Compact Zoom Lens Design with Cemented Elements
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Solution Overview
Problem
There is a need for a compact zoom lens system with high zoom ratio and large aperture for digital cameras that can maintain image quality across varying lighting conditions, including low-light environments, while minimizing lens diameter and number of lenses to achieve a compact design.
Innovation Solution
A zoom lens configuration comprising a first lens unit with positive refractive power, a second lens unit with negative refractive power, and a third lens unit with positive refractive power, where the first lens unit includes a cemented lens to correct chromatic aberration, and the lens units are arranged to satisfy specific conditional expressions to optimize focal lengths and movement ratios, ensuring a compact and high-performance lens design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of lenses and lens diameter are increased to achieve large aperture and high zoom ratio, then the image quality and light gathering capability are improved, but the lens size and device complexity increase
Solution Approach 1:
The zoom lens is divided into multiple lens units (first lens unit with positive refractive power, second lens unit with negative refractive power, third lens unit with positive refractive power) that can move independently during zooming. This segmentation allows each unit to contribute differently to the overall optical performance, enabling large aperture and high zoom ratio without requiring a single large complex lens
Solution Approach 2:
The lens units are designed to move dynamically during zooming operations. The first lens unit moves along the optical axis to change focal length, while the second and third lens units adjust positions to maintain focus and correct aberrations. This dynamic arrangement allows the lens to achieve variable aperture and zoom ratio without increasing the maximum lens diameter
2Adaptability or versatility
If more lens units are added to achieve high zoom ratio, then the zooming capability is improved, but the device complexity and number of components increase
Solution Approach 1:
Each lens unit serves multiple functions: the first lens unit provides primary zooming function, the second lens unit (with negative refractive power) contributes to both zooming and focus adjustment, and the third lens unit handles both imaging and aberration correction. This multi-functionality reduces the need for additional dedicated components
Solution Approach 2:
The lens system achieves high zoom ratio by changing the positions and spacing between lens units rather than adding numerous fixed components. The variable distances between the first, second, and third lens units during zooming allow continuous adjustment of focal length and magnification with a relatively simple structure
3Illumination intensity
If the lens design is optimized for large aperture, then the low-light photography capability is improved, but the lens diameter and overall size increase
Solution Approach 1:
The lens system achieves large aperture locally at the front element while maintaining compact overall size through the telecentric design. The entrance pupil is positioned such that the front lens element can have large diameter for light gathering, while the rear portions of the lens system remain compact, allowing large aperture without proportional increase in overall lens diameter
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 enables a compact zoom lens with a small F-number (large aperture) and high zooming capability, effectively addressing the challenge of maintaining image quality across different lighting conditions while reducing lens diameter and the number of lenses, thus achieving a compact and efficient optical design.
Implementation Method 1
the first lens unit includes a cemented lens to correct chromatic aberration
Data Source
AI summary
A zoom lens includes in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power, and at the time of zooming, the first lens unit moves, and the zoom lens satisfies the following conditional expressions (1-1a), (1-2a), and (1-3a). 0.43<(&bgr;2T/&bgr;2W)/(&bgr;3T/&bgr;3W)<0.68 (1-1a) 0.4<(&Dgr;1G/f1)/(&Dgr;4G/f4)<2.3 (1-2a) 2.1<f3/fW<4.1 (1-3a)