17-08-2012, 11:20 AM
Fiber optics
fiber optic.pptx (Size: 249.89 KB / Downloads: 28)
Introduction (Cont…)
Core – thin glass center of the fiber where light travels.
Cladding – outer optical material surrounding the core
Buffer Coating – plastic
coating that protects
the fiber.
Fiber Composition - (continued)
Fibers are specified by the outer diameters of the core and cladding.
A 50/150 fiber means that the core is 50 m while the outside dimension of both the core plus cladding together is 150 m.
The core and cladding are surrounded by the sheath.
Advantages of Optical Fibre
Thinner
Less Expensive
Higher Carrying Capacity
Less Signal Degradation& Digital Signals
Light Signals
Non-Flammable
Light Weight
Areas of Application
Telecommunications
Local Area Networks
Cable TV
CCTV
Optical Fiber Sensors
Mode of Propagation
Mode simply means path from which light is propagated.
If there is only one path for light to take down the cable, it is called single mode.
If there is more than one path, it is called multi-mode.
Type of Fibers
Optical fibers come in two types:
Single-mode fibers – used to transmit one signal per fiber (used in telephone and cable TV). They have small cores(9 microns in diameter) and transmit infra-red light from laser.
Multi-mode fibers – used to transmit many signals per fiber (used in computer networks). They have larger cores(62.5 microns in diameter) and transmit infra-red light from LED.
How Does Optical Fibre Transmit Light?
Total Internal Reflection.
Fibre Optics Relay Systems has
-Transmitter
-Optical Fibre
-Optical Regenerator
-Optical Receiver
How are Optical Fibre’s made?
Three Steps are Involved
-Making a Preform Glass Cylinder
-Drawing the Fibre’s from the preform
-Testing the Fibre
Testing of Optical Fiber
Tensile Strength
Refractive Index Profile
Fiber Geometry
Information Carrying Capacity
Operating temperature/humidity range
Ability to conduct light under water
Attenuation
Optical Fiber Laying
Mechanical Linking
Includes coupling of two connectors end to end
Optical distribution frames allow cross connect fibers from by means of connection leads and optical connectors
Soldering:
This operation is done with automatic soldering machine that ensures:
Alignment of fiber’s core along the 3 axis
Visual display in real-time of the fibers soldering
Traction test after soldering (50 g to 500 g)
Optical Fiber Laying (Cont…)
Blowing
Used in laying optical cables in roadways.
Cables can be blown in a tube high density Poly Ethylene
Optical fiber is then blown in the tube using an air compressor which can propel it up to 2 kilometers away.
Fiber Optics Test Kit
Features
Includes Smart FO Power Meter and Mini LED or laser source
FO test lite software for data logging
Tests all networks and cable plants
New versions of Gigabit Ethernet
Low Cost
Applications
Measure optical power or loss
Trouble shooting networks
Protecting Fibers
Tougher than copper wires
Designed in three concentric layers
Core – Cladding – Buffer
Two basic buffer types
Tight buffer
Loose tubes