Agilent Technologies N3970A User Manual

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CCURACY

ONSIDERATIONS

All measurements

Optical connectors should be kept clean and in good condition.

Due to emitter center

uncertainty (eg 1310 +/- 20 nm), fiber

attenuation may vary with different sources.

This

uncertainty can also affect power meter calibration. This

is significant with InGaAs in the 850 nm band, and absolute
errors in the order of 1 dB are possible. This issue affects
absolute power measurements. It does not significantly affect
attenuation measurements where the meter was referenced to
the same source.

Source power may drift: when you have finished a test, go back
to the start position to check if source power is still within
acceptable limits. It is worth noting that most sources only
quote typical drift after warm up. Actual drift may of course be
significantly worse, and will be very variable between
instruments. The N3974A Dual Laser Source is unusual in
offering maximum drift specifications, without warm up.

Most available laser sources ( except the N3974A Dual Laser
Source ) are sensitive to reflections. Varying reflections can
induce source instability of around 0.3 dB. This is very difficult
to verify without a special test system, but can be a source of
errors.

Polarisation changes create disturbances in both the optical
system and measurement equipment. To reduce this, keep your
system physically stable. Keep patch leads neat, coiled and
stable.

The N3970A Optical Power Meter has an InGaAs detector.