Optical Guide Extraction Microstructures for Finite-Distance Projection
Solution Overview
Problem
Existing optical guides project virtual images to infinity, causing convergence-accommodation conflict and requiring additional lenses that increase bulk and weight, leading to user discomfort.
Innovation Solution
An optical guide with a network of extraction microstructures having spherical active surfaces with controlled inclinations and semi-reflective coatings, integrated into the guide to project virtual images at a finite distance without additional lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If additional lenses are added to project virtual images at finite distance, then the virtual image can be projected at a finite distance, but the bulk and weight of the optical guide increase
Solution Approach 1:
The patent merges the image projection function with the optical guide structure itself. The extraction microstructures are integrated directly into the optical guide, eliminating the need for separate lenses. The microstructures serve dual purposes: guiding light through the optical guide and projecting the virtual image at a finite distance simultaneously.
Solution Approach 2:
The optical guide surface is segmented into multiple extraction microstructures with different inclinations. Each microstructure extracts light at a specific angle, and the collection of microstructures with varying inclinations works together to project the virtual image at a finite distance without requiring additional lenses.
2Ease of operation
If additional lenses are added to project virtual images at finite distance, then the virtual image can be projected at a finite distance, but the bulk of the optical guide increases
Solution Approach 1:
The patent merges the image projection function with the optical guide structure itself. The extraction microstructures are integrated directly into the optical guide, eliminating the need for separate lenses. The microstructures serve dual purposes: guiding light through the optical guide and projecting the virtual image at a finite distance simultaneously.
Solution Approach 2:
The patent solves the finite distance projection problem by introducing variation in the inclination angle of extraction microstructures across the optical guide surface. This angular dimensionality allows the system to project images at finite distances without adding physical depth through separate lenses.
3Device complexity
If conventional extraction microstructures are used, then the optical guide structure is simple, but the virtual image is projected to infinity causing convergence-accommodation conflict
Solution Approach 1:
Different regions of the optical guide surface have extraction microstructures with different inclination angles. This local variation in microstructure orientation allows different parts of the optical guide to contribute to projecting the virtual image at a finite distance, resolving the convergence-accommodation conflict while maintaining overall structural simplicity.
Solution Approach 2:
The extraction microstructures are designed with asymmetric inclination angles rather than uniform symmetric structures. This asymmetry in the microstructure arrangement enables the optical guide to project virtual images at finite distances, eliminating the convergence-accommodation conflict that occurs with conventional symmetric designs.
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 allows for compact, low-cost projection of virtual images at a finite distance, improving user comfort by eliminating convergence-accommodation conflict and reducing bulk.
Implementation Method 1
each active surface being spherical and having a lower inclination by an average angle θ than the possible active surface immediately preceding in the succession of microstructures according to the direction of propagation of the virtual image in the optical guide
Implementation Method 2
An optical guide is formed from a transparent material (plastic, glass) and is used to transport, by successive internal reflections, light signals constituting a virtual image injected from an injection zone to an extraction zone
Data Source
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AI summary
An optical guide (400) comprising a first part made of a transparent material, the first part having on its surface an array of extraction microstructures composed of a succession of extraction microstructures arranged to project an image injected into the optical guide (400) to a finite distance D. Each extraction microstructure has a prismatic shape with two faces, one face being called the active surface and having a semi-reflective coating to extract the image from the optical guide, and the other face being called the passive surface and having no semi-reflective coating. Each active surface (401b) is spherical and has a smaller inclination by a mean angle θ than the immediately preceding active surface (401a) in the succession of microstructures along the direction of image propagation in the optical guide (400).