Encapsulated Waveguide Cavities for Stable Near-Eye Displays
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Solution Overview
Problem
Optical waveguide systems in near-eye displays are susceptible to environmental contamination and distortions due to changes in ambient pressure and temperature, leading to image aberration and loss of sharpness.
Innovation Solution
An encapsulated waveguide system with first and second outer layers enclosing a waveguide substrate, sealed by a spacer and sealing element, forming cavities filled with inert gas or dry air to maintain consistent pressure and protect against moisture and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the waveguide substrate is exposed to the environment, then the device structure remains simple, but the optical performance deteriorates due to environmental contamination and pressure changes
Solution Approach 1:
The patent introduces an encapsulation structure comprising outer layers and spacers as an intermediary between the waveguide substrate and the external environment. This mediator protects the sensitive optical components from environmental factors such as moisture, dust, and pressure changes, thereby maintaining stable optical performance without requiring complex active control systems.
Solution Approach 2:
The patent extracts the waveguide substrate from direct environmental exposure by placing it within an encapsulated cavity. This separation removes the harmful interaction between the optical components and environmental contaminants, allowing the waveguide to maintain consistent optical properties regardless of external conditions.
2Manufacturing precision
If spacers are used to maintain distance between waveguide substrate and outer layers, then optical distortion is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent employs thin film spacers formed through deposition processes to maintain precise spacing between the waveguide substrate and outer layers. These thin film structures provide the necessary mechanical separation while being compatible with standard semiconductor manufacturing processes, thereby achieving high spacing accuracy without significantly increasing manufacturing complexity.
3Reliability
If the waveguide system is sealed to protect against contamination, then reliability improves, but pressure equalization becomes more difficult
Solution Approach 1:
The patent creates a sealed encapsulation environment that protects the waveguide substrate from environmental contamination. The encapsulation structure maintains a controlled internal atmosphere, preventing moisture and dust ingress while allowing for pressure management through the cavity design.
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 encapsulated waveguide system maintains optical performance by isolating the waveguide from environmental changes, preventing distortions and ensuring clear image projection.
Implementation Method 1
The projector light is coupled in by the input area into the transparent waveguide substrate, then propagates along said substrate via total internal reflection until being coupled out from said substrate by the output area towards the user's eye.
Implementation Method 2
The input area and the output area are typically made of a refractive index matched spin coated polymer layer on the transparent waveguide substrate surface that may be embossed by a master mold and cured by UV light (nano-imprinting), or exposed to UV through a mask and etched via a chemical process that discriminates between exposed and unexposed areas (nano-lithography), so as to form nanometer-sized patterns able to diffract light in a controlled manner.
Data Source
AI summary
An encapsulated waveguide system for a near eye optical display includes a first outer layer, a second outer layer, at least one waveguide substrate comprising an input area and an output area, a first spacer and a sealing element. The at least one waveguide substrate is disposed between the first and second outer layers and spaced therefrom by the first spacer. The sealing element joins edges of the first and second outer layers so as to encapsulate the at least one waveguide substrate within a cavity formed by the first and second outer layers. The formed cavity includes a first cavity between the at least one waveguide substrate and the first outer layer and a second cavity between the at least one waveguide substrate and the second outer layer.