Variable Magnification Projection Lens Aberration Control
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Solution Overview
Problem
Existing variable magnification projection optical systems face challenges in simultaneously achieving high resolution and high magnification ratio due to increased aberrations such as spherical, chromatic, and magnification chromatic aberrations, particularly at the telephoto and wide-angle ends.
Innovation Solution
A variable magnification projection optical system is designed with specific configurations, including a first lens group with negative refracting power, a second group movable during magnification, and a fourth lens group with negative refracting power and strategically placed negative lenses to correct aberrations, ensuring condition expressions are met to suppress aberrations and maintain telecentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the magnification ratio is increased to achieve high magnification projection, then the projection capability is improved, but spherical aberration, axial chromatic aberration, and magnification chromatic aberration increase, degrading image quality
Solution Approach 1:
The projection optical system is divided into multiple lens groups (first through sixth lens groups) with different refracting powers. Each lens group is responsible for correcting specific types of aberrations, allowing the system to maintain high magnification while controlling spherical, axial chromatic, and magnification chromatic aberrations through coordinated movement of these segmented groups.
Solution Approach 2:
Different lens groups are assigned specific functions based on their local optical properties. The second, third, and fifth lens groups with positive refracting power are optimized for correcting spherical aberration, while the fourth lens group with negative refracting power specifically addresses chromatic aberrations. This local optimization allows each component to contribute to overall aberration control.
2Manufacturing precision
If the resolution is increased to achieve high definition projection, then the image quality is improved, but the system becomes more sensitive to aberrations, making it difficult to maintain both high resolution and high magnification ratio
Solution Approach 1:
The optical system utilizes precise control of lens group positions and movements to dynamically adjust optical parameters. By changing the positions of the second, third, and fifth lens groups during magnification changes, the system maintains optimal aberration correction across the entire magnification range, enabling both high resolution and high magnification ratio to coexist.
3Manufacturing precision
If multiple lens groups are moved to correct aberrations during magnification change, then aberration control is improved, but the mechanical complexity and device size increase
Solution Approach 1:
The lens groups are designed to serve multiple functions simultaneously. For example, the second lens group with positive refracting power contributes to both magnification change and spherical aberration correction. The optical stop positioned in the fourth lens group serves both to control light flux and to aid in correcting spherical aberration. This multi-functionality reduces the need for additional dedicated correction components.
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 effectively suppresses spherical, axial chromatic, and magnification chromatic aberrations, achieving high resolving power and maintaining a wide angle of view while supporting high magnification ratios, thereby enhancing image projection quality.
Implementation Method 1
a fourth lens group with negative refracting power and strategically placed negative lenses to correct aberrations
Implementation Method 2
satisfy condition expressions related to focal lengths, back focus, total lens length, and Abbe numbers
Implementation Method 3
condition expressions related to abnormal dispersibility (θgF) and Abbe numbers
Data Source
AI summary
A variable magnification projection optical system includes, in order from a magnification conjugate side to a reduction conjugate side, a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and an optical stop which is arranged at any position from a front of a lens arranged closest to the magnification conjugate side in the fourth lens group to a front of a lens arranged closest to the magnification conjugate side in the fifth lens group, wherein the fourth lens group is configured to include, in order from the magnification conjugate side, two or more negative lenses and a positive lens, and wherein the following condition expressions (1), (2) and (3) are satisfied:|Et/ft|≧10 (1)|EW/fW|≧15 (2)0.87≦23φT/23WT≦1.15 (3).