Asymmetric Convex Structures for Oblique Light Antireflection
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Solution Overview
Problem
Existing optical elements face challenges in maintaining consistent antireflection performance, especially for obliquely incident light, due to variations in reflection characteristics across the optical surface.
Innovation Solution
The optical element features an uneven structure with specific convex portions arranged in a manner that gradually changes refractive index, where the lengths of the convex portions along the radial and circumferential directions satisfy certain relationships (r1>r2, r3≥r4, r1>r3, and r2<r4) to reduce reflection variations and improve antireflection performance for obliquely incident light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional antireflection film or uneven structure is formed on the optical surface, then reflection of incident light is suppressed, but antireflection performance varies for obliquely incident light compared to vertically incident light
Solution Approach 1:
The patent applies local quality by creating uneven structures with different convex portion sizes at different locations on the optical surface. Specifically, the first convex portions (for vertically incident light) have different dimensions than the second convex portions (for obliquely incident light), allowing each region to be optimized for its specific light incidence condition while maintaining overall performance consistency across the optical surface.
Solution Approach 2:
The patent changes geometric parameters of the uneven structures based on location and light incidence angle. The convex portions are designed with specific radius ratios (0.7≤r2/r1<1.0 for first convex portions, 0.7≤r4/r3<1.0 for second convex portions) and size relationships (r1<r3, r2<r4) to optimize antireflection performance for different light paths, thereby maintaining consistent performance across varying incidence angles.
2Ease of manufacture
If the orientations of fine protrusion-depression shapes coincide with the mold release direction, then manufacturing is simplified, but antireflection performance is reduced for obliquely incident light
Solution Approach 1:
The patent introduces asymmetry in the radial direction by making the convex portions elliptical rather than circular, with different radii in the radial and tangential directions (r1≠r2, r3≠r4). This asymmetric design allows the structures to maintain effectiveness for obliquely incident light while still being manufacturable through mold release in a specific direction, thus resolving the contradiction between manufacturing ease and optical performance.
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 effectively suppresses in-plane variation in antireflection performance and enhances the antireflection effect for obliquely incident light, maintaining high performance across the optical surface.
Implementation Method 1
the orientations of fine protrusion-depression shapes of a light diffusion member coincide with the mold release direction of a mold
Implementation Method 2
reflection of incident light on a surface and an inner surface of the optical element is not desirable because it causes a loss of transmitted light amount
Data Source
AI summary
An optical element includes an uneven structure having a plurality of convex portions on at least part of an optical surface, including a first convex portion and a second convex portion arranged closer to an optical surface center than the first convex portion. A first convex portion shape as viewed from a first convex portion normal direction has a length r1 in a first direction from the optical surface center toward an optical surface end and a length r2 in a second direction intersecting the first direction. A second convex portion shape as viewed from a second convex portion normal direction has a length r3 in a third direction from the optical surface center toward the optical surface end and a length r4 in a fourth direction intersecting the third direction. The following relationships are satisfied: r1>r2, r3≥r4, r1>r3, and r2<r4.