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Thread: LPC 826 658nm diode tests/infos

  1. #21
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    As far as I know, you can also stack 2 (or more) TECs together if you want to get some really, really low temperatures. But I'm not 100% sure about that, can somebody verify?

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    Quote Originally Posted by Stoney3K View Post
    As far as I know, you can also stack 2 (or more) TECs together if you want to get some really, really low temperatures. But I'm not 100% sure about that, can somebody verify?
    You are correct, it is called cascading peltiers the reason to do so is to create a larger temperature differential therefore allowing it to get colder/hotter. It means that you will have to disperse the heat from both TEC's in the same area as the outside. Big stacks are used to cool CCD's in infrared camera, telescopes etc (when liquid nitrogen is not used).

    Useful Link with Math: http://www.overclockers.com/peltier-stacking/

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    Laser (the acronym derived from Light Amplification by Stimulated Emissions of Radiation) is a spectacular manifestation of this process. It is a source which emits a kind of light of unrivaled purity and intensity not found in any of the previously known sources of radiation. - Lasers & Non-Linear Optics, B.B. Laud.

  3. #23
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    ok, we have to draw a line somewhere before this gets seriously out of control and we start building freon and phase change systems into projectors

    so, let's assume that we get a realy beefy tec and get everything to -50 celcius. we still have to feed it with 12-15 amps of power and we still have to dissipate 140 watts of heat. watercooling should be out of the question, as a projector with a radiator, pump and reservoir should be not too mobile...and huge too! and even if we do achieve deep freezing temps and we do approach 640nm out of a cheap LOC, how usable would this be anyway?

    i mean, it is ok for a test jig, but not too good for real life applications. so, as much as i like a serious helping of overengineering and "special" designs the outcome is not very usable. and the event of a tec failure should be catastrophic, as the diode will fry in seconds (given a fair or "unfair" amount of current overdrive)
    "its called character briggs..."

  4. #24
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    Quote Originally Posted by LaNeK779 View Post
    so, let's assume that we get a realy beefy tec and get everything to -50 celcius. we still have to feed it with 12-15 amps of power and we still have to dissipate 140 watts of heat. watercooling should be out of the question, as a projector with a radiator, pump and reservoir should be not too mobile...and huge too!
    Sorry to say it here, but I don't think people will run gigs with projectors designed for laptop-sized carrying bags and going to gigs on a bike. So something ultra-mobile is NOT necessary, considering the fact that you will have some kind of vehicle if you get gigs like this in the first place.

    Also, keep in mind that dumping 140W is a piece of cake. PC video cards have a similar heat footprint and they are completely air cooled. Even a limited amount of water cooling can give you tremendous heat sinking capacity (up to 0,5 kW) without making the thing insanely heavy -- PC's with water cooling are being used on LAN parties for a decade now with little going wrong and good results.

    Given the fact there's an argon laser sitting on my desk that's dumping about 1,5kW of heat in an AIR COOLED tube, dumping a few hundred Watts should be a serious breeze (literally!). Just don't count on your projector being iPhone-sized, but the same form factor as your good ol' VCR should be no problem at all.

    A very good added bonus of using a TEC/water cooling combo is that you can separate the air flow from the optics train and seal the optics -- completely. There is no reason to blow air over the optics train anyway, so water cooling the lot and making the optics air-tight not only fights condensation, but also prevents any dirt and fog residue from contaminating your optical path. Double win.

  5. #25
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    Quote Originally Posted by Stoney3K View Post
    Sorry to say it here, but I don't think people will run gigs with projectors designed for laptop-sized carrying bags and going to gigs on a bike. So something ultra-mobile is NOT necessary, considering the fact that you will have some kind of vehicle if you get gigs like this in the first place.

    Also, keep in mind that dumping 140W is a piece of cake. PC video cards have a similar heat footprint and they are completely air cooled. Even a limited amount of water cooling can give you tremendous heat sinking capacity (up to 0,5 kW) without making the thing insanely heavy -- PC's with water cooling are being used on LAN parties for a decade now with little going wrong and good results.

    Given the fact there's an argon laser sitting on my desk that's dumping about 1,5kW of heat in an AIR COOLED tube, dumping a few hundred Watts should be a serious breeze (literally!). Just don't count on your projector being iPhone-sized, but the same form factor as your good ol' VCR should be no problem at all.

    A very good added bonus of using a TEC/water cooling combo is that you can separate the air flow from the optics train and seal the optics -- completely. There is no reason to blow air over the optics train anyway, so water cooling the lot and making the optics air-tight not only fights condensation, but also prevents any dirt and fog residue from contaminating your optical path. Double win.
    I seriously doubt that a system with such a temperature delta within could have any practical value without some kind auf automatic convergence system or non at all... runnig monochrom and single diode.

    An Argon Laser dosen't have the convergenc problems of combined diode/DPSS systems, bad example.

    Isolating the optic path is something that should be done anyway.

    For the cost and effort of all this.. go for the 640 diodes and keep your sanity form trying to stabilize all this.

  6. #26
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    I just finished a session checking the focus of each of the 20 LOC-815 diodes in my TEC/ cooled water red module for my projector. These diodes benefit from a hermetically sealed container and each produce between 250 and 300 mw of 645-647 nm light at a conservative 420 ma. There is no attempt to stabilize the temperature, the diodes cost aprox. $200 and I can push them rather hard in that replacing one or two is easy(cheap). The entire projector with the enclosure weighs somewhere around 100 Kg and the water pump and radiator might add 7 Kg. I'll post some pic's in a few days. What the heck is an automatic convergence system?

  7. #27
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    Quote Originally Posted by Stoney3K View Post
    Sorry to say it here, but I don't think people will run gigs with projectors designed for laptop-sized carrying bags and going to gigs on a bike. So something ultra-mobile is NOT necessary, considering the fact that you will have some kind of vehicle if you get gigs like this in the first place.

    Also, keep in mind that dumping 140W is a piece of cake. PC video cards have a similar heat footprint and they are completely air cooled. Even a limited amount of water cooling can give you tremendous heat sinking capacity (up to 0,5 kW) without making the thing insanely heavy -- PC's with water cooling are being used on LAN parties for a decade now with little going wrong and good results.

    Given the fact there's an argon laser sitting on my desk that's dumping about 1,5kW of heat in an AIR COOLED tube, dumping a few hundred Watts should be a serious breeze (literally!). Just don't count on your projector being iPhone-sized, but the same form factor as your good ol' VCR should be no problem at all.

    A very good added bonus of using a TEC/water cooling combo is that you can separate the air flow from the optics train and seal the optics -- completely. There is no reason to blow air over the optics train anyway, so water cooling the lot and making the optics air-tight not only fights condensation, but also prevents any dirt and fog residue from contaminating your optical path. Double win.
    My recent experiments cooling LOC's revealed the first true hurdle to be overcome, that is dew point...

    The other night this was as high as 17c !!! The result is a diode block/lens covered in water.
    This space for rent.

  8. #28
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    Quote Originally Posted by planters View Post
    I just finished a session checking the focus of each of the 20 LOC-815 diodes in my TEC/ cooled water red module for my projector. These diodes benefit from a hermetically sealed container and each produce between 250 and 300 mw of 645-647 nm light at a conservative 420 ma. There is no attempt to stabilize the temperature, the diodes cost aprox. $200 and I can push them rather hard in that replacing one or two is easy(cheap). The entire projector with the enclosure weighs somewhere around 100 Kg and the water pump and radiator might add 7 Kg. I'll post some pic's in a few days. What the heck is an automatic convergence system?
    @ the wavelengths of 645-647 nm I would say your no where near the temp. previously discused (-50°C). Even though, how long did you test for beam allignment (convergenz) longterm stability? Did you use any special meterial for a base plate like invar or ceramic.
    That would be amazing if the allignment of 20 diodes would stay stable when the materials used are repeatedly set out a temp. delta of 60°C not to mention the effects of transportation. Or is this a fix installation with constant temp. conditioning?

    100kg.. do you have a large frame Argon in there?

    An automatic convergence system is a set of servo controlled mirror mounts with an external target sensor used for alligning RGBs. A similar system is used by medialas in the Infinity series except these are remote controlled. Very practical!

  9. #29
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    he he he.. this is indeed spiraling out of control. we are talking ceramic baseplates now and motorised, remote controlled linear motion stages for auto-RGB alignment!!!

    i like it!! i really like it!!! i really really like it!!!!

    have i told you how much i like it ? ? ? ?


    so, a dream come true would be a ceramic baseplate, in an hermetically sealed projector filled with nitrogen to avoid condensation, using micro-controlled motorized lens and dichro assemblies, and all things cooled to -50 (i don't think the dpss greenie will like this too much, but since i am dreaming, why not?)

    so, why not get a few vapochill and get this over with?

    http://www.extremeoverclocking.com/r...hill_LS_1.html
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  10. #30
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    Quote Originally Posted by Solarfire View Post
    An Argon Laser dosen't have the convergenc problems of combined diode/DPSS systems, bad example.
    I was only using the argon as an example to point out that 140W of heat is basically nothing, if you have enough conductive surface to get rid of it. With such power levels you're not going to need water cooling at all. I've seen people run 140W through a passive radiator heat sink!

    Isolating the optic path is something that should be done anyway.

    For the cost and effort of all this.. go for the 640 diodes and keep your sanity form trying to stabilize all this.
    What my idea would be is to use the micro TEC modules we found in the eBay thread to chill down each diode individually, instead of trying to cool the complete assembly and messing up alignment. The amount of heat you will have to dump is going to be a lot less, and the chill will be more localized reducing condensation and warping of all of the components.

    It also has a big advantage of being able to tune each individual diode by controlling the temperature, so you can run multiple lines of red in a single module.

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