Variable Magnification Optical System with Segmented Lens Groups

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Solution Overview

Problem

There is a demand for a variable magnification optical system with a wide angle of view that is compact in size while maintaining favorable optical performance, which existing systems have not adequately addressed.

Innovation Solution

A variable magnification optical system comprising a front group with two or fewer lens groups and negative refractive power, a middle group with a single positive refractive power lens, and a rear group with three or less lens groups, where the spacing between these groups changes during magnification, and the front group includes at least three negative lenses and a positive lens with a meniscus shape convex toward the object side, satisfying specific conditional expressions for optimal performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a variable magnification optical system is designed to achieve a wide angle of view, then the angle of view is improved, but the system size increases

Engineering Contradiction:

Improveangle of viewVSAvoidsystem size

Core Design Contradiction:

Illumination intensityVSVolume of moving object

Solution Approach 1:

The optical system is divided into three distinct lens groups (front group with negative refractive power, middle group with positive refractive power, and rear group) that can independently move along the optical axis. This segmentation allows each group to be optimized for specific functions while enabling compact overall structure through coordinated movement during magnification changes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic spacing between lens groups where the distances between front-middle and middle-rear groups change during magnification transitions. This dynamic configuration allows the system to achieve wide angle of view at telephoto end while maintaining compact size at wide angle end through calculated group movements.

Inventive Principle:

Principle #15Dynamics

2Volume of moving object

If the system is reduced in size, then the volume is improved, but the optical performance deteriorates

Engineering Contradiction:

Improvesystem sizeVSAvoidoptical performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

Each lens group is designed with specific local characteristics: the front group has negative refractive power with specific lens configurations, the middle group has positive refractive power, and the rear group has carefully selected lens combinations. This local optimization ensures that despite compact overall size, each region contributes to maintaining favorable optical performance including aberration correction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes conditional expressions that define specific parameter ranges for lens focal lengths, refractive powers, and spacing ratios. By controlling parameters such as the ratio of front group focal length to total focal length and the spacing between groups, the system achieves compact size while maintaining optical performance through precise parameter optimization.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If the front group consists of multiple lens groups with negative refractive power, then the angle of view is improved, but the complexity of the system increases

Engineering Contradiction:

Improveangle of viewVSAvoidlens group configuration

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The front group is segmented into specific lens configurations (including meniscus lenses and negative lenses) that work together to provide wide angle of view. This segmentation allows the complex function of wide angle coverage to be achieved through coordinated action of individual lenses while maintaining manageable overall system complexity.

Inventive Principle:

Principle #1Segmentation

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 wide angle of view while reducing size and maintaining favorable optical performance, with improved aberration correction and mechanical strength, and simplified lens movement mechanisms.

Implementation Method 1

a front group; a middle group; and a rear group. The front group consists of two or fewer lens groups and has a negative refractive power as a whole throughout an entire variable magnification range, the middle group includes only one lens group that has a positive refractive power as a lens group

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20230194840A1Variable magnification optical system and imaging apparatus

Publication Date: 2023.06.22 FUJIFILM CORP

AI summary

The variable magnification optical system consists of a front group, a middle group, and a rear group, in order from an object side. The front group consists of two or fewer lens groups and has a negative refractive power. The middle group includes only one lens group that has a positive refractive power as a lens group. The rear group consists of three or less lens groups. An aperture stop is disposed between a lens surface closest to an image side in the front group and a lens surface closest to the object side in the rear group. The front group includes at least three negative lenses and at least one positive lens. A negative meniscus lens convex toward the object side is disposed closest to the object side in the front group. The variable magnification optical system satisfies predetermined conditional expressions.