Free-Form Head-Mounted Display Optical System for Weight Reduction
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Solution Overview
Problem
Conventional head-mounted displays face challenges in simultaneously reducing size and weight while maintaining excellent optical performance, often requiring heavy glass materials that increase size and weight due to the need for multiple lenses to correct chromatic aberration.
Innovation Solution
A head-mounted display optical system comprising a light deflecting element, a first lens group with rotationally symmetrical and free-form surface lenses, a second lens group with a positive refracting power lens, a third lens group with a rotationally symmetrical and free-form surface lens, and a light reflecting element with a free-form surface, optimized with specific lens surface shapes and configurations to reduce size and weight while maintaining optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple lenses with high specific gravity glass material are used to correct chromatic aberration, then optical performance is improved, but size and weight of the optical system increase
Solution Approach 1:
The patent applies asymmetry principle by introducing free-form surface lenses with rotationally asymmetrical surfaces. These asymmetric surfaces enable more efficient correction of chromatic aberration and other optical errors compared to traditional rotationally symmetrical lenses, allowing reduction in the number and weight of lens elements while maintaining optical performance
Solution Approach 2:
The patent changes the surface shape parameter from rotationally symmetrical to free-form rotationally asymmetrical surfaces. This parameter change enables better control over light paths and aberration correction, achieving the same optical performance with fewer and lighter lens elements
2Reliability
If multiple lenses are used to correct chromatic aberration, then optical performance is improved, but the number of components and device complexity increase
Solution Approach 1:
The free-form surface lenses with rotationally asymmetrical surfaces provide enhanced aberration correction capability in a single element, reducing the total number of lenses required in the optical system while maintaining excellent optical performance
Solution Approach 2:
The free-form surface lenses serve multiple functions simultaneously: they correct chromatic aberration, spherical aberration, and other optical errors in a single component, replacing what would traditionally require multiple separate lens elements
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 system achieves a reduction in size and weight while maintaining good optical performance by efficiently correcting aberrations and reducing the number of lenses, allowing for a more compact and lightweight head-mounted display.
Implementation Method 1
a light deflecting element that changes a propagating direction of light from a light source
Implementation Method 2
a first lens group that has a positive refracting power as a whole, includes a plurality of rotationally symmetrical lenses formed in a rotationally symmetrical manner with respect to an optical axis and one free-form surface lens formed in a rotationally asymmetrical manner with respect to the optical axis, and condenses the light incident through the light deflecting element
Implementation Method 3
a light reflecting element that has a free-form surface shape formed in a rotationally asymmetrical manner with respect to the optical axis and has a reflection surface that reflects the light having transmitted through the third lens group
Data Source
AI summary
A head-mounted display optical system includes: a light deflecting element; a first lens group that has a positive refracting power as a whole, includes a plurality of rotationally symmetrical lenses and one free-form surface lens, and condenses the light incident through the light deflecting element; a second lens group that includes one lens having a positive refracting power that is arranged in a vicinity of an imaging position of an intermediate image formed by the first lens group; a third lens group that includes one rotationally symmetrical lens and one free-form surface lens; and a light reflecting element that has a free-form surface shape formed in a rotationally asymmetrical manner with respect to the optical axis and has a reflection surface that reflects the light having transmitted through the third lens group, in a sequence from a side of the light source side.