Had a bit more of a play with the serial commands; as it came, the reference power was 159mW, with about 120mW at the end of the fibre; the reference power limit is 450, so I turned it up in steps to 400 and read a maximum of 359mW at the fibre exit. LD current and voltage are well within the normal limits and the run time looks quite low as well. All in all quite a good purchase.