Non-rotationally Symmetric Optical Element for Compact Virtual Image Display
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Solution Overview
Problem
Current virtual image display systems face challenges in efficiently propagating light from an image display element to a light guide member while minimizing lens diameter and aberrations, leading to suboptimal image quality and increased size of the display device.
Innovation Solution
A propagation optical system comprising a relay optical system, an intermediate optical element with a non-rotationally symmetric curved surface, and a collimator optical system, which are sequentially arranged to form an intermediate image and reduce spherical and coma aberrations, allowing for effective light propagation and a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional optical system is used to propagate light from the image display element to the light guide member, then the light propagation function is achieved, but the lens diameter becomes large and aberrations increase
Solution Approach 1:
The optical system is divided into three distinct segments: a first optical system, an intermediate optical element, and a second optical system. This segmentation allows each component to be optimized independently, with the intermediate optical element specifically designed with a non-rotationally symmetric curved surface to correct aberrations while keeping individual lens diameters smaller than a single large lens would require
Solution Approach 2:
The intermediate optical element employs a non-rotationally symmetric curved surface design, where the cross-sectional shape in the first plane (including the optical axis with strongest positive power) is specifically non-arc shaped. This asymmetric geometry is tailored to correct spherical and coma aberrations that arise from the asymmetric light paths in the optical system, enabling better aberration control with smaller lens diameters
2Volume of moving object
If the lens diameter is reduced to make the device compact, then the device size decreases, but light propagation efficiency and image quality deteriorate
Solution Approach 1:
The intermediate optical element acts as a mediator between the first optical system and the second optical system. It forms an intermediate image and corrects aberrations that would otherwise propagate through the system, enabling compact lens diameters while maintaining image quality. The non-rotationally symmetric curved surface specifically addresses aberrations that would compromise reliability in smaller systems
Solution Approach 2:
The patent optimizes specific parameters of the intermediate optical element, including the curvature radius and refractive index, to achieve the desired balance between compact size and image quality. By carefully controlling these parameters, the system maintains reliable image formation while keeping the overall device size small
3Device complexity
If spherical and coma aberrations are not corrected, then the optical system remains simple, but image quality and viewing experience deteriorate
Solution Approach 1:
The intermediate optical element employs a non-rotationally symmetric curved surface design, where the cross-sectional shape in the first plane (including the optical axis with strongest positive power) is specifically non-arc shaped. This asymmetric geometry is tailored to correct spherical and coma aberrations that arise from the asymmetric light paths in the optical system
Solution Approach 2:
The optical system is divided into three distinct segments: a first optical system, an intermediate optical element, and a second optical system. This segmentation allows the intermediate element to specialize in aberration correction without requiring complex designs in 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 enables efficient light propagation with reduced aberrations and lens diameter, resulting in a lightweight and compact virtual image display device with a wide angle of view, enhancing imaging performance and user experience.
Implementation Method 1
The intermediate optical element has a non-rotationally symmetric curved surface, of which shape is non-rotationally symmetric about the optical axis. A cross-sectional shape, of the non-rotationally symmetric curved surface, in a first plane including the optical axis is non-arc shape.
Data Source
AI summary
A propagation optical system includes: a first optical system; an intermediate optical element; and a second optical system. The first optical system, the intermediate optical element, and the second optical system being sequentially arranged in a direction from the image display element toward the light guide member along an optical axis. The intermediate optical element has a non-rotationally symmetric curved surface, of which shape is non-rotationally symmetric about the optical axis. A cross-sectional shape, of the non-rotationally symmetric curved surface, in a first plane including the optical axis is non-arc shape. The first plane is a plane in which the non-rotationally symmetric surface has a strongest positive power among planes including the optical axis. The propagation optical system is configured to form, between the first optical system and the second optical system, an intermediate image corresponding to an image displayed on the image display element.