What is fibre optic and application on aircraft Other presentation canbe found at http://part66.blogspot.com

1. 5.10 FIBRE OPTIC

2. WHAT IS FIBRE OPTIC
• Flexible, transparent fiber made of a
pure glass (silica).
• It functions as light pipe, to transmit light
between the two ends of the fiber.
• It is an opto-electronic component (sensitive
to infrared, ultra violet that convert to
electrical signal)
• Use in medical, telecomunication and aviation
field.

4. ADVANTAGE
• Larger data carry – up to 3300MHz
• Low loss of signal
• Smaller diameter, lighter-weight cables
• Cross talk negligible – no effect to other cable(signal)
• Immunity to electromagnet interference
• Greater security – immune to wiretapping
• Greater safety – free from spark
• Low cost – material sand
• Long life span – double from conventional cable
• Greater reliability – resistance to corrotion and temp

5. DISADVANTAGE
• Installation cost high
• Fragile than wire
• Required special equipment for testing
• Required special skill and equipment to
splicing it

6. OPERATION
Receiver
Transmitter
Optical Coupling (Light
(Light Source)
Detector)
Transmitters: Light-emitting diodes (LED's) and Injected Lasers
Convert electrical signal to optical signal.
To send the optical signal over an optical fibre
Receivers: Photodiodes and Phototransistors.
To convert optical signal back to an electrical signal
Optical Coupling: Opto-isolators and Optical fibres

7. LIGHT
• Light wave more shorter than electromagnetic
wave (radio/radar).
• Velocity 3x108m/s, change depend on
medium.
• Propogation of light :
– Reflection
– Refraction
– Dispersion

8. REFLECTION
The light reflect back with same angle if surface is smooth
The light diffuse reflection if surface is irregular/rough

9. REFRACTION
Bending of light when passes through other medium
Air 1 00
Diamond 2 42
Ethyl Alcohol 1 36
Fused Quartz 1 46
Glass 1 55 - 1 9
Optical Fibre 15
Water 1 33
Index of refraction

10. DISPERSION
• Seperation of white light to the various color.
• Different color have a different
wavelength, different velocity and different
index of refraction.

11. CABLE STRUCTURE
High strength and tension resistance
Typically cable made in length of 1-3 km without splices.
Core - glass, polystyrene, polymethylmethacrylic.
Cladding - glass, silicon or Teflon.

12. TYPE OF CABLE
Wide graded index multimode
optical fibre
Single mode step index optical fibre
Large-core plastic-clad silica optical fibre

13. HOW IT WORK
Single Mode
Multimode

14. ACCEPTANCE ZONE

15. NUMERICAL APERTURE
• Its a colecting power of an optical fibre
• Its value from 0 to 1,
• Larger NA mean the greater amount light
accepted by fibre.
• NA is function of refractive index of the fibre.
• Define as NA = sin A

16. PULSE SPREADING
• The amount of acceptance signal have a limited
frequency due to the pulse(light) is being dispers inside
the cable.
• Dispersion tend to slow down the speed of the light.
• Two form of dispersion :
– Chromatic disepersion : Different speed due to
color
– Modal dispersion : Zigzag ray reach the end of cable
later than straight ray
• Total Dispersion = Chromatic + Modal

17. CONSEQUENCES
• The fastest the pulse travel, the worse
spreading its get.
• Need to limit the frequency of the signal travel

18. ATTENUATION
• Reduction of signal strength due to :
1. Atomic Absorption :
Atom of material absorb some of the light
2. Scatering by Flaw and Impurities :
Depend on size of scatering particle
inside the cable
3. Reflection by Splices and Conector :
Some light are reflected back even for perfect
splice or conector.

19. JOINING OPTICAL FIBRE
– Fusion Splicing
• Allign manually using micromanipulators and
microscope system.
• End of fibre are melt together using electric arc.
• Near perfect splice can lose as low 0.2dB
– Mechanical Splicing
• Two fibre end held together in splice equipment which
automatically allign the two fibre.
• Clamp it and expose to ultra-violet light to cures the
cement

20. SPLICING ERROR
• The end of fibre must be precisely line each
other to enable light pass from one fibre to
another.
• Typicall allignment error :

21. FIBRE OPTIC CONNECTOR
2 Type Conector A and B, both have :
- Allignment key and grooves
- Guide pin and cavities
- Color bands
- Three start threads
A type :
- 3 or 5 optical fibre
- Multichannel
- very low loss
B type :
- For LRU
- Multichannel
- For more frequent
conection and disconection

22. FIBRE OPTIC IN AIRCRAFT
• Advantage on aircraft :
– Can carry more data
– Less weight
– Immune to electromagnetic radiation
• Purpose:
– Network system: (OLAN),(AVLAN),(CABLAN)

23. AIRCRAFT NETWORK SYSTEM
• Flight attendent
– Keep sales data
– Enable and disable passenger functions
– Control the distribution of video entertainment
– Select boarding music
• Passenger
– Video and menu screen
– Games
– Inflight sales catalogue
– Instruction for telephone call
– Ground to airplane telephone pages
– Special video channel selection

24. ONBOARD LAN

25. CABIN LAN