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Topic 4 optical measurement (FIBER OPTIC TEST (Insertion Loss Testing …
Topic 4
optical measurement
4.1 optical measurement
Fiber Optic Test Procedure (FOTP)
✳️is a detialed, step by step sequence of action or the document them testing fiber optic systems and component.
✳️ most test procedures for fiber optic component have been standardized by national and international bodies,including telecommunication industries association (TIA) in the US and ISO/IEC internationally
Safety rules when working with fiber
✅keep all food and beverage out of the food work area . If faiber particles are ingested they can cause internal hemorrhaging
✅always wear safety glasses with side shields to protect your eyes from fibers shards and splinters
✅keep track of all fiber and cable scrap and dispose of them properly .
:green_cross: Never look directly into the end of fiber cables.
:green_cross:Contact lens wearers must not handle their
lenses.
:green_cross: Do not touch your eyes.
:check: Only work in well-ventilated areas.
:check: Keep all combustible materials safely away.
:check: Dispose of all
scraps properly.
:check: Thoroughly clean your work area when
you are done.
4.2 Fiber optic test equipment
Optical power -fiber optic power meter
Attenuation or loss of fiber - FO power meter
Source wavelenght - FO spectrum analyzer
Backscatter for lost - Optical Time Dominant Reflectometer OTDR.
Fault location - OTDR.
Bandwith/dispersion - Dedicated Bandwith Testers.
Reflectance - OTDR, ( Optical Continues Wave Reflectormeter) OCWR.
Fiber Geometry - Various mechanical and optical inspection tools.
Type Of Basic Fiber Optic Test Equipment.
a)
Fiber Optic Fault Locator.
:star: An essential tools that quickly and easily located problem area in fiber optic cable.
:star: By pinpointing the exact location of fiber damage we can diagnose troubleshoot and fix the problem efficiently.
b)
Fiber Optic Power Meter
:star: A benchtop/portable instrument comprises of receiver module for power level detection. It is use together with a light source.
:star: Fiber optic power meter measure the average optical power out of an optical fiber.
c)
Fiber Optic Test Source
:star: It is handheld/portable/benchtop instrument comprises of light source/sources
d)
Laser Beam Analyzer
:star: This device capture display and record the spatial intensity profile of laser beam.
:star: Many components such as add/drop multiplexers need to be aligned precisely into lenses, directed to other fiber, focus again and coupled back into fibers.
e)
Optical Fiber Identifier
:star: Fiber identifier are handheld fiber optic test instrument for detecting optical signal transmitted through a fiber without disrupting live traffic.
:star: They are use in installation, maintenance, rerouting or restoration to isolate a specific fiber.
f)
Optical Spectrum Analyzer
:star: An Optical Spectrum Analyzer (OSA) is a precision instrument designed to measure and display the distribution of power and optical source over specified wavelength span.
g)
Optical Time Dominant Reflectometer (OTDR)
:star: OTDR is useful for testing integrity of fiber optic cable. It can verify splice loss, measure lenght and find faults.
:star: OTDR are most effective when testing a long cable. (more than approximately 250 meter or 800 feet).
4.3 Fiber Optic Measurements Test Procedure
Equipment needed to perform this test :
Fiber Optic Power Meter.
Optical power meter.
Reference cable.
Cleaning supplies.
Test Procedure :
Turn on meter and allow time to warm up.
Set meter wavelenght of source & "dBm"
Clean all connector and mating adapter.
Attach reference cables to source if testing source power/disconnected cable from receiver.
Attach power meter to end of cable & read measure power.
FIBER OPTIC TEST
Continuity Testing
:pen: Tracing core.
:pen: Finding fractures/ bad splices with leaking light.
:pen: Locating core at the intermediate points by bending the fibers.
Insertion Loss Testing
Loss per unit lenght / Attenuation coefficient.
Including fiber attenuation connector loss & splice loss.
i.
0 dB reference test
:pencil2: One cable reference - same on the cable plant.
:pencil2: Two cable reference - not same
:pencil2: Three cable reference - if connector are plug/jack styles & reference cable are both ended.
ii.
Patchcord test (single-ended)
Measure the loss of
:pencil2: Fiber optic cable.
:pencil2: single mode/multimode.
:pencil2:Connector
iii.
Cable Plant Test (Double-ended)
Measure loss of
:pencil2: Installed fiber optic cable plant.
:pencil2: Singlemode/Multimode.
:pencil2: All fiber, splice and connector.
Optical Time Domain Reflectormeter Testing (OTDR)
:red_flag: Creates a snapshot of a fiber optic cable.
:red_flag: Verify the quality of the installation and troubleshoot problem.
:red_flag: Interpretation of the data required called the trace/signature.
Option For Testing
Use of the receive reference cable.
-Testing at more than one wavelenght.
4.4 Apply Measurement Procedure For Fiber Optic Testing
Fiber optic testing
:red_flag: testing : evaluate the performance of fiber optic compenents ,cable plants & systems.
:red_flag: testing confirm their perfomance specification & helps understand how they will work together.
:black_flag: Have the right tools & test equiment for the job
:black_flag: Know how to use your test equipment
:black_flag: Know the cabling network you're testing
