Aspherical Lens Group Layout for Compact, Low-Breathing Optical Systems
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Solution Overview
Problem
Existing optical systems face challenges in achieving a balance between reducing size and weight while effectively correcting various aberrations and minimizing focus breathing, particularly in bright optical systems with large aperture ratios.
Innovation Solution
The optical system is designed with specific lens group arrangements and aspherical surfaces, including a first lens group with positive refractive power, a second lens group with an aspherical lens that weakens convex power from the optical axis periphery, a third lens group with an aperture diaphragm, a fourth lens group with positive and negative refractive powers, and a fifth lens group with negative refractive power, all moving along different paths during focusing to correct aberrations and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a lens group with negative refractive power is moved to correct aberrations, then aberration correction is improved, but focus breathing increases
Solution Approach 1:
The focus correction function is divided into two separate lens groups (second lens group with positive refractive power and fourth lens group with negative refractive power) that move independently along different paths. This segmentation allows each group to contribute to aberration correction without causing excessive focus breathing, as the aperture diaphragm is positioned between them to balance the optical effects.
Solution Approach 2:
The aperture diaphragm positioned between the second and fourth lens groups acts as an intermediary element that balances the optical effects of the two focus groups. It mediates the interaction between the positive and negative refractive power groups, enabling effective aberration correction while suppressing focus breathing by controlling the light paths and optical power distribution.
2Manufacturing precision
If the optical system is made larger to correct aberrations, then aberration correction is improved, but size and weight increase
Solution Approach 1:
The second and fourth lens groups are designed to work together as a coordinated system, merging their aberration correction capabilities. By combining the positive refractive power of the second group with the negative refractive power of the fourth group, the system achieves effective aberration correction while keeping the overall structure compact and lightweight, avoiding the need for a single large heavy lens group.
Solution Approach 2:
The patent employs different movement paths for the second and fourth lens groups during focusing, utilizing spatial dimensionality to achieve aberration correction. By moving these groups along different trajectories rather than a single path, the system corrects aberrations effectively while maintaining a compact form factor and reducing overall weight.
3Use of energy by moving object
If the aperture ratio is increased for better light gathering, then light gathering capability is improved, but aberrations and focus breathing worsen
Solution Approach 1:
The optical system employs aspherical surfaces with specific conic constants (K values between -0.8 and -0.2) in the second and fourth lens groups to provide localized correction of optical aberrations. This local quality approach allows the system to maintain large aperture ratios for improved light gathering while correcting aberrations through targeted aspherical surface design rather than requiring a completely different optical architecture.
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
This configuration successfully reduces the optical system's size and weight while effectively correcting aberrations, including distortion, and minimizes focus breathing, even at large aperture ratios, enabling high-quality imaging and high-speed autofocusing.
Implementation Method 1
the second lens group G2 includes an aspherical lens G2asp having such a shape as to weaken a convex power from a center of the optical axis to a periphery
Implementation Method 2
a second lens group G2 with a positive refractive power, a fourth lens group G4 with a positive refractive power
Data Source
AI summary
The optical system is configured to include a first lens group G1, a second lens group G2 with a positive refractive power, a third lens group G3, a fourth lens group G4 with a positive refractive power, and a fifth lens group G5 with a negative refractive power. When focusing from infinity to a close distance, the second lens group G2 and the fourth lens group G4 move to an object side through different paths along an optical axis, the second lens group G2 includes an aspherical lens G2asp having such a shape as to weaken a convex power from a center of the optical axis to a periphery, and the fourth lens group G4 includes one or more lenses each having at least a positive refractive power and one or more lenses each having at least a negative refractive power.