Zoom Lens Design with Fixed Aperture Stop

Solution Overview

Problem

Conventional zoom lenses with multiple aspheric lenses face challenges in mass production due to strict tolerance requirements, increased cost, and complex interlinking mechanisms, leading to reduced yield and higher manufacturing costs.

Innovation Solution

A zoom lens design featuring a first lens group with negative and positive refractive powers, combined with a second lens group including both spherical and aspheric lenses, with a fixed aperture stop position, allowing for a wide viewing angle and infrared correction while minimizing the number of aspheric lenses to simplify the design and reduce costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple aspheric lenses are used to eliminate image aberration and achieve wide angle, then imaging quality is improved, but manufacturing cost and tolerance requirements increase

Engineering Contradiction:

Improveimage aberration correctionVSAvoidmass production tolerance control

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies aspheric surfaces only to specific lenses (first lens and fourth lens) rather than all lenses, concentrating the aberration correction function where most needed while using simpler spherical surfaces for other lenses, thereby reducing overall manufacturing complexity and cost

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If multiple aspheric lenses are used to eliminate image aberration and achieve wide angle, then imaging quality is improved, but production cost increases

Engineering Contradiction:

Improveimage aberration correctionVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies aspheric surfaces only to specific lenses (first lens and fourth lens) rather than all lenses, concentrating the aberration correction function where most needed while using simpler spherical surfaces for other lenses, thereby reducing overall manufacturing complexity and cost

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If aperture stop moves during zoom to maintain optical performance, then imaging quality is improved, but interlinking mechanism complexity and volume increase

Engineering Contradiction:

Improveimaging qualityVSAvoidinterlinking mechanism

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the aperture stop from the moving components and fixes it relative to the lens groups, separating the aperture function from the zoom mechanism, thereby eliminating the need for complex interlinking mechanisms while maintaining acceptable imaging quality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The fixed aperture stop serves multiple functions: controlling light intensity, defining the optical path, and acting as a reference for lens group movements, thereby simplifying the overall mechanism while maintaining imaging performance

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Manufacturing precision

If aperture stop moves during zoom to maintain optical performance, then imaging quality is improved, but zoom lens volume increases

Engineering Contradiction:

Improveimaging qualityVSAvoidzoom lens volume

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent extracts the aperture stop from the moving components and fixes it relative to the lens groups, separating the aperture function from the zoom mechanism, thereby eliminating the need for complex interlinking mechanisms while maintaining acceptable imaging quality

Inventive Principle:

Principle #2Taking out (Extraction)

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 design effectively reduces image aberration, maintains a wide viewing angle, and achieves a small size with lower production costs by using fewer aspheric lenses and a simpler interlinking mechanism, while ensuring better imaging quality across visible and infrared light spectra.

Implementation Method 1

The first lens group has a negative refractive power... The second lens group has a positive refractive power... The first lens group and the second lens group are capable of moving between the object side and the image side to make the zoom lens be switched between a wide end and a tele end

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

the aspheric lens has a fine effect for rectifying image aberration

Methodology Applied

Scientific EffectAspheric optical correction: Lens

Implementation Method 3

an aperture stop movably disposed between the first lens group and the second lens group

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentUS7944620B2Zoom lens

Publication Date: 2011.05.17 YOUNG OPTICS

AI summary

A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fw when the zoom lens is switched to a wide end. The zoom lens satisfies −2.8<f1/fw<−2.5 and 0.75<|f1/f2|<0.9.