Ocular Lens Aberration Correction via Segmented Groups
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Solution Overview
Problem
Ocular lenses with a large apparent field of view face challenges in maintaining sufficient eye relief and correcting aberrations across a wide angle of view without increasing lens diameter and overall length, as existing configurations lead to deteriorating peripheral aberrations and compactness issues.
Innovation Solution
The ocular lens configuration includes a first lens group with negative refractive power, a second lens group with a convex surface facing the viewer's eye side, and a third lens group with positive refractive power, where specific focal length and curvature radius conditions are met to optimize aberration correction and compactness, including the use of cemented lenses and aspheric surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the focal length of the positive lens group is made long to secure sufficient eye relief and wide apparent field of view, then the eye relief and apparent field of view are improved, but the lens diameter increases and compactness deteriorates
Solution Approach 1:
The ocular lens is divided into three lens groups with different refractive power characteristics. The first lens group (negative refractive power) controls peripheral aberrations, the second lens group (positive refractive power) provides eye relief, and the third lens group (positive refractive power) corrects residual aberrations. This segmentation allows each group to be optimized independently for its specific function while maintaining compact overall dimensions.
Solution Approach 2:
Different regions of the optical system are assigned different refractive power characteristics tailored to their specific functions. The first lens group has negative refractive power concentrated at the object side to control peripheral aberrations, while the second and third lens groups have positive refractive power positioned to provide eye relief and additional aberration correction. This local optimization of refractive power distribution enables compact lens diameters while maintaining sufficient eye relief.
2Reliability
If the focal length ratio of negative lens group to positive lens group is made closer to 1:1 to reduce Petzval sum, then the curvature of field correction is improved, but the lens diameter increases due to dispersion action
Solution Approach 1:
The lens system is segmented into three groups with distributed refractive power. The first lens group provides negative refractive power for Petzval sum reduction, while the second and third lens groups provide positive refractive power for aberration correction. This segmentation allows the Petzval sum to be reduced without requiring a 1:1 focal length ratio, thereby avoiding excessive lens diameter increase.
Solution Approach 2:
The refractive power distribution parameters are optimized across the three lens groups. By adjusting the focal lengths and refractive indices of individual lens components within each group, the Petzval sum is reduced while controlling the dispersion action that would otherwise increase lens diameter. The conditional expressions in the patent guide these parameter optimizations.
3Adaptability or versatility
If the apparent field of view is increased to 80 degrees or more, then the observation coverage is improved, but the peripheral aberrations deteriorate drastically
Solution Approach 1:
The optical system is divided into three lens groups that work cooperatively to control aberrations across the wide field of view. The first lens group (negative refractive power) is specifically designed to control peripheral aberrations, while the second and third lens groups (positive refractive power) correct residual aberrations and provide eye relief. This segmentation enables 80 degrees or more apparent field of view while maintaining acceptable peripheral aberration levels.
Solution Approach 2:
Each lens group is designed with specific refractive power characteristics tailored to its function in the overall aberration correction strategy. The first lens group has negative refractive power optimized for peripheral aberration control, while the second and third lens groups have positive refractive power optimized for residual aberration correction and eye relief. This local optimization enables wide field of view with controlled aberrations.
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 across a wide angle of view while maintaining sufficient eye relief and preventing an increase in lens diameter, ensuring a compact optical apparatus without a long total length.
Implementation Method 1
a first lens component having negative refractive power in a shape having a concave surface facing a viewer's eye side
Implementation Method 2
a second lens component in a meniscus shape having a convex surface facing the object side
Implementation Method 3
a third lens component having positive refractive power
Implementation Method 4
the second lens component included in the first lens group is a cemented lens
Data Source
AI summary
There are provided an ocular lens in which aberrations are favorably corrected across a sufficiently wide angle of view and a lens diameter is suppressed from increasing with a sufficient eye relief attained and without a total length being long, and an optical apparatus including the ocular lens. An ocular lens 3 used for an optical apparatus such as a telescope optical system TS includes: in order from an object side, a first lens group G1 including a first lens component G1A having negative refractive power and having a concave surface facing a viewer's eye side, a second lens component G1B in a meniscus shape having a convex surface facing the object side, and a third lens component G1C having positive refractive power; a second lens group G2 having a lens component having a convex surface facing the viewer's eye side; a third lens group G3 having positive refractive power. An object side focal plane of the third lens group G3 is positioned between the second lens group G2 and the third lens group G3.