EXFO IQS-12002B Calibration System - Manual (Page 62)

Calibration Methods
58 IQS-12002B
Power Meter
At all wavelengths, the output power of the laser sources is measured
several times alternating between the calibration power meter and the
power meter under test (DUT). A minimum of five responsivity constants
are calculated for the DUT and are statistically analyzed to ensure that they
are within appropriate limits (e.g. the calculated values must all be inside a
certain range of values). Whenever one or more responsivity constants are
outside the acceptable range, the measured values are considered invalid
and the measurements have to be redone.
The number of measurements taken with the calibration power meter and
the DUT, and the number of comparisons between the two units are set so
as to reduce uncertainties of Type A. These uncertainties include
connection uncertainty and interference due to reflections.
The system uses expanded uncertainty (U) values that are included in the
report. The following tables present the method used to establish the
uncertainty for calibration made at four wavelengths.