Multi-layer Diffractive Eyepiece Mitigating Optical Artifacts
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Solution Overview
Problem
Existing augmented reality display systems face challenges in reducing optical artifacts, such as ghost images, and improving heat management, which affects the reliability and performance of the systems.
Innovation Solution
The implementation of an optical device with a frame, temperature monitoring system, display assembly, and processor that adjusts the display output based on heat distribution, along with a projector assembly, imaging optics, and an eyepiece with diffractive optics and polarizing elements to mitigate optical artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If diffractive optics are used to redirect light in the eyepiece, then optical artifacts such as ghost images are reduced, but the device complexity increases due to the need for precise diffractive element fabrication and alignment
Solution Approach 1:
The diffractive optical element is segmented into multiple layers with each layer containing diffractive features at different positions and orientations. This segmentation allows the complex diffractive function to be distributed across multiple simpler layers, reducing the fabrication difficulty and alignment requirements compared to a single complex element.
Solution Approach 2:
Multiple diffractive layers are nested within the eyepiece structure, with each layer contributing to the overall light redirection function. The layers are positioned at different depths and orientations, creating a compact multi-layer structure that achieves complex optical functionality without proportionally increasing device complexity.
2Temperature
If heat dissipation features are added to the frame, then thermal management improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The heat dissipation features are merged with the existing frame structure rather than being separate add-on components. The frame serves dual purposes: structural support and thermal management, which reduces the total number of parts and simplifies manufacturing processes.
Solution Approach 2:
The frame material properties are modified to enhance thermal conductivity in specific directions. By changing the material parameters (such as using anisotropic materials or composite structures), the frame achieves improved heat dissipation without requiring complete structural redesign, thus maintaining ease of manufacture.
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 solution effectively reduces optical artifacts, improves heat management, and enhances the overall performance and reliability of augmented reality display systems, leading to improved image quality and user comfort.
Implementation Method 1
The viewing optics assembly includes a waveguide and a diffractive optical element positioned within the waveguide. The diffractive optical element is configured to redirect the injected light into the waveguide and outcoupled light toward the eye of a user.
Implementation Method 2
an artifact prevention element disposed between the set of imaging optics and the eyepiece. The artifact prevention element includes a linear polarizer, a first quarter waveplate disposed adjacent the linear polarizer
Implementation Method 3
a temperature monitoring system configured to monitor a distribution of heat within the frame
Implementation Method 4
a heat distribution system for directing heat generated by the optical device to heat dissipation regions of the optical device
Data Source
AI summary
An eyepiece includes a planar waveguide having a front surface and a back surface. The eyepiece also includes a grating coupled to the back surface of the planar waveguide and configured to diffract a first portion of the light propagating in the planar waveguide out of a plane of the planar waveguide toward a first direction and to diffract a second portion of the light propagating in the planar waveguide out of the plane of the planar waveguide toward a second direction opposite to the first direction and a wavelength-selective reflector coupled to the front surface of the planar waveguide. The wavelength-selective reflector comprises a multilevel metasurface comprising a plurality of spaced apart protrusions having a pitch and formed of a first optically transmissive material and a second optically transmissive material disposed between the spaced apart protrusions.