Image Forming Lens Aberration Correction via Segmented Groups

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Industrial cameras require image forming lenses that can produce high-definition images while effectively correcting various aberrations, especially spherical, coma, and axial chromatic aberrations, which are challenging due to the asymmetrical distribution of refractive power and the need for large apertures.

Innovation Solution

The image forming lens is designed by sequentially arranging a first lens group with positive refractive power, an aperture stop, and a second lens group with positive or negative refractive power, where the first lens group is formed by specific arrangements of positive and negative lenses, and the second lens group is fixed relative to the image surface during focusing, with specific conditional expressions to optimize air spaces and curvature radii to correct aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a lens with large aperture is used to form a bright image for long working distance, then the image brightness is improved, but spherical aberration and coma aberration increase due to asymmetrical distribution of refractive power

Engineering Contradiction:

Improveimage brightnessVSAvoidspherical aberration and coma aberration

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The lens is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power) separated by an aperture stop. This segmentation allows independent optimization of each group's contribution to aberration correction while maintaining overall system performance for bright image formation at long working distances.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the lens system are assigned different refractive powers and aberration correction characteristics. The first lens group handles brightness and the second lens group handles aberration correction, with each group optimized for its specific function rather than uniform design throughout the entire lens.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the refractive power distribution is made asymmetrical to correct aberrations, then aberration correction is improved, but the lens structure becomes more complex

Engineering Contradiction:

Improveaberration correctionVSAvoidlens structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The aperture stop acts as an intermediary element between the first and second lens groups, controlling the light path and enabling the asymmetrical refractive power distribution to function effectively. It mediates the interaction between the two lens groups to achieve aberration correction without requiring overly complex structural integration.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If focusing is performed from infinite distance to short distance objects, then the focus range is improved, but lens performance variation increases

Engineering Contradiction:

Improvefocus rangeVSAvoidlens performance consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The lens system is designed with movable lens groups that can dynamically adjust their positions and relative configurations during focusing from infinite distance to short distance objects. This dynamic capability allows the lens to maintain optimal aberration correction across different focus distances rather than being optimized for a single fixed distance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The lens system utilizes changes in optical parameters (such as the spacing between lens groups and the curvature of lens surfaces) during focusing operations. By allowing these parameters to vary dynamically, the lens maintains consistent performance across the focus range from infinite distance to short distance objects.

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 effectively corrects spherical and coma aberrations, reduces lens performance variation due to focusing, and maintains high image quality across different object distances, enabling high-definition image capture with minimal distortion and aberration.

Implementation Method 1

a first lens group having positive refractive power, an aperture stop, and a second lens group having positive or negative refractive power

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9772469B2Image forming lens and image capturing device

Publication Date: 2017.09.26 RICOH CO LTD

AI summary

An image forming lens is formed by sequentially arranging, from an object side to an image side, a first lens group having positive refractive power, an aperture stop, and a second lens group having positive or negative refractive power. The image forming lens satisfies a conditional expression:0.15<D1a/D1<0.50, whereD1a is an air space between the first positive lens and the second positive lens in the first lens group, and D1 is a distance on an optical axis from an object-side lens surface of the first positive lens to an image-side lens surface of the third positive lens in the first lens group.