Polarization Selective Light Guide Expands Field of View
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Solution Overview
Problem
Conventional light guide display systems have limitations in providing an expanded field of view (FOV) due to the restricted propagation angle of light within the guide, which affects the usability in applications like virtual and augmented reality.
Innovation Solution
The use of a light guide display assembly that incorporates polarization selective elements, such as gratings and holographic elements, to couple and decouple light within the guide through total internal reflection, allowing for the expansion of the FOV by diffracting and redirecting light to achieve a larger output FOV compared to the input FOV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional light guide display systems are used, then the structure is simple, but the field of view (FOV) is limited due to restricted light propagation angle
Solution Approach 1:
The patent divides the light guide system into multiple light guides (first light guide and second light guide) with separate in-coupling and out-coupling elements for each. This segmentation allows independent optimization of each light guide's light propagation path, enabling expanded FOV while maintaining manageable structural complexity through modular design
Solution Approach 2:
The patent uses polarization selective elements to manipulate light in the polarization dimension, creating non-overlapping output FOVs from different light guides. By exploiting the polarization degree of freedom, the system expands the effective FOV without proportionally increasing the physical footprint, effectively adding a dimensional aspect to FOV expansion
2Area of stationary object
If polarization selective elements are added to expand FOV, then the field of view increases, but the device complexity and material costs increase
Solution Approach 1:
The polarization selective elements serve multiple functions: they couple light into the light guide, maintain total internal reflection for FOV expansion, and decouple light at the output. This multi-functionality reduces the need for separate components, simplifying manufacturing despite the advanced optical functionality required for expanded FOV
Solution Approach 2:
The patent changes the polarization state parameter of light as it propagates through the light guide system. By utilizing polarization transformation and selective coupling based on polarization states, the system achieves FOV expansion through parameter manipulation rather than complex structural modifications, making the system more manufacturable
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 approach effectively doubles the FOV provided by the light guide display assembly, enabling a wider field of view while maintaining a compact form factor and reducing material costs and weight, suitable for applications in virtual and augmented reality.
Implementation Method 1
couple and decouple light within the guide through total internal reflection
Implementation Method 2
diffracting and redirecting light to achieve a larger output FOV compared to the input FOV
Data Source
AI summary
A device includes a light guide. The device also includes a first in-coupling element configured to couple a first input light into the light guide, and a first out-coupling element configured to couple the first input light out of the light guide as a first output light having a first output field of view (“FOV”). The device also includes a second in-coupling element configured to couple a second input light into the light guide. The device further includes a second out-coupling element configured to couple the second input light out of the light guide as a second output light having a second output FOV substantially non-overlapping with the first output FOV. A combination of the first and second output FOVs is larger than at least one of the first or second output FOV, and the first and second input lights have orthogonal polarizations.