Dicking around with a red diode and TEC

[andy_con]

had nothing to do today and got a bit bored so decided to dick around with a red diode.

the diode is a long open can x16 diodes, cost me £10

i used robins die4driver and his tec setup.

the big heat sink at the botton is from a computer, its has a copper centre with alum round the edge and a 12v fan attached. this has the hot side of the tec on it.

the diode is in an aixiz housing with an aixiz glass lens.

so i started off with just the diode on and no TEC runnings.

i set the diode to 300mw and left it for an hour, after which it was very hot (well he alum block its in way) and the power had dropped to 251mw.

then i turned the tec on, i had it set as shown by the blue line on the below pic

not 100% sure on the exact temp

left it for another hour and the diode power went up to 316mw.

then thought i would give the tec a good run and turned it half way, diode power went up to 328mw and the condensation started.

the lens was ok but you could see some slight water drop-lets on the alum block around the diode.

turned the temp all the way down to -5 just for fun and the lens fogged up.

after that bit of fun i turned the temp back to how the blue line is shown on the above pic and its been running now for 2 more hours. the diode is still giving out a soild 316mw and there is no condensation at all.

so the diode has been running for 5 hours total and its not had an easy time.

 

[DashApple]

thats a nice experiment there ill have to find some of them tec controllers when i get some money i have 2 150 watt tecs doing nothing and a 20mm tec too nice setup too.

 

[andy_con]

die4laser.co.uk or .com

there should be a link on my site somewhere to robins site where you can get the tec driver

 

[DashApple]

die4laser.co.uk or .com

there should be a link on my site somewhere to robins site where you can get the tec driver

Thanks

My new tecs use 12 volts 20amps and 15 volts 30 apms for my second tec

 

[Benm]

Thats pretty cool.. did you notice a visible improvement in output light when using the tec to get really low temperatures? It should shift the wavelength of the LD up a bit, giving more visibility per-mW, as well as increasing output power.

 

[Meatball]

There ought to be a point when you start to see power from the diode increase exponentially due to thermal runaway. It would interesting to see what that temperature range might be. Decreasing the diodes resistance can be a dangerous thing.

 

[andy_con]

i have been asked this before and its very very hard to tell. the wavelength change is so small i personally think you cant really tell.

 

[Benm]

The shift inst very big, in the order of 1 nm for every 10 kelvin. It might be observable starting with a 635 diode and cooling that down to freezing temperatures.

 

[Krutz]

its not that much, yes.. but cooling a 40° diode down to a perhaps condensation-friendly 10° would shift 3nm. not noticeable in color, but should be noticeable in brightness still!

thanks for posting, andy, nice read!

manuel