Fluke DSP-FTA420 User Manual page 57

Glossary
Margin
The difference between the measured power loss and the maximum loss
allowed for the link.
Microbending losses
Light losses due to microscopic imperfections in a fiber.
Multimode fiber
Fiber with a relatively large core (50 µm or more) that offers many paths, or
modes, for propagation of light.
n
See index of refraction.
Numerical aperture
A parameter that represents a fiber's ability to gather light. The numerical
aperture is the sine of the maximum angle at which a fiber accepts light. A fiber
with a higher numerical aperture gathers more light.
Optical power
Optical power measured at a source or the end of a fiber and expressed in
microwatts (µW) or in decibels with reference to one milliwatt (dBm).
Propagation delay
The time taken for a light pulse to travel the length of a fiber. Propagation
delay is a function of a the length of a fiber and its index of refraction.
Receive cable
A fiber patch cord used to couple a fiber to an optical receiver.
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