FBP PRoBE & HP3-60-P4 InsPEct and tEst systEm
9
Fiber optic connectors
cHaPter 2
Contamination
Dirt is everywhere,
and a typical dust particle (2–15 μm in diameter) can significantly
affect signal performance and cause permanent damage to the fiber end face. Most field
test failures can be attributed to dirty connectors, and most of them are not inspected
until the problem is detected, AFTER permanent damage has already occurred.
When dirt particles get on the core surface the light becomes blocked, creating
unacceptable insertion loss and back-reflection. Furthermore, those particles can
permanently damage the glass interface, digging into the glass and leaving pits that
create further back-reflection if mated. Also, large particles of dirt on the cladding layer
and/or the ferrule can introduce a barrier that prevents physical contact and creates an
air gap between the fibers. To further complicate matters, loose particles have a tendency
to migrate.
Scratches are typically created during polishing, cleaning or mishandling fiber connectors.
Scratches that touch the core are problematic because they create back reflection.
CleAn FiBeR
DiRt / ContAMinAtion
PitS / ChiPS
SCRAtCh
CLEAN CONNECTION
CORE
CLADDING
Light Transmitted
CleAn ConneCtion
Light Transmitted
INSERTION LOSS
DIRTY CONNECTION
CORE CLADDING
BACK REFLECTION
DiRty ConneCtion
