Retroreflective Colorants with Angle-Dependent Bragg Diffraction
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Solution Overview
Problem
Existing retroreflective materials fail to effectively retroreflect visible radiation in a direction normal to the surface while diffracting radiation outside the visible spectrum, lacking efficient angle-dependent color change and Bragg diffraction properties.
Innovation Solution
A multilayered crystalline colloidal array with particles encapsulated by a matrix material, exhibiting visible retroreflection and Bragg diffraction, where the wavelength of retroreflected radiation decreases with increasing viewing angle, and no visible radiation is retroreflected or diffracted normal to the surface, utilizing core-shell or hollow particles with controlled refractive index and size for tuned diffraction wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retroreflective materials are used, then retroreflection of visible radiation is achieved, but the materials fail to effectively retroreflect in a direction normal to the surface while diffracting radiation outside the visible spectrum
Solution Approach 1:
The patent changes the structural parameters of the retroreflective material by using a multilayered crystalline colloidal array with specific layer thicknesses and refractive indices. This creates angle-dependent diffraction where only specific wavelengths are retroreflected at specific angles, achieving both high retroreflection efficiency and angular selectivity simultaneously.
Solution Approach 2:
The patent employs a composite structure combining multiple layers of crystalline colloidal arrays with different refractive indices and thicknesses. This composite multilayered structure enables simultaneous achievement of strong retroreflection and Bragg diffraction at controlled wavelengths, resolving the contradiction between retroreflection efficiency and angular adaptability.
2Ease of manufacture
If the wavelength of retroreflected radiation is tuned for specific angles, then angle-dependent color change is achieved, but no visible radiation is retroreflected normal to the surface
Solution Approach 1:
The patent applies local quality by creating different optical properties at different locations (angles) within the multilayered structure. Each layer is designed with specific thickness and refractive index to control diffraction at particular angles, enabling angle-dependent color change while maintaining strong retroreflection at normal incidence through constructive interference of multiple layers.
Solution Approach 2:
The patent transitions from conventional single-angle retroreflection to a multi-dimensional angular response by stacking multiple crystalline colloidal arrays in a multilayered configuration. This adds the dimension of layer stacking to the angular dispersion effect, enabling simultaneous control of retroreflection intensity and wavelength across different viewing angles.
3Measurement precision
If Bragg diffraction is used to diffract radiation outside the visible spectrum, then wavelength selectivity is improved, but the diffraction intensity decreases in the visible range
Solution Approach 1:
The patent ensures continuity of useful action by designing the multilayered structure so that Bragg diffraction and retroreflection occur simultaneously across multiple wavelengths and angles. The continuous stacking of crystalline colloidal arrays maintains constructive interference conditions throughout the visible spectrum while preserving wavelength selectivity through precise control of layer parameters.
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 achieves angle-dependent color change and efficient retroreflection of visible radiation, with enhanced diffraction intensity and tunable diffraction wavelengths, suitable for various applications including coatings and pigments.
Implementation Method 1
the reflective material exhibiting: (i) visible retroreflection of incident radiation... and (ii) Bragg diffraction of the incident radiation
Implementation Method 2
visible retroreflection of incident radiation, wherein a wavelength of visible retroreflected radiation decreases from a first visible wavelength at a first angle to the primary surface to a second, shorter wavelength of visible retroreflected radiation as the viewing angle to the primary surface increases
Data Source
AI summary
A reflective material comprising a multilayered array of particles encapsulated by a matrix material, the reflective material defining a primary surface, the reflective material exhibiting: (i) visible retroreflection of incident radiation, wherein a wavelength of visible retroreflected radiation decreases from a first visible wavelength at a first angle to the primary surface to a second, shorter wavelength of visible retroreflected radiation as the viewing angle to the primary surface increases; and (ii) Bragg diffraction of the incident radiation, wherein the wavelength of radiation Bragg diffracted normal to the primary surface is longer than the wavelength of visible radiation, such that no visible radiation is retroreflected or Bragg diffracted in a direction normal to the primary surface.