Zoom Lens First Unit Decentering Sensitivity Reduction
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Solution Overview
Problem
High variable magnification zoom lenses suffer from significant optical performance deterioration due to decentering of the first lens unit, which is exacerbated by the need for engagement play and manufacturing errors, leading to compromised image quality.
Innovation Solution
The zoom lens design incorporates a first lens unit with a positive meniscus lens having an image side concave surface and a negative lens on the object side, with specific curvature radius and focal length ratios to minimize refractive power and aberration variations, and employs a configuration that reduces the optical performance deterioration sensitivity by aligning ray directions with surface normals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the first lens unit is largely moved toward the object to achieve high variable magnification ratio, then the magnification ratio is improved, but the decentering of the first lens unit increases causing optical performance deterioration
Solution Approach 1:
The invention changes the optical parameters of the first lens unit by specifying that it must include a positive meniscus lens with an image-side concave surface and a negative lens on the object side, with the curvature radius of the image-side concave surface satisfying a specific relationship with the focal length. This parameter optimization reduces the sensitivity to decentering while maintaining the ability to achieve high variable magnification ratios through lens unit movement.
2Ease of operation
If engagement play is provided to enable smooth movement of the first lens unit, then the ease of operation is improved, but the decentering increases causing optical performance deterioration
Solution Approach 1:
The invention optimizes the optical parameters of the first lens unit, specifically the curvature radius of the image-side concave surface of the positive meniscus lens, to reduce sensitivity to decentering. This allows the engagement play necessary for smooth operation to be minimized while maintaining optical performance, as the optimized lens configuration is less sensitive to positional variations caused by engagement play.
3Reliability
If the first lens unit includes multiple lenses with specific configurations, then the sensitivity to decentering is reduced, but the device complexity increases
Solution Approach 1:
The invention applies local quality by specifying particular lens configurations only for the first lens unit, which is the critical component affecting decentering sensitivity. The first lens unit includes a positive meniscus lens with an image-side concave surface and a negative lens on the object side, with specific curvature radius relationships. This localized optimization maintains overall system simplicity while improving the specific subsystem that causes the problem.
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 effectively reduces optical performance deterioration sensitivity for decentering, maintaining image quality across zoom ranges by optimizing the curvature and refractive indices of lens surfaces, thereby enhancing the zoom lens's ability to correct chromatic and spherical aberrations.
Implementation Method 1
The first lens unit is constituted by at least three lenses including a positive meniscus lens Li1 being disposed closest to the image among the at least three lenses and having an image side concave surface
Implementation Method 2
a negative lens being disposed on an object side next to the positive meniscus lens
Data Source
AI summary
The zoom lens includes a first lens unit being disposed closest to an object and having a positive optical power, and at least one subsequent lens unit being disposed closer to an image than the first lens unit. The first lens unit is moved toward the object during variation of magnification from a wide-angle end to a telephoto end. The first lens unit is constituted by at least three lenses including a positive meniscus lens being disposed closest to the image among the at least three lenses and having an image side concave surface, and a negative lens being disposed on an object side next to the positive meniscus lens. A condition of 1.55<Rpi/f1<2.90 is satisfied where Rpi represent a curvature radius of the image side concave surface of the positive meniscus lens, and f1 represents a focal length of the first lens unit.