Fixed First-Unit Zoom Lens for Lightweight Aberration Correction
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical performance, reduced weight, and correcting aberrations, particularly at the telephoto end, due to strong refractive power in the first lens unit.
Innovation Solution
A zoom lens configuration with a first lens unit that does not move during zooming, comprising two positive lenses and a second lens unit that moves, with specific focal length ratios and refractive power distributions to maintain convergence and correct aberrations, while reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the refractive power of the first lens unit is made strong to reduce lens diameter and weight, then weight is reduced, but spherical aberration, longitudinal chromatic aberration, and lateral chromatic aberration become difficult to correct
Solution Approach 1:
The first lens unit is divided into two subunits: a first subunit with two positive lenses and a second subunit with one positive lens and one negative lens. This segmentation allows each subunit to contribute differently to aberration correction while maintaining the overall strong refractive power needed for weight reduction.
Solution Approach 2:
Different lens elements within the first lens unit have different refractive powers and materials optimized for specific functions. The positive lenses provide convergence while the negative lens corrects chromatic aberrations, creating local optical quality variations that resolve the contradiction between strong refractive power and aberration correction.
2Weight of moving object
If the lens diameter is reduced to achieve lightweight design, then weight is reduced, but optical performance and aberration correction become difficult to maintain
Solution Approach 1:
By segmenting the first lens unit into multiple elements with specific configurations (two positive lenses and one negative lens in the second subunit), the design achieves compact dimensions while distributing aberration correction functions across different elements, maintaining manufacturing precision despite reduced overall size.
Solution Approach 2:
The patent specifies particular focal length ratios (−0.45 < f1a/f1b < 0.10 and −5.50 < f1/f2) to optimize the balance between compact lens diameter and aberration correction capability, allowing the lens to maintain high manufacturing precision in a lightweight configuration.
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 achieves a lightweight zoom lens with high optical performance across the entire zoom range, effectively correcting spherical, chromatic, and lateral aberrations, and reducing lens diameter and weight.
Implementation Method 1
a first lens unit having positive refractive power... The first lens unit consists of, in order from the object side to the image side, a first subunit and a second subunit. The first subunit consists of two positive lenses. The second subunit consists of a single positive lens and a single negative lens.
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a subsequent unit including a plurality of lens units. A distance between adjacent lens units changes during zooming. The first lens unit does not move and the second lens unit moves during zooming. The first lens unit consists of, in order from the object side to the image side, a first subunit and a second subunit. The first subunit consists of two positive lenses. The second subunit consists of a single positive lens and a single negative lens. A predetermined condition is satisfied.