Optical Element with Concave Triangular Mesh for Anti-Reflective Performance
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Solution Overview
Problem
Existing optical elements with anti-reflective structures face challenges in achieving high anti-reflective performance and antifouling properties, as they are prone to stain deposition and structural fragility, especially with high aspect ratios, which also complicate fabrication and increase the risk of foreign object deposition.
Innovation Solution
The optical element features a structure with a plurality of concavities and prominent convex protrusions arranged in a triangular mesh pattern, where the protrusions protrude in the opposite direction, providing a high aspect ratio while maintaining structural integrity and reducing the risk of stain deposition through controlled refractive index changes and surface morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aspect ratio of fine prominent convex protrusions or concavities is increased to improve anti-reflective performance, then the refractive index change becomes more gradual and anti-reflective performance improves, but the structure becomes fragile and difficult to maintain shape
Solution Approach 1:
The patent inverts the conventional approach by forming concavities instead of protrusions. This inversion allows achieving high aspect ratio (depth to width) for gradual refractive index change while the concavity structure inherently maintains better structural integrity compared to high protrusions, resolving the contradiction between anti-reflective performance and structural strength
Solution Approach 2:
The patent changes the geometric parameters by creating concavities with controlled depth and width ratios. By optimizing the aspect ratio of concavities (depth/width) rather than protrusions, the patent achieves gradual refractive index change for superior anti-reflective performance while maintaining structural stability through the concavity geometry
2Reliability
If the aspect ratio of fine prominent convex protrusions or concavities is increased to improve anti-reflective performance, then the refractive index change becomes more gradual, but fabrication becomes more complicated and the mold becomes clogged with resin
Solution Approach 1:
The patent inverts the structure from protrusions to concavities, which fundamentally changes the fabrication challenges. Concavities are less prone to clogging during resin transfer and molding processes compared to high aspect ratio protrusions, while still achieving the desired gradual refractive index change for high anti-reflective performance
Solution Approach 2:
The patent optimizes the dimensional parameters of concavities (depth, width, aspect ratio) to achieve a balance between anti-reflective performance and manufacturability. By controlling the aspect ratio within specific ranges, the patent ensures gradual refractive index change while avoiding excessive complexity in fabrication and mold design
3Object-generated harmful factors
If a concavo-convex structure with size variation is used to reduce coloration in reflection, then high aspect ratio protrusions can be reduced, but randomness in pitches between concavities and protrusions poses difficulties in enhancing optical transparency in the desired wavelength
Solution Approach 1:
The patent applies local quality by creating domains with different characteristics. Within each domain, concavities are arranged with specific pitch and size variations to reduce coloration, while the overall periodic structure across domains maintains optical transparency in the desired wavelength range
Solution Approach 2:
The patent segments the surface into multiple domains, each with controlled concavity arrangements. This segmentation allows local variation in pitch and size to reduce coloration while maintaining global periodicity for optical transparency, resolving the contradiction between reducing coloration and maintaining transparency
4Reliability
If fine prominent convex protrusions and concavities are used for anti-reflective effect, then reflection is reduced, but deposition of fine foreign objects between protrusions or in concavities impairs the anti-reflective effect
Solution Approach 1:
The patent changes the surface geometry parameters by creating concavities with optimized depth and width. The controlled aspect ratio and dimensions are designed to minimize foreign object deposition while maintaining the anti-reflective effect through gradual refractive index change
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
This configuration achieves excellent anti-reflective and antifouling performance by reducing reflection and preventing stain deposition, while maintaining structural strength and ease of fabrication, as demonstrated by simulation and experimental results.
Implementation Method 1
Moth-eye structures seek to prevent reflection by continuously varying the refractive index with respect to incident light in the thickness direction of the substrate, thereby eliminating a discontinuous interfaces of the refractive index
Data Source
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AI summary
This optical element has, on one surface thereof, a plurality of recessed sections arranged at a most frequent pitch equal to or less than the wavelength of light in the operating environment, the optical element having, when seen in plan view, a plurality of domains in which the plurality of recessed sections are aligned in a predetermined arrangement, and a plurality of protruding sections formed in a region sandwiched between the plurality of domains and/or in a region surrounded by the plurality of recessed sections inside the domains, the plurality of protruding sections accounting for a surface area ratio of 1%-15% as seen in plan view.