Optically variable device with diffraction-based micro-optics, method of creating the same, and article employing the same
A security device includes an optically variable device (OVD) having diffraction-based micro-optics including at least one moiré magnified visual representation of a micro-object. A diffractive structure provides micro-objects with unique optical effects when the OVD is viewed through the micro-object structure from a predetermined relative observation point. In addition to magnifying the micro-objects, the diffractive structure can impart optical effects such as change in observed color, enhanced contrast, animation of the observed visual representation, and change in size or shape of the observed visual representation. The micro-objects and the diffractive structure can be disposed on the same or different portions of a substrate. A method of making OVDs, and an article employing such OVDs are also disclosed.
1. A method of creating a security device having at least one optically variable device with diffraction-based micro-optics, the method comprising:
originating a master of said optically variable device, said master including a diffractive structure;
generating an object layer including at least one micro-object;
replicating said master; and
converting said master into final form to provide said optically variable device;
wherein said converting step includes combining said object layer and said diffractive structure on a first portion and a second portion, respectively, of a substrate;
wherein at least one magnified visual representation of said micro-object is observed when said optically variable device is observed from a predetermined relative observation point and said micro-object is disposed between said diffractive structure and said observation point; and
wherein the diffractive structure is structured to provide an optical effect of magnifying the at least one micro-object to create the at least one magnified visual representation: and
wherein the substrate is disposed between the diffractive structure and the at least one micro-object.
2. The method of claim 1 wherein said step of originating said master further comprises:
designing said diffractive structure, and
interfacing with equipment structured to make said diffractive structure.
3. The method of claim 2 further comprising:
employing at least one of electron beam lithography and holography to make said diffractive structure, combining a number of elements of said master, and electroforming said master.
4. The method of claim 1 wherein said step of replication further comprises:
reproducing said master by a mass reproduction method selected from the group consisting of embossing into a. thermoplastic film using applied heat and pressure, casting liquid resin onto the grating structure and curing said resin to create a film, and injection molding.
5. The method of claim 1 further comprising:
creating said at least one micro-object integrally with said diffractive structure.
6. The method of claim 1 wherein said converting step further comprises:
providing at least one additional layer selected from the group consisting of a metallic layer, a transparent refractive layer, a reflective layer, a protective layer, and an additional substrate.
7. The method of claim 1 wherein said step of converting further comprises:
converting said optically variable device to final form, said final form being selected from the group consisting of label, laminate, thread, and transfer film.
8. The method of claim 1 further comprising:
providing an article,
incorporating said security device into a transfer medium, and
transferring said security device onto said article.
9. The method of claim 1 further comprising:
providing an article, and
incorporating said security device directly into or onto said article.
10. The method of claim 1 wherein at least some of the steps of said method are computer automated.
11. The method of claim 1 wherein an optical effect of magnifying the at least one micro-object to create the at least one magnified visual representation is wholly provided by the diffractive structure.