Ocular Optical System Compact Design Aberration Correction
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Solution Overview
Problem
Existing ocular optical systems for electronic view finders face challenges in achieving compactness and good optical performance while maintaining high magnification, often resulting in aberrations such as pin-cushion distortion and chromatic aberration.
Innovation Solution
The proposed ocular optical system consists of a positive first lens, a negative second lens, and a positive third lens, with specific focal length and distance relationships, including cemented configurations and aspherical surfaces, to correct aberrations and ensure tele-centricity, compactness, and high magnification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ocular optical system is used to achieve high magnification, then magnification is improved, but the optical system becomes large in size
Solution Approach 1:
The ocular optical system is divided into three separate lenses (first positive lens, second negative lens, and third positive lens) with specific focal length relationships. This segmentation allows the system to achieve high magnification while maintaining compact dimensions by distributing the optical function across multiple smaller elements rather than requiring a single large lens assembly.
Solution Approach 2:
The patent applies specific parameter constraints including the focal length relationship (2.50 < f1/fe < 8.00), the distance parameter (0.41 < d12/fe < 0.80), and the diopter adjustment mechanism. These parameter changes enable the system to optimize both magnification and compactness by precisely controlling the focal lengths and spacing of the lenses.
2Volume of moving object
If the ocular optical system is made compact, then size is reduced, but optical performance deteriorates due to aberrations
Solution Approach 1:
The patent employs different lens types (positive and negative lenses) with specific focal length characteristics at different positions within the optical system. The first lens has a focal length of 2.50-8.00 times the system focal length, while the second lens has a focal length of 0.41-0.80 times the system focal length. This local differentiation of optical properties allows compact design while correcting aberrations.
Solution Approach 2:
The patent specifies that at least one of the second lens or third lens has an aspherical surface. This curvature modification enables the system to reduce optical aberrations (such as pin-cushion distortion and chromatic aberration) while maintaining a compact overall structure, as aspherical surfaces provide better aberration correction than simple spherical surfaces.
3Volume of moving object
If the distance between lenses is reduced to compact the system, then size is reduced, but aberration correction becomes difficult
Solution Approach 1:
The patent establishes specific parameter ranges for the distance between lenses relative to the system focal length (0.41 < d12/fe < 0.80). This parameter control ensures that while the system remains compact, the lenses are spaced sufficiently to allow effective aberration correction. The third lens is positioned at a distance of 0.05-0.30 times the system focal length from the second lens, maintaining this balance.
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 effectively corrects aberrations, maintains tele-centricity, and achieves high magnification while reducing the overall size of the optical system, improving image quality and user experience in digital single-lens reflex cameras.
Implementation Method 1
a first lens L1 which is a positive lens
Implementation Method 2
a second lens L2 which is a negative lens
Implementation Method 3
a third lens L3 which is a positive lens
Implementation Method 4
at least one of the second lens and the third lens has an aspherical surface
Implementation Method 5
the image display element and the first lens are cemented
Data Source
AI summary
An ocular optical system EL for observing an image displayed on an image display element Ob has, in order from the image display element Ob: a first lens L1 which is a positive lens; a second lens L2 which is a negative lens having a strong concave surface facing the image display element Ob; and a third lens L3 which is a positive lens having a strong convex surface facing the eye point EP in order to implement both high magnification and size reduction, wherein the first lens L1 is cemented and integrated with the image display element Ob, in order to reduce the size of the ocular optical system EL while ensuring tele-centricity and sufficiently wide luminous flux.