Imaging Assembly Moth Eye Anti-Reflection Structure
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Solution Overview
Problem
Current imaging assemblies with solid state or wafer scale image sensors suffer from unwanted internal reflections due to non-light transmissive surfaces, which are not effectively addressed by existing anti-reflection coatings, leading to ghost images and stray light effects, and the stress-induced warping of glass substrates during manufacturing.
Innovation Solution
The implementation of a moth eye anti-reflection structure with nanoscale projections smaller than visible light wavelengths on non-light transmissive regions, combined with optically absorbent materials, to reduce internal reflections, and the use of similar refractive indices for the optical elements to minimize stress and warping during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional anti-reflection coatings are applied to reduce internal reflections, then reflectivity is reduced, but stress-induced warping and cracking of glass substrates occurs during manufacturing
Solution Approach 1:
The patent changes the physical state and dimensions of the anti-reflection structure by creating nanoscale projections (moth eye structure) with heights between 20-200 nm, transforming the conventional flat surface coating approach into a three-dimensional nanoscale topography that reduces reflections without inducing stress-induced warping or cracking
Solution Approach 2:
The patent employs a porous or projected surface structure on the glass substrate that creates gradual refractive index transitions, effectively reducing internal reflections while maintaining substrate mechanical integrity without the stress problems associated with traditional thin-film dielectric coatings
2Object-affected harmful factors
If black anti-reflection coating is applied to non-light transmissive surfaces, then reflections are reduced, but ghost images and stray light effects still occur due to 4% or more reflectance
Solution Approach 1:
The patent applies the nanoscale projected surface structure (moth eye anti-reflection structure) to the inner faces of spacer members, changing the surface topology at the nanoscale level to achieve reflectance below 1%, thereby eliminating the 4% or more reflectance problem that causes ghost images and stray light effects
3Stability of the object's composition
If glass spacer members and package lid are expansion matched to silicon wafer, then thermal compatibility is improved, but anti-reflection coatings cannot be applied due to stress and warping issues
Solution Approach 1:
The patent changes the approach to anti-reflection from applying stress-inducing thin-film coatings to creating nanoscale surface projections directly on the glass surfaces, maintaining the expansion-matched glass-silicon construction while eliminating the manufacturing problems of coating application
4Object-affected harmful factors
If nanoscale projections with height less than visible light wavelength are used, then internal reflections are reduced to less than 1%, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs curved or rounded nanoscale projections (moth eye structure) rather than sharp geometric features, which provides tolerance to manufacturing variations while maintaining the anti-reflection effect, as the curved surfaces gradually transition refractive index and are less sensitive to precise dimensional control
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
Significantly reduces internal reflections to less than 1%, eliminating ghost images and stray light effects while avoiding the stress-related issues associated with traditional anti-reflection coatings, allowing for improved manufacturing processes and mechanical properties of the imaging assembly components.
Implementation Method 1
An anti-reflection structure is provided on substantially all non-light transmissive regions of the imaging assembly exposed to the air gap to reduce internal reflections within the imaging assembly. The anti-reflection structure includes a plurality of projections having dimensions smaller than the wavelength of the radiation to be imaged by the imaging assembly to reduce unwanted reflections.
Implementation Method 2
The anti-reflection structure includes a plurality of projections having dimensions smaller than the wavelength of the radiation to be imaged by the imaging assembly to reduce unwanted reflections
Implementation Method 3
The implementation of a moth eye anti-reflection structure with nanoscale projections smaller than visible light wavelengths on non-light transmissive regions, combined with optically absorbent materials, to reduce internal reflections
Data Source
AI summary
An image assembly may include a substrate having a face, a first optical layer and at least one spacer member. The imaging assembly may also include an anti-reflection structure. The at least one spacer member may be arranged between the substrate and the first optical layer to define an air gap therebetween. The anti-reflection structure may be coupled to at least part of the face and at least one of the first optical layer and the at least one spacer member. The anti-reflection structure may also include a plurality of projections having dimensions smaller than a wavelength of radiation to be imaged by the imaging assembly.