Optical devices comprising microlenses and laser-fabricated patterns or structures, their manufacture and use
AssigneesBank of Canada, The Governing Council of the University of Toronto
InventorsCharles Douglas Macpherson, Badr Omrane, Sean Magnus Malmberg, Peter Herman, Stephen Paulchi Ho, Ehsan Alimohammadian
Life of this patent
Estimating the term…
Abstract
Disclosed are optical devices suitable as security devices for document authentication, which comprise at least one array of patterns such as laser-fabricated patterns, or other structures, optionally formed for example from elongate laser-modified tracks extending within a document substrate. The patterns are combined with at least one array of microlenses to cause certain optical effects. Also disclosed are the use of such devices for document authentication, and methods for their production.
Claims22
An optical device comprising:
- a periodic array of microlenses;
- and
- a periodic array of distinct laser-fabricated patterns, wherein the patterns are the same or different from one another, and each pattern comprises a periodic array of continuous or non-continuous laser-modified tracks in a polymer substrate material;
- wherein the substrate material has a general refractive index n, and each laser-modified track comprises a continuous or discontinuous elongate volume of modified polymer material at least 4 times longer than its narrowest width extending at least partially within and across a thickness of the substrate material, that comprises a modified form of the substrate material, that has a refractive index that is different to the general refractive index n of the substrate material from which each laser-modified track originated from;
- wherein the patterns, together with the microlenses, collectively provide an optical effect.
Dependencies are inferred from the claim text.