Waveguide Display Interface for Uniform Wide Field-of-View Imaging
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Solution Overview
Problem
Conventional compact optical display devices suffer from large field-of-view limitations, bulkiness, and sensitivity to eye movements, leading to poor image quality and practical impracticality, especially in head-mounted applications.
Innovation Solution
A compact optical device using a light-transmitting substrate with refractive index, two major surfaces, and edges, coupled with optical elements for total internal reflection and beam-splitting arrangements, utilizing optical adhesives with different refractive indices to achieve uniform light distribution and mixing of rays within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional free-space optical module is used to increase field-of-view, then the field-of-view increases, but the device becomes larger, heavier and bulkier
Solution Approach 1:
The patent combines multiple optical functions (collimation, reflection, beam expansion, and image projection) into a single integrated waveguide substrate. The waveguide acts as both the optical path carrier and the beam expander, eliminating the need for separate free-space optical components and reducing overall device volume while maintaining wide field-of-view capability.
Solution Approach 2:
The patent transitions from conventional two-dimensional display projection to three-dimensional volumetric light field manipulation within the waveguide. By utilizing the waveguide's thickness dimension and creating multiple internal reflection paths, the system achieves wide field-of-view without increasing the lateral footprint of the device.
2Volume of moving object
If compact optical solutions are implemented to reduce device size, then device compactness improves, but manufacturing complexity increases and eye-motion-box becomes very small
Solution Approach 1:
The waveguide substrate performs multiple functions simultaneously: it guides light from the display source, expands the beam width, provides total internal reflection for compact folding of optical paths, and projects the final image. This multi-functionality reduces the number of separate components needed, simplifying manufacturing while achieving compact form factor and adequate eye-motion-box.
3Volume of moving object
If compact optical solutions are implemented, then device size reduces, but the eye-motion-box becomes very small making the system sensitive to eye movements
Solution Approach 1:
The patent creates a dynamic light field distribution within the waveguide that adapts to different eye positions. The waveguide's internal reflection geometry and beam expansion characteristics are designed to maintain adequate illumination and image quality across a range of pupil positions, effectively increasing the functional eye-motion-box while keeping the device compact.
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
Enables wide field-of-view and large eye-motion-box with high-quality images, accommodating pupil movements and providing a physically compact display suitable for mobile devices.
Implementation Method 1
an optical element for coupling light waves into the substrate for effecting total internal reflection
Implementation Method 2
light waves coupled inside the substrate are partially reflected from the interface plane and partially pass through it, wherein the refractive index of the optical adhesive is different than the refractive index of the light transmitting substrate
Data Source
AI summary
There is provided an optical device, including a light-transmitting substrate having a refractive index, at least two major surfaces and edges, an optical element for coupling light waves into the substrate for effecting total internal reflection, at least one element carried by the first substrate for coupling light waves out of the substrate, and a first transparent plate, having at least two major surfaces, one of the major surfaces of the first transparent plate being optically cemented, with a first optical adhesive having a refractive index, to one of the major surfaces of the light-transmitting substrate, defining a first interface surface, light waves coupled inside the substrate are partially reflected from the interface plane and partially pass through it, wherein the refractive index of the optical adhesive is different than the refractive index of the light transmitting substrate.