Variable-Magnification Optical System Compact Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional digital cameras with variable-magnification optical systems face challenges in achieving a compact design while maintaining good optical performance, as the movement of lens groups for zooming often results in an unduly long optical system due to a positive-negative-positive-positive optical power arrangement, leading to increased length and aberrations.
Innovation Solution
A variable-magnification optical system is designed with a specific arrangement of lens groups, including a first lens group with positive optical power, a second lens group with negative optical power, and a third lens group with positive optical power, where the optical powers are optimized to balance movement distances and reduce the total system length, using conditional formulas to define the optimal range for focal lengths and optical powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a positive-negative-positive-positive optical power arrangement is used with conventional lens group movement for zooming, then magnification variation is achieved, but the total length of the optical system becomes unduly long
Solution Approach 1:
The patent introduces an optical axis changing element (prism) that deflects the optical axis by a predetermined angle, effectively utilizing a spatial dimension change to reduce the axial length of the optical system. This allows the system to achieve compactness in the optical axis direction while maintaining zooming functionality through lens group movement perpendicular to the deflected axis.
Solution Approach 2:
The patent optimizes specific parameters including the focal length of the second lens group (f2) relative to the geometric mean of wide-angle and telephoto focal lengths (0.12/√(fw×ft) < |f2/√(fw×ft)| < 0.45), and the optical power distribution among lens groups. These parameter optimizations enable reduced movement distances for lens groups during zooming, thereby reducing the total system length while maintaining magnification variation capability.
2Adaptability or versatility
If lens groups are moved through long distances for zooming, then magnification variation is achieved, but the movement distance becomes excessive making the system unduly long
Solution Approach 1:
The patent optimizes the optical power distribution among lens groups, particularly setting the focal length of the second lens group (f2) within a specific range (0.12/√(fw×ft) < |f2/√(fw×ft)| < 0.45). This parameter optimization enables the lens groups to achieve the required magnification variation with reduced movement distances, thereby reducing the overall system length and improving zooming efficiency.
3Length of moving object
If the optical system is made compact by reducing lens group movement distances, then total length is reduced, but optical performance and aberration correction may deteriorate
Solution Approach 1:
The patent introduces an optical axis changing element (prism) that deflects the optical axis by a predetermined angle. This dimensional change allows the system to achieve compactness in the optical axis direction while maintaining adequate lens group movement distances for proper aberration correction and optical performance through the deflected optical path.
Solution Approach 2:
The patent optimizes multiple parameters simultaneously including the focal length of the second lens group (0.12/√(fw×ft) < |f2/√(fw×ft)| < 0.45), the optical power distribution among lens groups, and the deflection angle of the optical axis changing element. These coordinated parameter optimizations enable the system to maintain good optical performance and aberration correction while achieving a compact total length.
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 allows for a compact variable-magnification optical system that effectively reduces the total length while minimizing aberrations, achieving a balance between size and optical performance.
Implementation Method 1
the first lens group includes a first optical axis changing element that changes the optical axis
Data Source
AI summary
A variable-magnification optical system has, from the object side to the image side, at least a first lens group having a positive optical power, a second lens group having a negative optical power, and a third lens group having a positive optical power. The first lens group includes an optical prism that changes the optical path, and a prescribed conditional formula is fulfilled.