Endoscope Objective Optical System with Movable Lens Groups
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Solution Overview
Problem
Endoscope objective optical systems face challenges in maintaining image quality due to diffraction issues with high-definition image sensors, requiring a reduction in F number and increase in focal length, which narrows the depth of field, and there is a need for systems capable of magnified observation for qualitative diagnosis.
Innovation Solution
An objective optical system comprising a positive first group, a negative second group, a negative third group, and a positive fourth group, where the second and third groups move together to focus from a long distance to a close distance, satisfying specific conditional expressions to ensure a suitable depth of field and size reduction, while using cemented lenses and parallel plates to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-definition image sensors with higher pixel count are used to improve image quality, then image resolution is improved, but image quality is degraded due to diffraction and the size of the image sensor increases
Solution Approach 1:
The patent changes the optical parameters of the system by reducing the F number from conventional values to approximately F1.9 or lower, and by optimizing the focal length to match the high-resolution sensor characteristics. This parameter optimization resolves the diffraction limitation while maintaining the benefits of high pixel count sensors.
2Object-affected harmful factors
If the F number is reduced and focal length is increased to avoid diffraction degradation, then image quality is improved, but the depth of field becomes narrow
Solution Approach 1:
The patent introduces a focusing mechanism with movable lens groups that dynamically adjust the optical path to extend the depth of field. By making portions of the lens system movable, the system maintains the low F number and appropriate focal length while achieving a sufficiently wide depth of field for endoscopic observation.
3Adaptability or versatility
If magnified observation capability is added for qualitative diagnosis, then diagnostic capability is improved, but the optical system complexity increases
Solution Approach 1:
The patent designs the optical system with movable lens groups that serve multiple functions: they enable both normal observation and magnified observation modes, provide focusing capability across different object distances, and maintain aberration correction. This multi-functionality achieves qualitative diagnosis capability without proportionally increasing system complexity.
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 high-performance, compact, and bright F number optical systems with reduced manufacturing error sensitivity, supporting high-resolution image sensors and enabling magnified observation with improved image quality and reduced size.
Implementation Method 1
An objective optical system includes, in order from an object side: a positive first group; a negative second group; a negative third group; and a positive fourth group
Implementation Method 2
using cemented lenses and parallel plates to correct aberrations
Data Source
AI summary
An objective optical system includes, in order from an object side: a positive first group; a negative second group; a negative third group; and a positive fourth group, in which the second group and the third group move together toward an image side to perform focusing from an object point at a long distance to an object point at a close distance, and the following conditional expression (2) is satisfied: 0.2<(t34f−t34n)/F<2 (2), where t34f is a distance between the third group and the fourth group at a time of focusing to the object point at the long distance, t34n is a distance between the third group and the fourth group at a time of focusing to the object point at the close distance, and F is a focal length of the overall objective optical system at a time of focusing to the object point at the long distance.