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Fiber Optic Testing Essentials

Fiber Optic Testing Essentials

There are three levels of tesing fiber optic link testing: Verification.  Confirmation. Certification. Here’s a brief explaination of the differences. at the bottom of this page is a list of the fiber testing products we have on our site.


Both of the fiber termination kits we sell come with a Visusal Fault Locator (VFL), origianlly developed to find breaks in a fiber run. The fiber optic jacket is translucent so, by shining a low-powered laser into the fiber, a break in the fiber would shine through the jacket showing the point of the break and where to install a fiber splice.

The VFL also is a handy tool to verify that you have light continuity from point A to point B along a run of fiber. So it’s the first step in testing: verification.


So you have verified that you have continuity. But there may be loss in your fiber link due to a mis-aligned or mis-attached fiber connector, dirt or other debris on the connector tip or lodged in an SFP input. The Cleerline SSF-TKITE100 is a low cost kit that contains a multi-mode light source, a single mode light source, and an optical power meter that allows you to verify the loss in your fiber link. After calibrating the the meters, you can easily measure the attenuation (loss) of light signal, allowing confirmation that your craftsmanship is good.



The Cleerline SSF-TKITP-400 is our top-of-the-line testing kit. It not only allows verification of each of your fiber runs, it has a data recorder built into the optical power meter so you can store the attenuation measurments of each of your fiber runs. Then, when you return to the shop, you can download your tests and print out a certification report for future reference.

Click Here to Learn More About Fiber Optic Testing

What’s a Good Reading on a Fiber Test?

The bottom line is that you should not see more than .25db to .50db of loss per connector, adapter, or coupler in the fiber run. most fiber will have 1.0db – 2.0db of loss per 1000 feet. So look for readings of -1.0db to -4.0db for most fiber runs. The SFP’s and other equipment we sell will usually work fine with losses up to -5.0db to -6.0db. IF you’re seeing losses like -17db, -30db, or higher, you should inspect your work (start at the connectors) figure out what has compromised your fiber link.

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