Re: How long will a diy red live when running at 1
wooooooolazer said:
I've had very bad experiances with ld's dying, most of the time cause i put to much current in them, i never measured but i would guess about 370ma.
This time im buying one more and im going to lower the current to only 180ma, so my question is if i have a full driver with cap and everything should i expect this too live as long as a bought laser, like say 3000-5000 hours?
370 mA ?! Oh good grief it's amazing they lasted at all. I would never take any of the Sony 16x diodes over 300 mA without active cooling.
The only reason these LDs can be pushed so hard without getting COD (instant damage to end facets) is they're designed to reach these power levels, but PULSED, not CW.
These diodes are rated for a CW power of around 80mW with a 130-140 mA current draw. Beyond about 200-250 mA you reach the point of diminishing returns. Overpowered LDs will often see a widening of the gain, and they sometimes will not look as 'pure' or speckly.
The way we're using these LDs they ARE going to have a shorter life than they are rated at. There are two things you can do to improve their life. First you need good heatsinking. Use thermal paste or glue to assure that heat can escape the LD package to the case efficiently. There is a direct relationship between an LDs lifespan and it's junction temperature. The warmer (above about room temp) the LD gets, the shorter its life. But it's not a linear degradation -- a part that's 2-4x as warm may see an exponential decrease in it's lifespan. For my next burner I'm going to a thermally conductive glue to assure the back of the diode can dump its waste heat efficiently to the case/heatsink.
The other thing you can do is assure the duty cycle remains very conservative, say no more than 1-3 minutes of use before letting it cool for a minute or two. Either that or have active cooling or very good passive cooling (that is a large heatsink properly attached to the LD).
I would suggest trying around 200 mA of current (mine is at 225 mA0). This will give you enough power to burn and increase the life considerably over a diode pushed with more than 350 mA of current.
{EDIT} These LDs may have lifespans of over 10K hours when driven at spec. A well made pointer will still hopefully have a life of 500-1000 hours, which is a LOOONG time for a pointer.
