Asymmetrical Optical Assembly for Differential Distortion Correction
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Solution Overview
Problem
Artificial reality headsets, particularly those designed as eyeglasses, face challenges in minimizing image distortion across the field of view due to the scanning process used in light projection systems, leading to blurred images and visual artifacts.
Innovation Solution
A light projection system that includes a light source and an optical assembly with asymmetrical optical elements relative to an optical axis, which corrects differential distortion across the field of view by providing positive optical power and controlling the rate of change of distortion, using a combination of rotationally symmetric and non-rotationally symmetric elements to minimize keystone distortion and chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a light projection system with a scan mirror is used to create a lightweight headset, then the headset weight and form factor are improved, but image distortion and visual artifacts increase
Solution Approach 1:
The patent applies asymmetry by using optical elements with different powers in the vertical and horizontal meridians. Specifically, the first optical element has a first power in a vertical meridian and a second power in a horizontal meridian, where the first power differs from the second power. This asymmetric design compensates for the differential distortion introduced by the scanning process, correcting image quality while maintaining the lightweight projection system architecture.
2Manufacturing precision
If asymmetrical optical elements are used to correct differential distortion, then image quality is improved, but optical alignment precision requirements increase
Solution Approach 1:
The patent applies local quality by positioning the asymmetric optical elements at specific locations within the optical path. The first optical element is positioned between the scan mirror and the second optical element, with each element having locally optimized asymmetric properties tailored to correct distortion at their specific positions. This localized approach to asymmetry allows correction of differential distortion while managing alignment requirements through strategic placement rather than requiring perfect alignment tolerance across all components.
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 solution effectively reduces image distortion and chromatic aberration, enhancing the clarity and brightness of the displayed content by maintaining pixel alignment and reducing visual artifacts, thereby improving the overall image quality in artificial reality applications.
Implementation Method 1
an optical assembly configured to provide positive optical power to the image light and optically correct the image light
Implementation Method 2
The optical assembly comprises a plurality of optical elements configured to correct differential distortion related to the image light across a field of view
Data Source
AI summary
A light projection system includes a light source configured to emit image light and an optical assembly configured to provide positive optical power to the image light and optically correct the image light. The optical assembly comprises a plurality of optical elements configured to correct differential distortion related to the image light across a field of view (FOV) within a threshold amount. The differential distortion is corrected based in part on asymmetry of the plurality of optical elements relative to an optical axis shared by the plurality of optical elements.