Zoom Optical System Aberration Correction via Cemented Lens

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Solution Overview

Problem

Conventional zoom optical systems fail to achieve good optical performance, particularly in maintaining image stabilization, due to uncorrected aberrations.

Innovation Solution

A zoom optical system configuration comprising a specific arrangement of lens groups with positive and negative refracting powers, including a cemented lens with a convex object-side surface, and orthogonal movement of the fourth lens group, satisfying specific conditions for focal lengths, Abbe numbers, and refractive indices to correct for aberrations and image stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional zoom optical system configurations are used, then the system structure is simple, but optical performance deteriorates due to uncorrected aberrations with image stabilization enabled

Engineering Contradiction:

Improveoptical performanceVSAvoidlens group configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The zoom optical system is divided into five distinct lens groups with alternating positive and negative refracting powers. The fourth lens group is further segmented into a cemented lens comprising a negative lens and a positive lens, allowing independent optimization of each segment's optical properties to correct aberrations while maintaining overall system performance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The positive lens in the cemented lens of the fourth lens group uses a specific glass material with Abbe number greater than 30.0, creating local optical quality enhancement. This localized material selection with specific refractive properties enables effective correction of chromatic aberrations in the critical fourth lens group region

Inventive Principle:

Principle #3Local quality

2Reliability

If the fourth lens group is moved orthogonally for image stabilization, then image stabilization performance improves, but aberration correction becomes more difficult

Engineering Contradiction:

Improveimage stabilizationVSAvoidaberration correction

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The cemented lens in the fourth lens group is pre-configured with specific refractive indices and Abbe numbers before the orthogonal movement for image stabilization occurs. This preliminary optimization of optical properties ensures that aberration correction is already built into the lens design, allowing the fourth lens group to be moved orthogonally for image stabilization without compromising aberration correction performance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent specifies precise parameter ranges for the lens materials, including Abbe number greater than 30.0 for the positive lens and specific refractive index ranges for both the negative and positive lenses. These parameter changes and optimizations enable the fourth lens group to maintain aberration correction capability while being moved orthogonally for image stabilization

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a cemented lens with specific material properties is used, then chromatic aberration correction improves, but manufacturing complexity increases

Engineering Contradiction:

Improvechromatic aberration correctionVSAvoidcemented lens fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent specifies precise parameter ranges for the lens materials, including Abbe number greater than 30.0 for the positive lens and specific refractive index ranges for both the negative and positive lenses. These parameter specifications enable effective chromatic aberration correction while providing clear manufacturing guidelines for producing the cemented lens with the required optical properties

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

The configuration ensures good optical performance and effective correction for aberrations, including spherical and chromatic aberrations, even with image stabilization enabled, by optimizing the movement and refractive properties of the lens groups.

Implementation Method 1

a cemented lens of a negative lens and a positive lens... νp>30.0, where νp is an Abbe number of the positive lens

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

at least a part of the fourth lens group is moved in a direction orthogonal to an optical axis

Methodology Applied

Scientific EffectInertia: Inertia

Data Source

PatentUS7839577B2Zoom optical system, optical instrument incorporating the zoom optical system, and method of manufacturing the zoom optical system

Publication Date: 2010.11.23 NIKON CORP

AI summary

A zoom optical system has a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a negative refracting power; and a fifth lens group having a positive refracting power, in the order from the object side. The fourth lens group is composed of a cemented lens of a negative lens and a positive lens in the order from the object side, and a condition of the following expression is satisfied: νp>30.0, where νp is an Abbe number of the positive lens.