A light guide device for illumination, lighting and display purposes that exhibits an output light having a predetermined, and preferably uniform, angular luminance profile is described. The device comprises a light guide (13) suitable for guiding light coupled thereto and a plurality of extraction features (10, 11) located on one or more surfaces of the light guide. The plurality of extraction features comprises an interleaved pattern of first (11) and second extraction features the arrangement of which provides a means for defining the predetermined angular and spatial luminance profiles for the output light. The device allows for a uniform angular luminance profile to be produced that is maintained even when the light guide is curved or bent.