CHAPTER 5 OPTICAL MEASUREMENT AND TESTING (5.1 REMEMBER THE OPTICAL…
OPTICAL MEASUREMENT AND TESTING
5.1 REMEMBER THE OPTICAL MEASUREMENT
5.1.1 DEFINE FIBER OPTIC TEST PROCEDURE
1-is used to evaulate for performance of fiber optic components, cable plants, and systems.
2-as the components like
fiber, connectors, splices,
LED or laser sources, detectors,
and receivers are being developed,
testing confirms thier performance
specifications and helps understand
how they will work together.
3- Design of fiber optic cable plants and networks depend on these specifications to determine if networks will work for the planned applications
List type of
Table of List Type of FOTP
This table consist of type of test conducted by using a specific equipment
identify the safety rules when working with fiber
keep all food and beverages out of the work area.
always wear safety glasses with side shields to protect your eyes from fiber shard or splinters.
Keep track of all fiber and cable scraps and dispose of them properly. If available, work on black work mats and wear disposable lab aprons to minimize fiber particles on your clothing.
APPLY FIBER OPTIC TEST EQUIPMENT
5.2.1 Function of the following fiber optic test equipment
A.Optic Fault Locator
Cable tracer is just a flashlight
VFL user an LED or Laser source to get more light into he fiber
Userful to test a fiber for continuity
4.To check to make sure the correct fiber is conneted
With bright sources, you can find the break by looking for light shinning through the jacket.
Visible light only goes 3-5 km through fber
Fiber Optic power meters are used for measuring power levels, and when used with a compatible source for loss testing.
Power meters measures the average optical power emanating from an optical fiber
Measurement of Optical Power is of fundamental importance in optical systems.
This measurement is the asic for loss measurement as well as the power form a source or at a receiver.
Photodiode detectors are normally used in power meters for optical fiber systems.
Optical power is based on the heating power of the light and some instruments actually measure the heat when light is absorbed in a detector.
Large-surface area preferred to ensure detection of all of the light from the fiber.
Photo of Test Equipment
Photos of Testing Equipment
Optical power levels of fiber optic communication systems
C.Fiber Optic Test Source
1.In order to make measurement of optical loss or attenuation in fibers, cables, and connectors one must have a standard signal source as well as a fiber optic power meter.
The source must be chosen for compatibility with the type of fiber in use and the wavelength desired for performing the test.
Most sources are either LEDs or lasers of the types commonly used as transmitters in actual fiber systems,making them representative of actual applications and enhancing he usefulness of the testing.
4.Typical wavelengths of sources are 665nm (plastic fiber),850 nm(short wavelength multimode glass fiber), and 1300 and 1550 nm(long wavelength multimode and singlemode fiber)
5.LEDs are typically used for testing multimode fiber and lasers are used for singlemode fiber,except for the testing of short single mode jumper cables
6.The broad spectral output of an LED has higher attenuation in single mode fiber than a laser,causing significant errors on cables longer that about 5 kilometers.
7.The source wavelength can be a critical issue in making accurate loss measurements on longer cable runs,since attenuation in single mode fiber than a laser,causing significant errors on cables longer than about 5 kilometers.
D. Laser Beam Analyzer
Used to measure the attributes of a laser beam.
Includes devices such as profiler systems that evaluate data from beam images to provide information
Offer a range of information as well as a greater amount of control over many laser applications by delivering detailed inforation about a tested laser.
E. Optical Fiber Identifier
Bends the fiber to detect the light
Can be used on live fiber without interrupting service.
Can detect a special moculated tone sent down a fiber
F. Optical Spectrume Analyzer
Used for measurement of optical power as a function of wavelength.
Include testing laser and LED light sources for spectral purity and power distribution as well as testing transmission characteristic of optical devices.
G. Optical Time Domain Reflector Meter (OTDR)
OTDR- Optical Time Domain Reflectometer
Used to verify the quality of the installation and troubleshoot problems.
Produces grahpic display of fiber status.
photos of test equipment C,D,E,F,G
5.3 APPLY FIBER OPTIC MEASUREMENT AND TEST PROCEDURE
5.3.2 SHOW THE FOLLOWING FIBER OPTIC TEST
5.3.1 EXPOSE OPTICAL POWER MEASUREMENT
The most basic fiber optic measurement. The measurement is the basis for loss measurements as well as the power from a source.
Measuring the power of a transmitter is done by attaching a test cable to the source and measuring the power at the other end.
Test source (#1) appropriate for the fiber being tested ( multimode: 850 and/or 1300nm LED, singlemode,1310 and/or 1550 nn laser)
Optical power meter (#2) calibrated at the same wavelengths as the source output.
Launch and receive reference cables (#3) of the same fiber type and size as the cable plant have connectors compatible to those on the cable plant . They should be tested per FOA-2 to ensure they are in good condition .
Mating adapters compatible to connectors (#4)
HOW TO TEST FIBER CABLE PATCH
A. CONTINUITY TESTING
The most fundamental fiber optic test
the simplest visual test of a fiber optic cable link
Trace the fiber from end to end through any interconnections to ensure that the path is properly installed
To test for continuity, attach the fiber to the fiber optic tracer or VFL . If light is visible at the far end, the fiber is not damaged
Attach your fiber optic tracer to the connector of the cable being tested
Send a light signal into the cable . Watch the other end of the cable,
Using the fiber microscope , inspectthe connectors' fiber ends to ensure that they are smoothly polished
NOTE & PHOTOS
B. INSERTION LOSS TESTING
The primary performance parameter of most fiber components
including fiber attenuation, connector loss and splice loss
Used light source and power meter
Have 2 method which is Patch cord test and Installed cable plant test.
0dB reference test
Turn on equipment and allow time to warm-up.
Attach launch cable to source for the duration of the test.
Clean all the connectors and mating adapters.
Set "0dB" reference using method shown below . Meter may be set to read "0dB".
Attached source/ref cable toand meter/ref cable to the cable plant under test and make loss measurement.
(HOW TO TEST THE INSERTION LOSS OF FIBER OPTIC CABLE)
Used to find bad splices in connectors and splices in a single mode cable plant.
The OTDR can also be used to find bad connectors or splices in a high loss cable plant.
Turn on OTDR
Set parameter on OTDR - range, wavelength, no. averages and etc
Clean all connector and mating adapter
Attach ref. cable to OTDR & to cable plant under test
Attach optional receive cable to far end of cable under test .
Acquire trace and analyze.
Types of OTDR
Complex, powerful, expensive
Simplified, shows distance to a fault
Examples of OTDR Display
OTDR TESTING OF FIBER OPTIC CABLE PLANTS
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