Leaky Mode Light Deflection Structures for Bottom Exit
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Solution Overview
Problem
Leaky mode light systems face challenges with light exiting the edge rather than the bottom of devices, leading to thicker, more expensive, and harder-to-process devices, as well as difficulties in fabricating high spatial frequency gratings, which reduce the field of view and cause virtual points to shift when users move.
Innovation Solution
Incorporating light deflection structures within the leaky mode device to redirect light towards the bottom and divide it into different orders, using gratings, mirrors, or prisms, which can be laser-induced, allowing for internal structures and facilitating bottom exit without the need for complex grating fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light exits the edge of the device, then the device can be simpler in structure, but the device thickness increases and aperture efficiency decreases
Solution Approach 1:
The patent redirects light propagation from lateral edge exit to vertical bottom exit by introducing internal light deflection structures. This dimensional change in light path orientation allows devices to be stacked in two-dimensional arrays without blocking adjacent devices, solving the aperture efficiency problem while maintaining reasonable device thickness through optimized internal light routing.
Solution Approach 2:
The patent introduces internal light deflection structures (mirrors, prisms, or gratings) as intermediary elements within the device. These structures mediate the light path by reflecting or diffracting light toward the bottom exit, enabling compact device designs with reduced thickness while maintaining edge-free aperture performance.
2Ease of operation
If bottom exit gratings are used to direct light, then light can exit from the bottom, but the field of view is reduced
Solution Approach 1:
The patent segments the light path into multiple controlled segments using internal deflection structures. By dividing the light propagation into distinct stages (input coupling, internal deflection, output coupling), the system can optimize each segment independently to maintain wide field of view while achieving bottom exit configuration.
Solution Approach 2:
The patent employs adjustable parameters in the internal light deflection structures, such as variable grating periods, mirror angles, or prism geometries. By optimizing these parameters, the system achieves bottom exit light direction while preserving wide field of view through careful control of angular dispersion and spatial frequency mapping.
3Manufacturing precision
If high spatial frequency gratings are fabricated, then light can be effectively coupled, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent replaces complex high-precision mechanical grating fabrication with alternative approaches such as photonic crystal structures, layered material compositions, or self-assembled patterns. These substitutions achieve the required spatial frequency control through material properties and geometric arrangements rather than direct lithographic patterning, significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The patent transforms the grating design from high spatial frequency periodic structures to equivalent structures with lower spatial frequencies that achieve the same optical coupling effect. By changing the physical parameters (grating period, depth, material composition) while maintaining the functional outcome, the patent enables standard photolithographic processes to fabricate the required structures.
4Ease of operation
If bottom exit gratings are used, then light exits from the bottom, but virtual points shift when users move
Solution Approach 1:
The patent designs internal light deflection structures that perform multiple functions simultaneously: directing light to bottom exit, maintaining angular information for wide field of view, and preserving virtual point stability. The universal design accommodates different viewing angles and user positions while maintaining consistent virtual reality image registration.
Solution Approach 2:
The patent incorporates feedback mechanisms in the form of angularly-resolved light collection and processing that continuously adjusts the optical path to maintain stable virtual point positions. By monitoring and compensating for viewing angle variations, the system prevents virtual point shifting while maintaining bottom exit 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
Enables tiling of devices in two-dimensional arrays, increases the field of view, and stabilizes the perception of virtual points as users move, by redirecting light and splitting it into multiple orders that can be directed at different angles, enhancing the overall performance of leaky mode devices.
Implementation Method 1
surface acoustic waves ('SAW') for a leaky mode device are generated by a transducer that encodes electrical information as a pattern of surface acoustic waves. This surface acoustic wave pattern acts both to mode couple light so that it is no longer guided
Implementation Method 2
The structures may also be gratings, mirrors, prisms, or similar structures... divide the light from an illuminated SAW into different orders. In general, each order is light bent at a different angle
Implementation Method 3
The structures may also be gratings, mirrors, prisms, or similar structures
Data Source
AI summary
A method and system for using laser-induced structures to direct light to exit the bottom of a leaky mode device, and further to divide leaky mode light into multiple orders, and to implement one or more pulsing/strobing patterns such that a field of view is increased for a viewer, or the view zone is increased for a viewer. A leaky mode device may comprise a substrate, a surface acoustic wave (“SAW”) transducer, a waveguide having a higher refractive index than the substrate, an input region for input light, and laser induced structures such as grating. The SAW transducer may be positioned on a top surface of the substrate, and may be configured to emit a SAW wave to propagate across the substrate. The waveguide may be positioned below the SAW. The input wave region may be configured to couple light onto the waveguide. When light is coupled onto the waveguide, the refractive index may change such that the light in the waveguide exits the waveguide as leaky mode light and interacts with the laser-induced grating, which is below the waveguide. The laser-induced grating is configured to divide the leaky mode light into multiple orders, each bent at a different angle.