Driven by constant current, the handheld VFL uses a 650nm laser as the luminescent device to emit red light.

After the device is connected to the optical interface, the red light goes into the optical fiber to be tested (singlemode or multimode) to realize the function of optical fault detection.

The handheld VFL is a useful supplement to OTDR and an indispensable auxiliary tool of optical construction, fiber-optic network maintenance, optical device production and research and other fields.