Retro-focus Zoom Lens with Meniscus Front Unit for Wide-Angle Aberration Control
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Solution Overview
Problem
Conventional wide-angle zoom lenses face challenges in achieving a super-wide angle of view while maintaining a small optical system size and minimizing aberrations such as curvature of field and astigmatism, particularly when zooming from the wide-angle end to the telephoto end.
Innovation Solution
The zoom lens design incorporates a front unit with a negative refractive power and a rear unit with a positive refractive power, including an aperture stop, where the front unit features a meniscus shape with a convex surface directed towards the object side and the rear unit includes lens units that adjust their distances to correct aberrations, allowing for a retro-focus type optical system with a super-wide angle of view and reduced aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional wide-angle zoom lens design is used, then the angle of view can be widened, but the optical system size increases and aberrations such as curvature of field and astigmatism worsen
Solution Approach 1:
The zoom lens is divided into multiple lens units with different refractive powers (front unit with negative refractive power, rear unit with positive refractive power). Each unit is independently optimized to contribute to the overall wide-angle performance while controlling the total system size. The front unit specifically uses a meniscus lens with convex surface toward the object to expand the angle of view without proportionally increasing system volume.
Solution Approach 2:
The patent employs specific parameter ranges for lens curvature, refractive power, and spacing between lens units to achieve super-wide angle of view while controlling system size. By optimizing parameters such as the meniscus lens curvature and the distance between front and rear units during zooming, the system achieves compact dimensions despite the wide angle requirement.
2Illumination intensity
If the angle of view is widened to super-wide, then more scene coverage is achieved, but aberrations such as curvature of field and astigmatism increase
Solution Approach 1:
Different regions of the optical system are assigned different functional qualities. The front unit with negative refractive power specifically addresses off-axis ray control to reduce astigmatism and curvature of field, while the rear unit with positive refractive power handles focal convergence. The meniscus lens shape in the front unit is specifically designed to pre-correct aberrations before light enters the rear unit, enabling super-wide angle performance with controlled aberrations.
Solution Approach 2:
The aperture stop positioned in the rear unit acts as an intermediary element that controls the cone of light passing through the system. By strategically positioning the stop and using it in conjunction with the meniscus lens, the system limits the angle of incident rays on subsequent elements, thereby reducing the magnitude of aberrations like astigmatism and curvature of field that would otherwise occur at super-wide angles.
3Manufacturing precision
If lens units are moved to correct aberrations during zooming, then imaging performance is maintained, but the complexity of the optical system increases
Solution Approach 1:
The optical system is designed with dynamic adjustability where the distance between the front unit and rear unit changes during zooming from wide-angle to telephoto end. This dynamic reconfiguration allows the system to maintain optimal imaging performance across different focal lengths by adjusting the relative positions of lens units, while the meniscus lens configuration provides inherent aberration correction that simplifies the overall system compared to static designs.
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 a super-wide angle of view while maintaining a compact optical system size and minimizing aberrations, enabling high imaging performance even at close distances and during zooming, with improved focusing sensitivity and reduced fluctuation in curvature of field.
Implementation Method 1
the first lens is disposed nearest to an object, and has a meniscus shape of which a convex surface is directed toward the object side
Implementation Method 2
at the time of zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit changes
Data Source
AI summary
A zoom lens includes a front unit having a negative refractive power and a rear unit having a positive refractive power, which includes an aperture stop, and the front unit includes a first lens having a negative refractive power, and the first lens has a meniscus shape of which a convex surface is directed toward the object side, and the rear unit includes a first lens unit A and a second lens unit B, and at the time of zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit changes.