Movable First Lens Group for Aberration Control
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Solution Overview
Problem
Industrial cameras face challenges in maintaining constant image accuracy across various object distances due to lens performance deterioration during focusing, which existing lens configurations fail to adequately address.
Innovation Solution
An image-forming lens configuration featuring a movable first lens group with specific refractive power arrangements and a stationary second lens group, satisfying conditional expressions to optimize focal lengths and reduce aberrations, ensuring consistent optical performance across focusing distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lens configuration is used, then the lens can focus on objects at various distances, but lens performance deteriorates due to focusing, causing image accuracy to vary
Solution Approach 1:
The patent applies the Dynamics principle by making the first lens group movable relative to the stop. The first lens group moves toward the object side when focusing from infinity to close distances, while the second lens group remains stationary. This dynamic configuration allows the lens to maintain consistent optical performance across different focusing distances by adjusting the position of the first lens group according to the object distance, thereby resolving the contradiction between varying image accuracy and consistent lens performance.
2Measurement precision
If the first lens group is made movable to improve focusing performance, then image quality is maintained across distances, but the device complexity increases
Solution Approach 1:
The patent applies the Segmentation principle by dividing the lens into two distinct groups: a first lens group with positive refractive power that moves, and a second lens group with negative refractive power that remains stationary. This segmentation allows the moving portion to be optimized for focusing adjustment while the stationary portion maintains optical performance, thereby reducing the overall complexity compared to making the entire lens assembly movable.
Solution Approach 2:
The patent applies the Local quality principle by assigning different functional characteristics to different parts of the lens system. The first lens group is designed with positive refractive power and is positioned to move for focusing, while the second lens group has negative refractive power and remains fixed. This local differentiation optimizes each segment's contribution to image quality while minimizing the complexity of the overall movement mechanism.
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 solution effectively corrects spherical, chromatic, and coma aberrations, maintaining high image quality and accuracy from infinity to close object distances with minimal change in optical performance, enhancing the reliability of industrial cameras.
Implementation Method 1
The first lens group includes a first lens having positive refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having negative refractive power, and a fifth lens having positive refractive power
Data Source
AI summary
An image-forming lens includes a stop, a first lens group and a second lens group. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in that order from the object side. The second lens group includes a negative subgroup and a positive subgroup arranged in that order from the object side. The first lens group is movable to the object side to increase a distance between the stop and the first lens group in a change in focusing from an object at infinity to an object close to the image-forming lens. Conditional expression (1) below being satisfied:0.45<f1G/f<0.75 wheref1G is a focal length of the first lens group, andf is a focal length of an entire system of the image-forming lens focused on the object at infinity.