Waveguide Display Grating Beam Splitting and Polarization Control
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Solution Overview
Problem
Waveguide-based display systems face challenges in maintaining image quality and providing effective beam expansion while allowing users to see both virtual images and real-world views, with existing technologies struggling to optimize beam distribution and polarization control for enhanced image clarity and wider field of view.
Innovation Solution
The display system incorporates an optical waveguide with an incoupling grating, an intermediate grating, and an exit grating, where the polarization state of each beam is controlled by a dynamically variable retarder film, enabling multiple parallel versions of each input beam to be diffracted outwardly, forming a virtual image that can be viewed over a larger area without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If waveguide-based display systems use TIR mechanism with diffraction gratings for beam expansion, then the viewing area is expanded, but image quality deteriorates due to distortion and banding effects
Solution Approach 1:
The waveguide is divided into multiple functional zones with distinct gratings: incoupling grating for beam entry, intermediate gratings for beam manipulation and polarization control, and exit grating for beam output. Each grating is optimized for its specific function to maintain image quality while achieving beam expansion.
Solution Approach 2:
Different regions of the waveguide have different optical properties and grating configurations tailored to local requirements. The incoupling region, intermediate expansion regions, and exit region each have specialized structures that optimize performance for their specific function while maintaining overall image quality.
2Ease of operation
If multiple parallel versions of beams are created through intermediate gratings, then the virtual image visibility is improved, but device complexity increases
Solution Approach 1:
Multiple functions are merged into the waveguide structure: beam splitting, polarization control, and beam expansion are all achieved within the single waveguide component using integrated gratings and retarder films, eliminating the need for separate external optical components.
Solution Approach 2:
The system uses dynamically adjustable retarder films that can change their optical properties in response to control signals, allowing the waveguide to adaptively optimize beam manipulation and polarization control for different viewing conditions and image requirements.
3Manufacturing precision
If polarization state is controlled by retarder film, then image clarity is improved, but manufacturing complexity increases
Solution Approach 1:
The retarder films are designed with specific optical parameters (retardation values, orientation angles) that are precisely controlled during fabrication. By optimizing these parameters, the system achieves superior image clarity and polarization control while maintaining compatibility with standard waveguide manufacturing processes.
4Area of stationary object
If beam expansion is achieved through multiple gratings, then eye box area is increased, but light loss increases
Solution Approach 1:
The system replaces traditional mechanical beam expansion methods with optical diffraction gratings that manipulate light through wave-optical effects. This substitution enables more efficient beam expansion with reduced light loss compared to mechanical alternatives, as the gratings redirect light through controlled diffraction rather than physical obstruction or absorption.
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 configuration enhances image quality and expands the viewing area, allowing users to see virtual images and real-world views simultaneously with improved clarity and reduced banding effects, while maintaining high modular transfer function performance.
Implementation Method 1
the incoupling grating is arranged to couple each beam into the intermediate grating, in which that beam is guided onto multiple splitting regions of the intermediate grating
Implementation Method 2
the intermediate grating is arranged to split that beam at the splitting regions to provide multiple substantially parallel versions of that beam
Implementation Method 3
the exit grating is arranged to diffract the multiple versions of that beam outwardly, the multiple input beams thus causing multiple exit beams to exit the waveguide which form a version of the virtual image
Implementation Method 4
a polarization state of each beam interacting with the modulations forming the intermediate grating on the first surface of optical waveguide is controlled by a retarder film on a second surface of the optical waveguide opposing the first surface
Implementation Method 5
a retarder film on a second surface of the optical waveguide opposing the first surface, and a retardation pattern of the retarder film is dynamically variable
Implementation Method 6
Waveguide-based display systems typically transport light from a light engine to the eye via a TIR (Total Internal Reflection) mechanism in a waveguide
Data Source
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Figure 3A
AI summary
A display system comprises an optical waveguide and a light engine. The light engine generates multiple input beams which form a virtual image. An incoupling grating of the waveguide couples each beam into an intermediate grating of the waveguide, in which that beam is guided onto multiple splitting regions. The intermediate grating, formed by modulations on a first surface of the waveguide, splits that beam at the splitting regions to provide multiple substantially parallel versions of that beam. Those multiple versions are coupled into an exit grating of the waveguide, in which the multiple versions are guided onto multiple exit regions. The exit grating diffracts the multiple versions of that beam outwardly. The multiple input beams thus cause multiple exit beams to exit the waveguide which form a version of the virtual image. A polarization state of each beam interacting with the modulations is controlled by a retarder film.