Ocular Optical System with Negative Lens for Chromatic Aberration Correction
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Solution Overview
Problem
Conventional electronic viewfinders face challenges in achieving a wide field of view and large image display while minimizing the viewfinder size, as increasing observation magnification leads to on-axis and magnification chromatic aberrations, which are difficult to correct with a positive lens-only ocular optical system.
Innovation Solution
An ocular optical system comprising a first positive lens, a second negative lens, a third positive lens, and a fourth positive lens, arranged from the object side to the observation side, with specific curvature radius and Abbe number conditions to correct chromatic and off-axis aberrations, ensuring a wide angle of view and high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the observation magnification of the ocular optical system is increased to reduce viewfinder size, then the viewfinder size is reduced, but on-axis chromatic aberration and magnification chromatic aberration occur frequently
Solution Approach 1:
The ocular optical system is divided into multiple lens units with different refractive powers (positive first lens, negative second lens, positive third lens, and positive fourth lens). Each lens unit contributes differently to the overall optical function, allowing the system to achieve high magnification while correcting chromatic aberrations through the combined effect of segmented components with opposite refractive powers.
Solution Approach 2:
Different regions of the optical system are assigned different optical properties. The negative second lens is specifically positioned to correct chromatic aberrations generated by the positive lenses, while the fourth lens on the observation side is optimized for eye comfort and final image quality. Each lens has specific curvature radius and Abbe number requirements to address local aberration problems.
2Measurement precision
If a positive lens only ocular optical system is used to increase observation magnification, then the observation magnification is increased, but it is difficult to correct on-axis chromatic aberration and magnification chromatic aberration
Solution Approach 1:
The negative second lens acts as an optical counterweight to the positive first and third lenses. By positioning a negative lens between positive lenses, the system balances the chromatic aberrations generated by the positive lenses. The negative refractive power of the second lens compensates for the positive refractive power of other lenses, enabling effective correction of on-axis and magnification chromatic aberrations while maintaining high observation magnification.
3Area of stationary object
If the image display surface is enlarged to achieve wide field of view and large image display, then the field of view and image size are improved, but the viewfinder size increases
Solution Approach 1:
The system changes key optical parameters including the refractive powers of individual lenses, curvature radii ratios, and Abbe numbers to achieve high magnification. By optimizing parameters such as f1/f2 ratio, R12/R11 ratio, and selecting lenses with specific Abbe numbers (νd1, νd2, νd3, νd4), the system achieves wide field of view and large image display while keeping the physical viewfinder size compact through high magnification.
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 effectively corrects chromatic and off-axis aberrations, enabling a wide angle of view and high optical performance, while maintaining a compact viewfinder size by optimizing the curvature radii and refractive indices of the lenses.
Implementation Method 1
an ocular optical system includes a first lens L1 having positive refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, and a fourth lens L4 having positive refractive power
Data Source
AI summary
In an ocular optical system including a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a fourth lens having positive refractive power which are arranged in this order from an object side to an observation side, the shape and position of each lens is set appropriately to increase the angle of view and to minimize on-axis and magnification chromatic aberrations.