Volumetric Phase Diffractive Elements for Robust Waveguide Optics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies for displaying virtual content in virtual or augmented reality rely on complex and costly surface relief type diffractive elements, which are fragile and prone to damage or contamination.
Innovation Solution
The use of volumetric phase diffractive elements, which can be manufactured in a more robust and cost-effective manner without the need for lithographic and etching processes, and can be arranged in various configurations to serve their intended purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface relief type diffractive elements are used, then pupil expansion and virtual content display functions are achieved, but manufacturing cost increases and structural fragility worsens
Solution Approach 1:
The patent changes the fundamental parameter of diffractive element structure from surface relief to volume phase, transforming the physical state from two-dimensional surface patterns to three-dimensional embedded structures within the waveguide substrate. This parameter change achieves both improved durability (no fragile surface microstructures) and simplified manufacturing (direct writing without lithography/etching).
Solution Approach 2:
The patent replaces the mechanical lithographic and etching processes with a direct writing method that uses optical or electron beam writing to create volume phase diffractive elements. This substitution eliminates complex manufacturing steps while achieving the same optical functionality, resolving the contradiction between manufacturing ease and structural reliability.
2Ease of manufacture
If surface relief type diffractive elements are used, then pupil expansion function is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the multi-step mechanical lithographic process with direct optical or electron beam writing. This substitution reduces manufacturing cost by eliminating reticle fabrication, photoresist coating, and chemical etching steps, while maintaining or improving diffractive pattern precision through direct digital writing methods.
Solution Approach 2:
The patent uses direct writing to create the diffractive pattern directly in the waveguide substrate without requiring physical reticles or masks. This copying method eliminates the need for expensive reticle fabrication and transfer processes, reducing manufacturing cost while preserving pattern precision through direct digital fabrication.
3Reliability
If surface relief type diffractive elements are used, then virtual content display is achieved, but vulnerability to damage and contamination increases
Solution Approach 1:
The patent changes the structural parameter from surface-level relief features to volume-embedded phase modulations. This parameter change protects the diffractive pattern from surface contamination and physical damage, as the optical function is distributed throughout the bulk material rather than confined to vulnerable surface features.
Solution Approach 2:
The patent replaces complex lithographic and etching manufacturing systems with direct writing systems. This substitution reduces device complexity by eliminating multiple processing steps, cleanroom requirements, and intermediate materials, while achieving the same protective effect of embedding the diffractive pattern within the substrate.
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 the production of stereoscopic images for virtual reality and augmented reality systems with enhanced durability and reduced manufacturing costs, while maintaining effective pupil expansion and out-coupling functions.
Implementation Method 1
diffractive elements to redirect light beams from an image source
Implementation Method 2
a waveguide to propagate the light beams
Data Source
Figure 1A~1C
Figure 1D
Figure 1E
AI summary
Several unique configurations for interferometric recording of volumetric phase diffractive elements with relatively high angle diffraction for use in waveguides are disclosed. Separate layer EPE and OPE structures produced by various methods may be integrated in side-by-side or overlaid constructs, and multiple such EPE and OPE structures may be combined or multiplexed to exhibit EPE/OPE functionality in a single, spatially-coincident layer. Multiplexed structures reduce the total number of layers of materials within a stack of eyepiece optics, each of which may be responsible for displaying a given focal depth range of a volumetric image. Volumetric phase type diffractive elements are used to offer properties including spectral bandwidth selectivity that may enable registered multi-color diffracted fields, angular multiplexing capability to facilitate tiling and field-of-view expansion without crosstalk, and all-optical, relatively simple prototyping compared to other diffractive element forms, enabling rapid design iteration.