EXFO IQS-12004B DWDM Passive Component Test System for IQS-500 - Manual (Page 154)

Using the Wavelength Calibration Software
142 IQS-12004B
Preparing the Calibration
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.
The nulling is performed on all channels of the IQS-1600 Power Meters as
well as those on the IQS-9401 WRM. It is important to put protective caps
on all channels on these modules. Using the Turn Source Off option
avoids having to disconnect rigid patchcords; when used, you must wait at
least 30 minutes after the source is turned on to allow it to warm up.
Wavelength Response
The wavelength response is the system's wavelength calibration.
If it has already been performed (by the IQS-12004B DWDM Passive
Component Test System system), this sub-step can be skipped. Therefore,
the same calibration measurements will be used and the message
Not required will appear.
However, if it has not already been performed, the IQS-9401 WRM output
must be connected to the first channel of the first IQS-1600 Power Meter, as
indicated to the right of the Perform WR button. The Wavelength Response
sub-step follows the order of the channels, from first to last. In addition, if a
IQS-5150 Polarization State Adjuster is present in the system, the Optimize
Power command will be performed prior to calibration.
I
MPORTANT
Light must not reach the detector when nulling offsets.