Variable Magnification Optical System Aberration Control

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Solution Overview

Problem

Conventional variable magnification optical systems face challenges in achieving high optical performance while being compact and maintaining a high variable magnification ratio, as they struggle to suppress variations in distortion, astigmatism, and spherical aberration during zooming.

Innovation Solution

A variable magnification optical system comprising a specific configuration of lens groups with varying distances between them, including a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fifth lens group, where the fifth lens group is fixed, and satisfying specific conditional expressions for focal lengths to control aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the variable magnification optical system uses a conventional lens group configuration, then the structure is simple, but the optical performance deteriorates due to inability to suppress variations in distortion, astigmatism, and spherical aberration during zooming

Engineering Contradiction:

Improveoptical performanceVSAvoidlens group configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The optical system is divided into five distinct lens groups (G1-G5) with specific refractive power assignments. Each lens group is independently designed to address specific aberration types, allowing precise control over optical performance across the zoom range while managing system complexity through functional segmentation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different lens groups are assigned specific refractive powers (positive or negative) to correct specific types of aberrations at different locations in the optical path. The conditional expressions define local optical properties (focal lengths f1-f5) that must be satisfied to achieve uniform aberration suppression across the entire zoom range.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the optical system is designed for high variable magnification ratio, then the zoom capability is improved, but the apparatus size increases and optical performance deteriorates

Engineering Contradiction:

Improvevariable magnification ratioVSAvoidapparatus size

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The optical system achieves high variable magnification ratio (13.6x) through dynamic adjustment of inter-lens group distances during zooming. The conditional expressions define the dynamic ranges of these distances, allowing the system to maintain compact size while achieving extensive magnification variation through coordinated movement of lens groups.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the optical system uses more lens groups to improve optical performance, then the aberration suppression is improved, but the device complexity and apparatus size increase

Engineering Contradiction:

Improveaberration suppressionVSAvoidnumber of lens groups

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system achieves effective aberration suppression with five lens groups by precisely controlling key parameters (focal lengths f1-f5 and inter-group distances) within specific ranges defined by conditional expressions. This parameter optimization allows adequate aberration correction without unnecessarily increasing the number of lens groups, balancing performance with complexity.

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 system achieves a high variable magnification ratio, compact size, and excellent optical performance by effectively suppressing distortion, astigmatism, and spherical aberration during zooming, as demonstrated by the provided numerical examples.

Implementation Method 1

a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10126535B2Variable magnification optical system, optical device, and production method for variable magnification optical system

Publication Date: 2018.11.13 NIKON CORP

AI summary

Comprising, in order from an object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; a third lens group G3 having positive refractive power; a fourth lens group G4 having positive refractive power; and a fifth lens group; upon zooming from a wide-angle end state to a telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 being varied, and the fifth lens group G5 being fixed in a position; and a predetermined conditional expression being satisfied, thereby providing a variable magnification optical system that has a high variable magnification ratio, is compact in size and has high optical performance, an optical apparatus, and a method for manufacturing the variable magnification optical system.