Endoscope Objective Optical System Magnification Focus Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Medical endoscopes face challenges in performing both normal and magnifying observations with a single objective optical system, as the object position in magnifying observation is often out of the depth of field of the system configured for normal observation, resulting in out-of-focus images.
Innovation Solution
An objective optical system comprising a first lens group with negative refractive power, a second lens group with positive refractive power and an aperture stop, and a third lens group with positive refractive power, where the second lens group moves to change magnification, satisfying specific conditional expressions to correct astigmatism and ensure a long back focal length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical system is configured to make the object position in the normal observation and the focus position coincide, then the normal image becomes in-focus, but the magnifying image becomes out-of-focus because the object position in magnifying observation is apart from the object position in normal observation and not within the depth of field
Solution Approach 1:
The patent applies the dynamics principle by making the second lens group movable to change magnification. The second lens group moves along the optical axis between a first position for normal observation and a second position for magnifying observation. This dynamic adjustment allows the optical system to adapt to different object distances and maintain focus accuracy for both normal and magnifying observations, resolving the contradiction between focus accuracy and observation mode adaptability.
2Adaptability or versatility
If the objective optical system has a focusing function to produce in-focus object image in magnifying observation, then both normal image and magnifying image can be in-focus, but the structural complexity increases
Solution Approach 1:
The patent applies the universality principle by designing the second lens group to serve multiple functions: it acts as both a magnification-changing element and a focusing element. By moving the second lens group along the optical axis, the system achieves both magnification adjustment and focus adjustment simultaneously, eliminating the need for separate focusing mechanisms and reducing overall structural complexity while maintaining focusing capability.
3Adaptability or versatility
If the second lens group moves to change magnification, then both normal and magnifying observations are enabled, but astigmatism aberration occurs
Solution Approach 1:
The patent applies the local quality principle by assigning specific optical properties to different lens groups. The second lens group is designed with particular refractive power and is positioned at specific locations (first position for normal observation, second position for magnifying observation). This localized optimization of optical properties allows the moving second lens group to enable magnification adjustment while controlling astigmatism aberration through careful design of its optical characteristics and movement range.
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 both normal and magnifying observations with a single optical system, maintaining image focus and correcting aberrations, particularly astigmatism, to achieve a deep focal depth and improved imaging performance.
Implementation Method 1
an objective optical system includes, in order from an object side: a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power
Data Source
AI summary
An objective optical system includes, in order from an object: a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The second lens group includes an aperture stop and moves at a time of changing magnification.