Pulsed drivers debate!

I just did a quick search for any LD data sheet and found this one...

CW is 150mW
PW is 280mW at 0.1uS @50% Duty Cycle.... a bit higher in frequency than in the kHz range...




Jerry

I'll talk about the comparison with the incandescent lightbulb since pulsing for lasers is being discussed very elaborately.

For Incandescents, they are cold on start up, and as such have low resistance, hence the current spikes when you first turn it on. If you pulse an incandescent fast enough, say 60Hz and above, each pulse will not give the same spike as when you first turn it on. This is because the bulb hasn't enough time to cool down, and as such, it's resistance remains practically the same.

For LEDs and LDs, their cold resistance against their hot resistance is not significant mainly due to the temperature range in which they operate. Incandescents need to be hot enough to glow! While for LEDs and LDs, heat is an unwanted by-product that has to be gotten rid off.

So, you wouldn't be using more power when pulsed, and thus the circuit will not be hotter.