The Optical Wavelength Labs VOLT-1 Visual Optical Length Tester functions as a Visual Fault Locator (VFL). However, the VOLT has the added benefit of doubling as a looping length tester. Many cabling warranties and bids are requiring meter based length tests to prove length of links.

The VOLT uses two fibers and patch cables to establish a length test accurate to +/- 7 feet. The VOLT's VFL functions up to 5 kilometers (3.1 miles). Loop length testing functions up to 1.5 kilometers.

The VOLT uses a "round-robin" method of measuring fiber length. This is accomplished by looping back two fibers at one end of the fiber run. The round trip time that the light takes to travel through the fibers is converted to length in kilometers, then divided by two to show the length of the fiber cable. There is no need to measure the length of all the fibers; the length measurement can be applied to all fibers in the cable.

As far as VFL function, VOLT holds its own against the best in the industry. As with any quality VFL, the VOLT is a precision coupled laser diode: a multi-million dollar semiconductor machine is used in the manufacture of a special precision coupled micro-sized ball lens. This precision coupling allows the VOLT to couple maximum red laser light into the tiny connector orifice of fiber optic links up to 5 kilometers (3.1 miles) of distance.