Abstract: The invention pertains to a method of manufacturing a layer of a cholesterically ordered polymer material, in which the material is oriented in such a way that the axis of the molecular helix of the cholesterically ordered material extends transversely to the layer, wherein the method comprises the steps: a) providing a layer comprising a cholesterically ordered mixture of a low-molecular weight polymerizable material and a high-molecular weight material, which high-molecular weight material comprises a quantity of a convertible group, which in its non-converted and in its converted state determines the pitch or the material to a different extent, the conversion of said high-molecular weight material being inducible by radiation, and the layer absorbs said radiation; b) irradiating the layer to convert at least a part of the convertible groups it the irradiated parts of the layer; c) letting at least the low-molecular weight material reorient to form the required helical structure; d) at least partially polym