Five-Lens Display Optics for High Magnification and Long Eye Relief
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Solution Overview
Problem
Existing display optical systems face challenges in achieving high magnification, long eye relief, and effective aberration correction while managing the high cost and manufacturing difficulties associated with high refractive materials.
Innovation Solution
A display optical system comprising a sequence of single lenses with specific refractive indices and focal lengths, including a high refractive index for the second lens to correct aberrations, and optimized lens shapes to maintain high magnification and long eye relief, while minimizing the use of expensive high refractive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high refractive materials are used for lenses to achieve high magnification, then magnification is improved, but cost and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by using high refractive index material only for the second lens where it is most needed for aberration correction, rather than using it for all lenses. This selective application maintains high magnification performance while reducing overall cost and manufacturing complexity.
Solution Approach 2:
The patent changes the refractive index parameter strategically by setting nd2 (refractive index of second lens) to be greater than 1.7, and establishing specific relationships between focal lengths (0.05 < f2/f1 < 0.40 and 0.60 < f2/f3 < 1.50). These parameter optimizations achieve high magnification with reduced reliance on expensive high-refractive materials throughout the entire system.
2Speed
If refracting power of each lens is increased for high magnification, then magnification is improved, but manufacturing precision and sensitivity increase
Solution Approach 1:
The patent optimizes the distribution of refracting power across lenses by establishing specific focal length relationships (0.05 < f2/f1 < 0.40 and 0.60 < f2/f3 < 1.50). This balanced parameter distribution achieves high magnification while avoiding excessive sensitivity to manufacturing tolerances that would result from overly strong individual lens powers.
3Speed
If high magnification and long eye relief are achieved, then observation quality is improved, but aberration correction becomes more difficult
Solution Approach 1:
The patent applies local quality by concentrating the high refractive index material (nd2 > 1.7) specifically in the second lens, which is positioned to provide optimal aberration correction for the high magnification design. This targeted approach corrects chromatic and spherical aberrations effectively while maintaining long eye relief.
Solution Approach 2:
The patent employs composite material strategy by combining lenses with different refractive indices (nd1, nd2 > 1.7, nd3) in a multi-lens configuration. This composite approach enables effective aberration correction across the high magnification field while maintaining long eye relief, as each lens contributes differently to the overall optical performance.
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 high magnification, long eye relief, and effective aberration correction with reduced material costs and manufacturing complexity, ensuring wide field observation of small display elements.
Implementation Method 1
a second lens having positive refractive power... nd2 is a refractive index of the second lens for d-line... high refractive index for the second lens to correct aberrations
Data Source
AI summary
A display optical system configured to enable an image displayed on a display element to be observed includes, in order from a display element side to an observation side, a first lens having positive refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, and a fifth lens having positive refractive power. Each of the first lens, second lens, third lens, fourth lens, and fifth lens is a single lens that is not a cemented lens. A predetermined condition is satisfied.