Zoom Lens Fixed First Unit Compact High Performance
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Solution Overview
Problem
Existing zoom lenses for image pickup apparatuses face challenges in achieving a balance between compact size and high optical performance across the entire zoom range, particularly when dealing with increased pixel density and sensor size, as they either become too large or fail to provide sufficient optical performance.
Innovation Solution
A zoom lens design that includes a first lens unit with positive refractive power, a second lens unit with negative refractive power, and subsequent units, where the first lens unit remains fixed during zooming, and the distance between adjacent lens units changes, adhering to specific focal length and optical length ratios to maintain compactness while ensuring high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the zoom lens uses more pixels with a wider pixel pitch of an image sensor (larger image sensor), then the optical performance is improved, but the zoom lens becomes larger and heavier
Solution Approach 1:
The zoom lens is divided into multiple lens units (first through fifth lens units) with different refractive powers arranged in sequence. Each lens unit can move independently during zooming, allowing the system to achieve high optical performance for large image sensors while maintaining a compact overall structure through distributed optical power.
Solution Approach 2:
The zoom lens employs dynamic movement of the second, third, and fourth lens units during zooming operations. By selectively moving specific lens units while keeping others stationary, the system adapts its optical configuration to maintain performance across different focal lengths without requiring a larger overall lens size.
2Weight of moving object
If the zoom lens is made smaller and lighter, then the portability is improved, but the optical performance becomes insufficient for the increased number of pixels in the image sensor
Solution Approach 1:
Different lens units are assigned specific refractive powers (positive or negative) and positioned at different locations within the zoom lens structure. The first lens unit has positive refractive power, while the second has negative refractive power, and this alternating pattern continues. This local differentiation of optical properties allows compact design while maintaining sufficient optical performance for high-resolution sensors.
3Adaptability or versatility
If the zoom lens has a relatively high magnification ratio, then the versatility is improved, but the zoom lens becomes large to deal with the increased size of the image sensor
Solution Approach 1:
The zoom lens achieves high magnification ratio (about 5 times) through dynamic zooming operations where the second, third, and fourth lens units move to different positions. This dynamic reconfiguration of lens unit positions enables high versatility across different focal lengths while maintaining a compact form factor suitable for modern image sensors.
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
This design achieves high optical performance and compact size by optimizing the refractive powers and focal lengths of the lens units, effectively correcting spherical aberration, coma, and chromatic aberration across the entire zoom range.
Implementation Method 1
a first lens unit having a positive refractive power
Implementation Method 2
a second lens unit having a 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 a positive refractive power, a second lens unit having a negative refractive power, and a subsequent unit. The first lens unit is configured not to move for zooming. A distance between each pair of adjacent lens units changes in zooming. A predetermined condition is satisfied.