Single-Layer Holographic Waveguide for Full-Color Beam Expansion
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Solution Overview
Problem
Existing waveguide displays face challenges in implementing full color displays efficiently due to the difficulty in aligning separate red, green, and blue waveguide layers, which are costly and prone to low yield, and single grating configurations struggle to operate over the full visual spectral bandwidth.
Innovation Solution
A waveguide display is designed with a single grating layer that includes a source of data-modulated light, input couplers, and multiplexed fold gratings to direct and beam-expand different spectral bands orthogonally, utilizing a single exposure process to reduce complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate red, green, and blue waveguide layers are used to implement full color displays, then color display capability is improved, but manufacturing complexity and alignment difficulty increase significantly
Solution Approach 1:
The patent combines multiple spectral band handling capabilities into a single waveguide layer by multiplexing different gratings (first grating for first spectral band, second grating for second spectral band) within the same layer, eliminating the need for separate red, green, and blue waveguide layers while maintaining full color display capability
Solution Approach 2:
The single waveguide layer is designed to perform multiple functions simultaneously: it handles different spectral bands through different gratings, provides beam expansion in multiple directions, and enables full color display, making the structure universal and multi-functional rather than requiring specialized separate layers for each function
2Manufacturing precision
If multiple waveguide layers are used for full color displays, then color accuracy is improved, but manufacturing yield decreases due to alignment challenges
Solution Approach 1:
By merging all spectral band handling into a single waveguide layer with multiplexed gratings, the patent eliminates the alignment challenges between multiple layers while maintaining the ability to accurately handle different spectral bands for full color display, thus improving manufacturing yield without sacrificing color accuracy
3Device complexity
If a single grating configuration is used in a waveguide, then device simplicity is improved, but the ability to operate over the full visual spectral bandwidth is limited
Solution Approach 1:
The single grating layer is designed with multi-functionality by incorporating multiple gratings (first grating, second grating) that can handle different spectral bands respectively, allowing the simple single-layer structure to operate over the full visual spectral bandwidth through the multiplexed grating configuration
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 reduces manufacturing complexity and cost by eliminating the need for multiple layers, improving yield, and enabling efficient two-dimensional beam expansion and light extraction for full color displays.
Implementation Method 1
planar waveguides can be designed to utilize diffraction gratings to diffract and couple incident light into the waveguide structure
Implementation Method 2
the in-coupled light can proceed to travel within the planar structure via total internal reflection (TIR)
Implementation Method 3
the monomers polymerize and the mixture undergoes a photopolymerization-induced phase separation, creating regions densely populated by liquid crystal micro-droplets
Implementation Method 4
the mixture undergoes a photopolymerization-induced phase separation, creating regions densely populated by liquid crystal micro-droplets, interspersed with regions of clear polymer
Implementation Method 5
A least one fold grating for directing the first spectral band along a first path from the first pupil to the output coupler which provides a first beam expansion
Data Source
AI summary
A waveguide display comprises: a waveguide supporting a single grating layer; a source of data-modulated light; a first input coupler for directing a first spectral band of light from the source into a first waveguide pupil; a second input coupler for directing a second spectral band of light from the source into a second waveguide pupil; an output coupler comprising multiplexed first and second gratings, at least one fold grating for directing the first spectral band along a first path from the first pupil to the output coupler and providing a first beam expansion; at least one fold grating for directing the second spectral band along a second path from the second pupil to the output coupler and providing a first beam expansion. The first multiplexed grating directing the first spectral band out of the waveguide in a first direction with beam expansion orthogonal to the first beam expansion. The second multiplexed grating directing the second spectral band out of the waveguide in the first direction with beam expansion orthogonal to the first beam expansion.