[Laser] Mod Power to several lasers?

[David Rea, K2THZ]

Art and Andy have a good point - as long as the lasers aren't being
driven near their damage thresholds, constant current can work. Just
don't run them any closer than about 80% of the damage threshold power
output and you'll be fine. Keep in mind that the damage threshold power
output may change as the diode ages.

Generally, lower-powered diodes (<100mW) come with photodiodes, but
those that don't have photodiodes are manufactured to have more
consistent current/power transfer curves and less temeperature
dependence.

The bottom line - if your diode provides a photodiode and you're
concerned about consistent output power, you should use the photodiode.
If your diode doesn't come w/ a monitor photodiode, don't sweat it. But
of course that's the "do it proper or don't do it at all" commercial
product engineer in me... I have to keep reminding myself that ham radio
projects don't necessarily need this kind of attitude, since more often
than not only a handful will ever be made! 

Now off to the bench to work on receivers for September! Happy Labor
Day, y'all!

73
Dave K2THZ

On Sun, 2003-08-31 at 15:27, Art wrote:
> >  That's something I'm considering with these $20 120mw IR diodes from 
> > digikey...
> 
> 
> Those diodes have a wide margin, which is why they don't come with a 
> photodiode. You will have no problems with them running with a constant 
> current supply (as long as you don't try to run them at max power all the 
> time).
> 
> Keep dem lasers lit.
> 
> Art
> 
> 
> _______________________________________________
> Laser mailing list
> Laser@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/laser