Endoscope Objective Optical System for Wide-Angle Stereoscopic Viewing

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Solution Overview

Problem

Existing endoscope objective optical systems face challenges in achieving wide-angle stereoscopic viewing with high pixel compatibility due to increased beam-bundle diameters and vignetting, particularly when trying to maintain a wide angle greater than or equal to 90°.

Innovation Solution

The endoscope objective optical system consists of a negative first lens group, a positive second lens group, and a pair of third lens groups disposed in a direction of parallax, with individually positioned aperture stops in the third lens groups, satisfying conditional expressions Fob_n/Fob_p > −0.5, fs/fb < 2.5, and optionally employing reflection optical systems with two reflection surfaces to reduce beam-bundle diameters and prevent vignetting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If a wide-angle configuration is adopted to achieve stereoscopic viewing with angle ≥ 90°, then the field of view is improved, but beam-bundle diameters increase and vignetting occurs

Engineering Contradiction:

Improvefield of viewVSAvoidvignetting

Core Design Contradiction:

Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The optical system is divided into multiple lens groups (first lens group with negative focal length, second lens group with positive focal length, and third lens groups) with individual aperture stops. This segmentation allows each group to control specific aspects of light propagation, reducing overall beam-bundle diameter while maintaining wide field of view for stereoscopic viewing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Aperture stops are individually positioned in specific lens groups rather than using a single centralized aperture. This local control of beam diameter at different stages of the optical path prevents vignetting in the wide-angle configuration while maintaining image quality across the stereoscopic field of view.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If aperture stops are positioned to reduce beam-bundle diameters, then vignetting is reduced, but the F-number increases

Engineering Contradiction:

ImprovevignettingVSAvoidF-number

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

Multiple aperture stops are distributed across different lens groups rather than using a single large aperture stop. This segmentation allows each aperture to be optimized for its specific location in the optical path, controlling beam diameter locally to reduce vignetting while maintaining an overall low F-number for good light transmission.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The focal lengths of different lens groups are specifically designed with particular ratios (|Fob1/Fob2| < 0.5) to optimize the beam-bundle diameter progression through the system. This parameter optimization allows aperture stops to effectively control vignetting without excessively increasing the F-number.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the focal length ratio |Fob1/Fob2| is reduced below 0.5, then beam-bundle diameters are controlled, but the optical system complexity increases

Engineering Contradiction:

Improvebeam-bundle diameterVSAvoidoptical system structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The focal lengths of the lens groups are designed with a specific ratio relationship (|Fob1/Fob2| < 0.5) to naturally control beam-bundle diameter progression. This parameter optimization reduces the need for additional complex optical elements while achieving effective beam control and reduced vignetting in the wide-angle stereoscopic configuration.

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

This configuration enables wide-angle endoscope objective optical systems with angles greater than or equal to 90°, allowing for stereoscopic viewing while reducing the F-number and vignetting, and ensuring compatibility with high pixel counts.

Implementation Method 1

consists of, sequentially from the object side, a negative first lens group, a positive second lens group, and a pair of third lens groups that are disposed side-by-side in a direction of parallax and that form two optical images with parallax

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

aperture stops are individually provided in the third lens groups

Methodology Applied

Scientific EffectAbsorption/Blocking: Absorption (EM radiation)

Data Source

PatentUS9706906B2Endoscope objective optical system

Publication Date: 2017.07.18 OLYMPUS CORPORATION(JP)

AI summary

Provided is a small endoscope objective optical system that allows stereoscopic viewing even though a wide angle is used, that reduces the F-number, and that also reduces vignetting.Provided is an endoscope objective optical system that consists of, sequentially from the object side, a negative first lens group, a positive second lens group, and a pair of third lens groups that are disposed side-by-side in the direction of parallax and that form two optical images with parallax, wherein aperture stops are individually provided in the third lens groups, and conditional expression M below is satisfied:Fob_n/Fob_p>−0.5 (1),where Fob_n is a focal length of the first lens group, and Fob_p is a focal length of the second lens group.