Anti-Reflection Film with Void Nanostructure
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Solution Overview
Problem
Conventional anti-reflection films with concave-convex nanostructures face challenges in maintaining effective anti-reflection performance under high-temperature and high-humidity conditions and are prone to mechanical damage due to poor scratch resistance, as the protective coatings can fill the concave parts and disrupt the refractive index gradient, leading to reduced performance.
Innovation Solution
An anti-reflection film comprising a base layer, a concave-convex nanostructure layer with a pitch width less than the incident light wavelength, and a cover layer formed by physical vapor deposition with a refractive index between 1.15 and 1.8, which covers the convex parts of the nanostructure while leaving a void between the cover layer and the concave parts, enhancing both scratch resistance and anti-reflection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coat is provided on the surface of the concave-convex nanostructure to prevent mechanical damage and water adsorption, then scratch resistance and high-temperature high-humidity resistance are improved, but the concave parts are filled with cover layer material which disrupts the refractive index gradient and deteriorates anti-reflection performance
Solution Approach 1:
The cover layer is designed to selectively cover only the convex parts of the nanostructure while leaving the concave parts exposed, creating different functional zones: the convex parts gain mechanical protection while the concave parts maintain their optical function for refractive index gradient formation
Solution Approach 2:
Instead of completely covering the nanostructure surface, the cover layer is applied partially only to the convex parts, which is sufficient to provide scratch resistance without excessively filling the concave parts and disrupting the refractive index gradient
2Manufacturing precision
If the concave-convex nanostructure is used to form a gradual refractive index distribution, then anti-reflection performance is improved, but the surface area increases which causes water adsorption under high-temperature high-humidity conditions and deteriorates reliability
Solution Approach 1:
The cover layer is selectively applied only to the convex parts where mechanical protection is needed, while the concave parts remain uncovered to maintain the refractive index gradient and reduce water adsorption surface area
Solution Approach 2:
The concave parts of the nanostructure, which create large surface area and potential water adsorption sites, are intentionally left uncovered to maintain their optical function, while the convex parts are protected, effectively converting the potential harm of large surface area into the benefit of maintained anti-reflection 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
The solution significantly improves the anti-reflection performance, scratch resistance, and high-temperature and high-humidity environment resistance by maintaining the refractive index gradient and preventing water adsorption, resulting in reduced reflectance across a wide wavelength range and improved durability.
Implementation Method 1
a cover layer as a second optical thin film that covers peaks of the convex part constituting the concave-convex nanostructure
Data Source
AI summary
An object of the present invention is to provide an anti-reflection film excellent in high-temperature and high-humidity environment resistance and scratch resistance in addition to improved anti-reflection performance of a concave-convex nanostructure. To achieve the object, an anti-reflection film 10 comprises: a base layer 11 as a first optical thin film that is provided on an optical surface 21a of an optical element 21; a concave-convex nanostructure layer that is provided on a surface of the base layer 11 and is composed of a concave-convex nanostructure 12 formed so as to have a pitch width p between the convex parts 12b of shorter than an incident light wavelength; and a cover layer 13 as a second optical thin film that covers peaks of the convex part 12b with a void 14 being provided between the cover layer 13 and concave part 12a constituting the concave-convex nanostructure 12.