EXFO IQS-1500 Power Meters for IQS-500/600 - Manual (Page 41)

Power Meters 33
6 Measuring Power
Power measurements can be displayed in two ways:
³
absolute
³
relative
It is also possible to add an offset value to your power measurement.
Displaying Absolute Power
When in absolute power, measured values are displayed in either dBm or
W units (pW, nW, μW, mW...) and the displayed value represents the
absolute optical power reaching the detector within specified uncertainty.