Sub-wavelength AR Coating for Wide-Angle Reflectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional anti-reflective (AR) coatings for optical components have uniform thickness and refractive index, optimizing for a narrow field of view and specific wavelength range, leading to increased reflectivity at varying angles of incidence and limited broadband applicability, which complicates image sensing in light-sensitive applications.
Innovation Solution
The implementation of sub-wavelength openings in the surface of optical components to customize the refractive index, altering the native refractive index and reducing reflectance by forming a pattern of openings with specific diameters and pitches, allowing for optimized transmittance across a wide field of view and broadband spectrum without the need for complex multi-layer coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional uniform AR coatings are applied to optical components, then reflectivity is reduced at a middle angular range, but the field of view becomes narrow and reflectivity increases at varying angles of incidence
Solution Approach 1:
The patent applies local quality by varying the refractive index across different regions of the optical component surface. Specifically, the refractive index is customized at different angular positions from the normal incidence direction, allowing each region to optimize light transmission for its specific angle of incidence. This spatial variation in refractive index enables the component to maintain low reflectivity across a wide field of view rather than being optimized for a single middle angular range.
2Object-affected harmful factors
If conventional AR coatings are designed for a particular wavelength, then reflectivity is minimized at that wavelength, but broadband spectral coverage is limited
Solution Approach 1:
The patent utilizes parameter changes by varying the refractive index as a function of wavelength and angle of incidence. Instead of using a single fixed refractive index, the invention customizes the refractive index parameters across different spectral bands and angular ranges. This allows the optical component to maintain low reflectivity properties across multiple wavelength bands (broadband) while accounting for the angular dependence of light transmission.
3Object-affected harmful factors
If complex multi-layer AR coatings are used to achieve wide field of view and broadband coverage, then optical performance improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies composite materials by creating a structured surface layer with varying refractive index properties. Instead of using multiple discrete AR coating layers, the invention employs a composite surface structure where the refractive index is continuously or discretely varied across the surface. This approach achieves wide field of view and broadband optical performance while simplifying the overall structure compared to traditional multi-layer coatings.
4Object-affected harmful factors
If multiple layers of AR coatings are applied, then optical performance across wide angles improves, but delamination risk increases
Solution Approach 1:
The patent merges the functionality of multiple AR coating layers into a single integrated surface structure. By combining the refractive index modulation and angle-dependent optical optimization into one unified surface layer with varying properties, the invention eliminates the interfaces between multiple coating layers. This merging approach maintains the optical performance benefits of multi-layer systems while removing the delamination risks associated with multiple coating interfaces.
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 approach minimizes reflectance and maximizes transmittance across a wide range of angles and wavelengths, reducing the number of AR material layers required and mitigating delamination issues, while maintaining high performance even at extreme angles of incidence.
Implementation Method 1
The embodiments include optical components with sub-wavelength openings in the surface of the optical component that change a refractive index at an air/surface interface of the optical component
Implementation Method 2
forming a pattern of openings with specific diameters and pitches, allowing for optimized transmittance across a wide field of view and broadband spectrum
Implementation Method 3
Anti-reflective (AR) coatings are often applied to an optical component to reduce surface reflectivity
Implementation Method 4
Light that is reflected by an optical component is not transmitted through the optical component, and thus, such reflected light is not sensed by the image sensor
Data Source
AI summary
Mechanisms for customizing a refractive index of an optical component are disclosed. In one example, sub-wavelength openings are formed in a top layer of anti-reflective (AR) material of an optical component to tailor transmission characteristics of the AR material over a range of angles of incidence and a range of wavelengths. In another example, sub-wavelength openings are formed at different filling fractions in the surface of the optical component.