Light Field Waveguide Display Using MEMS Scanning for VAC Relief
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Solution Overview
Problem
Waveguide-based augmented reality near-eye displays suffer from vergence-accommodation conflict due to a mismatch between vergence and focus depth, causing eye strain and visual fatigue, and existing solutions either obstruct the view or have overly complex structures.
Innovation Solution
A light field near-eye display assembly utilizing a MEMS scanning mirror and spatial light modulator to adjust illumination beam angles and modulate image light, combined with a waveguide assembly for efficient propagation and coupling, achieving a true three-dimensional display effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective spatial light modulator is placed on the optical axis to achieve three-dimensional light field display, then the vergence-accommodation conflict is resolved, but the view of the actual scene is obstructed
Solution Approach 1:
The patent transitions from placing the spatial light modulator on the optical axis (2D plane) to positioning it at an angle relative to the optical axis, utilizing three-dimensional spatial arrangement. This allows the SLM to modulate light for 3D display while avoiding direct obstruction of the optical path to the user's eye, thereby resolving the view obstruction problem while maintaining 3D display capability
Solution Approach 2:
The patent separates the functions of light modulation and light coupling by positioning the spatial light modulator and waveguide at different angular orientations. The SLM handles the 3D image generation while the waveguide handles light transmission, allowing each component to be optimized independently and avoiding the need for the SLM to be directly in the optical path
2Reliability
If multiple reflections are used to project light to the retina to achieve three-dimensional display, then the vergence-accommodation conflict is resolved, but the device structure becomes overly complex
Solution Approach 1:
The patent combines the spatial light modulator and waveguide into an integrated assembly where the SLM is positioned at an angle to the optical axis and the waveguide is coupled to the SLM output. This merging reduces the number of separate reflection components needed while maintaining the three-dimensional display effect, thereby simplifying the overall device structure
Solution Approach 2:
The patent employs a dynamic spatial light modulator that can be electronically controlled to display different three-dimensional images without requiring physical movement or multiple fixed reflection components. The electronic switching capability of the SLM replaces complex mechanical optical paths, reducing structural complexity while maintaining 3D display flexibility
3Volume of moving object
If waveguide-based AR display is used to achieve small volume and thinness, then the display device becomes compact, but the vergence-accommodation conflict persists due to infinite virtual image distance
Solution Approach 1:
The patent changes the fundamental parameter of image distance by using the spatial light modulator to create light fields at multiple depths rather than a single infinite distance. This allows the virtual image to be positioned at finite distances, enabling the eye to accommodate at different focal planes and eliminating the vergence-accommodation conflict while maintaining the compact waveguide structure
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
Resolves the vergence-accommodation conflict by providing high-resolution, realistic three-dimensional imagery while reducing the assembly's volume and optimizing its structure for lightness and thinness.
Implementation Method 1
The MEMS scanning mirror is provided on a projection side of the lighting assembly and configured to deflect the illumination beam projected by the lighting assembly to adjust an incident angle of the illumination beam
Implementation Method 2
The spatial light modulator is provided in a light path between the MEMS scanning mirror and the coupling-in device and configured to modulate the illumination beam deflected by the MEMS scanning mirror into image light at a corresponding viewing angle
Implementation Method 3
The waveguide assembly includes an optical waveguide, and a coupling-in device and a coupling-out device provided on the optical waveguide
Implementation Method 4
an image source generated by a micro-projection optical machine enters a waveguide after passing through a collimating lens and a coupling-in device, is totally reflected in the waveguide to a coupling-out section
Implementation Method 5
is diffracted into human eyes through a coupling-out device
Data Source
AI summary
A light field near-eye display assembly, a light field near-eye display apparatus, and a light field near-eye display method are provided. The light field near-eye display assembly includes: a lighting assembly, configured to project an illumination beam; an MEMS scanning mirror, provided on a projection side of the lighting assembly and configured to deflect the illumination beam projected by the lighting assembly to adjust an incident angle of the illumination beam; a waveguide assembly, including an optical waveguide, and a coupling-in device and a coupling-out device provided on the optical waveguide; and a spatial light modulator, having the same refresh rate as the MEMS scanning mirror and configured to modulate the illumination beam deflected by the MEMS scanning mirror into image light at a corresponding viewing angle to propagate to the coupling-in device.