Endoscope Distal Tip Wall Shielding for Halation Reduction
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Solution Overview
Problem
Conventional endoscopes suffer from adverse effects such as halation and lens flare due to direct illumination light entering the objective lens, which degrades image quality, especially when attempting to achieve wide view angles like 140° or more.
Innovation Solution
The endoscope design incorporates an illumination lens adjacent to the objective lens, with a wall portion between them to shield illumination light, and uses inclined illumination optical axes to prevent direct illumination from reaching the objective lens, ensuring effective illumination of the image pickup range while preventing harmful light beams from entering the objective lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the illumination optical system is placed adjacent to the objective optical system, then the illumination efficiency is improved, but harmful light beams (halation and lens flare) enter the objective lens and degrade image quality
Solution Approach 1:
A light shielding member is introduced as an intermediary element between the illumination optical system and the objective optical system. This member selectively blocks harmful light beams (those causing halation and lens flare) while allowing beneficial illumination light to reach the objective lens, thus resolving the contradiction between illumination efficiency and image quality degradation
Solution Approach 2:
The light shielding member is designed with specific optical characteristics (transparency, reflectivity, or absorptivity) at different locations or wavelengths. It allows certain light paths (illumination light) to pass through while blocking other light paths (harmful reflection light), achieving local differentiation in optical behavior to simultaneously satisfy illumination efficiency and image quality requirements
2Adaptability or versatility
If a convex meniscus lens is used for the objective optical system to achieve wide view angle, then the view angle is increased to 140° or more, but the complexity of the optical system increases
Solution Approach 1:
The patent employs a convex meniscus lens with specifically designed optical parameters (curvature radii, refractive index, thickness distribution) to achieve the desired wide view angle of 140° or more. By optimizing these parameters, the system achieves the required field of view while controlling the complexity of the lens structure itself
3Area of stationary object
If the illumination light is directed to illuminate the entire image pickup range, then the illumination coverage is improved, but more harmful light beams are generated that can enter the objective lens
Solution Approach 1:
The light shielding member acts as a mediator that is positioned to block harmful light beams generated during wide-area illumination. It allows the illumination light to cover the entire image pickup range while preventing the harmful reflections and scattered light from reaching the objective lens, thus decoupling illumination coverage from harmful light generation
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 clear and bright endoscope images with a wide view angle of 140° or more, preventing halation and lens flare, and maintaining a compact distal end portion diameter.
Implementation Method 1
a wall portion which is placed between the objective lens and the illumination lens, and shields the illumination light
Data Source
AI summary
An endoscope of the present invention includes an insertion section including a distal end portion, an objective lens placed in the distal end portion, an illumination lens which is placed in the distal end portion adjacently to the objective lens and emits illumination light from a light source, and a wall portion which is placed between the objective lens and the illumination lens, and shields the illumination light, and thereby, secures a sufficient illumination range for an image pickup range with a wide field of view, can obtain a favorable endoscope image and can reduce the diameter.