Endoscope Objective Optical System with Movable Lens Group
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Solution Overview
Problem
Medical endoscopes face challenges in simultaneously achieving clear normal and magnifying observations due to the limited depth of field and focusing range, making it difficult to observe lesions in detail without switching between different optical systems.
Innovation Solution
An objective optical system comprising a first lens group with negative refractive power, a second lens group that moves for focusing, and a third lens group with positive refractive power, including a front and rear group with cemented lenses, which allows for both normal and magnifying observations with a single system by adjusting the second lens group's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the F-number of the objective optical system is made small to enable detailed observation of lesion parts, then the imaging resolution and light gathering capability are improved, but the depth of field becomes narrow, making it difficult to maintain focus across different observation distances
Solution Approach 1:
The patent employs a movable second lens group that can be positioned at different locations along the optical axis. By moving this lens group between a first position for normal observation and a second position for magnifying observation, the system dynamically adjusts its optical characteristics to maintain adequate depth of field while preserving high imaging resolution. This dynamic repositioning allows the same optical system to adapt to different observation requirements without compromising either resolution or depth of field.
2Device complexity
If a single objective optical system is used for both normal observation and magnifying observation, then the device complexity is reduced, but the focusing range becomes insufficient to cover both distant and close object positions
Solution Approach 1:
The patent makes the second lens group movable along the optical axis, allowing it to be repositioned between a first position for normal observation of distant objects and a second position for magnifying observation of close objects. This dynamic adjustment extends the focusing range of the single optical system to cover both observation modes, eliminating the need for separate optical systems while maintaining versatility.
Solution Approach 2:
The single objective optical system is designed to perform multiple functions by repositioning the second lens group. The same lens group serves both normal observation and magnifying observation purposes, making the optical system universal and adaptable to different observation requirements without requiring separate dedicated systems for each function.
3Measurement precision
If the second lens group is positioned for normal observation, then the normal image is in focus, but the magnified image becomes out of focus due to the narrow depth of field
Solution Approach 1:
The patent employs dynamic repositioning of the second lens group along the optical axis. When normal observation is required, the lens group is positioned at a first location that optimizes focus for distant objects. When magnifying observation is required, the lens group is moved to a second location that extends the depth of field to accommodate close object positions. This dynamic adjustment allows the system to maintain focusing accuracy across different observation ranges.
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
Enables sharp imaging in both normal and magnifying observations with a wide angle of view and adequate back focus, while maintaining a compact optical system design, thus improving the ability to observe lesions in detail.
Implementation Method 1
an objective optical system includes a first lens group having a negative refractive power, a second lens group, and a third lens group having a positive refractive power
Data Source
AI summary
An objective optical system includes in order from an object side to an image side, a first lens group having a negative refractive power, a second lens group, and a third lens group having a positive refractive power. At a time of focusing, the second lens group moves in an optical axial direction. The third lens group includes, from the object side to the image side, a front group and a rear group. The front group includes a cemented lens having a positive refractive power or includes a single lens having a positive refractive power. The rear group includes a cemented lens having a positive refractive power, and the following conditional expression (1) is satisfied:0.45<d3t/f32<0.8 (1).