Covert Security Marking via Wavelength-Dependent Emission
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Solution Overview
Problem
Current security features in documents and materials are visible and can be easily replicated by counterfeitters once their presence is known, making them ineffective in preventing unauthorized copying and forgery.
Innovation Solution
A covert security marking system using a combination of fluorescent or phosphorescent emitters and absorptive taggants, which create unique optical signatures across the ultraviolet to infrared spectrum, undetectable to the naked eye, and can be authenticated using differential illumination responses from two pump sources at different wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional visible security features (watermarks, security threads, holograms) are used, then authentication capability is provided, but the security features become visible and replicable by counterfeitters
Solution Approach 1:
The patent applies color changes by using materials that exhibit different optical properties under different illumination conditions. The security features remain invisible under normal lighting but display specific colors or patterns when illuminated with particular wavelengths of light, making them undetectable to casual observation and difficult to replicate
Solution Approach 2:
The patent changes the optical parameters of the security features by using materials with specific absorption and emission spectra. The security marking absorbs light at certain wavelengths and emits at others, creating a unique spectral signature that is undetectable by conventional means but can be verified with appropriate optical instrumentation
2Object-affected harmful factors
If covert security markings are used that are undetectable to the naked eye, then replicability by counterfeitters is reduced, but detection and verification becomes more complex
Solution Approach 1:
The patent employs periodic action by using alternating illumination at different wavelengths to excite the security marking. The marking absorbs light at one wavelength and emits at another, creating a periodic response that can be detected and measured systematically
Solution Approach 2:
The patent implements feedback by comparing the detected emission spectrum against expected reference patterns. The detection system measures the light emitted by the security marking and uses this information to verify authenticity, providing a clear yes/no authentication result
3Reliability
If multi-wavelength excitation and emission materials are used, then security against counterfeiting is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses composite materials by combining absorption materials and emission materials in a single security marking layer. These materials work together to absorb light at specific wavelengths and re-emit at different wavelengths, creating a complex optical response from a relatively simple structure that can be manufactured using conventional printing or coating techniques
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
Provides a secure and covert means to authenticate documents and materials by creating undetectable optical signatures, making it difficult for counterfeitters to replicate the security features, while allowing for simple and cost-effective detection using optical instrumentation.
Implementation Method 1
an emitter material which emits light in response to illumination by a wavelength
Implementation Method 2
florescent or phosphorescent coatings, inks, security threads
Implementation Method 3
an absorptive taggant which absorbs light in a narrow spectral range
Data Source
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AI summary
A system and method for authentication of secure products is disclosed. The security feature contains a first component in the form of an emitter capable of emitting light in response to external pump light. The security feature also contains a second component in the form of a taggant that absorbs light in a spectrally narrow range compared to the broader excitation spectrum of the first material. In this manner the emitter and taggant work in combination with one another to create an emission response significantly dependent on the illumination wavelengths and unique to the specific combination of the components. The emitter and taggant can be in the form of a mixture. Further the emitter and taggant may be applied in close proximity to one another, such as within two separate coating layers on a suitable substrate.