Which of the following fiber optic testing devices uses light pulses to estimate a fiber cable’s length and measure attenuation?

  • Flashlight
  • Visual Fault Locator (VFL)
  • Optical Time Domain Reflectometer (OTDR) (Correct)
  • Time Domain Reflectometer (TDR)

A variety of devices can be used to test fiber optic cables, including:

  • Light sources: Flashlight, LED, or laser used to check the continuity and polarity of a cable
  • Visual Fault Locators (VFL): A very powerful light source, such as a Class 2 laser, used to check the continuity and polarity of a fiber
  • Fiber optical power meters: Devices that measure absolute light power in dBm
  • Optical Time Domain Reflectometers (OTDR): which sends a series of light pulses into a fiber and extracts, from the same end, light that is scattered and reflected back. The returning light is measured as a function of time, allowing the OTDR to determine optical return loss and locate events in the fiber (breaks, bends, connectors, splices). The OTDR can then determine the distance to each event from the end of the fiber to which it is connected.