Endoscope Magnification Optical System Aberration Correction

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Solution Overview

Problem

Existing endoscope magnification optical systems suffer from insufficient aberration correction, particularly axial chromatic aberration and magnification chromatic aberration, which deteriorate optical performance, especially at the telephoto end, even with high-pixel image sensors.

Innovation Solution

The endoscope magnification optical system incorporates a first lens group with negative power and a second lens group that moves along the optical axis, including a meniscus lens with a concave surface facing the object side, while maintaining a constant distance from the first lens group to the image plane, with specific conditional expressions for magnification and focal length ratios to optimize aberration correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the second and third lens groups having positive power are moved to achieve magnification control, then the amount of freedom in design relating to magnification control is high, but axial chromatic aberration and chromatic aberration of magnification are not sufficiently corrected and dramatically change during magnification

Engineering Contradiction:

Improvemagnification control freedomVSAvoidaberration correction

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the power configuration parameter of the lens groups, specifically setting the third lens group to have negative power instead of positive power. This parameter change fundamentally alters the aberration characteristics while maintaining magnification control capability. The negative power of the third lens group counteracts the chromatic aberrations introduced by the positive power second lens group during magnification changes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite lens group system where the second lens group (positive power) and third lens group (negative power) work together in a complementary manner. This composite structure allows the positive and negative power elements to balance each other's chromatic aberrations, achieving both magnification control freedom and superior aberration correction simultaneously.

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If high-pixel image sensors are mounted to improve image quality, then resolution is enhanced, but a large aberration in the endoscope magnification optical system prevents obtaining high-quality images

Engineering Contradiction:

Improveimage sensor pixel densityVSAvoidoptical performance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by pre-correcting chromatic aberrations through the specific configuration of the third lens group with negative power. This preliminary correction counteracts the aberrations before they reach the high-pixel image sensor, ensuring that the sensor receives already-corrected light rays and can fully utilize its high resolution capability without being degraded by optical aberrations.

Inventive Principle:

Principle #9Preliminary anti-action

3Productivity

If the entire length from the first lens group to the image plane is changed to achieve magnification, then magnification is achieved, but focus cannot be maintained

Engineering Contradiction:

Improvemagnification speedVSAvoidfocus maintenance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the magnification function from the focusing function by assigning different roles to different lens groups. The second lens group handles magnification control through its movement, while the third lens group with negative power is configured to maintain focus during these changes. This segmentation allows independent optimization of both magnification speed and focus maintenance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic configuration where the third lens group's negative power is specifically designed to dynamically compensate for focus shifts that occur during magnification changes. This dynamic balance between the movable second lens group and the configured third lens group enables rapid magnification adjustment while automatically maintaining focus through the optical design.

Inventive Principle:

Principle #15Dynamics

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 effectively corrects aberrations across various magnification ranges, enhancing optical performance and enabling precise focus adjustment while maintaining a compact design, suitable for high-pixel image sensors.

Implementation Method 1

a third lens group including at least a meniscus lens with a concave surface facing the object side and a positive lens

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10036883B2Endoscope magnification optical system and endoscope

Publication Date: 2018.07.31 HOYA CORPORATION

AI summary

An endoscope magnification optical system includes, in order starting from an object side, a first lens group having positive power, a second lens group having positive power, and a third lens group including at least a meniscus lens with a concave surface facing the object side and a positive lens, and the endoscope magnification optical system is configured to magnify an optical image by moving at least the second lens group in an optical axis direction with respect to the first lens group, which is a fixed lens group, while a distance from a lens surface located the closest to the object of the first lens group to an image plane is kept constant.