Keysight Technologies 86120B, User Manual

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26
Getting Started
Cleaning Connections for Accurate Measurements
ver can be pushed onto the glass surface. Scratches, fiber movement, or glass con-
tamination will cause loss of signal and increased reflections, resulting in poor
return loss.
Inspecting Connectors
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 connec-
tor 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 1-4 shows the end of a clean fiber-optic cable. The dark circle in the center of
the micrograph is the fiber’s 125
μ
m core and cladding which carries the light. The
surrounding area is the soft nickel-silver ferrule. Figure 1-5 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 1-6 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 30 .