Compact AR Projection Illumination Layout for Reduced Light Leakage
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Solution Overview
Problem
Conventional augmented reality (AR) display systems face challenges in providing a comfortable and natural presentation of virtual image elements among real-world imagery due to mismatches between accommodative and vergence states, leading to user discomfort.
Innovation Solution
An AR optical system with a set of illumination sources and waveguide layers positioned in specific angular offsets, along with a lens assembly and spatial light modulator, is designed to reduce system size and light leakage, while maintaining efficient image projection by using a tri-layout super pupil configuration and absorption pads to optimize brightness and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AR display systems are used, then virtual image elements can be presented, but user discomfort occurs due to mismatches between accommodative and vergence states
Solution Approach 1:
The patent changes the optical parameters of the waveguide system by introducing multiple illumination sources at different lateral positions and wavelengths, with corresponding diffractive elements positioned at specific angular offsets. This configuration modifies the light propagation paths and pupil formation characteristics to align accommodative and vergence cues, resolving the user discomfort issue.
2Volume of moving object
If system size is reduced for compact design, then portability improves, but light leakage increases
Solution Approach 1:
The patent transitions from a single-plane illumination layout to a three-dimensional configuration where illumination sources are positioned at different lateral positions and the waveguide stack incorporates multiple layers with diffractive elements at specific angular offsets. This spatial arrangement in multiple dimensions enables compact form factor while maintaining optical isolation to prevent light leakage.
3Volume of moving object
If illumination sources are positioned closer together for compact design, then system size decreases, but optical interference and light leakage increase
Solution Approach 1:
The patent employs asymmetric positioning of illumination sources and corresponding diffractive elements, with angular offsets of 120 degrees between sources and 180 degrees for diffractive element pairs. This asymmetric configuration creates distinct optical paths for each wavelength channel, preventing interference while maintaining compact dimensions.
4Illumination intensity
If multiple illumination sources are used for full-color display, then color quality improves, but system complexity increases
Solution Approach 1:
The patent merges multiple illumination sources and their corresponding waveguide layers into a single integrated waveguide stack structure. The diffractive elements are positioned at specific angular offsets within the same waveguide substrate, combining multiple optical functions into one compact unit, thereby reducing overall system complexity despite using multiple wavelengths.
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 compact design with reduced light leakage, providing efficient image projection and minimizing user discomfort by aligning accommodative and vergence cues, resulting in a more realistic and comfortable AR experience.
Implementation Method 1
a first waveguide layer including a first incoupling diffractive element disposed at a fourth lateral position offset by 180 degrees from the first lateral position; and a first outcoupling diffractive element optically coupled to the first incoupling diffractive element
Implementation Method 2
an eyepiece waveguide stack disposed adjacent the set of illumination sources and including a first waveguide layer
Data Source
AI summary
An apparatus including a set of three illumination sources disposed in a first plane. Each of the set of three illumination sources is disposed at a position in the first plane offset from others of the set of three illumination sources by 120 degrees measured in polar coordinates. The apparatus also includes a set of three waveguide layers disposed adjacent the set of three illumination sources. Each of the set of three waveguide layers includes an incoupling diffractive element disposed at a lateral position offset by 180 degrees from a corresponding illumination source of the set of three illumination sources.