Keysight Technologies N4373D, User Manual

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Measurement Concepts
Keysight
N4373D Lightwave Component Analyzer, User’s Guide 65
Measuring at Different Wavelengths and with the External Optical Source
Input
You can also make EO, OE and OO measurements on devices at
wavelengths that are different from the default wavelengths.

For OE and OO measurements, the option 050 “External Optical
Source Input” is required.
The LCA uses two wavelength correction files "LCA_TxCorr.csv"
and "LCA_RxCorr.csv". These files contain typical correction
data for the wavelength dependency of the LCA's internal
transmitter and receiver. When starting up or resetting, the LCA
server reads the data of these two files.
For higher accuracy, you could measure the Rx correction data
for your specific test head and wavelength and enter these
values into the "LCA_RxCorr.csv" file. Since the LCA uses
relative correction values between the closest internal
wavelength and the wavelength you select, it is important that
you measure the Rx responsivity for every internal wavelength
and your additional wavelengths. The file “LCA_RxCorr.csv” is
located in the directory:
C:\Program Files\
Keysight
\LCA\Table\ SN... \
where SN... is the serial number of the optical test set.
We do not recommend to change the values in the
"LCA_TxCorr.csv" file. Instead we recommend you measure with
user calibration for measurements using an external input.
EO measurements
The wavelength box on the EO tab is an editable, drop down list.
This means you can select one of the default wavelengths, or
enter a different wavelength.
If you select a wavelength other than the default wavelengths,
the LCA checks for the closest default wavelength. The
calibration data for this wavelength is used for the LCA
measurements.
Next the LCA checks if the "LCA_RxCorr.csv" file is available.
• If not, no wavelength correction is applied.
• If the file is found, the LCA performs a wavelength
correction.