Endoscope Objective Optical System Aberration Control
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Solution Overview
Problem
Existing objective optical systems for endoscopes face challenges in widening the angle of view while minimizing variations and aberrations caused by lens surface tilting and eccentricities, as the burden of widening the angle of view is often concentrated on a single lens, leading to significant changes in the angle of view and increased aberrations.
Innovation Solution
An objective optical system comprising a first lens group with negative refractive power and a second lens group with positive refractive power, where the first lens group includes a negative single lens and a cemented negative lens, and the second lens group includes a positive single lens and a cemented positive or negative meniscus lens, configured to satisfy specific focal length ratios to distribute the burden of widening the angle of view across multiple lens surfaces, thereby reducing the impact of tilting and eccentricities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the radius of curvature of the image side lens surface of a negative lens is decreased to widen the angle of view, then the angle of view is widened, but field curvature is overcorrected and aberrations increase significantly
Solution Approach 1:
The patent divides the lens system into multiple groups (first lens group with negative refractive power, second lens group with positive refractive power) and distributes the angle of view correction burden across multiple lens surfaces rather than concentrating it on a single lens surface. This segmentation approach reduces the impact of tilting and eccentricities on overall optical performance.
Solution Approach 2:
The patent applies different refractive power characteristics to different lens groups and surfaces. The first lens group has negative refractive power while the second lens group has positive refractive power, creating local variations in optical properties that balance field curvature correction with angle of view widening, preventing overcorrection.
2Adaptability or versatility
If the burden of widening the angle of view is concentrated on a single lens, then the angle of view can be widened, but small tilts or eccentricities cause significant changes in angle of view and increased aberrations
Solution Approach 1:
The patent segments the angle of view correction function across multiple lens surfaces in different groups. The first lens group (with negative refractive power) and second lens group (with positive refractive power) both contribute to widening the angle of view, so that tilting or eccentricity in one lens does not dominate the overall performance degradation.
Solution Approach 2:
The patent optimizes the refractive powers and focal lengths of multiple lens groups to achieve a balanced optical system. By controlling the combined focal length ratios and individual lens parameters, the system achieves angle of view widening while maintaining stability against manufacturing variations and assembly misalignments.
3Adaptability or versatility
If a retro focus type optical system is adopted to widen the angle of view, then the angle of view is widened, but the back focus space is reduced affecting the insertion of optical path converting prisms
Solution Approach 1:
The patent changes the optical parameters by introducing a two-group lens configuration with specific refractive power distributions. This allows the system to achieve wide angle of view while maintaining adequate back focus space, as the positive refractive power in the second lens group helps extend the image side focal length.
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 a wider angle of view while maintaining low distortion and field curvature, suppressing variations in the angle of view and aberrations, even with tilting or eccentricities in individual lens surfaces, by balancing the focal lengths of the lens groups to achieve stable optical performance.
Implementation Method 1
a first lens group having a negative refractive power; an aperture stop; and a second lens group having a positive refractive power, provided in this order from an object side
Data Source
AI summary
An objective optical system includes: a first lens group having a negative power; an aperture stop; and a second lens group having a positive power, provided in this order from an object side. The first lens group includes a first lens, which is a negative single lens, and a cemented lens formed by a positive lens and a negative lens, provided in this order from the object side. The second lens group includes a fourth lens, which is a positive single lens, and a cemented lens formed by a positive lens and a negative lens, provided in this order from the object side. The objective optical system simultaneously satisfies Conditional Formulae (1) −1.5<f123/f<−0.5 and (2) 1.8<f456/f<2.1, wherein f is the focal length of the entire system, f123 is the combined focal system of the first lens group, and f456 is the combined focal length of the second lens group.