Imaging Lens Aberration Correction via Cemented Groups

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Solution Overview

Problem

Existing imaging lenses face challenges in achieving a fast F number of approximately 2 with high performance, minimal distortion, and satisfactory correction of field curvature and chromatic aberration, especially at peripheral image heights, due to insufficient aberration correction and high costs associated with aspherical surfaces.

Innovation Solution

The imaging lens consists of a first lens group with a positive lens, a negative meniscus lens, a biconcave negative lens, and cemented lenses, and a second lens group with positive lenses, arranged to satisfy specific conditional expressions for focal lengths, radii of curvature, and Abbe numbers, allowing for effective correction of aberrations and distortion while maintaining a fast F number.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If aspherical surfaces are used to achieve fast F number and wide angle of view, then the F number and angle of view are improved, but the manufacturing cost increases and peripheral resolution is not improved due to insufficient aberration correction

Engineering Contradiction:

ImproveF numberVSAvoidmanufacturing cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent changes the optical parameters by using a specific lens configuration (first lens group with positive lens, negative meniscus lens, biconcave negative lens, and cemented lens; second lens group with positive lenses) and satisfying specific conditional expressions for focal lengths (2.0f1a/f8.0) and Abbe numbers (50<Σνm/2) to correct aberrations without requiring aspherical surfaces, thus reducing manufacturing cost while maintaining fast F number

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite lens structures including cemented lenses (positive lens and negative lens combined) to achieve superior aberration correction. The cemented lens in the first group and the cemented lens in the second group work together to correct chromatic aberration and field curvature, enabling high peripheral resolution without aspherical surfaces

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If lens configuration is simplified to reduce cost, then manufacturing cost is reduced, but aberration correction becomes insufficient and peripheral performance deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidaberration correction

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent divides the lens system into two distinct lens groups with specific functions: the first lens group (containing the positive lens, negative meniscus lens, biconcave negative lens, and cemented lens) primarily handles aberration correction, while the second lens group (containing positive lenses) handles focusing and image formation. This segmentation allows each group to be optimized for its specific function, achieving high peripheral resolution without excessive complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different lens types and properties to different positions in the optical path. The negative meniscus lens and biconcave negative lens are specifically positioned to correct field curvature and chromatic aberration at peripheral regions, while the positive lenses handle central imaging. This local optimization of lens quality ensures high peripheral performance without requiring aspherical surfaces throughout the entire lens

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If F number is increased to improve resolution, then resolution is improved, but the lens becomes slower and peripheral performance is not improved due to insufficient aberration correction

Engineering Contradiction:

ImproveresolutionVSAvoidF number

Core Design Contradiction:

Manufacturing precisionVSIllumination intensity

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

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 results in an imaging lens with a fast F number of approximately 2, improved peripheral performance, minimal distortion, and effective chromatic aberration correction, achieving higher resolution and cost-effectiveness by eliminating the need for aspherical surfaces.

Implementation Method 1

an imaging lens which performs focusing at each object distance by moving a second lens group along an optical axis

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9122038B2Imaging lens and imaging apparatus

Publication Date: 2015.09.01 FUJIFILM CORP

AI summary

An imaging lens substantially consisting of a first lens group, a stop, and a second lens group in this order from the object side, the first lens group includes at least a positive lens, a negative meniscus lens with a convex surface toward the object side, a biconcave negative lens, and a cemented lens substantially constituted by two lenses, which are a positive lens and a negative lens, in this order from the object side; the second lens group includes at least a first positive lens with a convex surface toward the image side, a cemented lens substantially constituted by two lenses, which are a positive lens and a negative lens, and a second positive lens with a convex surface toward the image side, in this order from the object side; and a predetermined conditional expression is satisfied.