Variable Magnification Zoom Lens for Compact Visible-SWIR Imaging
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Solution Overview
Problem
Existing zoom lenses for monitoring cameras face challenges in achieving high optical performance across a wide wavelength range from visible light to near-infrared light while maintaining a small size and high zoom ratio, with issues in chromatic aberration correction and lens speed.
Innovation Solution
A zoom lens design comprising a first lens unit with positive refractive power that does not move for zooming, and a variable magnification unit with positive and negative lenses that monotonously move during zooming, adhering to specific inequalities for partial dispersion ratios and Abbe numbers to correct chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aberration correction is performed for a wide wavelength band from visible light to near-infrared light, then optical performance is improved, but the size of the zoom lens increases
Solution Approach 1:
The patent applies parameter changes by carefully selecting lens materials with specific Abbe numbers and partial dispersion ratios. The positive lens in the variable magnification unit has an Abbe number vdVpx between 24 and 55 and a partial dispersion ratio θCtVpx satisfying 0.5466 < (θCtVpx - 0.004693×vdVpx) < 0.6466. These precise parameter specifications enable effective chromatic aberration correction across the wide wavelength band from visible light to SWIR light while controlling the overall lens size.
Solution Approach 2:
The patent employs composite materials by combining multiple lens units with different optical properties. The variable magnification unit includes at least one positive lens and at least one negative lens, creating a composite optical system. This combination allows the lens to correct chromatic aberration for both visible light and SWIR light wavelengths while maintaining a compact form factor suitable for monitoring cameras.
2Adaptability or versatility
If a high zoom ratio is achieved, then monitoring range is improved, but chromatic aberration correction becomes more difficult
Solution Approach 1:
The patent applies segmentation by dividing the zoom lens into multiple functional lens units: a first lens unit with positive refractive power that remains stationary during zooming, and a variable magnification unit that moves monotonously toward the image side from wide-angle to telephoto end. This segmentation allows each unit to be optimized for specific functions, with the variable magnification unit specifically designed to correct chromatic aberration while enabling high zoom ratio performance.
Solution Approach 2:
The patent uses parameter changes by specifying precise optical properties for lenses in the variable magnification unit. The positive lens has an Abbe number vdVpx between 24 and 55 and a partial dispersion ratio satisfying a specific inequality relationship. These parameter constraints enable effective chromatic aberration correction across the zoom range, allowing the lens to maintain high optical performance while achieving a high zoom ratio for broad monitoring coverage.
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 design achieves high optical performance across visible to short wavelength infrared light with reduced size and improved chromatic aberration correction, enabling effective monitoring in diverse lighting conditions.
Implementation Method 1
a positive lens satisfying the following inequalities: 0.5466 < (θCtVpx - 0.004693×vdVpx) < 0.6466, and 24 < vdVpx < 55, where vdVpx denotes an Abbe number regarding d-line of the positive lens included in the variable magnification unit and θCtVpx denotes a partial dispersion ratio regarding C-line and t-line
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit with positive refractive power which does not move in zooming, and a plurality of lens units which moves in zooming. Each of intervals between the respective adjacent lens units varies in zooming. The plurality of lens units includes a variable magnification unit consisting of one or a plurality of lens units which monotonously moves toward the image side in zooming from a wide-angle end to a telephoto end. The variable magnification unit includes at least one positive lens and at least one negative lens and has negative refractive power at the wide-angle end. The zoom lens satisfies a specific inequality regarding average values of partial dispersion ratios in the variable magnification unit. The variable magnification unit includes a positive lens satisfying specific inequalities regarding an Abbe number and a partial dispersion ratio.