Zoom Optical System RN Lens Group Weight Reduction
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Solution Overview
Problem
Conventional zoom optical systems lack sufficient reduction in the weight of the focusing lens group, leading to inefficiencies in size and performance.
Innovation Solution
A zoom optical system comprising a specific arrangement of lens groups with varying refractive powers and distances, including a front lens group, M1 lens group, M2 lens group, and RN lens group, where the RN lens group moves upon focusing, and satisfies certain conditional expressions to optimize aberration correction and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the focusing lens group is made lighter to improve autofocus speed, then autofocus performance is improved, but aberration correction capability deteriorates
Solution Approach 1:
The patent changes the optical parameters of the RN lens group by incorporating both positive and negative power lenses with specific focal length ratios (0.25 < |fFN/fFP| < 0.75). This parameter optimization allows the lightweight focusing group to achieve both fast autofocus and effective aberration correction through balanced refractive power distribution
Solution Approach 2:
The RN lens group uses a composite lens structure combining multiple lenses with different refractive powers and materials. This composite approach enables the focusing group to achieve complex optical functions (aberration correction + focusing) with reduced weight compared to single-material or single-power designs
2Volume of moving object
If the focusing lens group is made smaller to reduce overall lens size, then compactness is improved, but optical performance deteriorates
Solution Approach 1:
The patent optimizes the focal length ratio parameter (0.25 < |fFN/fFP| < 0.75) to achieve maximum optical efficiency within the compact RN lens group. This parameter control allows small size while maintaining aberration correction capability through efficient use of limited optical space
Solution Approach 2:
The RN lens group is designed as a movable focusing unit with dynamic adjustment capability. The conditional expression (0.27 < -fF/f1 < 0.45) ensures that during focusing movement, the optical parameters remain within optimal ranges, maintaining performance despite size constraints
3Reliability
If the RN lens group contains both positive and negative power lenses to improve aberration correction, then optical performance is improved, but device complexity increases
Solution Approach 1:
The RN lens group serves multiple functions simultaneously: focusing (moving the group), spherical aberration correction (through positive/negative lens combination), and coma aberration control (through specific focal length ratios). This multi-functionality reduces the need for separate dedicated components, managing complexity while improving performance
Solution Approach 2:
The patent applies different refractive powers and materials locally within the RN lens group - positive power lenses for one type of aberration correction and negative power lenses for another. This localized optimization achieves comprehensive aberration control without requiring a complete redesign of the entire optical system
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 achieves reduced size and weight of the focusing lens group, enabling high-speed autofocus and silence during operation while effectively suppressing aberration variations during zooming and focusing, thereby enhancing optical performance.
Implementation Method 1
the RN lens group moves, the RN lens group comprises at least one lens having a positive refractive power, and at least one lens having a negative refractive power
Implementation Method 2
upon zooming, a distance between the front lens group and the M1 lens group changes, a distance between the M1 lens group and the M2 lens group changes, and a distance between the M2 lens group and the RN lens group changes
Data Source
AI summary
A zoom optical system comprises, in order from an object: a front lens group (GFS) having a positive refractive power; an M1 lens group (GM1) having a negative refractive power; an M2 lens group (GM2) having a positive refractive power; and an RN lens group (GRN) having a negative refractive power, wherein upon zooming, distances between the front lens group and the M1 lens group, between the M1 lens group and the M2 lens group, and between the M2 lens group and the RN lens group change, upon focusing from an infinite distant object to a short distant object, the RN lens group moves, the RN lens group comprises at least one lens having a positive refractive power, and at least one lens having a negative refractive power, and following conditional expressions are satisfied, 2.70<fFP/(−fFN)<4.50, 0.25<(−fF)/f1<0.45, where fFP: a focal length of a lens having a strongest positive refractive power in the RN lens group, fFN: a focal length of a lens having a strongest negative refractive power in the RN lens group, fF: a focal length of the RN lens group, and f1: a focal length of the front lens group.