Foveated Near-Eye Optics Using Polarization Switching for Wide FOV
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Solution Overview
Problem
Conventional display technologies face challenges in achieving both high retinal resolution and a large field of view in a compact form factor, particularly in foveated near-eye displays.
Innovation Solution
A foveated near-eye display system utilizing a lens assembly with polarization selective and transmissive components, including a reflective polarization selective lens and a switchable half-wave plate, to provide two optical paths for peripheral and foveal views, enabling high resolution in the gaze direction and lower resolution in peripheral vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional display technologies are used, then high retinal resolution can be achieved, but the field of view is limited and form factor increases
Solution Approach 1:
The display is divided into two distinct optical paths: a first optical path for peripheral view and a second optical path for foveal view. This segmentation allows each path to be optimized independently - the peripheral path provides wide field of view while the foveal path delivers high retinal resolution, resolving the contradiction between these two requirements.
Solution Approach 2:
Different optical configurations are provided for different regions of the visual field. The peripheral region receives light through the first optical path with appropriate optical power for wide viewing, while the central foveal region receives light through the second optical path with different optical power for high resolution. This local differentiation allows each region to have optimal quality without compromising the other.
2Measurement precision
If high resolution display components are used, then retinal resolution improves, but device weight and form factor increase
Solution Approach 1:
The optical system is segmented into two paths that can use different optical components optimized for their specific function. The peripheral path can use lighter, simpler optics while the foveal path uses more sophisticated optics only where high resolution is needed, reducing overall weight compared to providing high resolution across the entire field of view.
Solution Approach 2:
High resolution is provided only where it is most needed (the foveal region) rather than uniformly across the entire display. This partial action approach delivers retinal resolution where it matters most while using fewer resources, thereby reducing device weight and form factor.
3Device complexity
If a single optical path is used, then device complexity is reduced, but both high resolution and large field of view cannot be achieved simultaneously
Solution Approach 1:
The system uses a polarization switch to selectively activate different optical paths based on the required function. This segmentation allows the system to maintain simplicity by using only one path at a time, while still achieving both high resolution and large field of view capabilities when needed through the available second path.
Solution Approach 2:
The optical system is made dynamic through the use of a polarization switch that can reconfigure which optical path is active. This dynamic switching allows the system to adapt between peripheral and foveal viewing modes, achieving both high angular resolution and large field of view without requiring both paths to be simultaneously complex.
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
The system achieves a small form factor, lightweight design with retinal resolution and a large field of view, enhancing user experience in artificial reality systems by delivering high angular resolution within a wide field of view.
Implementation Method 1
a reflective polarization selective lens configured to transmit a first polarization of light received from the display element along a first optical path and reflect a second polarization of light received from the display element
Implementation Method 2
a switchable half-wave plate configured to convert the second polarization of light to the first polarization when the switchable half-wave plate is switched to a second retardance value
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A device includes a display element (104) and a lens assembly (102). The lens assembly includes a polarization non-selective partial reflector (137), a polarization selective reflector (117) and a polarization switch (129) disposed at opposite sides of the polarization non-selective partial reflector (137), and a polarization selective transmissive lens (125) disposed between the polarization switch and the polarization non-selective partial reflector. The device also includes a controller (116) configured to: during a first sub-frame of a display frame, control the display element to display a first virtual sub-image including content of a first portion of a virtual image, and control the polarization switch (129) to operate in a switching state. The controller (116) is also configured to: during a second sub-frame of the display frame, control the display element to display a second virtual sub-image including content of a second portion of the virtual image, and control the polarization switch (129) to operate in a non-switching state.