Abstract: A character generator for use in photocomposing comprises a fibre optic faceplate (23) of which the front face is polished and bevelled at its leading and trailing edges. On the rear surface of the faceplate is a mask which has an array of apertures each aperture encompassing a multiplicity of the fibres. Photoemissive diodes or other illuminators (25) are approximately aligned with the holes in the mask and are disposed for connection to terminals 22 on a printed circuit mounting. The generator is intended for use in the constitution of characters by selective illumination of elementary areas. The faceplate is intended to be in close proximity to a film or other radiation sensitive recording medium which is moved relative to the faceplate to build up lines of composition.