Image-Directing Light Guides for Compact Aperture Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing near-eye display systems face challenges in miniaturization and cost-effective manufacturing due to the reliance on embedded partial reflectors or diffractive patterns for optical aperture expansion, which require precise cutting and polishing of rectangular light guides.
Innovation Solution
An optical system utilizing a partial-internal-reflection rectangular light guide (PRLG) with a partially-reflecting coating and external partially-reflecting surfaces for light redirection, coupled with a second light guide portion and a coupling-out configuration, allows for efficient optical aperture expansion without embedded facets, enabling easier manufacturing and reduced geometrical constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If embedded partial reflectors or diffractive patterns are used for optical aperture expansion, then image conveyance function is achieved, but manufacturing complexity and cost increase due to precise cutting and polishing requirements
Solution Approach 1:
The patent extracts the partial reflector function from the light guide body and implements it as a separate coating layer on the light guide surface. This allows the light guide to be manufactured without precise cutting and polishing of embedded reflectors, while still achieving the required optical aperture expansion through the applied coating
Solution Approach 2:
The patent introduces a coating layer as an intermediary element that provides the partial reflection function. This coating acts as a mediator between the light guide structure and the optical function, eliminating the need for complex embedded reflector structures while maintaining the desired optical performance
2Area of stationary object
If rectangular light guides with embedded partial reflectors are used, then optical aperture expansion is achieved, but device size increases due to geometrical constraints
Solution Approach 1:
The patent transitions from embedded three-dimensional reflector structures to two-dimensional surface coatings for achieving partial reflection. This dimensional reduction allows for more compact device integration while maintaining the optical aperture expansion function, thereby reducing the overall device volume
3Reliability
If precise cutting and polishing of rectangular light guides is performed, then optical performance is improved, but manufacturing cost and time increase
Solution Approach 1:
The patent applies the partial reflecting coating as a preliminary step before final assembly, allowing the light guide to be manufactured with standard precision rather than requiring post-manufacturing precise cutting and polishing. This preliminary coating application ensures optical performance while enabling more efficient manufacturing processes
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 achieves compact and cost-effective optical aperture expansion, allowing for miniaturized near-eye displays with improved manufacturing precision and flexibility, while maintaining image quality and reducing manufacturing costs.
Implementation Method 1
the first, second and third major surfaces supporting internal reflection for a range of incident angles
Implementation Method 2
at least part of the fourth major surface provided with a non-diffractive, partially-reflecting coating
Implementation Method 3
the second light guide portion containing a set of planar, mutually-parallel, partially-reflecting surfaces located between, and non-parallel to, the pair of major surfaces
Implementation Method 4
the third light guide portion including a coupling-out configuration deployed for coupling-out the light beams propagating within the third light guide portion by internal reflection
Data Source
AI summary
An optical system includes a partial-internal-reflection rectangular light guide (PRLG) (10) having three surfaces supporting internal reflection and a partially-reflecting fourth surface (34) with which a second light guide portion (30) is associated. A light beam redirecting arrangement, typically including a set of embedded partially-reflecting surfaces (12), in light guide portion (30) redirects light emerging from the PRLG towards a third light guide portion (20) that includes a coupling-out configuration (122), such as a further set of partially-reflecting surfaces (28), coupling-out light beams of an image towards the eye of a user.