Time-Interleaved Optical Merging for AR Headsets
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Solution Overview
Problem
Existing electronic devices with optical systems for merging display content and real-world content face challenges in maintaining optical quality and performance characteristics, particularly in wearable devices like head-mounted displays.
Innovation Solution
The implementation of an optical system with adjustable components such as linear polarizers, tunable lenses, and geometrical phase lenses that allow for time-interleaved and polarization-controlled merging of real-world and display images, enabling precise placement of computer-generated content at desired focal planes while minimizing interference with real-world objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical system merges real-world images and display images, then augmented reality functionality is achieved, but optical quality and performance deteriorate due to interference between real-world objects and virtual content
Solution Approach 1:
The patent employs time-interleaved operation where the optical system alternates between displaying real-world images and display images in sequential frames. The polarization state is periodically switched between first and second states, allowing the system to present different content types at different time intervals while maintaining optical quality through temporal separation
Solution Approach 2:
The patent applies different polarization states to different types of content (real-world vs. display images) and uses spatially selective optical elements including variable focus lenses that provide different focal planes for different content types. This allows each content type to be optimized locally without interfering with the other
2Measurement precision
If display images are placed at different focal planes, then depth perception is improved, but device complexity increases due to additional optical components
Solution Approach 1:
The patent incorporates variable focus lenses that can dynamically adjust their focal length to place display images at different focal planes. The polarization state is also dynamically switched between first and second states, allowing the optical system to adaptively control focal plane placement without requiring multiple fixed lenses for each depth level
Solution Approach 2:
The patent uses a single optical system that performs multiple functions: it displays both real-world and virtual content, provides multiple focal planes, and maintains polarization control all through integrated components. The variable focus lenses and polarization switches serve dual purposes of content separation and focal plane control
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 enhances the optical quality and performance by allowing seamless integration of virtual objects into the real-world environment without affecting the focus of real-world objects, providing an improved user experience in augmented reality applications.
Implementation Method 1
a polarization switch operated in a first state in which linearly polarized light of a given polarization is not rotated by the polarization switch and a second state in which the linearly polarized light of the given polarization is rotated by 90°
Implementation Method 2
Different objects may be displayed in alternating image frames. The optical system may be adjusted in synchronization with the alternating image frames to display the different objects at different focal planes
Implementation Method 3
Tunable lenses may be used to place display images at different respective focal plane distances from the eye boxes
Implementation Method 4
geometrical phase lenses that present different lens powers to images with different polarizations
Data Source
AI summary
An electronic device such as a head-mounted device may have a display that produces a display image. The head-mounted device may have an optical system that merges real-world images from real-world objects with display images. The optical system provides the real-world images and display images to an eye box for viewing by a user. The optical system may use time interleaving techniques and/or polarization effects to merge real-world and display images. Switchable devices such as polarization switches and tunable lenses may be controlled in synchronization with frames of display images. Geometrical phase lenses may be used that exhibit different lens powers to different polarizations of light.