Zoom Lens Layout for Lightweight Aberration Correction
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical performance over the entire zoom range while maintaining a lightweight design, particularly due to difficulties in correcting spherical aberration, longitudinal chromatic aberration, and lateral chromatic aberration at the telephoto end, especially when strengthening the positive refractive power of the first lens unit.
Innovation Solution
The zoom lens design includes a first lens unit with two positive lenses and a second lens unit with a single positive and single negative lens, where the first lens unit remains stationary during zooming, and the second lens unit moves. This configuration satisfies specific focal length ratios to balance weight reduction and aberration correction, using inequalities to optimize lens diameters and refractive powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the positive refractive power of the first lens unit is strengthened to reduce weight, then the weight of the zoom lens 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 separate lens units: a first lens unit with positive refractive power and a second lens unit with negative refractive power. This segmentation allows independent optimization of each unit's refractive power and aberration correction characteristics, resolving the contradiction between overall weight reduction and aberration correction capability.
Solution Approach 2:
Different lens units are assigned different refractive power characteristics and aberration correction functions. The first lens unit provides positive refractive power with specific aberration correction, while the second lens unit provides negative refractive power with complementary aberration correction. This local differentiation of optical properties enables simultaneous weight reduction and aberration correction.
2Weight of moving object
If the lens diameter of subsequent units is reduced to reduce weight, then the weight of the zoom lens is reduced, but optical performance over the entire zoom range deteriorates
Solution Approach 1:
The patent optimizes the focal length ratios between lens units (specifically -0.45 < f1a/f1b < -0.250 for the first subunits and -5.50 < f1/f2 < -3.400 for the lens units) to achieve the best balance between weight reduction and optical performance. By carefully adjusting these parameter ranges, the system maintains high optical performance while minimizing lens diameters and overall weight.
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 various aberrations and maintaining a compact size, thereby addressing the challenges of weight and optical quality.
Implementation Method 1
a first lens unit having positive refractive power, a second lens unit having negative refractive power
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.