Fiber inspection

Test purpose

Optical fiber inspection The main purpose is to ensure the quality of the system connection, reduce failure factors and find out the failure point of the optical fiber when it fails.

Detection method

It is mainly divided into manual simple measurement and precision instrument measurement.

1. Test index of optical fiber system

The test of optical fiber line only requires one test result──Attenuation:

·Attenuation <1.5dB, (1300nm)

·Attenuation <2.5dB, (850nm)

2, test items

·Connectivity test

·Full-process attenuation and SC connector attenuation test

3. Specific test methods

·Multimode fiber horizontal subsystem requires the parameters of the test end;

Along one direction Test the attenuation value at the wavelength of 850nm or 1300nm

·The parameters to be tested for the multimode fiber backbone system;

Test the attenuation value at the wavelength of 850nm and 1300nm along one direction



Because the difference between the values ​​of the test in different directions is generally very small, and most of it is caused by the accuracy of the test instrument or the test method, a single direction test is sufficient. The standard limit for the distance of the horizontal subsystem is very short (90 meters), so the difference in the test values ​​at different wavelengths is not big, so single-wavelength testing is sufficient).

In order to meet the requirements of TIA/EIA528-14A on "multi-mode fiber installation and optical power loss test", the fiber test adopts FTK200 tester for testing. For the fiber system, the test index can be determined by the following formula Calculated:

The entire link loss value = the loss value of the optical cable + the loss of the coupler fiber connector

Note: The coupling connection depends on the type of the connecting plug. The related test indicators are as follows:

50um multimode fiber system

multimode Optical fiber


Signal wavelength

Maximum attenuation dB/km

Maximum capacity MHz/km


Maximum attenuation dB




Multimode LC/LC connector p>





More Mode LC/LC connector


50um multimode fiber loss formula :

Loss of optical fiber cable = length of optical fiber cable (km)×(3.50dB/km at 850nm or 1.50dB/km at 1300nm)

Attenuation of coupler Consumption (ST or SC connector)=(number of connectors×0.39dB)+0.42dB

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