Optical Effect Structures for Iridescence Reduction
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Solution Overview
Problem
Existing optical coating structures exhibit significant iridescence, meaning the color changes with viewing angle, and struggle to maintain a consistent appearance over a broad range of angles, and they also face challenges in altering reflectivity effectively.
Innovation Solution
The introduction of sub-micron-sized scattering structures with a pseudo-random or non-periodic arrangement in optical coating structures, which include elongate profile elements that induce subtle distortions in the multilayer reflector, preventing diffraction and maintaining a consistent color appearance across various angles, and enhancing transmission or omni-directional reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multilayer reflector with alternating refractive index layers is used to achieve precise wavelength reflection, then the color discrimination is sharp and well-defined, but the color changes with viewing angle causing significant iridescence
Solution Approach 1:
The patent introduces scattering structures at specific locations within the optical coating structure - specifically in the basal layer, upper layers, or middle layers of the multilayer reflector. These localized scattering elements have different optical properties than the surrounding layers, creating local quality variations that scatter light and reduce the angular dependence of the reflected color, thereby maintaining color consistency across viewing angles while preserving the sharp wavelength discrimination of the multilayer reflector.
2Ease of manufacture
If the optical coating structure uses a smooth surface to maintain simple manufacturing, then the structure is easy to manufacture, but it produces strong directional reflections and significant diffraction effects
Solution Approach 1:
The patent applies scattering structures with specific dimensional characteristics - the scattering structures have main dimensions (width and height) of less than 1.5 μm, and more preferably less than 1 μm. This partial application of scattering at the sub-micron scale is sufficient to reduce diffraction and create omni-directional reflections without requiring complete surface roughening, thus maintaining ease of manufacture while effectively reducing harmful diffraction effects and directional reflections.
3Stability of the object's composition
If scattering structures with dimensions less than 1.5 μm are introduced to reduce iridescence, then color consistency across viewing angles is improved, but the structural complexity increases
Solution Approach 1:
The patent uses scattering structures as intermediary elements within the optical coating structure. These scattering structures act as mediators that interact with light between the multilayer reflector and the external environment. By placing scattering structures in the basal layer, upper layers, or middle layers of the reflector, they modify the light path and reduce iridescence without requiring fundamental changes to the multilayer reflector design, thus achieving color consistency while limiting the increase in structural complexity.
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 a consistent and bright color appearance over a wide range of angles with minimal iridescence and allows for enhanced transmission or directional reflections, providing a visually striking effect while preventing significant diffraction.
Implementation Method 1
The scattering structures are mainly sub-micron in size... to cause a degree of scattering in the multilayer reflector
Implementation Method 2
an optical coating structure can be constructed to accurately and selectively reflect certain wavelengths of visible light... Objects coated with such structures can take on a sharp and well-defined colour
Implementation Method 3
elongate profile elements that induce subtle distortions in the multilayer reflector, preventing diffraction and maintaining a consistent color appearance
Data Source
AI summary
An optical coating structure applied to the surface of an object having scattering structures introduced to the basal, upper or middle layers of a multilayer reflector to cause a particular (calculated) degree of scattering, or to the surface of a black/colour pigmented object. The scattering structures are mainly sub-micron in size, and arranged in a pseudo-random or non-periodic manner. Consequently they serve only to broaden the angular range of the light reflected at the surface normal from a multilayer reflector, or to provide (actual and/or perceived) reduced reflectivity of a surface by deflecting incident light through the surface rather than away from it or by scattering otherwise beam-like (narrow-angle) reflections from a surface into a broad-angle reflection. The scattering structures can include profile elements, which are in the form of elongate bars having convexly curved sides or hemispherical rods, that are introduced to a basal layer of a multilayer reflector.