Variable Power Endoscope Lens System Aberration Control
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Solution Overview
Problem
Existing variable power optical systems for endoscopes with a negative-leading lens configuration face challenges in maintaining adequate optical performance across the entire range from wide angle to telephoto, requiring larger lens diameters and limiting the installation of components like light guides and forceps due to restricted freedom in component placement, and exhibit significant aberration fluctuations with magnification changes.
Innovation Solution
A variable power optical system comprising a first lens group with a negative power, a second lens group with positive power, and a third lens group, where the second lens group moves along the optical axis while the first and third lens groups are fixed, with specific focal length ratios and conditions to maintain optical performance and reduce lens diameter, including a concave-convex meniscus lens configuration and an aperture stop to suppress aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a negative-leading lens configuration is used to achieve wide angle observation, then the angle of view is improved, but the effective diameter of the most object side negative lens must be increased to suppress aberrations
Solution Approach 1:
The first lens group is divided into multiple lenses including a negative lens and a positive meniscus lens arranged in specific order. This segmentation allows the negative lens to have a smaller effective diameter while still achieving wide angle observation through the combined effect of multiple lens elements that correct aberrations collectively.
Solution Approach 2:
Different lens elements within the first lens group have different optical properties - the negative lens provides the necessary divergence for wide angle, while the positive meniscus lens locally corrects the aberrations introduced. This local quality differentiation allows each lens to be optimized for its specific function rather than requiring the entire lens group to have uniform large diameter.
2Reliability
If the effective diameter of the negative lens is increased to suppress aberrations, then optical performance is improved, but the radial size of the endoscope tip increases
Solution Approach 1:
The optical system is segmented into multiple lens groups with different functions. The first lens group handles wide angle collection with smaller individual lens diameters, while subsequent lens groups handle image formation and magnification. This segmentation allows the overall radial size to be reduced compared to a single large negative lens approach.
Solution Approach 2:
Instead of solving the aberration problem by increasing diameter in the radial dimension, the patent uses additional optical elements arranged along the optical axis (longitudinal dimension). The multiple lens groups correct aberrations through their combined optical power distribution along the axis, thereby avoiding the need for larger radial dimensions.
3Area of stationary object
If a negative-leading lens configuration is used, then wide angle observation is achieved, but the degree of freedom for disposing components in the tip portion is reduced
Solution Approach 1:
The lens system is segmented into multiple compact lens groups that can be arranged in a space-efficient manner. This segmentation creates more flexible spatial arrangements, allowing components like light guides, forceps, and air/water supply channels to be disposed of more freely in the tip portion compared to a single large negative lens configuration.
Solution Approach 2:
The multiple lens groups are arranged in a nested or compact configuration along the optical axis, maximizing the use of the longitudinal dimension while minimizing radial space requirements. This nesting approach frees up radial space in the tip portion for other components.
4Length of stationary object
If focusing is achieved by moving the second lens group, then the entire length is kept constant, but the degree of change of power is small
Solution Approach 1:
The patent employs variable power lens groups (specifically the second and third lens groups) that can dynamically change their optical power. By moving these variable power lens groups along the optical axis, the system achieves both focusing and significant power change while maintaining constant entire length, overcoming the limitation of fixed power lens configurations.
5Measurement precision
If the observing magnification is changed, then fine observation capability is improved, but the fluctuation of aberration becomes larger
Solution Approach 1:
Different lens groups are assigned different local functions: the first lens group optimizes for wide angle field of view, the second lens group provides variable power for magnification control, and the third lens group optimizes for image formation. This local quality differentiation allows each group to be optimized for its specific function, reducing overall aberration fluctuation across the magnification range.
Solution Approach 2:
The patent uses variable power lens groups with adjustable optical parameters. By carefully designing the power distribution and movement characteristics of these lens groups, the system maintains adequate optical performance across different magnification levels, suppressing aberration fluctuations through parameter optimization rather than allowing them to vary freely with magnification changes.
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 effectively suppresses lens diameter, maintains optical performance across the entire range, and secures adequate observing magnification, enhancing the installation of other components in the endoscope tip while minimizing aberration fluctuations.
Implementation Method 1
a variable power optical system having the variable power function for conducting fine observation for lesions
Implementation Method 2
a cemented lens formed by cementing together a negative lens and a positive lens
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A variable power optical system for an endoscope comprising a first lens group having a negative power, a second lens group having a positive power and a third lens group, and wherein the first lens group includes at least a negative lens having a concave surface pointing to an image side and a positive meniscus lens having a concave surface pointing to an object side, the second lens group includes at least a meniscus lens having a convex surface pointing to the object side and a cemented lens formed by cementing together a negative lens and a positive lens, and the third lens group includes at least a positive lens having a convex surface pointing to the object side, and wherein the variable power optical system for an endoscope is configured to satisfy a predetermined condition.