Basic Features of Fibre-Optic Installations

Question 1

What are the four main components of a fibre-optic system and briefly discuss their use

Answer 1

Transmitter: converts an electrical signal into a light signal
Receiver: converts a light signal into an electrical signal
Fibre-optic cable: carries the light signal between the transmitter and receiver
Optical connector: a device used to terminate the fibre-optic cable

Question 2

What type of light is used in most fibre-optic systems?

Answer 2

Infrared light

Question 3

What are the three main parts of a basic fibre?

Answer 3

• Core
• Cladding
• Buffer

Question 4

What are the two common materials used for optical fibre construction?

Answer 4

Glass and plastic

Question 5

A particle of light is called a _____________

Answer 5

photon

Question 6

As the frequency of a waveform increases, does its wavelength increase or decrease?

Answer 6

It decreases

Question 7

The bending of light as it travels from one material to another is called __________

Answer 7

refraction

Question 8

What is meant by the term attenuation?

Answer 8

A power loss that occurs as a signal travels over a distance

Question 9

What are four advantages of fibre-optic systems?

Answer 9

• Wide bandwidth
• Low loss
• Electromagnetic immunity
• Light weight
• Small size
• Safety
• Electrical isolation

Question 10

What important safety precaution must be observed when working with fibre-optic systems?

Answer 10

Never look directly into a light source or into the end of a fibre energized by a source, because the infrared light can cause permanent eye damage

Question 11

Of the three fundamental layers of an optical fibre, which two layers cannot be separated?

Answer 11

The core and the cladding

Question 12

What does 50/125 for an optical fibre refer to?

Answer 12

50 refers to the core diameter and 125 refers to the diameter of the cladding

Question 13

For fibre-optic cables, what is the fundamental difference between a loose-buffer and a tight-buffer?

Answer 13

In the loose-buffer, the fibre is contained within a tube that has a diameter several times that of the buffer; the tight-buffer is directly bonded to the fibre

Question 14

What are the three categories of fibre-optic cables?

Answer 14

• Non-conductive cables
• Conductive cables
• Hybrid cables

Question 15

List three hazards of working with optical fibre cables

Answer 15

Loose fibre: glass fibres can penetrate skin and eyes and can be transported through the body by blood circulation
Solvents and cleaners: they are often inflammable or noxious
Laser operation: the invisible ultraviolet light can cause eye damage

Question 16

What are seven basic steps for fibre-optic cable installations?

Answer 16

• Survey the cable run and choose the best possible path
• Always test a cable before and after you pull it
• Treat the cable with care
• Do not exceed the minimum bend radius for the cable
• Always leave extra cable at the beginning and end of the cable run, as well as at junction boxes and at the top of risers
• Keep records of the installation

Question 17

What are the two basic methods of terminating optical fibres?

Answer 17

Using connectors and splices

Question 18

What is the name given to the process of applying an electric arc to fuse the ends of two optical fibres?

Answer 18

Fusion splice

Question 19

What type of cleaning agent is commonly used for optical fibres together?

Answer 19

Isopropyl alcohol (rubbing alcohol)

Question 20

What must be done to the fibre after you have glued it into a connector with epoxy?

Answer 20

Grind and polish it

Question 21

What is the key element in a proper fibre-optic interconnection?

Answer 21

Proper alignment of the interconnected fibre cores