Five-Unit Optical Lens Layout for Fast Autofocus Aberration Control
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Solution Overview
Problem
Optical systems with long focal length and large aperture ratio face challenges in correcting various aberrations, particularly when weight reduction is necessary for faster autofocus, leading to difficulty in suppressing aberration fluctuations during focusing from infinity to the shortest distance.
Innovation Solution
An optical system comprising a specific configuration of lens units, including a first lens unit with positive refractive power, a second lens unit with negative refractive power, a third lens unit with positive or negative refractive power, a fourth lens unit with positive refractive power, and a fifth lens unit with negative refractive power, where the second and fourth lens units move during focusing, while the first, third, and fifth lens units remain stationary, adhering to specific focal length and refractive power ratios to achieve high optical performance and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the weight of the focus lens unit is reduced for faster autofocus, then the autofocus speed is improved, but it becomes difficult to suppress aberration fluctuations during focusing from infinity to the shortest distance
Solution Approach 1:
The optical system divides the lens into five separate lens units (L1-L5) with different functions. The focus lens unit (L2 and L4) is segmented from other lens units, allowing independent movement for autofocus while other units remain stationary to maintain aberration correction. This segmentation enables the focus unit to be optimized for speed while other units handle aberration control.
Solution Approach 2:
Different lens units are assigned different refractive powers and positions to perform specific functions. The negative-powered L2 and positive-powered L4 form the focus unit with specific focal length ratios (0.25<f2/f<0.50 and 0.40<f4/f<0.65) to locally optimize for fast autofocus, while L1, L3, and L5 remain stationary to provide stable aberration correction across the optical path.
2Measurement precision
If optical systems have a long focal length and large aperture ratio, then the imaging performance is improved, but it becomes difficult to correct various aberrations
Solution Approach 1:
The lens system is segmented into five units with alternating positive and negative refractive powers. This segmentation allows each unit to be optimized for specific aberration corrections while collectively achieving long focal length and large aperture ratio with superior overall aberration control.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens unit including focal length ratios (0.25<f2/f<0.50, 0.40<f4/f<0.65), movement distances during focusing, and refractive power distributions. These parameter optimizations enable the system to achieve both long focal length with large aperture while maintaining excellent aberration correction across the imaging field.
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 enables high-speed autofocus with small size and high optical performance by effectively correcting aberrations and reducing the weight of the focus lens unit, maintaining image quality across the focus range.
Implementation Method 1
a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive or negative refractive power, a fourth lens unit L4 having positive refractive power, and a fifth lens unit L5 having negative refractive power
Data Source
AI summary
An optical system includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive or negative refractive power, a fourth lens unit having positive refractive power, and a fifth lens unit having negative refractive power. During focusing from infinity to the shortest distance, the second lens unit and the fourth lens unit move, the first lens unit, the third lens unit, and the fifth lens unit do not move. A predetermined condition is satisfied.