Anamorphic Relay Optics for AR Pupil Expansion
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Solution Overview
Problem
In augmented and mixed reality display systems, the high frequency movement of MEMS mirrors can lead to image quality degradation, increased cost, and reduced reliability due to mirror surface distortion, as well as higher power consumption when attempting to increase mirror size for improved field of view.
Innovation Solution
The implementation of a display system that includes a fast scan mirror, a slow scan mirror, and anamorphic relay optics, where the anamorphic optics magnify the display light in the cross-scan direction, allowing for a larger pupil size without distorting the fast scan mirror and reducing the need for larger mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the mirror is increased to improve field of view, then the field of view is improved, but image quality degrades due to mirror surface distortion and power consumption increases
Solution Approach 1:
The patent introduces anamorphic relay optics that asymmetrically magnify the pupil in the cross-scan direction (perpendicular to the fast scan direction). This dimensional transformation allows the system to achieve a larger effective field of view by expanding the pupil size in one dimension without requiring proportionally larger mirror surfaces in all dimensions, thereby avoiding mirror surface distortion while still improving field of view.
2Area of stationary object
If the size of the mirror is increased to improve field of view, then the field of view is improved, but power consumption increases
Solution Approach 1:
By using anamorphic relay optics to magnify the pupil asymmetrically in the cross-scan direction, the system achieves improved field of view without requiring a proportional increase in mirror size. This allows the fast scan mirror to maintain its original size and operate at the same high frequency, thereby avoiding the increased power consumption that would result from driving larger mirrors.
Solution Approach 2:
The patent replaces the mechanical approach of simply enlarging the mirror to improve field of view with an optical approach using anamorphic relay optics. This substitution allows the system to achieve the same field of view improvement through optical magnification rather than mechanical enlargement, avoiding the additional power consumption that would be required to drive larger, heavier mirrors at high frequencies.
3Area of stationary object
If the size of the mirror is increased to improve field of view, then the field of view is improved, but reliability reduces
Solution Approach 1:
The anamorphic relay optics enable the system to achieve a larger effective field of view by magnifying the pupil in the cross-scan direction without requiring larger physical mirrors. This maintains the original mirror dimensions and operating conditions, thereby preserving the high reliability of the fast scan mirror system that would otherwise be compromised by the high-frequency operation of larger mirrors.
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 enhances the field of view while maintaining image quality, reducing power consumption, and improving the reliability and cost-effectiveness of the display system by allowing for a larger pupil size without the drawbacks of larger mirrors.
Implementation Method 1
The anamorphic relay optics are configured to magnify the display light in the cross-scan direction
Implementation Method 2
The fast scan mirror has a fast scan arc in a scan direction of the display light
Implementation Method 3
The slow scan mirror has a slow scan arc in a cross-scan direction of the display light that is perpendicular to the scan direction
Implementation Method 4
The waveguide is positioned to receive display light from the slow scan mirror and in-couple the display light into the waveguide
Data Source
AI summary
A display system for presenting visual information to a user includes a fast scan mirror, a slow scan mirror, and anamorphic relay optics positioned optically between the fast scan mirror and slow scan mirror. The fast scan mirror has a fast scan arc in a scan direction of a display light provided by a light source. The slow scan mirror has a slow scan arc in a cross-scan direction of the display light that is perpendicular to the scan direction. The anamorphic relay optics are configured to magnify the display light in the cross-scan direction.