Endoscope Objective Lens Unit for Wide-Angle View
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Solution Overview
Problem
Endoscopes lack an objective lens capable of efficiently utilizing image sensors with large incident angles, limiting the angle of view while maintaining good optical performance.
Innovation Solution
An endoscope objective lens unit comprising a front lens group with negative refractive power, a diaphragm, and a rear lens group with positive refractive power, where specific focal length and curvature radius relationships are established to enhance the angle of view without compromising optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small number of lenses are used to reduce the size of the distal end portion, then the device size is reduced, but the optical performance deteriorates
Solution Approach 1:
The objective lens is divided into multiple lens groups (front lens group with negative lenses, middle lens group with positive and negative lenses, rear lens group with positive and negative lenses) that can be segmented and arranged along the optical axis. This segmentation allows each lens group to perform specific optical functions, achieving high optical performance with a compact overall structure suitable for small distal end portions.
Solution Approach 2:
Multiple lens groups are nested along the optical axis in a compact arrangement, with the front lens group, middle lens group, and rear lens group positioned sequentially. This nested configuration maximizes the use of available space, allowing complex optical systems to be packaged within a small distal end portion volume.
2Adaptability or versatility
If the angle of view is increased to utilize CMOS image sensors with large incident angles, then the image sensor utilization is improved, but the outer diameter and length of the distal end portion increase
Solution Approach 1:
The patent optimizes specific parameter relationships within the lens system, including the focal length ratio between front and rear lens groups (|fF/fR| = 0.3 to 0.8), the curvature radius ratios of lens surfaces (R1/R2 = 0.5 to 2.0), and the position ratios of lens groups. These parameter optimizations enable the lens to achieve large angle of view (100 degrees or more) while maintaining a compact distal end portion size.
Solution Approach 2:
The lens design incorporates dynamic optimization of light ray paths through carefully designed surface curvatures and lens group positions, enabling the system to handle wide-angle light rays effectively. The variable curvature radii and strategic positioning of lens groups allow dynamic control of light convergence angles, achieving both large field of view and compact size.
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
The configuration allows for an increased angle of view exceeding 100 degrees, maintaining good optical performance and preventing excessive outer diameter and length at the distal end portion.
Implementation Method 1
The objective lens unit includes a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power in order from an object side
Data Source
AI summary
The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies −1.6<fF/fR<−1.2 and −1.0<SF5<−0.5. fF and fR are the focal lengths of the front lens group and the rear lens group, SF5 is (R51+R52)/(R51−R52), and R51 and R52 are respectively the curvature radiuses of surfaces.