A method of manufacturing light panels using a plate- or sheet-like carrier having optical fibers therein ending according to a certain pattern. The optical fibers (4) taken from a fiber supply are positioned in accordance with said pattern by means of a pattern plate (5). The optical fibers (4) lying on the side of the pattern plate (5) remote from the fiber supply (21) are introduced into a mould (1) in order to have them surrounded by a layer of a castable or injectable and quickly setting material (3) for forming the carrier. The fibers (4) are held in the desired position at the upper surface of the carrier to be formed within the mould (1) and the fiber ends are deflected in a group out of the mould (1). The fibers (4) exiting from the carrier are then cut near the surface of the carrier within the mould (1) directed to the positioning means (5) after the material has set to an extent that the optical fibers (4) exiting out of the carrier surface directed to the positioning means (5) maintain their orientation substantially normal to said carrier surface. The invention also includes an apparatus to carry out this method.