EXFO IQS-1600 High-Speed Power Meter for IQS-500/600 - Manual (Page 46)

Preparing Your High Speed Power Meter for a Test
38 IQS-1600
Nulling Offsets
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 unit is equipped with an offset nulling
function.
Your unit is designed not to require offset nulling under normal operation,
but you should perform it whenever environmental conditions change
significantly or when measuring very low power values.
Your IQS-1600 High Speed Power Meter automatically performs nulling of
the offset each time you turn it on.
However, you might need to perform a manual nulling of the offset when
environmental conditions change significantly or when you are measuring
very low power.
Note: The manual nulling offset is valid for the current test session only; it no
longer applies when you turn off your power meter. The next time you turn
it on, the automatic offset nulling is performed again. You will achieve
better results if you perform the manual offset nulling at a temperature
around 23
o
C after a running period of 45 minutes.
I
MPORTANT
When the application is launched after a cold start, allow the power
meter to warm up for about 20 minutes (30 minutes for IQS-1600W
modules) until the electronics stabilize before nulling offsets.
I
MPORTANT
Light must not reach the detector when performing an offset
nulling operation. Always use a protective screw cap. Do not use a
soft rubber cover