Volumetric Laser Marking for Anti-Delamination Security Documents

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Solution Overview

Problem

Security documents with viewing direction-dependent features face challenges in durability and protection against delamination and external mechanical influences, as existing structures are difficult to create and can be easily manipulated or replaced.

Innovation Solution

The security document features a transparent volume region with laser-induced material changes formed at different distances relative to the outer surface, creating a plane structure that is easy to verify and resistant to manipulation, using ultra-short laser pulses to focus light inside the document body and form localized material changes that span a flat or semi-plane structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If viewing direction-dependent security features are implemented using existing structures, then optical verification capability is improved, but durability and resistance to delamination and mechanical influences deteriorate

Engineering Contradiction:

Improveoptical verification capabilityVSAvoiddurability and resistance to manipulation

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The patent transitions from surface-level security features to volumetric features embedded within the transparent material. By creating laser-induced material changes at different distances from the outer surface (at the focal point and in areas in front of or behind the focal point), the security feature gains three-dimensional depth, making it resistant to delamination and mechanical damage while maintaining optical verification capabilities.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The security feature is nested within the transparent material volume rather than being applied on the surface. The laser-induced material changes are embedded inside the document body, with features at multiple depth levels, creating a hierarchical structure that protects the security feature from external manipulation while preserving its optical properties.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Difficulty of detecting and measuring

If complex surface structures are used for viewing direction-dependent features, then security effect is improved, but susceptibility to environmental damage and destruction increases

Engineering Contradiction:

Improveviewing direction-dependent effectVSAvoidenvironmental damage susceptibility

Core Design Contradiction:

Difficulty of detecting and measuringVSObject-affected harmful factors

Solution Approach 1:

The patent replaces complex mechanical surface structures with laser-induced material changes within the volume. Instead of using delicate surface reliefs or coatings that are susceptible to environmental damage, the security feature is created through optical-field interactions (laser focusing) that produce robust material changes embedded within the bulk material, resistant to environmental factors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If markings are located within a narrow radius of the document body surface, then ease of creation is improved, but vulnerability to layer replacement and manipulation increases

Engineering Contradiction:

Improveease of feature creationVSAvoidprotection against delamination and replacement

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The security feature is segmented into multiple discrete laser-induced material changes at different depth levels within the transparent volume. By distributing the markings throughout the volume rather than concentrating them at the surface, the feature becomes resistant to layer replacement while maintaining manufacturability through controlled laser processing.

Inventive Principle:

Principle #1Segmentation

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

This solution provides a secure and easily verifiable security feature that is resistant to delamination and external influences, with a clearly viewing direction-dependent effect, allowing for targeted and varied material changes that enhance the document's anti-counterfeiting capabilities.

Implementation Method 1

localized laser-induced material changes are formed

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 2

using ultra-short laser pulses to focus light inside the document body and form localized material changes

Methodology Applied

Scientific EffectLight focusing: Focusing

Implementation Method 3

Due to refraction effects at these lens-like elements, the laser light emitted during the formation of the markings within the document is focused

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentEP3967510B1Security document with viewing direction-dependent safety feature

Publication Date: 2023.09.27 BUNDESDRUCKEREI GMBH

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Figure 3~4b
Figure 5

AI summary

The invention relates to a security document with a viewing-direction-dependent security feature, wherein the security document (10) has a document body (1) with a transparent volume region (20) extending at least to an outer surface (12), in which the document body (1) is formed from a transparent material, in the interior of which localized laser-induced material changes (500) are formed, wherein the laser-induced material changes (500) are formed at different distances relative to the outer surface (12) in the transparent volume region (20). Furthermore, the invention relates to a method for producing such a security document.