EXFO IQS-1600 High-Speed Power Meter for IQS-500/600 - Manual (Page 50)

Measuring Power
42 IQS-1600
Displaying Absolute Power
To display absolute power:
1. Select the Instrument function tab or the Channels tab of the Settings
function tab (you can use either).
2. Select the channel for which you want to set the offset if you are using
a multichannel power meter.
Note: Step 3 is not mandatory, but will help you achieve more precise results).
3. Select the appropriate wavelength by using the arrow buttons next to
the corresponding list.
4. Select the appropriate unit by using the arrow buttons next to the
corresponding list.
5. If you are in the Settings function tab, click Apply to confirm your new
setting.
6. Return to the Instrument function tab and click Absolute to activate
the mode.
An absolute power measurement in negative W units indicates that the
nulling of the offset was improperly done. If this happens, repeat the offset
nulling operation (see Nulling Offsets on page 38).