Endoscope Optical System Magnification Switching

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Solution Overview

Problem

Existing endoscope optical systems face challenges in seamlessly switching between normal and magnified observations while maintaining high imaging performance and correcting chromatic aberrations, due to limitations in refractive power distribution and lens group movements.

Innovation Solution

An endoscope optical system comprising a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with positive refractive power, where the second lens group moves to switch between observations, and the third lens group includes a cemented lens with specific refractive index and Abbe number differences to correct chromatic aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the second lens group moves to switch between normal and magnified observations, then the switching function is achieved, but chromatic aberration fluctuations occur

Engineering Contradiction:

Improveswitching between normal and magnified observationsVSAvoidchromatic aberration correction

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The optical system is divided into three lens groups with distinct functions: the first lens group (negative refractive power) for overall focal length control, the second lens group (positive refractive power) for magnification switching by movement, and the third lens group (positive refractive power with cemented lens) for chromatic aberration correction. This segmentation allows each group to be optimized independently for its specific function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cemented lens in the third lens group uses specific refractive index (nd01, nd02) and Abbe number (vd01, vd02) parameters that satisfy conditional expressions. By carefully selecting glass materials with specific optical parameters, the system maintains chromatic aberration correction across different magnification states achieved by moving the second lens group.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple lens groups are used to achieve magnification switching, then the magnification function is improved, but the system size and complexity increase

Engineering Contradiction:

Improvemagnification switching capabilityVSAvoidnumber of lens groups and movements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The second lens group serves multiple functions: it provides the primary magnification effect when moved, and its movement simultaneously adjusts the overall optical path length. The third lens group with the cemented lens structure provides both chromatic aberration correction and contributes to the overall positive refractive power needed for the imaging system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cemented lens combines two lens elements with different refractive properties into a single integrated unit. This merging of elements achieves chromatic aberration correction within a compact structure, reducing the overall system size compared to using separate correction lenses.

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If the third lens group includes a cemented lens with specific refractive properties, then chromatic aberration is corrected, but manufacturing precision requirements increase

Engineering Contradiction:

Improvechromatic aberration correctionVSAvoidlens material selection and assembly

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent defines specific conditional expressions for the refractive indices (nd01, nd02) and Abbe numbers (vd01, vd02) of the cemented lens materials. These parameter specifications provide clear manufacturing guidelines, allowing manufacturers to select from standard glass catalogs that meet the required ranges, thereby balancing optical performance with manufacturing feasibility.

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

Enables efficient switching between normal and magnified observations with improved imaging performance and reduced aberration fluctuations, while simplifying manufacturing adjustments and reducing system size and cost.

Implementation Method 1

the cemented lens includes an object-side lens and an image-side lens, and the following conditional expressions (1) and (2) are satisfied: 0.471 < (nd02−nd01)/(vd01−vd02) where nd01 denotes a refractive index of the object-side lens for a d-line, nd02 denotes a refractive index of the image-side lens for the d-line, vd01 denotes Abbe number for the object-side lens for the d-line, and vd02 denotes Abbe number for the image-side lens for the d-line

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10845586B2Endoscope optical system

Publication Date: 2020.11.24 OLYMPUS CORPORATION(JP)

AI summary

The endoscope optical system includes in order from an object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. Switching between a normal observation and a magnified observation is possible by fixing the first lens group and the third lens group, and moving the second lens group. The third lens group includes a cemented lens. The cemented lens includes an object-side lens and an image-side lens, and the following conditional expressions (1) and (2) are satisfied:0.471<nd02−nd01<0.475 (1)52.6<vd01−vd02<53 (2).