Agilent Technologies 86038A User Manual page 277

Cleaning Connections for Accurate Measurements
Agilent 86038A Optical Dispersion Analyzer, Third Edition
While these often work well on first insertion, they are great dirt magnets.
The oil or gel grabs and holds grit that is then ground into the end of the
fiber. Also, some early gels were designed for use with the FC, non-
contacting connectors, using small glass spheres. When used with
contacting connectors, these glass balls can scratch and pit the fiber. If an
index matching gel or oil must be used, apply it to a freshly cleaned
connector, make the measurement, and then immediately clean it off.
Never use a gel for longer-term connections and never use it to improve a
damaged connector. The gel can mask the extent of damage and continued
use of a damaged fiber can transfer damage to the instrument.
• When inserting a fiber-optic cable into a connector, gently insert it in as straight
a line as possible. Tipping and inserting at an angle can scrape material off the
inside of the connector or even break the inside sleeve of connectors made with
ceramic material.
• When inserting a fiber-optic connector into a connector, make sure that the fib-
er end does not touch the outside of the mating connector or adapter.
• Avoid over tightening connections.
Unlike common electrical connections, tighter is not better. The purpose of
the connector is to bring two fiber ends together. Once they touch,
tightening only causes a greater force to be applied to the delicate fibers.
With connectors that have a convex fiber end, the end can be pushed off-
axis resulting in misalignment and excessive return loss. Many
measurements are actually improved by backing off the connector
pressure. Also, if a piece of grit does happen to get by the cleaning
procedure, the tighter connection is more likely to damage the glass.
Tighten the connectors just until the two fibers touch.
• Keep connectors covered when not in use.
• Use fusion splices on the more permanent critical nodes. Choose the best con-
nector possible. Replace connecting cables regularly. Frequently measure the
return loss of the connector to check for degradation, and clean every connec-
tor, every time.
All connectors should be treated like the high-quality lens of a good
camera. The weak link in instrument and system reliability is often the
inappropriate use and care of the connector. Because current connectors
are so easy to use, there tends to be reduced vigilance in connector care
and cleaning. It takes only one missed cleaning for a piece of grit to
permanently damage the glass and ruin the connector.
Troubleshooting and Upgrades
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