EXFO IQS-12004B DWDM Passive Component Test System for IQS-500 - Manual (Page 125)

DWDM Passive Component Test System 113
9 Referencing the System with
MultiPath Testing Option
This section presents the procedures to perform reference and calibration
on your system when working with the MultiPath Testing Option. This is
particularly useful if you develop your own MPT application (without using
the provided LabVIEW application).
All the procedures presented in the current section are included in the
LabVIEW application provided with the MPT option. If you intend to use the
provided application, see Testing Multiple DUTs with the LabVIEW
Application on page 117.
Nulling Electrical Offsets
The offset nulling process provides a zero-power reference measurement,
thus eliminating the effects of electronic offsets and dark current due to
detectors.
Temperature and humidity variations affect the performance of electronic
circuits and optical detectors. For this reason, EXFO recommends
performing a nulling of the electrical offsets whenever environmental
conditions change.
A nulling should be performed during the initial installation, after the
system has reached a stable operating temperature (approximately
30 minutes). It should be repeated if there is a significant change in
environmental conditions. EXFO also recommends that a detector null
measurement be performed, prior to the wavelength response calibration
and/or before the return loss calibration. For more information, see Nulling
Electrical Offsets on page 75.
I
MPORTANT
Light must not reach the detector when nulling offsets.