Dichroic Optical Structures for Anti-Counterfeiting
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Solution Overview
Problem
Existing color shifting security features used in documents like banknotes are prone to counterfeiting due to their susceptibility to reproduction by electronic and photographic equipment, and they often require complex structures that can confuse the general public when verifying authenticity.
Innovation Solution
The development of at least partially transmissive optical structures that exhibit color shifts in both reflection and transmission modes with changes in viewing angle, utilizing a stack of metal layers and transparent dielectric layers with specific refractive indices, which can be integrated into documents and packaging to enhance security and authenticity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing color shifting security features are used in documents, then color shifting effect is achieved, but they are susceptible to counterfeiting by electronic and photographic equipment
Solution Approach 1:
The patent applies dichroic interference structures that exhibit different colors in reflection mode versus transmission mode. This dual-mode color presentation creates a security feature that cannot be replicated by standard electronic or photographic copying equipment, which only captures a single viewing mode. The color shifting effect with viewing angle combined with the reflection/transmission dichotomy provides reliable anti-counterfeiting capability.
Solution Approach 2:
The invention adds the dimension of transmission mode to traditional reflection-mode color shifting features. By creating structures that simultaneously provide color information in both reflection and transmission modes with different color presentations, the patent creates a multi-dimensional security feature that is difficult to counterfeit while maintaining ease of verification.
2Reliability
If complex structures are used to enhance security features, then anti-counterfeiting capability is improved, but ease of verification by the general public deteriorates
Solution Approach 1:
The patent uses visually striking color changes between reflection and transmission modes that are immediately apparent to the general public. The dichroic structures produce distinct colors that can be easily observed without specialized equipment, making verification simple while maintaining high security reliability through the complexity of the optical physics involved.
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
These structures provide a clear and distinct visual difference in reflection and transmission modes, making it easier for the public to verify authenticity under various lighting conditions and reducing the risk of counterfeiting by being difficult to replicate with standard copying equipment.
Implementation Method 1
thin interference optical structures, films, coatings and pigments for producing color in both reflection mode and transmission mode
Implementation Method 2
these structures, films, coatings, and pigments exhibit large color shifting properties with changes in both reflection and transmission potentially with a change in the angle of incidence or the viewing angle
Data Source
AI summary
A document, product, or package, such as a banknote, passport or the like comprises structures having dichroic effects that change color with viewing angle in both transmission and reflection. Such structures can be useful as security features that counter the ability to effectively use counterfeit documents, products, packages, etc.