Diffractive device having embedded light source mechanism

An optical device comprising an at least substantially transparent substrate having a first side comprising a source layer having an arrangement of source elements and a second side comprising an Optically Variable Device (OVD) layer having a corresponding arrangement of diffractive elements, wherein each source element is configured to, upon illumination of the first side by an external light source, provide an embedded light source being a light source which provides light for an associated diffraction element substantially independent of the external light source, and wherein the diffractive elements are configured for producing an optical effect observable when the diffractive elements are viewed by a viewer, such as the naked eye, upon illumination by the source elements, wherein each diffraction element is configured in accordance with the shape of its associated source element.