Endoscope Objective Optics With Prism Layout for Wide-Angle Imaging
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Solution Overview
Problem
Existing endoscopes face challenges in achieving a wide angle of view, small size, and good optical performance.
Innovation Solution
An objective optical system for an endoscope comprising a front group with a negative lens, optical path deflecting prism, and positive lens, and a rear group with cemented lenses, adhering to specific conditional expressions to optimize optical performance and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lens system is used for endoscope, then the structure is simple, but the angle of view is narrow and optical performance is insufficient
Solution Approach 1:
The lens system is divided into a front group (with negative lens, optical path deflecting prism, aperture stop, and positive lens) and a rear group (with multiple cemented lenses). This segmentation allows each group to be optimized independently for specific functions such as wide angle of view, chromatic aberration correction, and overall image quality, thereby achieving high optical performance while maintaining manageable system complexity
Solution Approach 2:
The optical path deflecting prism is integrated within the front group, and multiple cemented lenses are combined in the rear group. This nesting approach compactly arranges optical elements to achieve a wide angle of view and correct aberrations without proportionally increasing system length, resolving the contradiction between performance and complexity
2Reliability
If more lenses are added to improve optical performance, then image quality improves, but system length increases
Solution Approach 1:
Multiple cemented lenses are nested within the rear group with optimized spacing and configuration. The cemented lens structure combines multiple elements in a compact arrangement that corrects chromatic and spherical aberrations effectively while minimizing the axial length required, thus improving image quality without proportionally increasing system length
Solution Approach 2:
The patent applies specific conditional expressions for curvature radii (Rca, Rcb, Rci), distances (Lca, Lcb, Lci), and Abbe numbers (vpa, vna, vpb, vnb) of the lens elements. By optimizing these parameters within defined ranges, the system achieves high image quality with corrected aberrations while controlling the overall system length through precise parameter control rather than simply adding more elements
3Adaptability or versatility
If a wide angle of view is achieved through lens design, then field of view increases, but chromatic aberration increases
Solution Approach 1:
The patent uses cemented lenses in the rear group where positive and negative lenses with different Abbe numbers are combined. This configuration converts the potentially harmful chromatic dispersion into a beneficial effect by using the dispersion differences to correct chromatic aberration across the wide field of view, thereby achieving both wide angle of view and effective chromatic aberration correction
Solution Approach 2:
Specific conditional expressions involving Abbe numbers (vpa, vna, vpb, vnb) of the lens materials are applied to control chromatic dispersion characteristics. By selecting materials and designing lens parameters within optimized ranges, the system achieves wide angle of view while maintaining effective chromatic aberration correction through material parameter optimization
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 system achieves a wide angle of view, small size, and good optical performance, effectively correcting chromatic aberrations and reducing system length while maintaining image quality.
Implementation Method 1
an optical path deflecting prism, and one positive lens arranged in this order from the object side toward the image side
Data Source
AI summary
An objective optical system for an endoscope consisting of, in order from an object side toward an image side: a front group; and a rear group, wherein: the front group consists of, in order from the object side toward the image side: one negative lens; an optical path deflecting prism; an aperture stop; and one positive lens. The objective optical system for an endoscope satisfies a predetermined conditional expression.