think it may have things like an aluminium tail boom, maybe upgraded electronics or a brushless motor or something. Just a bit more premium. the cp is more of a fully featured budget model that is not too expensive to repair.
If there was one thing i wish the cp had it would be a proper gyro, dealing with that tail is a pain in the ass.

 

[brtaman]

Yeah stock e-sky gyro's are pretty bad from what i've read. An upgrade to a logictech 2100t (GY-401 equvivalent, some say better, but cheaper, also a gy-240 or any csm HL gyro would do your setup wonders, and their really not that expensive especially compared to some laser and equipment...).

Have you been considering an upgrade? I think that a new gyro will pay for itself in the money you will save on parts...

ATM all I am flying is my piccolo around my living room, great fun, however this is with the new CSM hl-200 which is an excellent gyro that can be had for an extremelly low price, the older gyro only caused agravation and broken parts...90 degree self imposed pyros in closed quarters spells nothing but disaster

Oh and an update on the project, I was contacted by a member and will most likely be purchasing 2 15mw 635 diodes, I will post more results when the project gets mocing again.

Thanks
brtaman

 

[Exerd]

I am so sorry to everyone for bringing this thread back.

But, there was something going here which seems to have been forgotten about; Supercooling a laser!

C'mon, what happened?

I am currently milling parts for a TEC lab 445nm. The lens holding block is held on the aluminum base, separate from the copper flat with copper diode pinch mount. This way, the lens is not cooled. The TEC is sandwiched between the copper flat, and a socket 771 copper heatsink with blower fan. The copper flat transmits cold forward to the diode pinch block. I have tested 91W TEC, but the surface area of the 771 cooler is allowing me to use a 400W input TEC on the way to me.

I hope to determine in my own venture how much further a diode can be pushed under the added cooling.

 

[HIMNL9]

Please, considerate the current drawed from the TEC too, and if you really need to use a 400W one.

Also, if you need a more lower temp, you cannot just use a bigger TEC, cause there's a phisical limit about the DIFFERENCE of temperature that you can obtain from the 2 faces (around 70 C, at the best) ..... but, from the opposite, you CAN use more than one plate in serie, for increase the temperature difference .....

I mean, place 2 plates one on the other, with the hot side of the first on the cold side of the second, and you can increase the total difference of temperature (not, ofcourse, 70x2, but like, almost 100C) if you grant an adequate cooling of the final hot face .....

Only if you need extreme differences, you need to use different powers plates (cause the heat to transfer increases almost exponentially), but for experiment with only 2 plates, a pair of cheap 90W ones are enough .....

 

[Seoul_lasers]

I am so sorry to everyone for bringing this thread back.

But, there was something going here which seems to have been forgotten about; Supercooling a laser!

C'mon, what happened?

I am currently milling parts for a TEC lab 445nm. The lens holding block is held on the aluminum base, separate from the copper flat with copper diode pinch mount. This way, the lens is not cooled. The TEC is sandwiched between the copper flat, and a socket 771 copper heatsink with blower fan. The copper flat transmits cold forward to the diode pinch block. I have tested 91W TEC, but the surface area of the 771 cooler is allowing me to use a 400W input TEC on the way to me.

I hope to determine in my own venture how much further a diode can be pushed under the added cooling.

I just killed a 445nm diode by cooling it to -20c. IT drew too much current and diode popped. I had it at 1.2A at 4.65Vdc.

Go for lower current and you might be ok. I suggest you not cool the diode as these diodes are nominally at 70c

 

[HIMNL9]

BTW ..... someone is more "crazy" than me, about some ideas .....

Have you seen this FerroTec product ?

"specifically designed for 5.6 mm CAN type laser diodes" .....

 

[brtaman]

Wow, talk about a blast from the past, I think this might have been my first post/thread on this forum. :tinfoil:

Seoul_Lasers:

I don't believe it was excess current that killed your 445nm diode.

If you look at the datasheet of any laser diode you will notice, that generally a cooler diode requires less current for the same power output than the same diode which is running at an ambient or above ambient temperature.

What I believe happened: is that you were running your diode at a high current, which at normal temperatures would have resulted in ~1W Po. However, at -20C, the power output would have been much higher, probably close to 2W.

I am of the opinion that your diode suffered COD. Basically the die and mirrors went up in smoke, as they would when running any diode past its designated datasheet Po specs.


Best Regards,
brtaman

 

[Exerd]

Here is an example of the design layout.

The copper plate is 3/16" thickness. The width of the plate is that of the TEC, 50mm. I think the heat should transmit effectively down the short length of plate it has to travel to the pinch mount. I suppose I could try 1/4" plate if 3/16" is too thin still. There will be an insulative layer between the copper plate and the thick aluminum base.

 

[oic0]

You guys should know the same guys that overclock would be the same ones to get in to lasers, especially DIY ones where you can push them.

My current babies are a E5400 at 3.8ghz 1.25v, an E7200 at 4.0ghz 1.216v, and a 4200+ at 2.9ghz. I haven't given the hobby up per say, but now I just use it as a tool to keep a powerful gaming rig up on the cheap. No more $400+ cpus for me! Also, strictly air cooling now, a plain ol TRUE. Running for towels every time a thunderstorm killed the power got old.

You would think with these laser diodes though that you wouldn't need much of a pelter. They put out what? like 3-5 watts of heat? That's outright piddly compared to a CPU.

 

[Exerd]

You guys should know the same guys that overclock would be the same ones to get in to lasers, especially DIY ones where you can push them.

My current babies are a E5400 at 3.8ghz 1.25v, an E7200 at 4.0ghz 1.216v, and a 4200+ at 2.9ghz. I haven't given the hobby up per say, but now I just use it as a tool to keep a powerful gaming rig up on the cheap. No more $400+ cpus for me! Also, strictly air cooling now, a plain ol TRUE. Running for towels every time a thunderstorm killed the power got old.

You would think with these laser diodes though that you wouldn't need much of a pelter. They put out what? like 3-5 watts of heat? That's outright piddly compared to a CPU.

OK on the subject of lasers and cooling, any thermal wattage difference equates to a temperature difference. If one TEC is used, there is a maximum temperature difference which can occur, and that is at the greatest difference between TEC thermal ability and thermal load wattage. So, while the difference between a 90W TEC and a 400W TEC on a laser diode may only be a 1-3 degree difference, as example, it is still a difference. It is small because of a parallel difference and not a series. I like the idea of stacking plates to get a series temperature difference potential, but not sure that I wanted to try it.

My goal in this project is just to keep the diode cool, but not extremely cool to the point where lots of condensation will be a problem, and it is the reason I choose to use one large TEC.

Another reason I choose the 400W plate is the width and area difference, and being that in my setup, the temperature needs to travel down a plate, I want that plate to be wider. So it made more sense to use a wider TEC, and with that came higher wattage potential. One final point I will make is that I will not be running the 400W TEC at that wattage, because that requires 26 amps. Probably only half that or a third.

 

[Meatball]

There is a point (temperature) where each diode will lase with the most efficiency it can muster. I have yet to discover if that point is typically just above room temp, below it, or right at room temp. There is work being done on this now by another member, it should yield some interesting results.

 

[Seoul_lasers]

Wow, talk about a blast from the past, I think this might have been my first post/thread on this forum. :tinfoil:

Seoul_Lasers:

I don't believe it was excess current that killed your 445nm diode.

If you look at the datasheet of any laser diode you will notice, that generally a cooler diode requires less current for the same power output than the same diode which is running at an ambient or above ambient temperature.

What I believe happened: is that you were running your diode at a high current, which at normal temperatures would have resulted in ~1W Po. However, at -20C, the power output would have been much higher, probably close to 2W.

I am of the opinion that your diode suffered COD. Basically the die and mirrors went up in smoke, as they would when running any diode past its designated datasheet Po specs.


Best Regards,
brtaman

right, I think I should re frase that statement. 1# cooling the diode makes it output more efficient for the current it consumes. So i over drove the diode at 1.2A at -20c because the lasing current for 1W output at -20c is lower than 1.2A (500-600mA) possibly?

 

[Meatball]

At -20C, I'd be more concerned about the frost/condensation you would develop around the diode!

 

[brtaman]

right, I think I should re frase that statement. 1# cooling the diode makes it output more efficient for the current it consumes. So i over drove the diode at 1.2A at -20c because the lasing current for 1W output at -20c is lower than 1.2A (500-600mA) possibly?

Basically yes.

The cooler the diode the less current it needs for a given output power (up to a point)

Diode:1 @-10C needs 100mA for 300mW
Diode:1 @ 25C needs 350mA for 300mW

(completely hypothetical, just used as an example)

 

[Wizzard]

What you should do is put the TEC between the evap unit and diode. Pump all the heat out of the diode, with the hot end of the TEC at -(whatever)*C. That'll be your best arrangement- I'm doing something similar with a Stirling cryocooler

(sorry if idea is repost- TLR comments)