Zoom Lens Intermediate Image Aberration Correction
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Solution Overview
Problem
Existing zoom lenses for projection display devices face challenges in achieving a wide angle with a small F number, leading to inadequate aberration correction and increased lens diameter, which affects the optical performance.
Innovation Solution
A zoom lens configuration that forms an intermediate image and re-images it, comprising a 5-group optical system with specific cemented lens configurations and refractive power distributions, allowing for adjustable spacings between lens groups to maintain optical performance across zooming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the angle of view is widened and F number is reduced, then the optical performance is improved, but the lens diameter increases and aberration correction becomes inadequate
Solution Approach 1:
The optical system is divided into multiple lens groups (first through fifth lens groups) with specific refractive power distributions. The first lens group has negative refractive power while the second through fifth groups have positive refractive power, allowing segmented correction of aberrations across different zones of the lens system.
Solution Approach 2:
Different lens groups are assigned specific refractive power characteristics tailored to their positions and functions. The cemented lens structure combines lenses with different Abbe numbers to provide localized chromatic aberration correction, while the aspheric surface provides localized spherical aberration correction at the aperture stop region.
2Illumination intensity
If the angle of view is widened and F number is reduced, then the optical performance is improved, but the lens diameter increases
Solution Approach 1:
The lens system incorporates movable lens groups that can adjust their positions along the optical axis during zooming operations. The second through fifth lens groups can move relative to each other to change the focal length while maintaining the optimized aberration correction, allowing the system to adapt to different imaging requirements without increasing the overall lens diameter.
3Object-affected harmful factors
If a cemented lens with specific Abbe number relationships is used, then aberration correction is improved, but manufacturing complexity increases
Solution Approach 1:
The cemented lens combines multiple individual lenses with different glass types (having specific Abbe number relationships) into a single integrated optical element. This composite structure provides superior aberration correction by leveraging the complementary optical properties of each lens material while maintaining a compact form factor.
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 provides a high optical performance zoom lens with a small F number and wide angle, effectively correcting aberrations and minimizing lens diameter, thereby enhancing the projection display device's imaging capabilities.
Implementation Method 1
a zoom lens which forms an intermediate image at a position conjugate to a reduction side imaging plane and causes the intermediate image to be re-imaged on a magnification side imaging plane
Implementation Method 2
a first cemented lens which is formed by cementing a positive lens, a negative lens, and a positive lens in order from the magnification side, and an Abbe number of each of the two positive lenses within the first cemented lens at the d line is larger than that of the negative lens within the first cemented lens
Data Source
AI summary
In the zoom lens, a first optical system is formed on the magnification side, and a second optical system is formed on the reduction side, with the intermediate image formed between the first optical system and the second optical system. The first optical system has a 5-group configuration, where the second to fourth lens groups move during zooming. In the first optical system, three or more negative lenses are disposed continuously in order from a position closest to the magnification side. The first optical system has a first cemented lens that is formed by cementing a negative lens and two positive lenses, of which Abbe numbers are larger than that of the negative lens, in order of positive, negative, and positive powers.