Optically Variable Security Element With Laser-Ablated Microholes
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Solution Overview
Problem
Current security elements for data carriers, such as identity cards and banknotes, lack effective means to prevent unauthorized reproduction and ensure authenticity, particularly in modern copying technologies.
Innovation Solution
A security element featuring a transparent substrate with an array of microlenses and a laser-sensitive recording layer containing superimposed sub-layers, where microholes of varying diameters are created by laser radiation, allowing for distinct motifs to be visible in reflected and transmitted light from specific viewing angles, enhancing visual appeal and forgery protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional numbering methods are used for personalization, then the individualization process is simple, but the integration with security elements is limited and the security level is low
Solution Approach 1:
The patent combines personalization and security functions into a single integrated system. Laser beams are used to create microholes in the recording layer that serve dual purposes: forming personalized information (names, numbers) and creating security motifs visible through microlenses. This merging eliminates the need for separate personalization and security element application processes, while achieving both individualization and high-level security protection.
Solution Approach 2:
The patent replaces conventional mechanical personalization methods (such as stamping or adhesive application) with laser-based direct writing. The laser beam directly ablates the recording layer to create microholes, eliminating mechanical contact and enabling precise integration with the optical security element structure. This substitution enables complex 3D motifs and personalized information to be created in a single non-contact process.
2Reliability
If single-layer recording structures are used, then the manufacturing process is simple, but the visual effects and forgery protection are limited
Solution Approach 1:
The recording layer is segmented into multiple functional sub-layers: a first sub-layer containing larger microholes for reflected light motifs, and a second sub-layer containing smaller microholes for transmitted light motifs. This segmentation allows different viewing angles to reveal different security features, with the first sub-layer providing security visible from the front and the second sub-layer providing security visible from the back, thereby enhancing forgery protection through multi-angle verification.
Solution Approach 2:
The patent adds the dimension of viewing angle to the security feature. By creating microholes at different depths in the multi-layer recording structure, the invention enables security motifs to be visible only from specific angles. The microlenses focus light to make microholes visible only when viewed from predetermined angles, creating three-dimensional security effects that cannot be reproduced by flat copying methods.
3Reliability
If microholes of uniform size are created, then the laser processing is simple, but the visual contrast and security effect are reduced
Solution Approach 1:
The patent applies local quality by creating microholes with different diameters in different regions of the recording layer. The first sub-layer contains microholes with a first diameter optimized for reflected light visibility, while the second sub-layer contains microholes with a second diameter optimized for transmitted light visibility. This local differentiation of microhole sizes enables distinct visual effects and security motifs to be created in specific areas, enhancing overall security while maintaining manageable laser processing through systematic parameter variation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a high level of protection against forgery and authenticity verification by creating unique visual effects that change with viewing angles, making it difficult to reproduce using modern copying methods, while maintaining an attractive visual appearance.
Implementation Method 1
a plurality of microholes produced in the laser-sensitive recording layer by the action of laser radiation
Implementation Method 2
each microhole being associated with a microlens and being visible through the associated microlens when the security element is viewed from a specific viewing angle
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~5b
AI summary
The invention relates to an optically variable security element (12) for security papers, documents of value and other data carriers, having a substantially transparent carrier (20) with first and second main surfaces (22, 24) located opposite one another, having an arrangement of microlenses (26) on the first main surface (22) of the carrier, having a laser-sensitive recording layer (30), which is arranged on the second main surface (24) of the carrier and contains first and second sub-layers (32, 34) arranged one above the other, wherein the first sub-layer (32) is arranged between the carrier (20) and the second sub-layer (34), and having a multiplicity of microholes (40) which are generated in the laser-sensitive recording layer by the action of laser radiation and of which each microhole (40) is assigned to a microlens (26) and, with the security elements being viewed from a certain viewing angle, can be seen through the associated microlens (26), wherein the multiplicity of microholes comprise a multiplicity of first and a multiplicity of second microholes (42, 44) wherein the first microholes (42) are present in the first sub-layer (32), and do not pass through the recording layer (30), and the second microholes (44) pass through the recording layer (30) with the first and second sub-layer (32, 34), and wherein the diameter of the first microholes (42) is larger than the diameter of the second microholes (44).