Objective Optical System for Wide-Angle Imaging
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Solution Overview
Problem
Conventional objective optical systems for endoscopes and cameras face challenges in achieving a wide viewing angle with high definition while maintaining a small size and suppressing aberrations, particularly off-axis aberrations, which affects image quality.
Innovation Solution
The optical system configuration includes an aperture stop followed by a positive first group, a positive second group, and a third group, with specific lens arrangements and focal length ratios that correct comatic aberration, astigmatic difference, and field curvature, ensuring a wide viewing angle and high-definition imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a retrofocus-type four- to six-lens configuration is used, then a wide viewing angle is achieved, but the system size increases and complexity increases
Solution Approach 1:
The optical system is divided into four distinct lens groups with specific focal length relationships (|f1|<|f2|<|f3|<|f4|), where each group contributes differently to aberration correction and wide-angle performance. This segmentation allows achieving wide viewing angle with fewer total lenses compared to conventional retrofocus designs.
Solution Approach 2:
The patent applies specific conditional expressions for focal length ratios (0.1<|f1/f2|<0.5, 0.1<|f2/f3|<0.5, 0.1<|f3/f4|<0.5) and curvature relationships to optimize the balance between wide viewing angle and compact size. By controlling these parameters, the system achieves wide-angle performance without requiring the larger size of traditional retrofocus configurations.
2Manufacturing precision
If more lenses are added to achieve high definition with wide angle, then image quality improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The four-group configuration with progressively increasing focal lengths creates a hierarchical structure where each group addresses specific aberration types. This segmentation enables effective aberration correction with only four lens groups, avoiding the need for more lenses that would increase complexity and cost.
Solution Approach 2:
Each lens group serves multiple functions: the first group (shortest focal length) primarily corrects off-axis aberrations while contributing to wide-angle performance; subsequent groups progressively correct remaining aberrations. This multi-functionality allows high-definition imaging with a compact four-group design rather than requiring additional specialized lenses.
3Volume of stationary object
If a compact configuration is used to reduce size, then portability improves, but off-axis aberrations increase
Solution Approach 1:
The patent assigns different focal length characteristics to different lens groups (|f1|<|f2|<|f3|<|f4|), where the first group with the shortest focal length is specifically optimized for handling off-axis rays. This local optimization of optical properties in different zones of the system enables effective off-axis aberration correction within a compact overall size.
Solution Approach 2:
By enforcing specific conditional expressions on focal length ratios and curvature relationships, the patent optimizes the compact configuration to minimize off-axis aberrations. The controlled parameter relationships ensure that even in a compact four-group design, off-axis performance remains high without requiring larger system dimensions.
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 effectively suppresses off-axis aberrations and maintains high image quality, making it suitable for high-pixel-count solid-state imaging devices with a compact size.
Implementation Method 1
a positive first group, a second group, a positive third group, and a fourth group... the first group is formed of a single meniscus lens or plano-convex lens, whose convex surface faces an image side
Data Source
AI summary
Provided is an objective optical system comprising, in order from an object side: an aperture stop; a positive first group; a second group; a positive third group; and a fourth group, wherein the first group is formed of a single meniscus lens or plano-convex lens, whose convex surface faces an image side, the second group is formed of a single lens, the third group is formed of a cemented lens consisting of a positive lens and a negative lens, the fourth group is formed of a single lens, and Conditional Expressions (7) and (8) below are satisfied, where f is a focal length of an entire system, f4 is a focal length of the fourth group, and f2 is a focal length of the second group. −0.5<f/f4<−0.001 (7) 0.1≦̸|f4/f2|≦̸5. (8)