Wedge Light Guide with Polarization Selective Redirector
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Solution Overview
Problem
Conventional head-mounted display devices are limited by their size and weight, which restricts their application and user satisfaction.
Innovation Solution
The use of a compact and lightweight optical design featuring a polarization selective redirector and a wedge-shaped light guide, allowing the light guide to operate as both a slab and a wedge, enabling more efficient light projection and reducing the device's overall size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wedge shaped light guide is used, then image breakup is reduced, but the light guide length increases
Solution Approach 1:
The patent embeds a polarization selective redirector inside the light guide structure, allowing the light guide to function as both a slab and a wedge. This nested configuration enables the light guide to achieve wedge functionality without requiring the entire light guide to be a wedge shape, thus reducing the overall length while maintaining image quality.
Solution Approach 2:
The light guide is designed to dynamically change its functional state based on polarization. When receiving light from the projector, it operates as a slab; when receiving returned light with rotated polarization, it operates as a wedge. This dynamic functionality allows a single compact structure to perform what would traditionally require separate components, reducing overall length.
2Volume of moving object
If a slab light guide is used, then the light guide is compact, but image breakup occurs
Solution Approach 1:
The light guide dynamically switches between slab and wedge modes based on the polarization state of the incoming light. For projector light (first polarization), it functions as a compact slab; for returned light (second polarization), it functions as a wedge to prevent image breakup. This dynamic adaptation allows a single compact structure to avoid image breakup without requiring a longer wedge-shaped light guide.
Solution Approach 2:
The patent changes the effective geometric parameters of the light guide by introducing a polarization selective redirector that redirects light based on its polarization state. This parameter change enables the same physical structure to present different optical paths depending on the incident light's polarization, maintaining compactness while preventing image breakup.
3Adaptability or versatility
If conventional light guide designs are used, then the device provides adequate functionality, but the device size and weight increase
Solution Approach 1:
The patent merges the functions of a slab light guide and a wedge light guide into a single integrated structure. By incorporating a polarization selective redirector, the same light guide performs both slab functionality (for projector light) and wedge functionality (for returned light), eliminating the need for separate components and reducing overall device weight.
Solution Approach 2:
The light guide is designed with universal functionality to handle both incoming projector light and returned light with different polarization states. The polarization selective redirector enables the light guide to adapt its behavior based on the incident light's polarization, providing multi-functionality in a single compact component that reduces overall 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
This design enables more compact and lightweight head-mounted display devices, improving user satisfaction and application flexibility by maintaining image quality while minimizing physical bulk.
Implementation Method 1
The polarization selective redirector is transparent to rays from the projector having a first polarization state but reflects rays in a second polarization state orthogonal to the first polarization state
Implementation Method 2
a polarization rotating redirector positioned at a slanted angle... The polarization selective redirector is transparent to rays from the projector having a first polarization state but reflects rays in a second polarization state orthogonal to the first polarization state
Data Source
AI summary
An optical device includes an optical assembly having a first end and a second end, the optical assembly including a first optical component and a second optical component, the first optical component having at least a first optical surface, a second optical surface, and a third optical surface that are non-parallel to one another. The first optical surface is curved and extends between the first end and the second end. A first polarization selective redirector is located between the first optical component and the second optical component, and a first polarization rotating redirector is disposed at the second end.