Eyepiece Optical System with Large Field-of-View and Low Distortion
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Solution Overview
Problem
Existing eyepiece optical systems for head-mounted displays face challenges in achieving a large field-of-view angle while maintaining high image quality, low distortion, and comfort due to issues like small effective viewing angles, residual aberrations, and increased weight and complexity.
Innovation Solution
The eyepiece optical system comprises a first lens group with a negative focal length and a second lens group with a positive focal length, featuring biconvex and negative lenses with specific refractive indices and Abbe numbers, and aspheric surfaces to optimize the field-of-view angle and reduce aberrations, using glass or plastic materials to minimize weight and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a three-coaxial-lens assembly with positive-negative-positive structure is used, then the field-of-view angle can be increased to greater than 50 degrees, but residual aberrations such as field curvature and astigmatism become too large, resulting in poor image quality at field edges
Solution Approach 1:
The eyepiece optical system is divided into multiple lens groups with different functions: a first lens group (positive focal length) for field-of-view expansion, a second lens group (negative focal length) for aberration correction, and a third lens group (positive focal length) for further optimization. This segmentation allows each group to address specific optical requirements independently, achieving both large field-of-view and high image quality.
Solution Approach 2:
Different regions of the optical system are designed with different properties: the first lens group uses positive focal length lenses for off-axis light control, the second lens group uses negative focal length lenses for aberration correction, and the third lens group optimizes the final image quality. Each lens within these groups has specifically designed curvature radii and refractive indices to address local optical quality requirements.
2Manufacturing precision
If the eyepiece optical system is designed to achieve high image resolution and low distortion, then the optical performance is improved, but the system complexity and manufacturing difficulty increase
Solution Approach 1:
The patent establishes specific parameter ranges for the optical system to achieve high image quality while controlling complexity. Key parameters include: focal length ratios (f1/fw between -5 to -0.5, f2/fw between 0.3 to 0.8), curvature radius relationships (R21/R22 between -2.0 to -0.4, R31/R32 between 0.3 to 2.0), and refractive index constraints (1.50 < Nd1 < 1.80, 1.45 < Nd2 < 1.75, 1.50 < Nd3 < 1.80). These parameter specifications provide clear manufacturing guidance while ensuring optimal optical performance.
3Manufacturing precision
If multiple lenses with complex configurations are used to correct aberrations, then the optical resolution is improved, but the weight and size of the head-mounted display apparatus increase
Solution Approach 1:
The patent specifies using optical plastics for the lenses instead of traditional glass materials. The refractive index and Abbe number constraints (1.50 < Nd1 < 1.80, 35 < Vd1 < 70; 1.45 < Nd2 < 1.75, 20 < Vd2 < 50; 1.50 < Nd3 < 1.80, 35 < Vd3 < 70) are designed to optimize both optical performance and weight. Optical plastics provide lighter weight while maintaining the required optical properties for high-resolution imaging.
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 achieves a large field-of-view angle with low distortion and high optical resolution, providing a comfortable and immersive visual experience with uniform image quality across the entire frame, reducing system aberrations and manufacturing complexities.
Implementation Method 1
a first lens L1 having a positive focal length f1 and a second lens L2 having a negative focal length f2 which are arranged coaxially and successively from an eye viewing side to an image source side
Data Source
AI summary
Disclosed is an eyepiece optical system with a large field-of-view angle, and a head-mounted display apparatus. The eyepiece optical system comprises a first lens group (G1) and a second lens group (G2) which are arranged coaxially and successively along an optical axis from a human eye to an image source and meet a certain focal length relationship. A distance (D12) between the first lens (L1) and the second lens (L2), a focal length relationship of lenses within the second lens group (G2) and the material properties of various lenses meet a certain relationship. The eyepiece optical system has the advantages of large aperture, large field-of-view, high resolution, low distortion, and small size, etc., and is suitable for a head-mounted display and similar apparatuses.