Transparent Waveguide Display With Passive SBG Grating Laminae for Wide FOV
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Solution Overview
Problem
Current transparent displays, particularly helmet-mounted displays, face challenges in achieving a compact, lightweight, and unobtrusive design that provides a panoramic see-through view with high-resolution, wide-field-of-view imagery while maintaining situational awareness, due to limitations in waveguide optics that constrain the field of view and digital resolution.
Innovation Solution
A transparent display apparatus utilizing Substrate Guided Optics (SGO) and Switchable Bragg Gratings (SBGs) with thin layers and passive mode operation, allowing for efficient light propagation and extraction, and a novel configuration of optical substrates to expand the field of view and improve digital resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional waveguide optics are used, then the display can be made compact and lightweight, but the field of view and digital resolution are constrained
Solution Approach 1:
The waveguide is divided into multiple functional layers including input coupling layer, core layer, and output coupling layer, with additional beam expander layers. This segmentation allows each layer to perform specific optical functions independently, enabling compact form factor while achieving wide field of view through coordinated operation of segmented components.
Solution Approach 2:
The patent introduces vertical beam expansion by stacking multiple waveguide layers in the vertical dimension. This allows the field of view to be expanded not just horizontally but also vertically, effectively utilizing the third dimension to overcome the limitations of conventional planar waveguide designs.
2Volume of moving object
If conventional waveguide optics are used, then the display can be made compact, but the pixel resolution is limited
Solution Approach 1:
The optical path is segmented into multiple precise layers with controlled thicknesses and refractive indices. This segmentation enables independent optimization of each layer for resolution enhancement, allowing high pixel resolution to be achieved within a compact form factor through precise manufacturing of individual layers.
Solution Approach 2:
The patent utilizes changes in refractive index parameters across different layers to achieve beam expansion and resolution enhancement. By carefully controlling the refractive index profile through material selection and layer thickness variation, high pixel resolution is achieved without increasing the overall display volume.
3Quantity of substance
If reflective or diffractive visors are used for see-through displays, then transparency is achieved, but the form factor becomes cumbersome
Solution Approach 1:
The patent extracts the light guiding function from bulky external visors and integrates it into a thin waveguide layer that can be positioned close to the eye. This extraction eliminates the need for large reflective or diffractive visors while maintaining see-through transparency, resulting in a compact and lightweight form factor.
Solution Approach 2:
The waveguide is implemented as a thin film structure with multiple functional layers, replacing the need for thick rigid visors. This thin-film approach maintains optical transparency while achieving compact form factor, as the waveguide can be made only a few hundred micrometers thick while still performing all necessary optical functions.
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
The solution enables a compact, lightweight display with a generous exit pupil, adequate eye relief, and high-resolution imagery, overcoming the limitations of conventional waveguide technologies by expanding the field of view and improving pixel resolution without increasing thickness or complexity.
Implementation Method 1
a first optical substrate comprising at least one waveguide layer configured to propagate light
Implementation Method 2
comprises at least one grating lamina configured to extract the light from the first substrate along the first direction
Implementation Method 3
The at least one grating lamina of at least one of the first and second optical substrates may comprise an SBG in a passive mode
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.