Aspherical Ocular Lens for Lightweight Headset Displays
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Solution Overview
Problem
Headset display optical systems face a challenge in balancing focal power and lightweight design, as increased focal power leads to increased lens curvature and weight, compromising imaging quality and field of view.
Innovation Solution
A single positive aspherical lens with specific surface parameters and relationships, combined with a Cyclo Olefin Polymer material, is used to create a compact and lightweight ocular lens that maintains a large field of view and reduces optical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal power of the optical system is increased, then the imaging quality is improved, but the lens weight and surface curvature increase
Solution Approach 1:
The patent applies aspherical surface design for both the object-side and image-side surfaces of the lens. The aspherical surfaces are defined by specific mathematical equations with multiple coefficients (e.g., 4th order, 6th order, 8th order terms) that allow precise control of surface curvature. This enables achieving high focal power (+50.00 D in the example) while maintaining manageable surface curvature and reducing lens weight compared to traditional spherical lenses.
2Measurement precision
If the focal power of the optical system is increased, then the imaging quality is improved, but the lens surface curvature increases
Solution Approach 1:
The patent employs aspherical surface equations with multiple coefficients to precisely control and optimize surface curvature distribution. The object-side surface uses coefficients including k1, c14, c16, c18 while the image-side surface uses k2, c24, c26, c28, allowing independent optimization of curvature at different zones of the lens surface to achieve high focal power without excessive overall curvature.
Solution Approach 2:
The aspherical surface design allows different zones of the lens surface to have different curvature characteristics. By varying the curvature locally across the surface (controlled by higher-order coefficients), the lens can achieve the required focal power while maintaining flatter regions where excessive curvature would cause problems, thus balancing imaging quality with manageable surface geometry.
3Device complexity
If a single positive lens is used, then the device complexity is reduced, but the optical aberration increases
Solution Approach 1:
The patent uses aspherical surfaces on both sides of the single positive lens to correct optical aberrations that would normally require multiple lens elements. The aspherical coefficients are specifically optimized to reduce spherical aberration, coma, and other monochromatic aberrations, allowing a simple single-lens structure to achieve imaging quality comparable to or better than traditional multi-element systems.
Solution Approach 2:
The patent systematically optimizes multiple parameters including the aspherical coefficients (k1, c14, c16, c18, k2, c24, c26, c28), lens thickness d, focal length f, and material refractive index n to achieve the best balance between simplicity and aberration control. By carefully adjusting these parameters, the single lens design achieves +50.00 D focal power with acceptable aberration levels.
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 achieves a lightweight headset display optical system with a 96° field of view, minimizing user burden and cost while optimizing imaging quality and aberration correction.
Implementation Method 1
An image generated by the display screen is magnified by the optical system to present a virtual image at a certain distance from human eyes
Data Source
AI summary
An ocular lens uses a single positive lens having a first surface convex to a light emission direction and a second surface convex to a light incident direction. The surfaces are both aspherical and satisfy the following surface-type parameters and relationships: an absolute value of a radius of the first surface is r1, with a quadratic term coefficient being k1; an absolute value of a radius of the second surface is r2, with a quadratic term coefficient being k2; a thickness of the positive lens is d; a total focal length of the optical system corresponding to the positive lens is f; wherein, 49<r1<150, 20<r2<40, 0.3<r1/r2<0.45;−3<k1<−0.5, −3<k2<−0.5; 33<f<40; 0.45<f/r1<0.65, 1.2<f/r2<1.8, 2.6<f/d<3.