Near-Eye Optical Waveguide Beam Splitting for Compact Display
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Solution Overview
Problem
Near-eye optical systems face challenges in achieving a large field of view with a small volume, as reducing the thickness of the optical waveguide compromises the optical coupling range and leads to incomplete image projection and discontinuous angle information, resulting in poor user experience.
Innovation Solution
The near-eye optical system incorporates a first optical waveguide with beam-splitting surfaces and reflective inclined surfaces, which receive the image beam, allowing a portion to pass through and another portion to be reflected, expanding the image area while maintaining waveguide thickness, and a second optical waveguide further expands the image beam, ensuring complete projection and reducing ghost images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the optical waveguide is reduced to decrease overall system thickness, then the overall thickness of the near-eye optical system is reduced, but the optical coupling range of the optical waveguide is reduced, causing incomplete image projection
Solution Approach 1:
The optical waveguide is divided into multiple waveguide segments with different thicknesses arranged in series. The first waveguide segment has a first thickness and the second waveguide segment has a second thickness greater than the first thickness. This segmentation allows the system to reduce overall thickness while maintaining sufficient optical coupling range through the thicker second segment.
Solution Approach 2:
Instead of uniformly reducing waveguide thickness in one dimension, the invention introduces variation in the thickness dimension by arranging waveguide segments of different thicknesses in series, creating a stepped thickness profile that optimizes both compactness and optical performance.
2Length of moving object
If the thickness of the optical waveguide is reduced to decrease overall system thickness, then the overall thickness of the near-eye optical system is reduced, but the number of total reflections of the image beam is reduced, causing discontinuous angle information and dark streaks
Solution Approach 1:
The optical waveguide is divided into multiple waveguide segments with different thicknesses arranged in series. The first waveguide segment has a first thickness and the second waveguide segment has a second thickness greater than the first thickness. This segmentation allows the system to reduce overall thickness while maintaining sufficient optical coupling range through the thicker second segment.
Solution Approach 2:
Instead of uniformly reducing waveguide thickness in one dimension, the invention introduces variation in the thickness dimension by arranging waveguide segments of different thicknesses in series, creating a stepped thickness profile that optimizes both compactness and optical performance.
3Measurement precision
If the pupil aperture is reduced to improve modulation transfer function, then the MTF is improved, but the expansion in the optical waveguide becomes more difficult
Solution Approach 1:
The optical waveguide is divided into multiple waveguide segments with different thicknesses arranged in series. The first waveguide segment has a first thickness and the second waveguide segment has a second thickness greater than the first thickness. This segmentation allows the system to reduce overall thickness while maintaining sufficient optical coupling range through the thicker second segment.
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 configuration allows for a larger image area to be projected with maintained waveguide thickness, preventing incomplete projection and ghost images, thereby enhancing user experience by ensuring the image beam is fully received and uniformly imaged on the projection target.
Implementation Method 1
The first beam-splitting surface and the second beam-splitting surface are configured to receive an image beam incident from the first surface so that a first portion of the image beam passes through and a second portion of the image beam is reflected
Implementation Method 2
a plurality of first reflective inclined surfaces, and a plurality of second reflective inclined surfaces... arranged along the first direction
Implementation Method 3
The first optical waveguide is configured to expand the image beam in a first direction
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A near-eye optical system receiving an image beam including a first optical waveguide is provided. The first optical waveguide expands the image beam in a first direction and includes first and second surfaces, first and second beam-splitting surfaces, and a plurality of first and second reflective inclined surfaces. The first and second beam-splitting surfaces are located in the first optical waveguide and disposed in a tilted manner relative to the first and second surfaces. The first and second beam-splitting surfaces have opposite tilt directions. The first and second beam-splitting surfaces receive an image beam incident from the first surface so that a first portion of the image beam passes through and a second portion of the image beam is reflected. The near-eye optical system further reduces a thickness of the optical waveguide and alleviates the issue that the image beam is not completely projected to the optical waveguide.