Agilent Technologies 86038A User Manual page 275

Cleaning Connections for Accurate Measurements
Inspecting Connectors
Agilent 86038A Optical Dispersion Analyzer, Third Edition
Because fiber-optic connectors are susceptible to damage that is not
immediately obvious to the naked eye, poor measurements result without
the user being aware. Microscopic examination and return loss
measurements are the best way to ensure good measurements. Good
cleaning practices can help ensure that optimum connector performance
is maintained. With glass-to-glass interfaces, any degradation of a ferrule
or the end of the fiber, any stray particles, or finger oil can have a
significant effect on connector performance. Where many repeat
connections are required, use of a connector saver or patch cable is
recommended.
Figure 22 shows the end of a clean fiber-optic cable. The dark circle in the
center of the micrograph is the fiber's 125 µm core and cladding which
carries the light. The surrounding area is the soft nickel-silver ferrule.
Figure 23 shows a dirty fiber end from neglect or perhaps improper
cleaning. Material is smeared and ground into the end of the fiber causing
light scattering and poor reflection. Not only is the precision polish lost,
but this action can grind off the glass face and destroy the connector.
Figure 24 shows physical damage to the glass fiber end caused by either
repeated connections made without removing loose particles or using
improper cleaning tools. When severe, the damage of one connector end
can be transferred to another good connector endface that comes in
contact with the damaged one. Periodic checks of fiber ends, and replacing
connecting cables after many connections is a wise practice.
The cure for these problems is disciplined connector care as described in
the following list and in "Cleaning Connectors" on page 279.
Use the following guidelines to achieve the best possible performance
when making measurements on a fiber-optic system:
• Never use metal or sharp objects to clean a connector and never scrape the con-
nector.
• Avoid matching gel and oils.
Troubleshooting and Upgrades
275