Bragg Waveguide Architecture for Wider HUD Field of View
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Solution Overview
Problem
Existing waveguide displays face challenges in achieving large fields of view and efficient light propagation while minimizing volumetric requirements, particularly in applications like near-eye displays and head-up displays.
Innovation Solution
The use of waveguides incorporating holographic polymer dispersed liquid crystal (HPDLC) layers with input and output gratings, along with fold gratings, to guide light via total internal reflection, and optionally including multiplexed gratings and quarter wave coatings for polarization control, allows for enhanced light manipulation and expanded fields of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If waveguides use traditional grating structures to guide light, then light propagation is achieved, but the field of view remains limited and volumetric requirements are not minimized
Solution Approach 1:
The patent implements a folded waveguide architecture that extends the light propagation path in three-dimensional space by introducing fold gratings at angled orientations. This allows the optical path to fold back on itself, effectively increasing the field of view coverage area while containing the physical volume within compact boundaries through spatial dimension utilization
Solution Approach 2:
The waveguide structure embeds multiple functional grating layers (input gratings, fold gratings, output gratings) within a single waveguide substrate. These nested grating structures perform multiple optical functions sequentially, allowing the system to achieve expanded field of view while maintaining minimized volumetric requirements through integrated layering
2Area of stationary object
If waveguides incorporate multiple grating layers to expand field of view, then display performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple grating functions (input coupling, folding, output coupling) into a single integrated waveguide structure with embedded HPDLC layers. This merging of previously separate optical components into one unified element simplifies the manufacturing process by reducing the number of assembly steps while achieving the same expanded field of view effect
Solution Approach 2:
The waveguide employs composite HPDLC (holographic polymer dispersed liquid crystal) material layers that can be directly formed within the waveguide substrate during manufacturing. This composite material approach allows gratings to be created in-situ through photopolymerization processes, eliminating the need for separate grating fabrication and alignment steps, thereby reducing manufacturing complexity while enabling multiple grating layers
3Loss of energy
If waveguides use HPDLC layers with multiple gratings to manipulate light, then light propagation efficiency improves and diffraction losses are reduced, but device complexity increases
Solution Approach 1:
The patent utilizes HPDLC material parameters (refractive index modulation, liquid crystal droplet distribution) to create gratings with optimized diffraction characteristics. By controlling the photopolymerization process and liquid crystal orientation, the gratings achieve high diffraction efficiency with minimized losses, balancing the increased device complexity against improved energy retention
Solution Approach 2:
The patent replaces traditional mechanical alignment and adjustment mechanisms with holographically recorded grating structures formed directly in the HPDLC layers. This substitution of mechanical systems with optically encoded structures eliminates the need for precise mechanical positioning while achieving controlled light manipulation, thereby managing device complexity through non-mechanical solutions
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 configuration enables waveguides to provide larger fields of view with reduced volume, improving display performance in applications such as near-eye displays and head-up displays by optimizing light propagation and reducing diffraction losses.
Implementation Method 1
During the recording process, the monomers polymerize and the mixture undergoes a photopolymerization-induced phase separation, creating regions densely populated by liquid crystal micro-droplets, interspersed with regions of clear polymer
Implementation Method 2
planar waveguides can be designed to utilize diffraction gratings to diffract and couple incident light into the waveguide structure such that the in-coupled light can proceed to travel within the planar structure via total internal reflection
Implementation Method 3
planar waveguides can be designed to utilize diffraction gratings to diffract and couple incident light into the waveguide structure
Data Source
AI summary
Systems and methods for generating head-up displays (HUDs) using waveguides incorporating Bragg gratings in accordance with various embodiments of the invention are provided. The term HUD is typically utilized to describe a class of displays that incorporates a transparent display that presents data without requiring users to look away from their usual viewpoints. HUDs can be incorporated in any of a variety of applications including (but not limited to) vehicular and near-eye applications, such as googles, eyewear, etc. HUDs that utilize planar waveguides that incorporate Bragg gratings in accordance with various embodiments of the invention can achieve significantly larger fields of view and have lower volumetric requirements than HUDs implemented using conventional optical components.