Zoom Lens Aberration Control via LN Lens Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Zoom lenses used in cameras face challenges in suppressing fluctuation in chromatic and spherical aberrations during zooming, particularly at the telephoto end, where the F number cannot be reduced effectively due to insufficient aberration control in existing lens systems.
Innovation Solution
A zoom lens configuration comprising a stationary first lens group with positive refractive power, a middle group with two or more movable lens groups having negative refractive power, and a subsequent group with an aperture stop, where specific refractive index and Abbe number conditions are met for the LN lenses to control aberrations, including Conditional Expressions (1) to (7) for refractive index, Abbe number, and partial dispersion ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refractive power of the movable lens group is increased to ensure the zoom ratio, then the zoom ratio is improved, but fluctuation in chromatic aberration and spherical aberration increases
Solution Approach 1:
The movable lens group is divided into multiple lens groups with different refractive powers (positive and negative). This segmentation allows each subgroup to contribute differently to the overall zoom function while enabling better control of aberrations through coordinated movement, thus achieving high zoom ratio with reduced aberration fluctuation.
Solution Approach 2:
The patent specifies precise refractive index ranges (1.72<Ndn<1.8) and Abbe number ranges (43<νdn<57) for the LN lens material. By controlling these optical parameters within specific ranges, the design achieves optimal balance between refractive power for zooming and dispersion characteristics for aberration suppression.
2Illumination intensity
If fluctuation in spherical aberration during zooming is not sufficiently suppressed, then the F number can not be reduced at the telephoto end
Solution Approach 1:
The patent introduces a specific lens group configuration in the middle group where certain lens groups have positive refractive power and others have negative refractive power. This local differentiation of optical properties within the movable system enables precise control of spherical aberration at different zoom positions, particularly at the telephoto end where F number reduction is needed.
Solution Approach 2:
The patent employs a composite lens system combining multiple lens materials with different optical properties (refractive indices and Abbe numbers). The LN lens with specific parameters (1.72<Ndn<1.8, 43<νdn<57) is combined with other lens groups to create a composite system that simultaneously achieves high refractive power for zooming and proper dispersion characteristics for spherical aberration control.
3Reliability
If chromatic aberration is not suppressed independently of the movable lens group and the positive lens group, then chromatic aberration fluctuation increases
Solution Approach 1:
The lens system is segmented into distinct functional groups: a stationary first lens group with positive refractive power, a middle group with multiple movable lens groups (including LN lens), and a subsequent group. This segmentation allows independent optimization of chromatic aberration correction in each group, with the stationary group providing baseline correction and the movable groups providing dynamic correction during zooming.
Solution Approach 2:
The LN lens with specifically controlled parameters acts as an intermediary element between the positive refractive power lens groups. By positioning the LN lens within the middle group and controlling its optical parameters (1.72<Ndn<1.8, 43<νdn<57), it mediates the chromatic aberration introduced by the positive lens groups, enabling independent suppression of chromatic aberration fluctuation.
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 effectively suppresses fluctuation in chromatic and spherical aberrations during zooming, enabling a smaller F number and higher magnification while maintaining lens system stability and reducing size, thus enhancing optical performance.
Implementation Method 1
a zoom lens consisting of, in order from an object side to an image side: a first lens group that remains stationary with respect to an image plane during zooming and has a positive refractive power; a middle group that consists of two or more movable lens groups moving along an optical axis by changing a distance between groups adjacent to each other during zooming
Data Source
AI summary
The zoom lens consists of, in order from an object side: a positive first lens group that does not move during zooming; a middle group that consists of two or more movable lens groups moving during zooming; and a subsequent group that has a lens group including a stop at a position closest to the object side. The middle group has at least two negative movable lens groups. At least one negative movable lens group in the middle group includes at least one negative LN lens which satisfies predetermined conditional expressions relating to the refractive index, the Abbe number, and the partial dispersion ratio.