CertiFiber measures fiber length using the "time of flight" technique where an optical pulse is launched into the fiber under test. The time that it takes for that pulse to return to its launch point is measured. This round-trip travel time is also called propagation delay.

Since we know the speed of light in a fiber, it is simple to convert this time into a length measurement. The advantages of this length measurement technique include simplicity (no launch cables, no cursors to set) and accuracy, especially with short lengths (zero dead zone).

CertiFiber also measures optical power and loss at 850 nm and 1300 nm and reference measurements are easy to perform. Simply connect the main and remote units, press the Set Reference button, and CertiFiber automatically measures and records the reference power for both fibers at both wavelengths.