Abstract: A fiber optic flaw detection system and method for detecting flaws in an optical fiber and for identifying the type of flaw as a lump, neckdown or other is provided. Three collimated beams of light rays illuminate the optical fiber substantially orthogonal to a longitudinal axis thereof. Each beam is scattered by a flaw-free optical fiber into an in-plane scattered light segment which is scattered in a radial plane substantially perpendicular to the longitudinal axis of the optical fiber. A flaw in the optical fiber scatters the light rays into an out-of-plane scattered light segment which is outside of the radial plane. A pair of photocells detects the out-of-plane scattered light segment for each of the beams. One photocell detects the portion of the out-of-plane light segment scattered opposite the direction of travel of the optical fiber. The other photocell detects the portion of the out-of-plane scattered light segment scattered toward the direction of travel of the optical fiber.

Abstract: A system for detecting flaws in an optical fiber includes a light source which generates a beam of collimated light rays to illuminate the optical fiber substantially orthogonal to a longitudinal axis thereof. The beam is scattered by a flaw-free optical fiber into an in-plane scattered segment which is scattered in a radial plane substantially perpendicular to the longitudinal axis of the optical fiber. A flaw in the optical fiber scatters the light rays into an out-of-plane scattered segment which are scattered outside of the radial plane. A light attenuator removes the in-plane scattered segment of the beam and a light detector detects the remaining out-of-plane scattered segment. An electrical circuit monitors the light detected by the light detector and determines whether a flaw is present in the optical fiber. To compensate for fluctuations in the power output of the light source, a linear light detector replaces the light attenuator to detect the in-plane scattered segment of the beam.