Planar Diffractive Optical Elements for Anti-Counterfeit 3D Images
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical security features, such as those on VISA plastic cards, lack sufficient protection against counterfeiting due to their analog optical recording and formation of 3D images in the first order of diffraction, which are easily replicable.
Innovation Solution
A computer-synthesized, single-layer diffractive optical element using multigrade Fresnel lenses forms 3D images in the zero order of diffraction, with a wireframe structure and microrelief accuracy of 10 nm, produced via electron-beam technology, allowing for secure and distinct visual recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog optical recording technology is used to create 3D images in the first order of diffraction, then equipment cost is reduced and manufacturing is simplified, but security protection against counterfeiting is significantly weakened
Solution Approach 1:
The optical element is divided into multiple elementary regions (smaller than 200 microns), each containing Fresnel lenses with specific phase functions. This segmentation allows complex 3D wireframe images to be constructed from simpler modular units, enabling both high security through computational design and feasibility for manufacturing through standardized production processes for each elementary region.
Solution Approach 2:
The patent replaces analog optical recording with computer-synthesized diffractive optical elements. Instead of using traditional holographic recording methods, the invention uses computational algorithms to design the phase function and microrelief structure, which are then manufactured with precision electron-beam technology. This substitution significantly enhances security while maintaining manufacturing capability through digital design and precision fabrication.
2Reliability
If computer-synthesized diffractive optical elements with precision microrelief are used, then security protection is enhanced, but manufacturing precision requirements increase significantly
Solution Approach 1:
The patent specifies that elementary regions should be smaller than 200 microns, and the microrelief accuracy should be approximately 10 nanometers. By optimizing these parameters, the invention achieves a balance between security enhancement through computer-synthesized complex phase functions and manufacturability through precision electron-beam technology that can reliably achieve the required 10 nm accuracy.
Solution Approach 2:
The invention uses computational models to design the exact phase function and microrelief structure needed for secure 3D wireframe image formation. These digital designs serve as precise templates that guide the electron-beam manufacturing process, ensuring that the manufactured elements replicate the intended optical properties with high fidelity, thereby achieving both security and manufacturing feasibility.
3Ease of operation
If 3D images are formed in the zero order of diffraction with wireframe structure, then visual recognition is improved, but the complexity of optical element design increases
Solution Approach 1:
Instead of forming 3D images in the first order of diffraction as in traditional holography, the patent forms images in the zero order of diffraction. This inversion of the traditional approach, combined with the wireframe structure representation, provides superior visual recognition characteristics while the computational design methods manage the increased design complexity through algorithmic optimization.
Solution Approach 2:
The patent represents 3D objects using wireframe structures consisting of vertices and edges, which is a dimensional simplification that enhances visual recognition. By using only the essential structural elements (edges and vertices) rather than full surface representation, the invention achieves better visual clarity and simpler manufacturing while maintaining three-dimensional visual effect through the diffractive optical element design.
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 method enhances security by creating secure 3D images that are difficult to counterfeit, utilizing electron-beam technology for precise microrelief production, ensuring only a few companies can produce these systems, thus reducing availability and increasing protection.
Implementation Method 1
a flat reflective diffractive optical phase element used to form visual 3D wireframe images
Implementation Method 2
in each of them an axial parabolic Fresnel lens with phase function Φ(x,y)=C(x2+y2) is placed
Implementation Method 3
The microrelief is produced using electron-beam technology, which is knowledge intensive and by no means widely available. The accuracy of the microrelief production is 10 nm in terms of depth.
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5~6
AI summary
The micro-optical system for the formation of visual images is a tool primarily intended for authentication of products and can be efficiently used to protect banknotes and securities. According to the invention formula, the micro-optical system has the form of a flat reflecting single-layer phase element, which consists of fragments of multigradational flat axial Fresnel lenses with parabolic phase function and of diffraction gratings. The design of the optical element makes it possible to form 3D wireframe images consisting of edges. When the micro-optical system is illuminated by a point source, it creates at diffraction angles smaller than 60° the effect of the alternation of two 3D images. At diffraction angles greater than 60° the observer sees another 2D color image over the entire region of the micro-optical system. The claimed combination of important features of the invention ensured the achievement of the technical result consisting in the expansion of the capabilities of visual control and in the enhancement of the protection of the micro-optical system against counterfeiting. The micro-optical system of the formation of visual images can be implemented using available standard equipment.