FLAT CONCAVE MICRO LENS FOR SECURITY AS AN INTEGRATED FOCUSING ELEMENT

摘要

An optical security element for currency or other products. The security element includes a film or substrate and an image element provided on an exterior surface of this substrate. The substrate is formed of a transparent material. A concave focusing element is formed upon the opposite side or surface of the substrate, with a focusing substrate with a first side abutting the substrate and a second side facing away from the substrate. Concave lenses are provided in this second side of the concave focusing element. The optical security element includes an outer layer formed of a transparent material that is applied so as to cover the concave focusing element and to “fill in” the concave lenses. The materials, e.g., a polyester or polypropylene, are chosen for the optical security element such that the concave focusing element has an index of refraction that is lower than that of the outer layer.

主权项

1. An apparatus for use as an optical security element, comprising:
a planar substrate with a first side and a second side opposite the first side, wherein the planar substrate comprises a transparent material with a first index of refraction; an image element provided on the first side of the planar substrate; a concave focusing element with a focusing substrate with a first side abutting the second side of the planar substrate and with a second side comprising a plurality of concave lenses, wherein the concave focusing element comprises a transparent material with a second index of refraction; and an outer layer comprising fill portions filling the concave lenses and further comprising a covering film over the fill portions, wherein the outer layer comprises a transparent material with a third index of refraction, wherein light striking a planar exterior surface of the covering film is focused through the outer layer, the concave lenses, and the planar substrate onto the image element.