EXFO PSO-100 Series Optical Sampling Oscilloscopes - Manual (Page 40)

Setting up and Using the Optical Sampling Oscilloscope
32 PSO-100
Adjusting the Zero Level (Nulling Offsets)
Adjusting the Zero Level (Nulling Offsets)
Temperature and humidity variations affect the performance of electronic
circuits and optical detectors, which can offset measurement results. To
compensate for this offset, the PSO-100 is equipped with an offset nulling
function.
EXFO recommends performing a nulling of the electrical offsets whenever
environmental conditions change.
To adjust the zero level:
1. From the main window, select the Utilities menu, then Adjust Zero
Level.
2. Remove the input signals from the unit, then click on the screen to start
the process.
The unit will set the average level to zero, then continue to measure.
Once the process is complete, you can turn on the input signal again and
continue the measurements.
I
MPORTANT
Light must not reach the detector when nulling offsets.