EXFO IQS-12002B Calibration System - Manual (Page 61)

Calibration System 57
A Calibration Methods
This chapter presents the methods, on which are based the procedures of
the IQS-12002B Calibration System., for the calibration of power meters
and OTDRs.
Power Meter
The calibration of a power meter includes the calibration of its absolute
power and, for a high-end unit (e.g., IQS power meter), the calibration of
its linearity.
Absolute Power Calibration
Power meter calibration is performed by comparing it with an
IQS-1502 Calibration Power Meter (working standard). Comparison
between the two is done by measuring the output power of a laser source,
such as the IQS-2400 (usually a DFB laser), having excellent wavelength
and power stability.
In order to improve accuracy, the system can integrate a polarization
scrambler, which reduces the uncertainty due to the polarization
dependant response (PDR) of photo detectors.
For calibration at the 850-nm wavelength, the IQS-2400 uses a stabilized FP
laser with the mandatory mode scrambler in order to obtain a stable laser
source.