Zoom Lens Aberration Correction via Segmented Refractive Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses for projectors face challenges in maintaining high optical performance throughout the zoom range due to asymmetric lens configurations, leading to issues like negative distortion at the wide-angle end and aberration variation, which are difficult to correct effectively.
Innovation Solution
A zoom lens configuration with a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of positive refractive power, a middle lens unit, and a last lens unit of positive refractive power, where all lens units except the first and last move during zooming, with specific focal length ratios and back focus conditions to ensure telecentricity and reduce aberration variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a lens unit of negative refractive power is disposed on the enlargement conjugate side and a lens unit of positive refractive power is disposed on the reduction conjugate side to achieve telecentricity and long back focus, then the back focus length is improved, but the lens configuration becomes asymmetric causing negative distortion at the wide-angle end and difficulty in correcting aberration variation
Solution Approach 1:
The lens is divided into multiple units with specific refractive powers arranged in a symmetric configuration. The first lens unit has negative refractive power while the second and third lens units have positive refractive power, creating a balanced structure that maintains telecentricity and long back focus while enabling effective aberration correction across the zoom range.
Solution Approach 2:
Each lens unit is designed with specific refractive power characteristics tailored to its position in the optical system. The negative refractive power of the first unit compensates for distortion, while the positive refractive power of the second and third units manages chromatic aberration, with the third unit specifically designed to correct variation in aberration during zooming.
2Reliability
If the third lens unit has great refractive power to provide high level of optical performance, then the optical performance is improved, but aberration variation during zooming occurs frequently and negative distortion at the wide-angle end increases
Solution Approach 1:
The refractive power of the third lens unit is specifically controlled to satisfy the condition f3/fw > 4.0, where f3 is the focal length of the third lens unit and fw is the focal length of the entire zoom lens at the wide-angle end. This parameter optimization ensures high optical performance while minimizing aberration variation during zooming operations.
Solution Approach 2:
The lens units are designed to move dynamically during zooming operations to maintain optimal optical characteristics. The second and third lens units move during zooming to correct image plane variation, while the first and last lens units remain fixed to maintain the overall symmetric configuration and control distortion.
3Reliability
If a symmetric lens configuration is used to correct distortion and aberration, then optical performance is improved, but the lens cannot maintain telecentricity and long back focus required for projector applications
Solution Approach 1:
The lens configuration employs a controlled asymmetric arrangement where the first lens unit has negative refractive power and the second and third lens units have positive refractive power. This specific asymmetric configuration satisfies the conditions for telecentricity on the reduction conjugate side and provides long back focus, while the overall structure maintains symmetry in aberration correction capabilities.
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 proposed lens configuration effectively corrects various aberrations during zooming, providing a high level of optical performance throughout the zoom range and ensuring a long back focus, suitable for projectors, while maintaining a compact design.
Implementation Method 1
a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of positive refractive power, a middle lens unit having at least one lens unit, and a last lens unit of positive refractive power
Data Source
AI summary
A zoom lens includes, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit of negative refractive power; a second lens unit of positive refractive power; a third lens unit of positive refractive power, the third lens unit having at least three lens elements; a middle lens unit including at least one lens unit; and a last lens unit of positive refractive power. All the lens units, except the first lens unit and the last lens unit, move during zooming. The zoom lens satisfies appropriate conditions.