Compact Optical System Bright F-Number Wide Angle View
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Solution Overview
Problem
Current compact imaging optical systems with wide angles of view, such as those for digital cameras, struggle to achieve both high optical performance and a bright F-number, with existing retro-type optical systems only reaching F-numbers of about 1.4, and there is a demand for even brighter systems.
Innovation Solution
A compact optical system design featuring a first lens unit with positive refractive power, a second lens unit with positive refractive power and an aperture stop, and optionally a third lens unit with positive or negative refractive power, where the intervals between lens units change during focusing, satisfying specific conditional expressions to achieve a brighter F-number and wider angle of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a retro type optical system is used to achieve wide angle of view, then the angle of view is improved, but the F-number becomes darker (worsens)
Solution Approach 1:
The optical system is divided into multiple lens units with different refractive powers. The second lens unit is further segmented into a first subunit and a second subunit with the aperture stop positioned between them. This segmentation allows independent optimization of each unit's function, enabling wide angle of view while maintaining bright F-number performance.
Solution Approach 2:
Different lens units are assigned different refractive power characteristics tailored to their specific functions. The first lens unit has positive refractive power for wide angle coverage, the second lens unit has positive refractive power for brightness control, and the third lens unit has flexible positive or negative power for aberration correction. This local quality differentiation resolves the contradiction between wide angle and bright F-number.
2Reliability
If lens units are added to improve optical performance, then aberration correction is improved, but device complexity increases
Solution Approach 1:
The third lens unit is designed with versatile positive or negative refractive power capability, allowing it to perform multiple functions including spherical aberration correction, coma correction, and field curvature control. This multi-functionality reduces the need for additional specialized lens units, thereby limiting complexity increase while maintaining high optical performance.
Solution Approach 2:
The intervals between lens units are designed to change during focusing operations. This dynamic adjustment allows the system to maintain optimal optical performance across different focus distances without requiring fixed complex multi-element designs for each focusing condition, thus balancing performance with simplicity.
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 provides a compact optical system with an F-number brighter than 1.3 and high optical performance, effectively addressing the limitations of existing systems by optimizing focal lengths and refractive powers to suppress aberrations and achieve miniaturization.
Implementation Method 1
a first lens unit having a positive refractive power, and a second lens unit having a positive refractive power. Intervals between adjacent lens units change during focusing.
Data Source
AI summary
An optical system includes, in order from an object side to an image side, a first lens unit having a positive refractive power, and a second lens unit having a positive refractive power. An interval between the first lens unit and the second lens unit changes during focusing. The second lens unit includes, in order from the object side to the image side, a first subunit having a positive refractive power, an aperture stop, and a second subunit having a positive refractive power. A predetermined condition is satisfied.