Superzoom Lens Second Group Segmentation

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Solution Overview

Problem

Conventional superzoom lenses face challenges in maintaining optical performance due to increased thickness when collapsed, which affects their zoom ratio and aberration correction, particularly with the second lens group comprising multiple lenses.

Innovation Solution

The superzoom lenses are designed with a first lens group of positive optical power, a second lens group consisting of a convex and a concave lens providing negative optical power, a third lens group of positive optical power, and a fourth lens group, optimizing the optical path length to image diameter ratio (3≦LW/ID<5) to maintain thinness and high zoom ratios, and incorporating a negative meniscus lens for aberration correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second lens group includes at least three lenses (conventional design), then the optical power can be achieved, but the thickness of the zoom lens is increased when collapsed

Engineering Contradiction:

Improveoptical powerVSAvoidthickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The second lens group is segmented into exactly two lenses (a negative lens and a positive lens) instead of three or more, reducing the overall thickness while maintaining the required negative optical power through optimized individual lens designs

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The optical parameters of the two lenses in the second lens group are optimized, including the negative lens having specific curvature radii and the positive lens being cemented to the negative lens, allowing achievement of required optical power with reduced thickness

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the zoom lens is designed for high zoom ratio (superzoom), then the zoom capability is improved, but the optical performance deteriorates due to increased thickness and aberration

Engineering Contradiction:

Improvezoom ratioVSAvoidoptical performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent optimizes multiple optical parameters including the optical path length to image diameter ratio (LW/ID between 3-5), focal length ratios, and lens curvature radii to achieve high zoom ratio while maintaining optical performance and correcting aberrations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of thick lens design into benefit by using a compact two-lens second lens group with optimized parameters, where the cemented lens structure and specific curvature designs help correct spherical and coma aberrations that typically worsen with high zoom ratios

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Length of moving object

If the second lens group is thinned by using two lenses, then the thickness is reduced, but the optical power may be compromised

Engineering Contradiction:

ImprovethicknessVSAvoidoptical power

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The optical power is maintained despite reduced lens count by optimizing parameters including the negative lens curvature radii (r1, r2), the positive lens properties, and the spacing between lenses, allowing two lenses to provide the required negative optical power

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The positive and negative lenses in the second lens group are cemented together to form a composite lens unit, where the combination of different lens materials and designs achieves the required optical power with reduced overall thickness

Inventive Principle:

Principle #40Composite materials

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 allows for high zoom ratios up to 15× while maintaining good optical performance by ensuring the second lens group is thinned, reducing spherical and coma aberrations, and enabling smooth focal plane compensation during magnification changes.

Implementation Method 1

a second lens group having negative optical power and including a convex lens and a concave lens

Methodology Applied

Scientific EffectOptical refraction: Refraction

Implementation Method 2

enabling smooth focal plane compensation during magnification changes

Methodology Applied

Scientific EffectOptical refraction: Refraction

Data Source

PatentUS8208206B2Superzoom lenses

Publication Date: 2012.06.26 ASIA OPTICAL INT LTD

AI summary

Superzoom lenses are disclosed. The superzoom lenses include, in order from an object side to an image side on an optical axis, a first lens group, a second lens group, an aperture, a third lens group, and a fourth lens group. The first lens group has positive optical power. The second lens group has negative optical power and is consisted of a convex lens and a concave lens. The third lens group has positive optical power. The fourth lens group has positive optical power. The superzoom lenses satisfy the following relationship when the superzoom lenses are collapsed:3≦LW/ID<5wherein LW stands for the optical path length, and ID stands for the diameter of the image circle.