Abstract: An optical waveguide has a core and a cladding. The inner surface of the cladding is roughened in a non-uniform manner to provide for extraction of diffuse light. The core is made from a light transmitting material and formed with an axis in the general direction of light flow through the optical waveguide. The cladding surrounds the core and has an index of refraction that is less than the index of refraction of the core. The cladding has an inner surface which is roughened with indentations to extract light from the core. The indentations are substantially non-parallel with respect to the axis of the core. The inner surface of the cladding may be roughened by a variety of methods including sandblasting, the formation of grooves using a rotating brush, and the vibration of particles provided within the cladding.