>
> Just don't exceed the ratings of the diode. And remember that the diode
> can be damaged by excessive optical output, not just excessive current.


Way easier now, than the ones from the bad old days.
40A pulses with picosecond rise times, and if it was a few uS too long,
POOF.

Mostly, you just need to keep them inside their ratings.
You can run them open loop if you're conservative or brave, and closed loop
with the feedback diode.

All the power meters I've seen were just PIN diodes or solar cells.
For calibration, compare with a known meter one way or the other.
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