Security Document Subwavelength Grating Azimuthal Rotation
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Solution Overview
Problem
Current security documents lack effective methods for personalization and authentication that combine high security with ease of verification and difficulty in imitation, particularly in preventing counterfeiting and data protection.
Innovation Solution
A personalized security document featuring a multilayer film structure with subwavelength gratings that act as wavelength subtractive filters, allowing for personalization and authentication by azimuthal rotation, combined with a personalization mask for enhanced visual effects and data integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional hologram registration methods are used, then personalization is achieved, but visual authentication from multiple angles is limited
Solution Approach 1:
The patent divides the single hologram structure into multiple separate DID components (first DID component with first grating vector, second DID component with second grating vector). Each component is structured independently with subwavelength gratings, allowing them to be positioned at different locations and orientations on the document, thereby enabling visual authentication from multiple angles while maintaining manageable structural complexity
Solution Approach 2:
The patent introduces azimuthal rotation as an additional dimension for authentication. By orienting the grating vectors of different DID components in different directions (e.g., first grating vector in radial direction, second grating vector in circumferential direction), the system enables verification by rotating the document around the optical axis, adding a rotational dimension to the authentication process
2Ease of operation
If DID components with different grating vectors are used, then visual effects vary by azimuthal rotation, but manufacturing precision requirements increase
Solution Approach 1:
Each DID component is designed with specific local characteristics - the first DID component has its grating vector oriented in the radial direction while the second DID component has its grating vector oriented in the circumferential direction. This local differentiation in grating orientation enables azimuthal rotation authentication, while each component can be manufactured and positioned independently, reducing overall manufacturing precision requirements
Solution Approach 2:
The patent utilizes changes in grating vector orientation as a key parameter to achieve azimuthal rotation effects. By varying the orientation angle of grating vectors between different DID components (e.g., 0 degrees for radial, 90 degrees for circumferential), the system enables authentication through rotation without requiring extremely tight manufacturing tolerances on absolute positioning
3Reliability
If multiple multilayer films are superpositioned, then security level increases, but device complexity increases
Solution Approach 1:
The patent combines multiple DID components (first and second DID components with different grating vectors) into a single integrated security document structure. The multilayer films containing these components are superpositioned and fused together, merging their security functions while maintaining a unified document structure that prevents removal or substitution of individual components
Solution Approach 2:
The security document employs a composite multilayer structure where different DID components are embedded in separate multilayer films that are then fused together. This composite approach allows each layer to contribute different security characteristics (different grating vectors, different optical effects) while forming an integrated whole that enhances overall security level
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 enables secure, easy-to-verify, and difficult-to-imitate authentication of personal data within the document, providing a high level of security and stability in visual effects across different observation angles.
Implementation Method 1
structured to form a subwavelength grating... behaves like a structured waveguide, making it possible to excite resonances of guided modes at different wavelengths depending on fee polarization, the angle of incidence and the azimuth
Implementation Method 2
a layer of high index of refraction encapsulated between two layers of low index of refraction... acts in zero order like a wavelength subtractive filter
Data Source
AI summary
According to one aspect, the invention relates to a customizable document for producing a customized security document (10, 20). The customizable document includes, according to an alternative: a layer (12) which can be customized by contact-free writing an opaque customization mask that is transparent in at least one transparency area (121); a first multilayer film (102) arranged on a first side of the customizable layer (12), including a layer having a high refractive index and encapsulated between two layers having a low refractive index, and structured over at least a portion of the surface thereof such as to form a first subwavelength array, characterized by a first array vector, such that the first multilayer film acts at zero order as a wavelength subtractive filter; a second multilayer film (102) arranged on a second side of the customizable layer, opposite the first side, including a layer having a high refractive index and encapsulated between two layers having a low refractive index, and structured over at least a portion of the surface thereof such as to form a second subwavelength array characterized by a second array vector, such that the second multilayer film acts at zero order as a wavelength subtractive filter, the first and second arrays being at least partially stacked.