Optical Coating Structure with Profile Elements to Reduce Iridescence
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Solution Overview
Problem
Existing optical coating structures struggle to provide a color that remains consistent and bright across a broad range of viewing angles without significant iridescence, while being easy and cost-effective to produce.
Innovation Solution
An optical coating structure comprising a base layer with profile elements of 5 to 500 μm in size, arranged in a non-periodic or periodic manner, and a reflector that conforms to the profile elements, allowing for minimal iridescence and a metallic appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a quarter-wave stack reflector with alternating dielectric layers is used, then precise wavelength discrimination and sharp color definition are achieved, but the color exhibits significant iridescence and changes with viewing angle
Solution Approach 1:
The base layer is segmented into multiple micro-structures (protrusions or recesses) with different orientations. Each micro-structure reflects light at different angles, and when combined, they create an overall color that remains consistent across a broad range of viewing angles while maintaining precise wavelength discrimination through the optical coating layers.
Solution Approach 2:
The invention introduces asymmetric micro-structures (protrusions or recesses) with specific orientation distributions on the base layer. This asymmetric geometry, when combined with the optical coating, enables the structure to reflect light in a controlled manner that minimizes iridescence while preserving color purity across different viewing angles.
2Illumination intensity
If sub-micron crevices are formed in the coating layers to produce color effects, then deep hue and high reflectivity are achieved, but the manufacturing process becomes complex and costly
Solution Approach 1:
The base layer is pre-formed with micro-structures (protrusions or recesses) before applying the optical coating layers. This preliminary structuring simplifies the overall manufacturing process by eliminating the need to create complex sub-micron crevices within the coating layers themselves, while still achieving the desired light diffraction and color effects.
Solution Approach 2:
Instead of directly creating complex three-dimensional micro-structures within the coating, the invention uses a simpler base layer structure that copies or replicates the essential optical function. The optical coating layers are then deposited over this simplified structure, achieving the color effect with reduced manufacturing complexity.
3Ease of manufacture
If a smooth flat surface coating is applied, then the manufacturing process is simple and cost-effective, but the color exhibits strong iridescence and is only visible at narrow viewing angles
Solution Approach 1:
The base layer is divided into multiple micro-structures (protrusions or recesses) that are relatively simple to manufacture. These segmented structures, when combined with the optical coating, broaden the viewing angle range while maintaining color consistency, achieving a balance between manufacturing simplicity and optical performance.
Solution Approach 2:
The invention changes the geometric parameters of the base layer by introducing micro-structures with specific size ranges (5 to 500 μm) and orientation distributions. This parameter modification enables the structure to maintain color consistency across broad viewing angles while remaining relatively simple and cost-effective to manufacture compared to sub-micron precision structures.
4Stability of the object's composition
If profile elements with size 5 to 500 μm are used, then minimal iridescence and broad viewing angle color consistency are achieved, but the structure becomes more complex than flat coatings
Solution Approach 1:
The base layer is given different local qualities through the distribution of micro-structures (protrusions or recesses) with specific orientations in different regions. This local variation in structure, combined with the optical coating, achieves color consistency across broad viewing angles while keeping the overall structural complexity manageable through systematic arrangement.
Solution Approach 2:
The invention optimizes the size parameters of the profile elements (5 to 500 μm) to achieve a balance between reducing iridescence and maintaining manufacturability. This parameter optimization allows the structure to provide broad viewing angle color consistency without excessive structural complexity, as the size range avoids both sub-micron precision requirements and macroscopic 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 bright, consistent color with minimal perceived iridescence across various angles, offering ease and cost-effectiveness in manufacturing, and provides a luxurious, deep matte effect.
Implementation Method 1
a quarter-wave stack reflector is a well-known building block of optical thin-film products. Such a stack generally comprises alternating layers of two or more dielectric materials with different refractive indexes, in which each layer has an optical thickness (i.e., the geometric thickness of the layer multiplied by the refractive index of the layer material) that corresponds to one-quarter of the principal wavelength of reflection.
Implementation Method 2
The visual effects produced by this device are, at least in part, caused by diffraction effects caused by the crevices formed in the top layer and other layers of the device.
Implementation Method 3
On top of the base structure is a coating made up of two polymeric layers alternately deposited on the substrate, one of the polymeric layers having a high refractive index and the other having a low refractive index.
Data Source
AI summary
An optical coaling structure is provided that when applied to a surface of an object to imparts a color to the object, the optical coating structure including: a base layer; a reflector on the base layer; and profile elements on the base layer under the reflector, the profile elements having a width and length which are each in the range of 5 to 500 μm in size, and being arranged in non-periodic manner or a periodic manner. The reflector may be a multilayer structure of alternating dielectric materials. A method of forming the optical coating structure is also provided.