Security Document Microlattice Structure via Laser Diffraction

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Solution Overview

Problem

Current security documents lack a forgery-proof feature that can be easily integrated into existing documents and verified, as existing features like holograms are complex to produce and replicate.

Innovation Solution

A security document with a transparent volume region extending into its interior, where highly focused laser radiation creates a microlattice structure that diffracts light, producing a unique optical effect that is difficult to reproduce, allowing for easy verification by observing diffraction patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If holograms are used as security features, then optical verification is enabled, but manufacturing complexity increases and integration during production is required

Engineering Contradiction:
Improvesecurity feature verificationVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical hologram manufacturing with a simpler laser-induced microstructure formation process. Instead of integrating pre-manufactured holograms, the invention uses focused laser radiation to directly create diffractive microstructures within the document body material, substituting a complex manufacturing system with a more straightforward laser processing approach

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the physical state and optical properties of the document body material by exposing it to high-intensity laser radiation. This creates permanent microstructural changes including voids, densified regions, or phase transitions that produce diffractive optical effects, thereby transforming the material parameters to achieve security verification functionality

Inventive Principle:
Principle #35Parameter changes

2Loss of information

If laser blackening is used for personalization, then information storage is achieved, but the security feature lacks optical verification capability

Engineering Contradiction:
Improveinformation storageVSAvoidoptical verification
Core Design Contradiction:
Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent extends laser processing beyond simple blackening to create microstructures with specific optical properties. By controlling laser parameters, the invention produces regions with varying refractive indices, densities, or void structures that interact with light to produce diffractive patterns, enabling optical verification while maintaining information storage capability

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The invention creates composite microstructures within the document body by combining differently processed regions. The laser produces a mixture of voids, densified material, and original material in specific patterns, creating a composite structure that provides both information storage and optical verification functions simultaneously

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If simple security features are used, then ease of manufacture is improved, but forgery-proof capability is reduced

Engineering Contradiction:
Improveintegration into finished documentVSAvoidforgery-proof capability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent transitions from two-dimensional surface features to three-dimensional microstructures within the document body volume. By creating diffractive structures that extend through the material depth and utilizing volumetric optical effects, the invention achieves enhanced security that is difficult to replicate while maintaining compatibility with finished document production

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention uses the document body material itself as an intermediary medium for creating the security feature. Instead of adding separate security elements, the laser processes the existing material to create permanent microstructural changes that serve as the security feature, simplifying integration while enhancing forgery resistance

Inventive Principle:
Principle #24Intermediary (Mediator)

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 imitation and falsification, as the diffraction structure is challenging to replicate and can be easily verified by shining light on the document, offering a simple and effective method for authentication.

Implementation Method 1

The microstructures are formed in such a way that they jointly form a micro-lattice structure that diffracts incident light, so that an optical effect is perceptible in the diffracted light

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

Using highly focused laser radiation, microstructures are introduced into the interior of the document body, preferably within the transparent volume region. These microstructures represent local material changes within the interior of the document body

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentEP4209355B1Security document with micro-grid structure
Publication Date: 2024.06.05 BUNDESDRUCKEREI GMBH
  • EP4209355B1 patent drawingFigure 1~2
  • EP4209355B1 patent drawingFigure 3~5

AI summary

The invention relates to a security document (1) and a method for its production, wherein the security document (1) comprises a document body (10) with a top (11) and an opposing bottom (12), wherein the document body (10) has at least one transparent volume region (100), wherein the at least one transparent volume region (100) extends from the top (11) into the interior of the document body (10), and wherein laser-induced microstructurings (200) are formed inside the document body (10), wherein at least one microlattice structure (210) is formed inside the document body (10) by means of the microstructurings (200), which diffractes light (300).