How To Set The Wavelength; How To Remove Electrical Offsets (Zero) - Keysight N7744A User Manual

How to Set the Wavelength

How to Remove Electrical Offsets (Zero)

N O T E
Keysight N774x Series
This is the wavelength value of the signal to be measured. The
responsivity of the Power Meter varies with wavelength.
For accurate absolute power measurement, you need to input the
wavelength of the optical input.
For relative power measurements, this setting is not critical.
Optical Power Meters measure optical power by converting optical
power to electrical current, and then measuring electrical current. An
electrical offset is electrical current that is always present, even if there
is no optical power input. If electrical offsets are not removed, they
affect the accuracy of power measurement, especially at low optical
power levels.
Performing a zero sets the zero power level to the average electrical
offset level for the current environmental conditions.
The environmental conditions and the temperature of the instrument NOTE affect
electrical offset.
For the best results you must:
•
Allow the instrument time to acclimatize (around 24 hours).
•
Allow the instrument time to warm up (around 20 minutes).
•
Make sure that the optical input is not receiving any light or use the
zeroing adapter. If you are using multi-mode fiberoptic cable, you
must disconnect the cable and cover the input to the Power Meter to
perform a zero.
It is good practice to perform a zero before making any sensitive
measurements.
Logging data over a wide dynamic range is a typical case that requires
a valid zero setting.
1 In the File menu, select Zeroing.
2
Power Measurement
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