Light-Guide Optical Element for Wide Field-of-View Head-Mounted Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compact optical display devices face challenges in achieving a wide field-of-view and large eye-motion-box, leading to bulky designs and poor image quality, especially in head-mounted and mobile applications, where they are impractical and inconvenient due to sensitivity to optical system movements and limited pupil motion.
Innovation Solution
A compact light-guide optical element with a light-transmitting substrate and external light coupling means, utilizing a combination of reflecting surfaces and optical elements like relay prisms and polarizing beamsplitters to achieve total internal reflection and minimize the overall size and weight of the optical module, allowing for a wide field-of-view and large eye-motion-box while maintaining high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional free-space optical module is used to achieve a wide field-of-view, then the imaging quality is improved, but the device becomes larger, heavier and bulkier
Solution Approach 1:
The patent combines the optical module functions (imaging lens and combiner) into a single integrated light-guide element. The light-transmissive substrate integrates multiple optical surfaces including a collimating lens surface and a combiner surface, eliminating the need for separate optical components and reducing overall device weight and size while maintaining wide field-of-view capability
Solution Approach 2:
The patent transitions from a conventional three-dimensional free-space optical module to a two-dimensional planar light-guide structure. By embedding optical surfaces within a thin light-transmissive substrate, the system achieves compact form factor suitable for head-mounted displays while preserving optical performance
2Illumination intensity
If the field-of-view is increased, then the imaging quality is improved, but the device size increases making it impractical for head-mounted applications
Solution Approach 1:
The patent merges the collimating lens and combiner into a single integrated light-guide element. The light-transmissive substrate contains both the collimating lens surface and the combiner surface, allowing wide field-of-view imaging while maintaining a compact form factor suitable for head-mounted displays
Solution Approach 2:
The patent embeds wide field-of-view optical surfaces within a thin two-dimensional planar substrate. By transitioning from a bulky three-dimensional optical module to a flat light-guide structure, the system achieves wide field-of-view capability without increasing device area
3Reliability
If conventional optical designs are used, then the optical performance is adequate, but the eye-motion-box is very small making the system sensitive to movements
Solution Approach 1:
The patent creates a large eye-motion-box by designing the combiner surface and light guide structure to provide uniform optical performance across a wide area. The local optical properties are optimized to maintain image quality and allow sufficient pupil motion range, reducing sensitivity to eye movements and improving ease of operation
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 enables the creation of compact, high-quality optical systems with wide field-of-view and large eye-motion-box, suitable for head-mounted and mobile applications, reducing the system's bulkiness and improving image quality, enabling the viewing of digital content on small devices like cellular phones.
Implementation Method 1
optical means having an output aperture for coupling light into said substrate by total internal reflection
Data Source
AI summary
An optical device, includes a light-transmitting substrate having an input aperture and first and second major surfaces parallel to each other and edges, one partially reflecting surface located in the substrate which is non-parallel to the major surfaces of the substrate and an external optical arrangement having an output aperture optically attached to the input aperture of the substrate with the part of the substrate located next to the substrate input aperture, being substantially transparent.