Endoscope Objective Optical System with Movable Lens Groups
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional endoscope objective lenses have a wide depth of field, making it difficult to achieve high-quality images with high-definition imagers due to the spreading of point images caused by diffraction, and they lack a focusing function necessary for magnified observations of lesions in medical applications.
Innovation Solution
An objective optical system comprising a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power, where the second and third lens groups move along the optical axis to focus from a long object distance to a short object distance, satisfying specific conditional expressions to maintain image quality and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the F-number of the objective lens is made small to reduce point image spreading, then image quality improves, but the depth of field becomes narrow
Solution Approach 1:
The patent applies the dynamics principle by making the second and third lens groups movable along the optical axis. This allows the optical system to dynamically adjust its focusing state, transitioning between different object distances (from long distance for normal observation to short distance for magnified observation). The movable lens groups enable the system to maintain sharp focus across varying depths, effectively resolving the contradiction between achieving small point images for high quality and maintaining adequate depth of field for practical observation.
2Measurement precision
If the focal length of the objective lens is made long to accommodate high-definition imagers, then the number of pixels can be increased, but the depth of field becomes narrow
Solution Approach 1:
The patent resolves this contradiction by implementing a dynamic focusing mechanism where the second and third lens groups can move along the optical axis. This dynamic adjustment capability allows the system to maintain sharp focus for high-definition imaging while adapting to different object distances, thereby preserving adequate depth of field despite the long focal length required for high pixel counts.
3Device complexity
If a single optical system is used for both normal and magnified observations, then device complexity is reduced, but the ability to focus at different object distances becomes difficult
Solution Approach 1:
The patent applies the dynamics principle by equipping the single optical system with movable second and third lens groups that can adjust their positions along the optical axis. This dynamic focusing capability enables the system to adapt to different object distances, achieving both normal observation (long object distance) and magnified observation (short object distance) with a single unified optical system, thereby maintaining simplicity while enhancing versatility.
Solution Approach 2:
The patent implements the universality principle by designing a single optical system that performs multiple functions: normal observation, magnified observation, and focusing adjustment. By making the second and third lens groups movable, the system becomes multi-functional, capable of adapting to different observation requirements without requiring separate optical systems, thus reducing overall device complexity while improving adaptability.
4Adaptability or versatility
If the second and third lens groups are made movable for focusing, then focusing function is achieved, but device complexity increases
Solution Approach 1:
The patent applies the dynamics principle by making the second and third lens groups movable along the optical axis to achieve the focusing function. This dynamic structure allows the lens groups to adjust their positions for different object distances, enabling both normal and magnified observations. While this increases structural complexity compared to a fixed lens system, it is a necessary trade-off to achieve the required focusing capability and adaptability.
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 magnified observations with a single optical system, providing sharp images across varying object distances and correcting various aberrations, thus enhancing the diagnostic capabilities of endoscopes.
Implementation Method 1
an objective optical system which includes, in order from an object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power
Implementation Method 2
The point image has a certain spreading due to an effect of diffraction
Data Source
AI summary
An objective optical system consists of, in order from an object side, a first lens group having a negative refractive power, which is stationary all the time, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power, which is stationary all the time. At a time of focusing from an object point at a long distance to an object point at a short distance, the second lens group moves toward the object side and the third lens group moves toward an image side. The following conditional expressions (1), (5), and (7) are satisfied:2<fG2/f<8 (1)0.2<(t34f−t34n)/f<0.5 (5)−8<fG1/f<−2 (7).