Five-Group Zoom Lens Layout for Compact High-Aperture Imaging
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Solution Overview
Problem
Existing variable magnification optical systems face challenges in achieving a small size, large aperture ratio, and high zooming ratio while satisfactorily correcting various aberrations.
Innovation Solution
A variable magnification optical system comprising five lens groups (G1 to G5) with specific refractive powers and movements, along with conditional expressions to optimize focal lengths and dispersions, ensuring efficient aberration correction and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture ratio is increased, then the brightness and light-gathering capability are improved, but the optical system size and aberration control become more difficult
Solution Approach 1:
The optical system is divided into five distinct lens groups (G1-G5) with alternating positive and negative refractive powers. Each group is optimized for specific functions: G1 and G3 for positive power contribution, G2 and G5 for negative power and aberration correction, and G4 for additional positive power. This segmentation allows independent optimization of each group to achieve large aperture ratio while controlling overall system size and aberrations.
Solution Approach 2:
Different lens groups are assigned specific local functions to optimize overall performance. The negative lens groups (G2, G5) are specifically designed for aberration correction, while positive lens groups (G1, G3, G4) focus on light gathering and image formation. This local quality differentiation enables the system to achieve high aperture ratio without compromising aberration control.
2Adaptability or versatility
If the zooming ratio is increased, then the versatility and field of view range are improved, but the optical system size and aberration correction difficulty increase
Solution Approach 1:
The optical system employs dynamic zooming mechanism where the distances between lens groups (G1-G2, G2-G3, G3-G4) are variable during zooming from wide-angle to telephoto end. This dynamic configuration allows the system to achieve high zooming ratio while maintaining compact size through coordinated movement of lens groups rather than simply increasing overall length.
Solution Approach 2:
The zooming function is distributed across multiple lens groups rather than relying on a single zooming mechanism. The five lens groups work in coordination with variable spacing to achieve the zooming ratio, allowing each group to contribute to both wide-angle and telephoto performance, thereby reducing the overall system size required for high versatility.
3Length of moving object
If the optical system size is reduced, then the compactness and portability are improved, but the aperture ratio and aberration correction become more challenging
Solution Approach 1:
Instead of the conventional arrangement starting with negative lens groups, this optical system inverts the sequence by starting with a positive lens group (G1) followed by negative (G2), positive (G3), positive (G4), and negative (G5) groups. This inverted configuration allows the positive power groups to be positioned closer to the object side, enabling compact design while maintaining large aperture ratio and effective aberration correction throughout the zoom range.
4Length of moving object
If the optical system size is reduced, then the compactness is improved, but the aberration correction capability deteriorates
Solution Approach 1:
Specific lens groups are assigned dedicated aberration correction functions. The negative lens groups (G2, G5) are optimized for correcting spherical and chromatic aberrations, while the positive lens groups (G1, G3, G4) are optimized for image formation and distortion control. This local quality assignment ensures that aberration correction is effectively distributed throughout the compact optical system.
Solution Approach 2:
The optical system uses composite lens designs within each group, combining multiple lens elements with different refractive indices and dispersion properties. This composite approach within each lens group enables effective aberration correction in the compact configuration by utilizing the complementary optical properties of different lens materials.
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 a small size, increased aperture ratio, and high zooming ratio with satisfactory correction of various aberrations, including spherical and chromatic aberrations across different focal lengths.
Implementation Method 1
a first lens group G1 having a positive refractive power; a second lens group G2 having a negative refractive power; a third lens group G3 having a positive refractive power; a fourth lens group G4 having a positive refractive power; and a fifth lens group G5 having a negative refractive power
Data Source
AI summary
A variable magnification optical system including: in order from an object side, a first lens group G1 having a positive refractive power; a second lens group G2 having a negative refractive power; a third lens group G3 having a positive refractive power; a fourth lens group G4 having a positive refractive power; and a fifth lens group G5 having a negative refractive power, wherein, during zooming from a wide-angle end to a telephoto end, a distance between the first lens group G1 and the second lens group G2 changes, a distance between the second lens group G2 and the third lens group G3 changes, and a distance between the third lens group G3 and the fourth lens group G4 changes, during focusing from an infinity end to a closest object end, any one of the fourth lens group G4 or the fifth lens group G5 moves along an optical axis.