SAFETY SUBSTRATES, SAFETY DEVICES AND THEIR MANUFACTURING PROCESSES

Abstract

The invention relates to a safety substrate comprising: a polymer substrate having first and second surfaces; an array of focusing elements; an optical adjustment layer; and at least one first masking layer. The focusing element array is in the form of a surface relief across a first region of the polymer substrate, the surface relief being defined within the surface of a transparent base layer, the transparent base layer comprising either the polymer substrate or a layer. The optical adjustment layer is disposed on the transparent base layer across a second region of the polymer substrate, which second region comprises at least the first region. The optical adjustment layer has a first surface in contact with the surface relief of the transparent base layer and a second opposing surface having a profile that is not functional for focusing visible light.The optical adjustment layer comprises a first transparent material extending through a first subregion of the focusing element array. This first subregion includes all or part of the first region. The first transparent material has a different refractive index than the transparent base layer, thereby making the focusing element(s) in the first subregion of the matrix functional focusing elements. The safety substrate further comprises at least one first masking layer, comprising a reflective and / or non-transparent material, disposed on the optical adjustment layer through a third region of the polymer substrate. This third region defines at least one gap in the first masking layer(s), the space of which includes at least part of the first subregion, such that functional focusing elements of the array are revealed through at least one gap.