Zoom Lens Aberration Control via Opposing Lens Group Movement
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a wide angle and small F number while maintaining high optical performance and minimizing aberration fluctuations during zooming, particularly in projection display devices that require a long back focal length and telecentricity.
Innovation Solution
A zoom lens system that forms an intermediate image, comprising a first optical system on the magnification side and a second optical system on the reduction side, with specific lens groups and focal length ratios that allow for controlled movement and refractive power distribution to suppress aberration fluctuations, ensuring a wide angle and small F number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the angle of view is increased by shortening the focal length, then the angle of view becomes wider, but the magnification side lens diameter becomes excessively large
Solution Approach 1:
The optical system is divided into multiple lens groups with different refractive powers (positive and negative groups). By segmenting the system and strategically positioning these groups, the patent achieves a wide angle of view while controlling the magnification side lens diameter through the coordinated movement and power distribution of the segmented groups.
2Shape
If the focal length is shortened to achieve a wide angle, then the angle of view increases, but aberration fluctuations become large during zooming
Solution Approach 1:
The patent employs conditional expressions that define specific parameter ranges for focal lengths, lens group powers, and spacing relationships. By controlling these parameters within specified ranges, the system maintains stable aberration characteristics across the zoom range while achieving a wide angle of view.
Solution Approach 2:
The patent implements dynamic adjustment of lens group positions and spacings during zooming. The conditional expressions govern how distances between lens groups change relative to focal lengths, enabling the system to adapt its configuration to maintain optical performance throughout the zoom range.
3Illumination intensity
If the F number is reduced to increase brightness, then the aperture becomes larger, but lens diameter increases
Solution Approach 1:
The patent applies local quality by assigning different refractive powers to different lens groups (positive and negative groups with specific focal length relationships). This localized optimization of optical properties allows the system to achieve a small F number with controlled lens diameter through the specific power distribution defined in the conditional expressions.
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 aberration fluctuations and maintains high optical performance across the zooming range, enabling a wide angle and small F number, suitable for projection display devices with improved telecentricity and reduced lens diameter.
Implementation Method 1
a second-1 lens group which has a positive refractive power, a second-2 lens group which has a positive refractive power... The second-1 lens group and the second-2 lens group move in directions opposite to each other while changing spacings between the groups adjacent to each other
Data Source
AI summary
The zoom lens includes: a first optical system on a magnification side; and a second optical system on a reduction side in a state where the intermediate image is formed between the magnification side and the reduction side. The second optical system includes, in order from the magnification side, a second-1 lens group which has a positive refractive power, a second-2 lens group which has a positive refractive power, and a second-3 lens group which has a positive refractive power. The second-1 lens group and the second-2 lens group move in directions opposite to each other while changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming. The second-3 lens group remains stationary with respect to the reduction side imaging plane during zooming. In addition, the zoom lens satisfies a predetermined conditional expression (1).