Optical Layered Composite for AR Image Propagation
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Solution Overview
Problem
Augmented reality devices face challenges in achieving a good field of view, image transmission, color fidelity, and wearability while maintaining anti-reflective properties and minimizing weight.
Innovation Solution
An optical layered composite is developed with a substrate and coating layers that satisfy specific refractive index and thickness criteria, optimizing image propagation and anti-reflective properties by using a combination of coating layers with varying refractive indices and thicknesses to enhance transverse image propagation and reduce optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional anti-reflective coatings are applied to the substrate, then anti-reflective properties are improved, but transverse image propagation is degraded
Solution Approach 1:
The coating is divided into multiple discrete layers (first coating layer and second coating layer) with alternating refractive indices, where each layer has a specific thickness range (50-200nm and 200-500nm respectively). This segmentation allows the coating to simultaneously achieve anti-reflective properties through interference effects and maintain transverse image propagation by controlling the optical path length in each layer.
Solution Approach 2:
Different regions of the coating have different refractive indices and thicknesses optimized for specific functions. The first coating layer (closer to the light source) has lower refractive index and thinner thickness for anti-reflective performance, while the second coating layer (closer to the observer) has higher refractive index and greater thickness for maintaining image transmission and color fidelity.
2Area of stationary object
If image propagation in transverse direction is improved, then field of view is improved, but anti-reflective properties are degraded
Solution Approach 1:
The patent optimizes specific parameters including the thickness of each coating layer (50-200nm for first layer, 200-500nm for second layer), the refractive indices of the coating materials, and the wavelength range (390-700nm) to simultaneously achieve wide field of view and effective anti-reflective properties across the visible spectrum.
3Object-affected harmful factors
If coating thickness is increased to improve anti-reflective properties, then device weight is increased
Solution Approach 1:
Instead of using a single thick coating layer, the patent applies multiple thinner layers with total thickness optimized for anti-reflective performance. The first coating layer has thickness of 50-200nm and the second has 200-500nm, providing sufficient anti-reflective properties while minimizing total coating material and device weight.
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 improves the field of view, image transmission, and color fidelity in augmented reality devices while maintaining good anti-reflective properties and reducing weight, resulting in a more effective and user-friendly augmented reality experience.
Implementation Method 1
a coating applied to the front face, the coating comprising one or more coating layers... wherein nc is a mean refractive index of the coating layers... for optimising the propagation of an image in a transverse direction
Implementation Method 2
the coating satisfies the following criterion... dc/4nk = λg/4π... providing anti-reflect properties for light incident in a longitudinal direction
Data Source
AI summary
An optical layered composite includes: a substrate having a front face, a back face, a thickness ds between the front face and the back face and a refractive index ns; and a coating applied to the front face. The coating comprises one or more coating layers. For at least one wavelength λg in the range from 390 nm to 700 nm, the coating satisfies one of the following criterion: nc<ns; or nc>ns, anddc<knc2-ns2·arctanns2-1nc2-ns2;nc is a mean refractive index of the coating layers, weighted by thickness; do is a total thickness of the coating; thicknesses are determined in a direction perpendicular to the front face; and k=λg/4π.