Transparent Waveguide Display Using SBGs for Wider Field of View
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Solution Overview
Problem
Current transparent displays, particularly those using waveguide optics, are limited by the range of internal angles that can propagate light, constraining the field of view and digital resolution, and face inefficiencies in coupling input image into waveguides, leading to thick waveguides and complex optical designs.
Innovation Solution
The use of Substrate Guided Optics (SGO) combined with Switchable Bragg Gratings (SBGs) that are thin and operate in both passive and switching modes, allowing for efficient light propagation and extraction, and a novel method of interlacing or tessellating SBGs to expand the field of view and improve digital resolution without the need for multiple layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional waveguide optics are used to provide see-through display, then transparency is achieved, but field of view and digital resolution are limited due to constraints on internal light propagation angles
Solution Approach 1:
The patent divides the waveguide into multiple discrete grating laminae layers, each capable of extracting light at different angles. This segmentation allows the system to overcome the single-angle limitation of conventional waveguides by providing multiple extraction points, thereby expanding the field of view while maintaining transparency through the waveguide substrate.
Solution Approach 2:
The patent transitions from single-layer to multi-layer waveguide architecture, adding the vertical dimension (z-axis) of layer stacking. This dimensional expansion enables light extraction at multiple angles simultaneously through different layers, effectively expanding the field of view without compromising the transparency function of individual layers.
2Illumination intensity
If conventional waveguide optics are used, then transparency is maintained, but digital resolution is constrained by the limited range of internal propagation angles
Solution Approach 1:
By segmenting the waveguide into multiple grating laminae layers with different orientation angles, the patent enables higher digital resolution. Each layer contributes to resolving fine details at specific angles, and the combination of multiple layers provides comprehensive high-resolution coverage across the expanded field of view while preserving transparency.
3Adaptability or versatility
If multiple layers are used to expand field of view and improve resolution, then performance is enhanced, but waveguide thickness and device complexity increase
Solution Approach 1:
The patent employs thin-film grating laminae structures that can be deposited or integrated into the waveguide substrate. These thin-film gratings provide the necessary optical extraction functionality while minimizing the thickness added to the waveguide, thus expanding field of view without significantly increasing overall device thickness.
Solution Approach 2:
The patent integrates multiple grating laminae layers within a compact waveguide structure, nesting the functional layers within the substrate thickness. This nesting approach allows multiple layers to coexist in a space-efficient manner, expanding field of view and resolution while keeping the overall waveguide thickness manageable.
4Ease of operation
If conventional coupling methods are used to input images into waveguides, then image display is achieved, but coupling efficiency is low leading to thick waveguides and complex optical designs
Solution Approach 1:
The patent replaces complex mechanical coupling optics with diffractive grating laminae structures that directly couple light into the waveguide at the desired angles. This substitution of mechanical optical systems with diffractive elements simplifies the overall optical design, improves coupling efficiency, and reduces the complexity of image input mechanisms while maintaining ease of operation.
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 enables a compact, lightweight display with a larger field of view and high digital resolution, reducing thickness and complexity while maintaining high transparency and ergonomic comfort, suitable for applications like helmet-mounted displays and automotive HUDs.
Implementation Method 1
Light propagates along a waveguide only over a limited range of internal angles. Light propagating parallel to the surface will (by definition) travel along the waveguide without bouncing. Light not propagating parallel to the surface will travel along the waveguide bouncing back and forth between the surfaces, provided the angle of incidence with respect to the surface normal is greater than some critical angle.
Implementation Method 2
a first optical substrate comprising at least one waveguide layer configured to propagate light in a first direction, wherein the at least one waveguide layer of the first optical substrate comprises at least one grating lamina configured to extract the light from the first substrate along the first direction
Implementation Method 3
The use of Substrate Guided Optics (SGO) combined with Switchable Bragg Gratings (SBGs) that are thin and operate in both passive and switching modes
Data Source
AI summary
One embodiment provides an apparatus for displaying an image comprising: a first optical substrate comprising at least one waveguide layer configured to propagate light in a first direction, wherein the at least one waveguide layer of the first optical substrate comprises at least one grating lamina configured to extract the light from the first substrate along the first direction; and a second optical substrate comprising at least one waveguide layer configured to propagate the light in a second direction, wherein the at least one waveguide layer of the second optical substrate comprises at least one grating lamina configured to extract light from the second substrate along the second direction; wherein the at least one grating lamina of at least one of the first and second optical substrates comprises an SBG in a passive mode.